Full DIY: Transaxle, FW, Clutch, IMS Bearing
04-28-2012, 08:02 PM
#1
Pro
Thread Starter
Full DIY: Transaxle, FW, Clutch, IMS Bearing
I needed to remove my transaxle for a rebuild and couldn’t find a DIY anywhere.
So I asked what special tools are needed (https://rennlist.com/forums/996-foru...ols-parts.html) and then just did the work.
Here’s an outline of the job (not every detail is included). Hopefully this will help other folks out there.
Tools Needed:
¼” metric sockets, 6 point and 12 point
3/8” metric sockets, 6 point and 12 point
½” metric sockets, 6 point and 12 point
(12pnt allow more clock-able fitment in close confines on 6pnt bolts, 6pnt allow better torque transmission to them).
32mm socket (cam tensioners)
24mm socket (crank bolt)
TWO sets of Harbor Freight wobble extension kits
Metric hex sockets (allen wrenches won’t do the job)
Extended length 8mm hex socket for axle shafts (short will still work)
Torque wrench (5-60ftlbs or so)
Misc screwdrivers and prybars
Blue Permatex
Green Loctite
Hylomar
High-temp grease (TO bearing)
Brake fluid (if replacing clutch slave or master cylinder)
8 flywheel bolts
6 clutch pressure plate bolts
IMS bearing retrofit kit and removal/install tools
Fork upgrade parts (fork, spring clip, ball seal, ball stud)
Clutch kit
Oil and filter
Clutch centering tool
XZN socket set (this is for ONE bolt holding the transaxle to the motor. Whatever, Porsche.)
If I missed anything I’ll add to this as I remember.
I didn’t have to drop the engine any to do this job.
It took 9 hours start to finish, no stopping for food.
Make sure when you remove the neg battery cable that you don’t fully close the front hood or you’ll need to use the emergency release to open it again.
This was a lot of work doing it with a lift and nice transmission jack - to all you guys doing this on your garage floor with the tail up on jack stands: you guys definitely have my respect.
I was going to replace the AOS since I was “in there”, but I found that even though it may be easier doing it with the transaxle dropped, it’s still no spring picnic and decided to cross that bridge when mine if it dies.
I did however replace the clutch slave cylinder which was on its way out, the flywheel, the clutch, and upgraded the IMS bearing with Flat6/LNE’s retrofit kit.
With the fresh transaxle and new clutch components, the car feels and drives literally brand new. I didn’t realize how bad everything was until now. I was contemplating the “spring delete” and “clutch switch delete” because of how finicky the clutch engaged, but replacing everything changed the entire character of how the car shifts and engages; I wouldn’t think of doing those mods now.
Trans was rebuilt due to worn 2nd gear syncros (grinding 3-2 downshift when cold) due to previous owner not knowing how to downshift properly. When the slave cyl went out I figured it was time to stop babying the downshifting and finally do the rebuild so I could finally drive this thing the way it was meant to be driven.
IMS bearing (dual row) was in perfect condition, no debris, no play between the races. But now I have a better peace of mind about it. Car is a 2001 C4 with 58k miles.
Let’s begin this thing.
Up on the lift. Tip: use hockey pucks under the lift points if the body contacts the lift arms.
Undercarriage plastic and aluminum cross brace need to be removed.
Shifter linkage ball-joints pop off with screwdriver prying.
Axles unbolted (helps to have long hex socket; I only had a short and the boot gets in the way a little)
Wobble extensions are your BEST friend for the entire job. And this isn’t the longest I used! 3/8” heavily used.
Here’s the longest, reaching the top bolt. It was broken loose first with a long hand reach and short extension to get the leverage needed. Breaking loose with extensions is tough because the extensions are not stiff and wind-up like a torsion spring.
Slave cylinder is a BIG pain, mostly when re-installing, because you can’t see anything. Use ¼” sockets and wobble extensions; the hardline is in the way of the bolt heads.
Support the engine, remove the front driveshaft (C4/C4S), unbolt the cross member, and the transaxle is dropped.
All clear for clutch and flywheel removal
Bag and label every nut and bolt, a bag for each subassembly. Note: every transaxle-to-engine bolt is different! Draw a circle and label where each bolt location is, and label each bolt in its own bag.
My flywheel was heat-checked and had a lip. I replaced it for good measure. I fabricated a locking tool seen in the install picts below.
Neither the RMS nor IMS bearing retainer was leaking. Good signs.
Cleaned up IMS bearing retainer. Shallow depth indicates a two row bearing inside.
This was my picture for motivation
Transaxle ready to be shipped off for the rebuild.
Now for the IMS bearing retrofit. Note: This is not meant to be a full step-by-step procedure with every detail; talk to Flat6 prior to doing this yourself.
Engine was locked at TDC (line up timing mark on crank pulley and engine, and use a rod to lock the “teardrop-shaped” hole into a corresponding hole in the engine), and then the first of two cam tensioners were removed (the third does not need to be removed). Here is where the tensioner was. Make sure to drain the oil first.
And here’s the tensioner
Second tensioner removed. A tip here is to unbolt the two tie-downs holding the line that is in the way of getting the socket onto the tensioner.
And here’s tensioner #2
The IMS bearing retainer is now ready to be unbolted and removed.
The area was first cleaned with brake cleaner and the bolts removed. A tip is to lightly tap the side of the bearing retainer with a drift to rotate it and break the seal. This also allows you to get a pry bar under the tabs to pull it out. Gently pry in two spots at once so it comes out more or less straight. It may have some suction, making it want to pull back in, so keep pulling until it pops free.
Retainer removed and bearing visable.
Thread on the pullers inner shaft onto the IMS bearing’s center support shaft.
Thread the puller onto the inner shaft’s set screw until fully threaded, seat the puller onto the rim of the IMS, and thread the bolt down snug. Verify that the puller is centered. Holding the puller threaded rod stationary with a wrench, begin tightening the nut. Once it feels like it’s getting “really tight”, tighten it a little more. You may have already heard the retaining wire clip break with a loud ‘pop’ sound, if not, let everything sit for a few minutes and it may happen. If it doesn’t tighten it more and let it sit. Once it ‘pops’, keep on tightening it down until the bearing is free. It should be easier to pull out now (not as much force needed), but mine still needed a lot of force. Next few pictures explain why.
Here’s the bearing removed and inside the puller.
Here’s why my bearing still needed lots of force to pull out: the wire retainer wedged itself between the bearing the puller! The bearing was being pulled into the puller tool with the interference of the wire. No harm done to anything, but since I was told the bearing would be easier to pull out once the ‘pop’ happened and mine did not, every turn of the nut made me more nervous until it was out.
IMS inside revealed.
I have no picts of installing the bearing, it’s a simple matter of putting it in the freezer for a couple of hours already installed on the install tool, tapping the IMS gently to make sure it’s fully seated against the oil pump at the other end, lining up the bearing straight into the IMS, and driving it in with a dead blow hammer. A tip here is that once it’s driven half way or more into the IMS, use a large socket and a socket extension (not wobble) to use as an extension to continue driving the bearing in. The engine/suspension cross member is in the way of being able to squarely hit the tool with the hammer, and extending out the driver with this method let me hit it perfectly every time.
Here’s the new bearing installed. NOTE!! Make sure to drive the bearing in as far as it will go, such that this groove is fully exposed! (I’m pointing at it with the tip of the screwdriver). Install the spiralock retaining ring into the groove, threading and spinning one end into the groove, while pushing the rest of the ring into the groove. Make sure the ring is fully seated in the groove. The spiralock is not shown in this picture.
Drop some oil into the IMS bearing, onto the o-ring inside the new bearing retainer, and push in the bearing retainer. I don’t recommend drawing in the retainer using the three bolts, instead push it in by hand, then take large socket and use it with a dead blow hammer to lightly tap it in until it’s fully seated. Put some Hylomar under the bolt heads of new pre-sealed bolts (or original bolts with Teflon sealant added) and torque down. Put some Hylomar under the nut for the bearing center stud and torque down. Add some green locktight to the nut and let it wick into the threads.
I fabricated this flywheel lockdown tool out of aluminum. Simple and effective and way cheaper than Porsche’s tool.
The flywheel bolts are torque-to-yield type, so they can only be used once. Using new bolts, they’re to be torqued to 19lbft then tightened a further 90 degrees. I decided not to use a degree-ing tool because they get such low reviews for working well. Instead, I marked the bolts at 3 o’clock with a marker, and beneath each one at 6 o’clock. In a star pattern, I tightened each one about 45 degrees, then finished to 90 degrees.
90 degree tightening complete.
Clutch disc and the alignment tool.
Pressure plate installed, blue Permatex thread locker on the threads. IMHO Permatex is a better product than the Loctite brand.
I tightened the hard line into the new slave cylinder by C-clamping it to the frame. Worked well.
My transaxle freshly rebuilt.
New updated 997 fork, spring clip, ball seal, and TO bearing.
New pivot ball installed in the trans and fork installed with some grease on the bearing retainer and a little on the splines.
NOTE! Make sure to put the upper cross member on the trans before you jack it into place; it can’t be installed after the transaxle is installed. Also fill it with oil now so you don’t need a pump.
Transaxle in place and cross member pieces installed.
Driveshaft is installed and all undercarriage pieces and plastic put back in place, and engine filled with oil. Remove the TDC engine lock pin if you haven’t already.
I bled the clutch since I put in a new slave cylinder, and since it’s the same reservoir as the brakes and it’s already setup, I flushed the brakes too. I use ATE blue and gold alternately so I know when all the fluid has been flushed each time.
And finally it’s back on the road as my daily driver.
So I asked what special tools are needed (https://rennlist.com/forums/996-foru...ols-parts.html) and then just did the work.
Here’s an outline of the job (not every detail is included). Hopefully this will help other folks out there.
Tools Needed:
¼” metric sockets, 6 point and 12 point
3/8” metric sockets, 6 point and 12 point
½” metric sockets, 6 point and 12 point
(12pnt allow more clock-able fitment in close confines on 6pnt bolts, 6pnt allow better torque transmission to them).
32mm socket (cam tensioners)
24mm socket (crank bolt)
TWO sets of Harbor Freight wobble extension kits
Metric hex sockets (allen wrenches won’t do the job)
Extended length 8mm hex socket for axle shafts (short will still work)
Torque wrench (5-60ftlbs or so)
Misc screwdrivers and prybars
Blue Permatex
Green Loctite
Hylomar
High-temp grease (TO bearing)
Brake fluid (if replacing clutch slave or master cylinder)
8 flywheel bolts
6 clutch pressure plate bolts
IMS bearing retrofit kit and removal/install tools
Fork upgrade parts (fork, spring clip, ball seal, ball stud)
Clutch kit
Oil and filter
Clutch centering tool
XZN socket set (this is for ONE bolt holding the transaxle to the motor. Whatever, Porsche.)
If I missed anything I’ll add to this as I remember.
I didn’t have to drop the engine any to do this job.
It took 9 hours start to finish, no stopping for food.
Make sure when you remove the neg battery cable that you don’t fully close the front hood or you’ll need to use the emergency release to open it again.
This was a lot of work doing it with a lift and nice transmission jack - to all you guys doing this on your garage floor with the tail up on jack stands: you guys definitely have my respect.
I was going to replace the AOS since I was “in there”, but I found that even though it may be easier doing it with the transaxle dropped, it’s still no spring picnic and decided to cross that bridge when mine if it dies.
I did however replace the clutch slave cylinder which was on its way out, the flywheel, the clutch, and upgraded the IMS bearing with Flat6/LNE’s retrofit kit.
With the fresh transaxle and new clutch components, the car feels and drives literally brand new. I didn’t realize how bad everything was until now. I was contemplating the “spring delete” and “clutch switch delete” because of how finicky the clutch engaged, but replacing everything changed the entire character of how the car shifts and engages; I wouldn’t think of doing those mods now.
Trans was rebuilt due to worn 2nd gear syncros (grinding 3-2 downshift when cold) due to previous owner not knowing how to downshift properly. When the slave cyl went out I figured it was time to stop babying the downshifting and finally do the rebuild so I could finally drive this thing the way it was meant to be driven.
IMS bearing (dual row) was in perfect condition, no debris, no play between the races. But now I have a better peace of mind about it. Car is a 2001 C4 with 58k miles.
Let’s begin this thing.
Up on the lift. Tip: use hockey pucks under the lift points if the body contacts the lift arms.
Undercarriage plastic and aluminum cross brace need to be removed.
Shifter linkage ball-joints pop off with screwdriver prying.
Axles unbolted (helps to have long hex socket; I only had a short and the boot gets in the way a little)
Wobble extensions are your BEST friend for the entire job. And this isn’t the longest I used! 3/8” heavily used.
Here’s the longest, reaching the top bolt. It was broken loose first with a long hand reach and short extension to get the leverage needed. Breaking loose with extensions is tough because the extensions are not stiff and wind-up like a torsion spring.
Slave cylinder is a BIG pain, mostly when re-installing, because you can’t see anything. Use ¼” sockets and wobble extensions; the hardline is in the way of the bolt heads.
Support the engine, remove the front driveshaft (C4/C4S), unbolt the cross member, and the transaxle is dropped.
All clear for clutch and flywheel removal
Bag and label every nut and bolt, a bag for each subassembly. Note: every transaxle-to-engine bolt is different! Draw a circle and label where each bolt location is, and label each bolt in its own bag.
My flywheel was heat-checked and had a lip. I replaced it for good measure. I fabricated a locking tool seen in the install picts below.
Neither the RMS nor IMS bearing retainer was leaking. Good signs.
Cleaned up IMS bearing retainer. Shallow depth indicates a two row bearing inside.
This was my picture for motivation
Transaxle ready to be shipped off for the rebuild.
Now for the IMS bearing retrofit. Note: This is not meant to be a full step-by-step procedure with every detail; talk to Flat6 prior to doing this yourself.
Engine was locked at TDC (line up timing mark on crank pulley and engine, and use a rod to lock the “teardrop-shaped” hole into a corresponding hole in the engine), and then the first of two cam tensioners were removed (the third does not need to be removed). Here is where the tensioner was. Make sure to drain the oil first.
And here’s the tensioner
Second tensioner removed. A tip here is to unbolt the two tie-downs holding the line that is in the way of getting the socket onto the tensioner.
And here’s tensioner #2
The IMS bearing retainer is now ready to be unbolted and removed.
The area was first cleaned with brake cleaner and the bolts removed. A tip is to lightly tap the side of the bearing retainer with a drift to rotate it and break the seal. This also allows you to get a pry bar under the tabs to pull it out. Gently pry in two spots at once so it comes out more or less straight. It may have some suction, making it want to pull back in, so keep pulling until it pops free.
Retainer removed and bearing visable.
Thread on the pullers inner shaft onto the IMS bearing’s center support shaft.
Thread the puller onto the inner shaft’s set screw until fully threaded, seat the puller onto the rim of the IMS, and thread the bolt down snug. Verify that the puller is centered. Holding the puller threaded rod stationary with a wrench, begin tightening the nut. Once it feels like it’s getting “really tight”, tighten it a little more. You may have already heard the retaining wire clip break with a loud ‘pop’ sound, if not, let everything sit for a few minutes and it may happen. If it doesn’t tighten it more and let it sit. Once it ‘pops’, keep on tightening it down until the bearing is free. It should be easier to pull out now (not as much force needed), but mine still needed a lot of force. Next few pictures explain why.
Here’s the bearing removed and inside the puller.
Here’s why my bearing still needed lots of force to pull out: the wire retainer wedged itself between the bearing the puller! The bearing was being pulled into the puller tool with the interference of the wire. No harm done to anything, but since I was told the bearing would be easier to pull out once the ‘pop’ happened and mine did not, every turn of the nut made me more nervous until it was out.
IMS inside revealed.
I have no picts of installing the bearing, it’s a simple matter of putting it in the freezer for a couple of hours already installed on the install tool, tapping the IMS gently to make sure it’s fully seated against the oil pump at the other end, lining up the bearing straight into the IMS, and driving it in with a dead blow hammer. A tip here is that once it’s driven half way or more into the IMS, use a large socket and a socket extension (not wobble) to use as an extension to continue driving the bearing in. The engine/suspension cross member is in the way of being able to squarely hit the tool with the hammer, and extending out the driver with this method let me hit it perfectly every time.
Here’s the new bearing installed. NOTE!! Make sure to drive the bearing in as far as it will go, such that this groove is fully exposed! (I’m pointing at it with the tip of the screwdriver). Install the spiralock retaining ring into the groove, threading and spinning one end into the groove, while pushing the rest of the ring into the groove. Make sure the ring is fully seated in the groove. The spiralock is not shown in this picture.
Drop some oil into the IMS bearing, onto the o-ring inside the new bearing retainer, and push in the bearing retainer. I don’t recommend drawing in the retainer using the three bolts, instead push it in by hand, then take large socket and use it with a dead blow hammer to lightly tap it in until it’s fully seated. Put some Hylomar under the bolt heads of new pre-sealed bolts (or original bolts with Teflon sealant added) and torque down. Put some Hylomar under the nut for the bearing center stud and torque down. Add some green locktight to the nut and let it wick into the threads.
I fabricated this flywheel lockdown tool out of aluminum. Simple and effective and way cheaper than Porsche’s tool.
The flywheel bolts are torque-to-yield type, so they can only be used once. Using new bolts, they’re to be torqued to 19lbft then tightened a further 90 degrees. I decided not to use a degree-ing tool because they get such low reviews for working well. Instead, I marked the bolts at 3 o’clock with a marker, and beneath each one at 6 o’clock. In a star pattern, I tightened each one about 45 degrees, then finished to 90 degrees.
90 degree tightening complete.
Clutch disc and the alignment tool.
Pressure plate installed, blue Permatex thread locker on the threads. IMHO Permatex is a better product than the Loctite brand.
I tightened the hard line into the new slave cylinder by C-clamping it to the frame. Worked well.
My transaxle freshly rebuilt.
New updated 997 fork, spring clip, ball seal, and TO bearing.
New pivot ball installed in the trans and fork installed with some grease on the bearing retainer and a little on the splines.
NOTE! Make sure to put the upper cross member on the trans before you jack it into place; it can’t be installed after the transaxle is installed. Also fill it with oil now so you don’t need a pump.
Transaxle in place and cross member pieces installed.
Driveshaft is installed and all undercarriage pieces and plastic put back in place, and engine filled with oil. Remove the TDC engine lock pin if you haven’t already.
I bled the clutch since I put in a new slave cylinder, and since it’s the same reservoir as the brakes and it’s already setup, I flushed the brakes too. I use ATE blue and gold alternately so I know when all the fluid has been flushed each time.
And finally it’s back on the road as my daily driver.
Last edited by peavynation; 04-28-2012 at 09:30 PM.
04-28-2012, 09:11 PM
#5
Pro
Thread Starter
Thx folks, hope it helps someone in the future.
Ooops, meant to add that info and totally forgot. I just edited my post and added it.
Syncros worn, 3-2 downshift grind, needed a rebuild.
IMS bearing in perfect condition, '01 C4 w/ 58k miles.
Syncros worn, 3-2 downshift grind, needed a rebuild.
IMS bearing in perfect condition, '01 C4 w/ 58k miles.
04-28-2012, 09:33 PM
#7
Rennlist Member
Impressively done.
Love Speed Yellow.
Enjoy the heck out of it.
Love Speed Yellow.
Enjoy the heck out of it.
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04-28-2012, 09:41 PM
#9
Rocky Mountain High
Rennlist Member
Rennlist Member
Strong work! Nice write up!
04-28-2012, 11:21 PM
#12
Thanks for documenting this. Great job. 01 C4 great choice brother. 
04-29-2012, 09:36 AM
#14
Race Director
Not only is your SY Porsche beautiful, but your pics and expertise rank high as well. Thanks for sharing. You must love starting your Porsche up now. Nice looking Deere in the barn/garage.
04-29-2012, 09:44 AM
#15
Track Day
Thanks, big job !
well at least i now know I could never do this, I don't have the resources, or the patience and skills particularly. So I need to pay, how much is reasonable to replace the IMS bearing anyway? Using L & N replacement stuff? My gearbox is ok, its only done 43 thousand, and i think the clutch is fine too. I have a singing noise which sounds to me like a wheel bearing in the rear left area at about 70 mph, how difficult is that procedure?. I did do a replacement water pump and thermostat but thats about the pinnacle of my workshop skills.