IMS upgrade TOTAL FAILURE

[perryinva]

SO Dan, what happened??!! Did you finally get it in??

[Wayne R. Dempsey]

Hi everyone. I have a new article coming out on the removal and installation of the IMS bearing with a few really neat tricks that will ease installation. I've been working with Charles on this and also Scott Slauson (Softronic), who originally pioneered the whole idea of removing the double-row bearing with the puller. We're also in the process of developing a different IMS replacement kit that will be less expensive than LN Engineering's kit, but will be recommended to be replaced every clutch job (about 30,000 miles). Charles' kit will still be the gold standard for replacement.

Stay tuned, I should have the article done in about a week or two. I have multiple engines in my garage that we're testing on right now!

-Wayne

[1schoir]

Hi everyone. I have a new article coming out on the removal and installation of the IMS bearing with a few really neat tricks that will ease installation. I've been working with Charles on this and also Scott Slauson (Softronic), who originally pioneered the whole idea of removing the double-row bearing with the puller. We're also in the process of developing a different IMS replacement kit that will be less expensive than LN Engineering's kit, but will be recommended to be replaced every clutch job (about 30,000 miles). Charles' kit will still be the gold standard for replacement.

Stay tuned, I should have the article done in about a week or two. I have multiple engines in my garage that we're testing on right now!

-Wayne

Our collective thanks to you, Charles and Scott for the work you have done and the information you are providing! :thankyou:

Good to hear that there will be a less expensive kit. It is, after all, only a bearing!

Looking forward to reading the article.

Regards, Maurice.

[Dan_C320]

SO Dan, what happened??!! Did you finally get it in??

Sorry, I haven't checked the forum lately; I've been very busy with work. I did get the bearing in and I've been driving the car for a few weeks now.

Thanks for everyone's suggestions. However, the problem was not with the bearing going in straight, I had plenty of clearance getting into the IMS bore and no problem being able to hit it straight on with the hammer. The problem was with the fit between the bearing and the IMS bore. As I mentioned earlier when I miked the IMS bore and the outer bearing raceway there was more than .001" of interference. From my experience a bearing this size with greater than .0005" of interference requires a hydraulic ram to press the parts together since the insertion force can be greater than 1000lbs. Pounding the bearing in with a hammer won't do it, you can damage the bearing, or get it only part way in.

From my experience in designing bearing fits, this application requires a slip/transition fit which would mean that you can have anywhere from .0004" clearance to .0005" interference. Bearing tolerances are held very tightly, typically +0 / -.0005" on the outer raceway diameter. I don't know how closely Porsche holds the IMS bore, but I suspect that it's probably around +/-.0006" (.02mm) and they probably press the bearing in with a hydraulic ram.

So what I had to do was to run a few passes with a cylinder hone to remove about .0003" from the IMS bore, I then froze the bearing so that the outer raceway decreased in size by about .001". I was then able to hammer it in and fully seat it in the IMS bore.

So I think that depending on the measurement of your IMS bore and the outer diameter of the bearing, the installation can either be very easy to install or nearly impossible. (No doubt the reason some people have had difficulty in pulling the bearings out and breaking the puller).

By the way, the original bearing I removed appeared to be in good condition turning very smoothly with no runout or excessive clearance. My car has more than 70,000 miles, so hopefully with the upgraded bearing I've bought some peace of mind.

Also a tip for getting the transaxle back in is to get some longer bolts, cut the heads off and place them in a couple of the engine mounting holes to help in aligning. Then also use longer bolts to pull the transaxle up close to the engine until you can get the driveshaft spline to mesh with the clutch.