996 Spares and Maintenance--Suggestions Requested
01-20-2019, 10:00 AM
#1
Rennlist Member
Thread Starter
996 Spares and Maintenance--Suggestions Requested
If you have a maintenance schedule, a list of spares to keep in the trailer or both, please share with me.
I'm watching hours on the motor, gearbox, dampers, and am top of fluid changes, but I've only changed out the axles once (blue to black for better longevity). The drive pins and stub axle bolts look pretty good, but the wheel lug nuts are probably due for replacement. What should I be thinking about?
I'm watching hours on the motor, gearbox, dampers, and am top of fluid changes, but I've only changed out the axles once (blue to black for better longevity). The drive pins and stub axle bolts look pretty good, but the wheel lug nuts are probably due for replacement. What should I be thinking about?
01-20-2019, 05:10 PM
#2
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Do a search here for recommendations for this. I am sure someone can point you at the latest thread for that. If no one responds I will find one later.
Consider us for the nuts, washers, and plenty more of the maintenance parts. We are here to support exactly this.
For the nuts and washers look for galling on the face of the nut that mates with the washers. If either the washer or nut has smeared looking material, it should be replaced. We have seen a 30% drop in clamp load with nuts and washers that look like this at the same torque value. We have also seen the stub bolts have significantly stretched threads even though they looked good. The recommendation is that they get changed when the axles get changed. Take a look at the middle picture here:
https://www.demonspeedmotorsports.co...71-DL-CLB.htm#
These stub bolts looked fine before we put them up on the comparitor. If you would like, you could even send them to us and we would put them up on the comparitor and take a pictures of the condition so you can judge for yourself.
Use coupon code rennlist for a discount over our already low prices.
https://www.demonspeedmotorsports.com/Driveline_c14.htm
Thanks
Ed
Consider us for the nuts, washers, and plenty more of the maintenance parts. We are here to support exactly this.
For the nuts and washers look for galling on the face of the nut that mates with the washers. If either the washer or nut has smeared looking material, it should be replaced. We have seen a 30% drop in clamp load with nuts and washers that look like this at the same torque value. We have also seen the stub bolts have significantly stretched threads even though they looked good. The recommendation is that they get changed when the axles get changed. Take a look at the middle picture here:
https://www.demonspeedmotorsports.co...71-DL-CLB.htm#
These stub bolts looked fine before we put them up on the comparitor. If you would like, you could even send them to us and we would put them up on the comparitor and take a pictures of the condition so you can judge for yourself.
Use coupon code rennlist for a discount over our already low prices.
https://www.demonspeedmotorsports.com/Driveline_c14.htm
Thanks
Ed
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ed@demonspeed.com
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Engineered Race and Track Products for your Porsche
https://www.goodaero.com/
Race Designed Aerodynamics
https://racingtirewarmers.com/
Win more races with tire warmers
Great products for racers by racers
ed@demonspeed.com
Demon Speed Motorsports is a proud sponsor of PCA and the Club Racing Program
01-20-2019, 07:42 PM
#3
Rennlist Member
Thread Starter
Thanks, Ed. I'm not entirely new here and did a rough and ready search for spares and maintenance information on Rennlist and have also looked at the meagre help in Porsche's service manual for my car. I have also viewed your web site, and that's where I first heard of the stub axles as being wear items. Very helpful photos on your site!. The threads on the front of my car look good and those on the rear are pretty good. I'll almost certainly replace the nuts, though, as they are reasonably beat up, so thanks for the discount code.
I'll do some more searching on Rennlist tomorrow morning and will summarise what I find in this thread.
I'll do some more searching on Rennlist tomorrow morning and will summarise what I find in this thread.
01-23-2019, 11:59 AM
#4
Rennlist Member
Thread Starter
Some more detail
I found remarkably little specific guidance for maintenance practices for cup cars, particularly 996 cup cars, in reviewing a large number of older threads here on Rennlist. Most of the discussion is on prospective running costs, including maintenance, and budgeting for a purchase and racing a car. It’s no surprise that costs are thought to be “high,” but again there are few specific numbers.
My car is for PCA club racing in GTC3 and will be driven this year by a couple of drivers who are not all that fast. No redline shifts or attacking each curb, but we would like to be competitive.
What I would like to have is a list of the items that generally need to be replaced or rebuilt and the indicators that guide the decision when to do so. Here is what I have so far.
Tires. Mark with dates and heat cycles. After runs scrape off rubber pickup and examine for damage. Expect laptimes to fall off when heat cycles reach middle to high single digits. Replace as budget permits and need-for-speed requires.
Nut and Bolt. Between each event put the car on a lift and check for apparent issues: loose fasteners, cracks, missing bits and whatever else one can see. Touch many parts and look for what is different or apparently worn. Pay particular attention to suspension parts and the plastic and rubber bits that may be damaged, such as CV boots, splitter, brake ducts and the like.
Lower Control Arms. This piece of the suspension has been called out several times as especially subject to damage, to the extent that it is suggested to be replaced every 30 hours. Is there support for that view and such preventive replacement?
Brake Pads. I favour Pagid RSL29 yellow pads for good modulation and long life. The RSL29 is supposed to have slightly more bite than the RSL19, but to me they feel equivalent. Replace when less than 30% of the original pad thickness is expected to remain after the next session. I have thought about using the RSL1 pads on the rear for more bite but have not tried them.
Brake Rotors. I have been using the single-piece, slotted rotors sold by DeMan Motorsports. Replace when the slots are almost no longer slots.
Hours. I have a Hobbes meter attached to a switch that turns on the meter when RPM are at or above 3,000. That enables me to track hours when the car is actually in motion and not just being warmed up.
Axles. As a preventive measure I replaced the blue axles that came with the car with black axles on which I repacked the CV joints with Krytox grease. The black axles weigh more but are thought to be more durable with a failure mode that causes less collateral damage. Is that true? How does one know to replace other than upon failure? Is there a generally accepted number of hours of use before service?
Wheel Bearings. I have never replaced wheel bearing. A shop has tested the bearings by putting the car on a lift and having a big guy attempt to twist the tire about a vertical axis. If there is virtually no play, the bearing is good. How does one know to replace other than upon failure? Is there a generally accepted number of hours of use before service? I have heard 30 hours.
Dampeners. I have had the dampeners rebuilt once and found the change to be remarkably good with much greater compliance. Since then I have not felt any deterioration, but the changes are likely to be very slight from day to day and hard to detect. Other than pulling and dynoing the dampeners, what do you look for to suggest a rebuild is due? Some say to rebuild/service between seasons.
Gearbox. I have had the gearbox checked once. Third gear was replaced along with other lesser parts. The flywheel looked good, but I replaced the clutch. After service shifting was more certain and smoother. I did not have good records on when the gearbox had last been serviced and was starting to have trouble finding the desired gear. Is there a generally accepted number of hours of use before service?
Motor (the $64,000 question). I have the records on the last rebuild by the previous owner. Since then I have monitored performance in an ad hoc and inadequate manner, but just did a careful leak down test with excellent results. Other than monitoring performance more carefully and repeating the leak down test from time to time, what should prompt me to pull the motor for a rebuild? Some Rennlist posts note use of as long as 90, 100 or even 150 hours without issue. Porsche recommends rebuilds in the 45-50-hour range, which many suggest would only be required for those driving their cars much harder than is common in PCA club racing. Another post claims that wear causes the crank main bearings to fail before a leak down will identify the need for a rebuild. For club racers, is it sufficient to monitor and conduct annual leak down tests?
Lug Nuts and Stub Bolts. There is a good discussion and links for helpful photographs in the posts above this one.
Now that you’ve read this far, what are your suggestions?
My car is for PCA club racing in GTC3 and will be driven this year by a couple of drivers who are not all that fast. No redline shifts or attacking each curb, but we would like to be competitive.
What I would like to have is a list of the items that generally need to be replaced or rebuilt and the indicators that guide the decision when to do so. Here is what I have so far.
Tires. Mark with dates and heat cycles. After runs scrape off rubber pickup and examine for damage. Expect laptimes to fall off when heat cycles reach middle to high single digits. Replace as budget permits and need-for-speed requires.
Nut and Bolt. Between each event put the car on a lift and check for apparent issues: loose fasteners, cracks, missing bits and whatever else one can see. Touch many parts and look for what is different or apparently worn. Pay particular attention to suspension parts and the plastic and rubber bits that may be damaged, such as CV boots, splitter, brake ducts and the like.
Lower Control Arms. This piece of the suspension has been called out several times as especially subject to damage, to the extent that it is suggested to be replaced every 30 hours. Is there support for that view and such preventive replacement?
Brake Pads. I favour Pagid RSL29 yellow pads for good modulation and long life. The RSL29 is supposed to have slightly more bite than the RSL19, but to me they feel equivalent. Replace when less than 30% of the original pad thickness is expected to remain after the next session. I have thought about using the RSL1 pads on the rear for more bite but have not tried them.
Brake Rotors. I have been using the single-piece, slotted rotors sold by DeMan Motorsports. Replace when the slots are almost no longer slots.
Hours. I have a Hobbes meter attached to a switch that turns on the meter when RPM are at or above 3,000. That enables me to track hours when the car is actually in motion and not just being warmed up.
Axles. As a preventive measure I replaced the blue axles that came with the car with black axles on which I repacked the CV joints with Krytox grease. The black axles weigh more but are thought to be more durable with a failure mode that causes less collateral damage. Is that true? How does one know to replace other than upon failure? Is there a generally accepted number of hours of use before service?
Wheel Bearings. I have never replaced wheel bearing. A shop has tested the bearings by putting the car on a lift and having a big guy attempt to twist the tire about a vertical axis. If there is virtually no play, the bearing is good. How does one know to replace other than upon failure? Is there a generally accepted number of hours of use before service? I have heard 30 hours.
Dampeners. I have had the dampeners rebuilt once and found the change to be remarkably good with much greater compliance. Since then I have not felt any deterioration, but the changes are likely to be very slight from day to day and hard to detect. Other than pulling and dynoing the dampeners, what do you look for to suggest a rebuild is due? Some say to rebuild/service between seasons.
Gearbox. I have had the gearbox checked once. Third gear was replaced along with other lesser parts. The flywheel looked good, but I replaced the clutch. After service shifting was more certain and smoother. I did not have good records on when the gearbox had last been serviced and was starting to have trouble finding the desired gear. Is there a generally accepted number of hours of use before service?
Motor (the $64,000 question). I have the records on the last rebuild by the previous owner. Since then I have monitored performance in an ad hoc and inadequate manner, but just did a careful leak down test with excellent results. Other than monitoring performance more carefully and repeating the leak down test from time to time, what should prompt me to pull the motor for a rebuild? Some Rennlist posts note use of as long as 90, 100 or even 150 hours without issue. Porsche recommends rebuilds in the 45-50-hour range, which many suggest would only be required for those driving their cars much harder than is common in PCA club racing. Another post claims that wear causes the crank main bearings to fail before a leak down will identify the need for a rebuild. For club racers, is it sufficient to monitor and conduct annual leak down tests?
Lug Nuts and Stub Bolts. There is a good discussion and links for helpful photographs in the posts above this one.
Now that you’ve read this far, what are your suggestions?
Last edited by Phokaioglaukos; 01-23-2019 at 01:24 PM.
01-23-2019, 12:41 PM
#5
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Lower Control Arms. and all the suspension links in general including tie rods. When the car comes in from the track hot, lift the car and check for movement. You will generally see more movement when the car is fresh from the track. This is a good way to check your monoball fittings to see that everything is still tight.
Dampeners, Depending on the hours per year, we use every other year rebuild as our rule of thumb.
Lug Nuts and Bolts. To follow up my input above, I will take some pictures and post them showing pictures of what we consider to be worn. We will also be doing different videos for our products and a demonstration for the clamp load on worn nuts and washers is one we are anticipating doing soon.
https://www.demonspeedmotorsports.com/Driveline_c14.htm
Brake Rotors, Not taking away anything from Deman, but mentioning that Demon Speed also has our own slotted rotors for the front and rear of the 996 cups at extremely competitive pricing.
https://www.demonspeedmotorsports.com/Brakes_c12.htm
Lock Pots and Drive Pins, Visual wear. If too worn, then replace them. The lock pots are no longer available from Motorsports. Demon Speed has them in production and anticipate having them released in late March. Drive pins, we have these in stock.
https://www.demonspeedmotorsports.co...0.htm?page=all
Air Jack components - Check for leaks and the car drooping after a short period of time. Cup Car Solutions is the best source for rebuild/replacement components.
Axles. As a preventive measure I replaced the blue axles that came with the car with black axles on which I repacked the CV joints with Krytox grease. The black axles weigh more but are thought to be more durable with a failure mode that causes less collateral damage. Is that true? How does one know to replace other than upon failure? Is there a generally accepted number of hours of use before service? - The black axles are less expensive than the blue axles. The blue axles are hollow and are made from different material than the black. The blue axles can break in the body diameter, but most of the failures are at the undercut of the spline area where axles comes through the upright. The black axles have also been known to fail. 30 hours is a good service number for the black axles. We also tear them down after every season and inspect for galling of the bearings and to clean and re-lube. Krytox and Neo are the good greases. We started running and selling an aftermarket DSS axle 4 years ago with great success. We have had these on customer cars since that time with over 60 hours with no failures. We now stock them rather than needing to wait for the build time. DSM and DSS are teaming up to roll out a DSM only cup/track version of the axles that upgrades specific areas of the shafts including the boot, bearing, and grease. The DSS axles are also a bit heavier than the blacks. The OD of the axle itself is larger diameter and they are not hollow.
https://www.demonspeedmotorsports.co...s-RA2393L5.htm
Throttle cables - Good to consider for a wear item or to carry a spare. These can break at the wrong time.
Nut and bolt - We are working to offer a nut and bolt spares kit. It will have many of the bolts that we need for these cars. Great for taking to the track.
We are trying to do our best to offer the products for the cup cars that most need in a one stop shop, so if this sounds like a sales ad, it is because we are trying to be the one to offer these parts for everyone. If anyone thinks we should add a particular product for the wear and tear on the cars, let me know, we will add it if we can.
Thanks
Ed
Dampeners, Depending on the hours per year, we use every other year rebuild as our rule of thumb.
Lug Nuts and Bolts. To follow up my input above, I will take some pictures and post them showing pictures of what we consider to be worn. We will also be doing different videos for our products and a demonstration for the clamp load on worn nuts and washers is one we are anticipating doing soon.
https://www.demonspeedmotorsports.com/Driveline_c14.htm
Brake Rotors, Not taking away anything from Deman, but mentioning that Demon Speed also has our own slotted rotors for the front and rear of the 996 cups at extremely competitive pricing.
https://www.demonspeedmotorsports.com/Brakes_c12.htm
Lock Pots and Drive Pins, Visual wear. If too worn, then replace them. The lock pots are no longer available from Motorsports. Demon Speed has them in production and anticipate having them released in late March. Drive pins, we have these in stock.
https://www.demonspeedmotorsports.co...0.htm?page=all
Air Jack components - Check for leaks and the car drooping after a short period of time. Cup Car Solutions is the best source for rebuild/replacement components.
Axles. As a preventive measure I replaced the blue axles that came with the car with black axles on which I repacked the CV joints with Krytox grease. The black axles weigh more but are thought to be more durable with a failure mode that causes less collateral damage. Is that true? How does one know to replace other than upon failure? Is there a generally accepted number of hours of use before service? - The black axles are less expensive than the blue axles. The blue axles are hollow and are made from different material than the black. The blue axles can break in the body diameter, but most of the failures are at the undercut of the spline area where axles comes through the upright. The black axles have also been known to fail. 30 hours is a good service number for the black axles. We also tear them down after every season and inspect for galling of the bearings and to clean and re-lube. Krytox and Neo are the good greases. We started running and selling an aftermarket DSS axle 4 years ago with great success. We have had these on customer cars since that time with over 60 hours with no failures. We now stock them rather than needing to wait for the build time. DSM and DSS are teaming up to roll out a DSM only cup/track version of the axles that upgrades specific areas of the shafts including the boot, bearing, and grease. The DSS axles are also a bit heavier than the blacks. The OD of the axle itself is larger diameter and they are not hollow.
https://www.demonspeedmotorsports.co...s-RA2393L5.htm
Throttle cables - Good to consider for a wear item or to carry a spare. These can break at the wrong time.
Nut and bolt - We are working to offer a nut and bolt spares kit. It will have many of the bolts that we need for these cars. Great for taking to the track.
We are trying to do our best to offer the products for the cup cars that most need in a one stop shop, so if this sounds like a sales ad, it is because we are trying to be the one to offer these parts for everyone. If anyone thinks we should add a particular product for the wear and tear on the cars, let me know, we will add it if we can.
Thanks
Ed
Last edited by Ed@Demonspeed; 01-28-2019 at 08:25 AM.
01-24-2019, 09:49 AM
#6
RL Community Team
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Rennlist Member
^^^ Ed, forgive me but what are lock pots? I have trouble getting the front wheels off my car without doing a backwards kick to the wheel as they tend to bind up on the drive pins. The rear wheels have no such issue. Does any of this indicate they might be due for replacement? Is your price for the drive pins for one pin or one complete corner? lastly what is involved in replacing them.
thanks
great thread
thanks
great thread
01-28-2019, 08:25 AM
#7
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^^^ Ed, forgive me but what are lock pots? I have trouble getting the front wheels off my car without doing a backwards kick to the wheel as they tend to bind up on the drive pins. The rear wheels have no such issue. Does any of this indicate they might be due for replacement? Is your price for the drive pins for one pin or one complete corner? lastly what is involved in replacing them.
thanks
great thread
thanks
great thread
It can. You are sure it is the drive pins that it is caught up on and you have the BBS wheels. One thing to do is to try and put a front wheel on the rear and see if it binds as well. That takes the wheels out of the equation.
Your pins may be tweaked or bent. The pins come out pretty easily. They are held in with screws in the back of the hub and are in counterbores. Remove the screw a few turns in the back and tap on the screw head. This will push the pin out the front. The other thing to look for when changing the pins, we have seen some hubs that were created from street (grand am) hubs rather than getting new cup hubs, so they are welded and machined. If they are not machined precisely, then this could cause a bind.
The price here:
https://demonspeedmotorsports.com/Dr...9971-DL-DP.htm
is each. We used to sell them as a set of 5, but then we got folks asking for one or two.
The lock pot:
https://demonspeedmotorsports.com/Lo...-DSM-DL-LP.htm
sits in the center of the wheel and pilots/centers the wheel on the hub. It also locks the stub bolt to the hub so that the stub bolt can not loosen from the axle shaft.
Thanks
Ed
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01-28-2019, 08:38 AM
#8
RL Community Team
Rennlist Member
Rennlist Member
Sorry for the delayed response, I was down enjoying the beautiful Daytona weather.
It can. You are sure it is the drive pins that it is caught up on and you have the BBS wheels. One thing to do is to try and put a front wheel on the rear and see if it binds as well. That takes the wheels out of the equation.
Your pins may be tweaked or bent. The pins come out pretty easily. They are held in with screws in the back of the hub and are in counterbores. Remove the screw a few turns in the back and tap on the screw head. This will push the pin out the front. The other thing to look for when changing the pins, we have seen some hubs that were created from street (grand am) hubs rather than getting new cup hubs, so they are welded and machined. If they are not machined precisely, then this could cause a bind.
The price here:
https://demonspeedmotorsports.com/Dr...9971-DL-DP.htm
is each. We used to sell them as a set of 5, but then we got folks asking for one or two.
The lock pot:
https://demonspeedmotorsports.com/Lo...-DSM-DL-LP.htm
sits in the center of the wheel and pilots/centers the wheel on the hub. It also locks the stub bolt to the hub so that the stub bolt can not loosen from the axle shaft.
Thanks
Ed
It can. You are sure it is the drive pins that it is caught up on and you have the BBS wheels. One thing to do is to try and put a front wheel on the rear and see if it binds as well. That takes the wheels out of the equation.
Your pins may be tweaked or bent. The pins come out pretty easily. They are held in with screws in the back of the hub and are in counterbores. Remove the screw a few turns in the back and tap on the screw head. This will push the pin out the front. The other thing to look for when changing the pins, we have seen some hubs that were created from street (grand am) hubs rather than getting new cup hubs, so they are welded and machined. If they are not machined precisely, then this could cause a bind.
The price here:
https://demonspeedmotorsports.com/Dr...9971-DL-DP.htm
is each. We used to sell them as a set of 5, but then we got folks asking for one or two.
The lock pot:
https://demonspeedmotorsports.com/Lo...-DSM-DL-LP.htm
sits in the center of the wheel and pilots/centers the wheel on the hub. It also locks the stub bolt to the hub so that the stub bolt can not loosen from the axle shaft.
Thanks
Ed
01-28-2019, 02:10 PM
#9
I found remarkably little specific guidance for maintenance practices for cup cars, particularly 996 cup cars, in reviewing a large number of older threads here on Rennlist. Most of the discussion is on prospective running costs, including maintenance, and budgeting for a purchase and racing a car. It’s no surprise that costs are thought to be “high,” but again there are few specific numbers.
My car is for PCA club racing in GTC3 and will be driven this year by a couple of drivers who are not all that fast. No redline shifts or attacking each curb, but we would like to be competitive.
What I would like to have is a list of the items that generally need to be replaced or rebuilt and the indicators that guide the decision when to do so. Here is what I have so far.
Tires. Mark with dates and heat cycles. After runs scrape off rubber pickup and examine for damage. Expect laptimes to fall off when heat cycles reach middle to high single digits. Replace as budget permits and need-for-speed requires.
Nut and Bolt. Between each event put the car on a lift and check for apparent issues: loose fasteners, cracks, missing bits and whatever else one can see. Touch many parts and look for what is different or apparently worn. Pay particular attention to suspension parts and the plastic and rubber bits that may be damaged, such as CV boots, splitter, brake ducts and the like.
Lower Control Arms. This piece of the suspension has been called out several times as especially subject to damage, to the extent that it is suggested to be replaced every 30 hours. Is there support for that view and such preventive replacement?
Brake Pads. I favour Pagid RSL29 yellow pads for good modulation and long life. The RSL29 is supposed to have slightly more bite than the RSL19, but to me they feel equivalent. Replace when less than 30% of the original pad thickness is expected to remain after the next session. I have thought about using the RSL1 pads on the rear for more bite but have not tried them.
Brake Rotors. I have been using the single-piece, slotted rotors sold by DeMan Motorsports. Replace when the slots are almost no longer slots.
Hours. I have a Hobbes meter attached to a switch that turns on the meter when RPM are at or above 3,000. That enables me to track hours when the car is actually in motion and not just being warmed up.
Axles. As a preventive measure I replaced the blue axles that came with the car with black axles on which I repacked the CV joints with Krytox grease. The black axles weigh more but are thought to be more durable with a failure mode that causes less collateral damage. Is that true? How does one know to replace other than upon failure? Is there a generally accepted number of hours of use before service?
Wheel Bearings. I have never replaced wheel bearing. A shop has tested the bearings by putting the car on a lift and having a big guy attempt to twist the tire about a vertical axis. If there is virtually no play, the bearing is good. How does one know to replace other than upon failure? Is there a generally accepted number of hours of use before service? I have heard 30 hours.
Dampeners. I have had the dampeners rebuilt once and found the change to be remarkably good with much greater compliance. Since then I have not felt any deterioration, but the changes are likely to be very slight from day to day and hard to detect. Other than pulling and dynoing the dampeners, what do you look for to suggest a rebuild is due? Some say to rebuild/service between seasons.
Gearbox. I have had the gearbox checked once. Third gear was replaced along with other lesser parts. The flywheel looked good, but I replaced the clutch. After service shifting was more certain and smoother. I did not have good records on when the gearbox had last been serviced and was starting to have trouble finding the desired gear. Is there a generally accepted number of hours of use before service?
Motor (the $64,000 question). I have the records on the last rebuild by the previous owner. Since then I have monitored performance in an ad hoc and inadequate manner, but just did a careful leak down test with excellent results. Other than monitoring performance more carefully and repeating the leak down test from time to time, what should prompt me to pull the motor for a rebuild? Some Rennlist posts note use of as long as 90, 100 or even 150 hours without issue. Porsche recommends rebuilds in the 45-50-hour range, which many suggest would only be required for those driving their cars much harder than is common in PCA club racing. Another post claims that wear causes the crank main bearings to fail before a leak down will identify the need for a rebuild. For club racers, is it sufficient to monitor and conduct annual leak down tests?
Lug Nuts and Stub Bolts. There is a good discussion and links for helpful photographs in the posts above this one.
Now that you’ve read this far, what are your suggestions?
My car is for PCA club racing in GTC3 and will be driven this year by a couple of drivers who are not all that fast. No redline shifts or attacking each curb, but we would like to be competitive.
What I would like to have is a list of the items that generally need to be replaced or rebuilt and the indicators that guide the decision when to do so. Here is what I have so far.
Tires. Mark with dates and heat cycles. After runs scrape off rubber pickup and examine for damage. Expect laptimes to fall off when heat cycles reach middle to high single digits. Replace as budget permits and need-for-speed requires.
Nut and Bolt. Between each event put the car on a lift and check for apparent issues: loose fasteners, cracks, missing bits and whatever else one can see. Touch many parts and look for what is different or apparently worn. Pay particular attention to suspension parts and the plastic and rubber bits that may be damaged, such as CV boots, splitter, brake ducts and the like.
Lower Control Arms. This piece of the suspension has been called out several times as especially subject to damage, to the extent that it is suggested to be replaced every 30 hours. Is there support for that view and such preventive replacement?
Brake Pads. I favour Pagid RSL29 yellow pads for good modulation and long life. The RSL29 is supposed to have slightly more bite than the RSL19, but to me they feel equivalent. Replace when less than 30% of the original pad thickness is expected to remain after the next session. I have thought about using the RSL1 pads on the rear for more bite but have not tried them.
Brake Rotors. I have been using the single-piece, slotted rotors sold by DeMan Motorsports. Replace when the slots are almost no longer slots.
Hours. I have a Hobbes meter attached to a switch that turns on the meter when RPM are at or above 3,000. That enables me to track hours when the car is actually in motion and not just being warmed up.
Axles. As a preventive measure I replaced the blue axles that came with the car with black axles on which I repacked the CV joints with Krytox grease. The black axles weigh more but are thought to be more durable with a failure mode that causes less collateral damage. Is that true? How does one know to replace other than upon failure? Is there a generally accepted number of hours of use before service?
Wheel Bearings. I have never replaced wheel bearing. A shop has tested the bearings by putting the car on a lift and having a big guy attempt to twist the tire about a vertical axis. If there is virtually no play, the bearing is good. How does one know to replace other than upon failure? Is there a generally accepted number of hours of use before service? I have heard 30 hours.
Dampeners. I have had the dampeners rebuilt once and found the change to be remarkably good with much greater compliance. Since then I have not felt any deterioration, but the changes are likely to be very slight from day to day and hard to detect. Other than pulling and dynoing the dampeners, what do you look for to suggest a rebuild is due? Some say to rebuild/service between seasons.
Gearbox. I have had the gearbox checked once. Third gear was replaced along with other lesser parts. The flywheel looked good, but I replaced the clutch. After service shifting was more certain and smoother. I did not have good records on when the gearbox had last been serviced and was starting to have trouble finding the desired gear. Is there a generally accepted number of hours of use before service?
Motor (the $64,000 question). I have the records on the last rebuild by the previous owner. Since then I have monitored performance in an ad hoc and inadequate manner, but just did a careful leak down test with excellent results. Other than monitoring performance more carefully and repeating the leak down test from time to time, what should prompt me to pull the motor for a rebuild? Some Rennlist posts note use of as long as 90, 100 or even 150 hours without issue. Porsche recommends rebuilds in the 45-50-hour range, which many suggest would only be required for those driving their cars much harder than is common in PCA club racing. Another post claims that wear causes the crank main bearings to fail before a leak down will identify the need for a rebuild. For club racers, is it sufficient to monitor and conduct annual leak down tests?
Lug Nuts and Stub Bolts. There is a good discussion and links for helpful photographs in the posts above this one.
Now that you’ve read this far, what are your suggestions?
Axles - From what I understand it's not possible to know/test their condition before hand. Follow the hours the way you do. I think there was a thread here on the black turbo axles and some people with experience that suggested replacing them "often", 25 hours if I remember correctly, if you are running hard. Happily they are "cheap".
Wheel bearings - Your mechanic can use a stethoscope to listen to the bearing. Helps with preventive maintenance.
Gearbox - Count the hours/miles. Then if you go "above" as you likely will, you do feel when the shifts are not as smooth as they should be any longer. There is a clear difference that builds up over time.
Dampers can be tested but depending where you live it may be better to just have them rebuild in any case when they are off... if labor is expensive. If you DYI then it would make sense after each season. Watch for leaks, they tend to leak...
Engine - Leak down/comp test, oil consumption....
02-09-2019, 01:43 PM
#10
My car is for PCA club racing in GTC3 and will be driven this year by a couple of drivers who are not all that fast. No redline shifts or attacking each curb, but we would like to be competitive.
What I would like to have is a list of the items that generally need to be replaced or rebuilt and the indicators that guide the decision when to do so. Here is what I have so far.
What I would like to have is a list of the items that generally need to be replaced or rebuilt and the indicators that guide the decision when to do so. Here is what I have so far.
Tires. I am fond of the Pirelli Slicks. Personally I use them 2-4 HCs racing and then go up to as many as a total of 24 HCs in DE. Minimum budget 1 set Qualifying, 2 Sprints and Enduro, use scrubs for practice. As they age or go up in HCs they gradually get slower (I don't generally care for DE) AND they are MUCH more slippery until warmed up - be VERY carefully to warm up if you decide to use old or high HC slicks. I don't push such tires until after 2 laps on short track (Lime Rock) or at least 1 lap on long track (WGI, VIR). Many others will use more new sets for race events and toss tires much sooner in terms of HCs.
Nut and Bolt. Before every event.
Lower Control Arms. Every 2 years/50 hours - and have had them (front) break in between. Break can be catastrophic - had one break at Summit, got lucky and ended up in infield with no contact. Have had inner bushings wear out more than once in between - causing slop in steering.
Brake Pads. I've run Pagid blacks, & yellows, PFC 8 & 11s. I prefer PFC-11s, to me they seem to modulate well, insulate the caliper well and be long lasting. For Sprints and DE I replace when the pad material is thickness of backing plate - at this point you still have a fair amount of braking material left but the insulation value is significantly reduced putting you at risk of transferring too much rotor heat to the caliper pistons (Cup Zircon "pucks" help - was bigger problem in Cayman before upgrading to Cup front calipers). For Enduros, I prefer to put new pads in if old pad is <50% to get the enhanced insulation value to reduce risk of boiling fluid, saving the old pads to use up in a Sprint or DE.
Brake Rotors. For 350mm rotors the value of the ATE Cayenne rotor is hard to beat. My Cup uses 380mm. Cracks approaching or at outer edge mean time to replace.
Axles. Every 2 years/50 hours. I use black.
Wheel Bearings. Every 2 years/50 hours and have had fronts fail in between.
Dampeners. Rebuild over winter every 2 years. Have had them leak in between.
Gearbox. When 3rd or 4th stop shifting smoothly - often around 50 hours. How much individual drivers abuse the gear box varies widely.
Motor (the $64,000 question). Ha! I'll go out on a limb here - I had leak down and oil testing done every year/50 hours. Was in new spec for leak down when rebuilt at 225 hours - I rebuilt because I could not see putting back in car after the fire without inspecting the innards.
Lug Nuts and Stub Bolts. 2 years
Chris, I know very fast racers that use the "I'll fix it when it breaks" approach. I invest more than that, but way less than what a pro team would do. I try to stay ahead of items that could cause a catastrophic failure (hit the wall if the part fails) and recognize that particularly when racing you have sizable expenses for the weekend (fees, transportation, lodging, support,etc.) and want your equipment to work. Some of this also comes down to how hard you are pushing the car - lap times, Gs, etc. - the faster and harder you drive, the sooner stuff wears out.
Last edited by obsessedone; 02-10-2019 at 10:44 AM.
02-10-2019, 09:02 AM
#11
Rennlist Member
Thread Starter
Lots of good and interesting information, thanks.
Yesterday we pulled the axles to replace the CV boots--one of them has an incipient tear. Will have to wait to do that after we get the right grease (tending towards Krytox GPL 215 this time) and parts, but with the axles off we could better check the wheel bearings. None of them had grinding or other noise and with the wheels on no play was evident about the vertical axis. with the suspension mostly off (callipers and shocks out for service) the left-side bearings were clearly bad. They spun too freely and there was noticeable play. After witnessing the result of a failed wheel bearing at last year's Monticello race we have checked and rechecked. Good thing, and now replacement of all four bearings is on the to do list.
Yesterday we pulled the axles to replace the CV boots--one of them has an incipient tear. Will have to wait to do that after we get the right grease (tending towards Krytox GPL 215 this time) and parts, but with the axles off we could better check the wheel bearings. None of them had grinding or other noise and with the wheels on no play was evident about the vertical axis. with the suspension mostly off (callipers and shocks out for service) the left-side bearings were clearly bad. They spun too freely and there was noticeable play. After witnessing the result of a failed wheel bearing at last year's Monticello race we have checked and rechecked. Good thing, and now replacement of all four bearings is on the to do list.
02-10-2019, 05:28 PM
#12
RL Community Team
Rennlist Member
Rennlist Member
obsessed one, that’s a good list. Alarming that you had wheel bearing failures in between the service interval! Are your bearings showing play by the time it comes to replace them? Also in regards to the leak down testing, what did you regard as “within spec”?
02-10-2019, 06:19 PM
#13
No bearings are not showing any significant play before replacement or they would be replaced when play was evident. When bearings failed between changes initial symptom was grinding noise on track, play noted upon inspection, they were replaced at track on race weekends. Because most tracks in the East (USA) go clockwise there is a tendency for parts on the LF to fail first.
Having a lower control arm fail or an axle break is typically WAY more alarming than a bearing failure. Bearing failures usually give some warning - noise or handling issues; axles & lower control arm failures tend to be sudden (while lower control arm bushing wear tends to give warning in handling issues similar to bearing play). Again, the harder you play, the more things break.
Can't help on the leak down spec, input was from shop doing the test. Someone probably has posted such info in these forums though, so a search may payoff.
11-21-2019, 05:48 PM
#14
Nordschleife Master
11-22-2019, 11:00 AM
#15
In my case, most common is bushing wear suddenly becomes bad enough that steering shake becomes a significant problem. I did have one instance of total failure where the 2 part LF control arm separated - the 2 connecting bolts went missing. Wear or faulty installation/over torquing?