LN IMS retrofit bearing technical question
06-19-2012, 01:19 PM
#1
5th Gear
Thread Starter
Join Date: Jun 2012
Location: Oregon
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
LN IMS retrofit bearing technical question
Hello all,
I am in the middle of the IMS bearing upgrade on my Y2K boxster.
I have removed the dual row bearing that was worn out (but still intact thank goodness).
Question:
The new bearing has one cover (seal) removed but the other (on the shaft/sprocket side) is still in place.
What is the rationale for the inside cover remaining?
Will this not reduce lubrication flow through the bearing?
Is it desirable to minimize oil flow inside the IMS tube?
At this point I am tempted to remove the inner seal/ cover but would like the designers/ LN Engineering's thoughts prior to doing so.
As an industrial mechanic we don't have a high opinion of sealed bearings to begin with as we know ball bearings like an oil bath. Sealed typically equals throw-away not long life.
Thank you in advance,
Ben
I am in the middle of the IMS bearing upgrade on my Y2K boxster.
I have removed the dual row bearing that was worn out (but still intact thank goodness).
Question:
The new bearing has one cover (seal) removed but the other (on the shaft/sprocket side) is still in place.
What is the rationale for the inside cover remaining?
Will this not reduce lubrication flow through the bearing?
Is it desirable to minimize oil flow inside the IMS tube?
At this point I am tempted to remove the inner seal/ cover but would like the designers/ LN Engineering's thoughts prior to doing so.
As an industrial mechanic we don't have a high opinion of sealed bearings to begin with as we know ball bearings like an oil bath. Sealed typically equals throw-away not long life.
Thank you in advance,
Ben
06-19-2012, 02:35 PM
#2
5th Gear
Thread Starter
Join Date: Jun 2012
Location: Oregon
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
I Called Flat 6 Innovations
Got my answer:
The inner (shaft/ sprocket) seal is left on the bearing to minimize collection of oil inside the tube which has no other exit point and so would likely become a waste cesspool which will not readily drain when the engine oil is changed.
The inner seal will at least slow down this process and hopefully eliminate collection of larger particles inside the tube.
This is the best compromise possible until a permanent solution to the IMS bearing issue is available....(I heard a rumor...)
What I have learned:
This bearing should be changed RELIGIOUSLY at 50k miles or when changing the clutch. From the condition of my bearing (dual row, 48,800 miles) I am strongly convinced that a single row bearing at this level of wear would not have remained intact.
When looking to buy a Boxster I will recommend that my friends buy Y2k or older to get the dual row bearing to the extent possible.
If they buy newer (e.g. single row IMS bearing 2001, 2002 & on) the IMS bearing retrofit MUST have been done recently or must be budgeted and performed ASAP.
DO NOT overlook an oil leak at the transmission/ engine joint (typically called Rear Main Seal (RMS) leak). Without regard to a leak I would definitely do the retro-fit at 50k, and plan to do it again in 50k.
My thoughts:
From my lifetime experience (20+ year career in heavy mechanical industry, millwright) IMO the problem is definitely a Porsche engineering flaw.
I work regularly with mechanical/ structural engineers.
The only question in my mind is was the flaw accidental or was it an economizing measure (calculated risk) by the the design team.
It is also true that engineers (& rest of us) sometimes value their (our) own opinion too highly...
(Pride is before a fall).
The inner (shaft/ sprocket) seal is left on the bearing to minimize collection of oil inside the tube which has no other exit point and so would likely become a waste cesspool which will not readily drain when the engine oil is changed.
The inner seal will at least slow down this process and hopefully eliminate collection of larger particles inside the tube.
This is the best compromise possible until a permanent solution to the IMS bearing issue is available....(I heard a rumor...)
What I have learned:
This bearing should be changed RELIGIOUSLY at 50k miles or when changing the clutch. From the condition of my bearing (dual row, 48,800 miles) I am strongly convinced that a single row bearing at this level of wear would not have remained intact.
When looking to buy a Boxster I will recommend that my friends buy Y2k or older to get the dual row bearing to the extent possible.
If they buy newer (e.g. single row IMS bearing 2001, 2002 & on) the IMS bearing retrofit MUST have been done recently or must be budgeted and performed ASAP.
DO NOT overlook an oil leak at the transmission/ engine joint (typically called Rear Main Seal (RMS) leak). Without regard to a leak I would definitely do the retro-fit at 50k, and plan to do it again in 50k.
My thoughts:
From my lifetime experience (20+ year career in heavy mechanical industry, millwright) IMO the problem is definitely a Porsche engineering flaw.
I work regularly with mechanical/ structural engineers.
The only question in my mind is was the flaw accidental or was it an economizing measure (calculated risk) by the the design team.
It is also true that engineers (& rest of us) sometimes value their (our) own opinion too highly...
(Pride is before a fall).
06-19-2012, 09:15 PM
#3
I'm gald to hear that a permenant IMS fix may be on the way. I have a 2008 engeine where the IMS bearing cannot be removed easily.
In my experience, German engineers believe that if the calculations say something will work, then it absolutely MUST work. I don't think this is pride as much as it is stubbon belief in the math. We American engineers are usually a bit more pragmatic, and understand that the math cannot always address the many variables involved.
In my experience, German engineers believe that if the calculations say something will work, then it absolutely MUST work. I don't think this is pride as much as it is stubbon belief in the math. We American engineers are usually a bit more pragmatic, and understand that the math cannot always address the many variables involved.
06-20-2012, 12:14 AM
#4
Race Director
Got my answer:
The inner (shaft/ sprocket) seal is left on the bearing to minimize collection of oil inside the tube which has no other exit point and so would likely become a waste cesspool which will not readily drain when the engine oil is changed.
The inner seal will at least slow down this process and hopefully eliminate collection of larger particles inside the tube.
This is the best compromise possible until a permanent solution to the IMS bearing issue is available....(I heard a rumor...)
What I have learned:
This bearing should be changed RELIGIOUSLY at 50k miles or when changing the clutch. From the condition of my bearing (dual row, 48,800 miles) I am strongly convinced that a single row bearing at this level of wear would not have remained intact.
When looking to buy a Boxster I will recommend that my friends buy Y2k or older to get the dual row bearing to the extent possible.
If they buy newer (e.g. single row IMS bearing 2001, 2002 & on) the IMS bearing retrofit MUST have been done recently or must be budgeted and performed ASAP.
DO NOT overlook an oil leak at the transmission/ engine joint (typically called Rear Main Seal (RMS) leak). Without regard to a leak I would definitely do the retro-fit at 50k, and plan to do it again in 50k.
My thoughts:
From my lifetime experience (20+ year career in heavy mechanical industry, millwright) IMO the problem is definitely a Porsche engineering flaw.
I work regularly with mechanical/ structural engineers.
The only question in my mind is was the flaw accidental or was it an economizing measure (calculated risk) by the the design team.
It is also true that engineers (& rest of us) sometimes value their (our) own opinion too highly...
(Pride is before a fall).
The inner (shaft/ sprocket) seal is left on the bearing to minimize collection of oil inside the tube which has no other exit point and so would likely become a waste cesspool which will not readily drain when the engine oil is changed.
The inner seal will at least slow down this process and hopefully eliminate collection of larger particles inside the tube.
This is the best compromise possible until a permanent solution to the IMS bearing issue is available....(I heard a rumor...)
What I have learned:
This bearing should be changed RELIGIOUSLY at 50k miles or when changing the clutch. From the condition of my bearing (dual row, 48,800 miles) I am strongly convinced that a single row bearing at this level of wear would not have remained intact.
When looking to buy a Boxster I will recommend that my friends buy Y2k or older to get the dual row bearing to the extent possible.
If they buy newer (e.g. single row IMS bearing 2001, 2002 & on) the IMS bearing retrofit MUST have been done recently or must be budgeted and performed ASAP.
DO NOT overlook an oil leak at the transmission/ engine joint (typically called Rear Main Seal (RMS) leak). Without regard to a leak I would definitely do the retro-fit at 50k, and plan to do it again in 50k.
My thoughts:
From my lifetime experience (20+ year career in heavy mechanical industry, millwright) IMO the problem is definitely a Porsche engineering flaw.
I work regularly with mechanical/ structural engineers.
The only question in my mind is was the flaw accidental or was it an economizing measure (calculated risk) by the the design team.
It is also true that engineers (& rest of us) sometimes value their (our) own opinion too highly...
(Pride is before a fall).
Well, I would change the IMS bearing in my 02 Boxster when the clutch needs doing but so far the original clutch has over 256K miles on it and thus the IMS bearing is original.
Thank goodness I didn't subscribe to that 50K bearing replacement schedule. The car would have cost me a fortune to keep on the road in unnecessary clutch replacements (and some believe the flywheel should be replaced at this time too) and IMS bearing upgrades/replacements.
Also, I do not think in the few instances the bearing fails it is an engineering flaw. If it was they'd all fail.
I think the problem is in some cases the majority of cases the bearing was overfilled (or underfilled but I believe overfilled) with grease at manufacturing time. (In other cases I think it just a bearing failure due to another manufacturing defect like a bad bearing spacer.)
This is not an engineering problem but a manufacturing/quality control problem.
Sure, if one owns a car that experiences a bearing failure he won't care what the root cause was and I can understand that.
Anyhow, if someone wants to do the bearing upgrade and repeat that every 50K miles... that's his call to make.
Sincerely,
Macster.
06-20-2012, 08:41 AM
#5
1st Gear
Join Date: Jun 2012
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
Reasons for bearing failure:-
1) Alignment & shaft deflection.
2) Fit on the housing and shaft of the outer and inner ring.
3) Rated Capacity. (Selection must be ok as the failure rate didn't change even when they went to double row.)
4) Temperature of bearing and more importantly the seal.
My guess failures can be all related to the temperature. Unless its a high temp seal its good for -40 to + 100C
for continuous use, or 120C very briefly.
How many cars have been overheated at some stage of their life?
Regards
Howe -- retired Mech Eng
1) Alignment & shaft deflection.
2) Fit on the housing and shaft of the outer and inner ring.
3) Rated Capacity. (Selection must be ok as the failure rate didn't change even when they went to double row.)
4) Temperature of bearing and more importantly the seal.
My guess failures can be all related to the temperature. Unless its a high temp seal its good for -40 to + 100C
for continuous use, or 120C very briefly.
How many cars have been overheated at some stage of their life?
Regards
Howe -- retired Mech Eng
06-21-2012, 06:21 PM
#6
Burning Brakes
Every forum has a bunch of engineers theorizing as if they know the cause. Even the experts who have seen hundreds or thousands aren't completely sure.
All rotating parts fail at some point and the bell curves of use, initial quality and installation variations all intersect to make some fail at 10k and some not even at 250k.
Face it folks, we don't know the cause for sure or the frequency.
As to why, my guess is a combination of cost pressures from the accountants, the available materials at the time and the rush to put out a car that would bring in revenue (recall the Boxster saved Porsche). They could only afford so many test engines and mules and they weren't able to test all the possible use combinations. If you run 5 engines and 5 cars to 100k miles and everything looks good, you assume you got it right. But you don't get those to 100k the same way a customer does...you test night and day, not every other weekend. Not putting the engine in hibernation for 4 months of the year. Just a guess.
And the replacement parts (available from at least 4 sources now that I know of) have different materials, lubrication, costs, testing, experience in actual use. May be even more I don't know of.
All rotating parts fail at some point and the bell curves of use, initial quality and installation variations all intersect to make some fail at 10k and some not even at 250k.
Face it folks, we don't know the cause for sure or the frequency.
As to why, my guess is a combination of cost pressures from the accountants, the available materials at the time and the rush to put out a car that would bring in revenue (recall the Boxster saved Porsche). They could only afford so many test engines and mules and they weren't able to test all the possible use combinations. If you run 5 engines and 5 cars to 100k miles and everything looks good, you assume you got it right. But you don't get those to 100k the same way a customer does...you test night and day, not every other weekend. Not putting the engine in hibernation for 4 months of the year. Just a guess.
And the replacement parts (available from at least 4 sources now that I know of) have different materials, lubrication, costs, testing, experience in actual use. May be even more I don't know of.
06-23-2012, 01:06 PM
#7
5th Gear
Thread Starter
Join Date: Jun 2012
Location: Oregon
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
Thank you for your thoughts
It is nice to see some thoughts from some of the more experienced ones on this site. Thank you for your comments.
I have completed the IMS bearing replacement (clutch kit, RMS, trans main seal, pilot bearing etc.). It was a rather involved project. But everything is running well.
I also changed the spark plug tubes, and now I have a leak free engine!
I will try to post some pix soon.
Compliment to Porsche:
IMS flaws or no, THIS IS a great car and the engineering and design overall are great (as a result I love to drive this thing).
Time to road-trip.. Canada.... Hopefully the rain will quit for a bit aye?
Back roads with the top down in British Columbia sounds pretty nice...
I have completed the IMS bearing replacement (clutch kit, RMS, trans main seal, pilot bearing etc.). It was a rather involved project. But everything is running well.
I also changed the spark plug tubes, and now I have a leak free engine!
I will try to post some pix soon.
Compliment to Porsche:
IMS flaws or no, THIS IS a great car and the engineering and design overall are great (as a result I love to drive this thing).
Time to road-trip.. Canada.... Hopefully the rain will quit for a bit aye?
Back roads with the top down in British Columbia sounds pretty nice...
