986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - IMS

Silber · 07-27-2017, 07:22 AM

All,

Starting a new thread so that the waters are clear.

Was originally going to go with an SKF Hybrid, later determined to be unsuitable, as discussed here:

IMS - Going with SKF hybrid

Came up with a theory that the grease washout in the IMS bearing was caused by the "lung effect:"

IMS - Going with SKF hybrid

So my new plan is as follows:

Acquire dead IMS shaft for testing. Plug the end with a freeze plug, measure that this causes no deformity of shaft. install a pressure gauge on the air space inside, then heat to 300 degrees, see how much pressure we get. Once I have that number, take compressed air and double it to make sure the freeze plug will hold.

then, discard test shaft and install pelican parts bearing, as supplied by Pelican, with the addition of a freeze plug on my vehicle in situ.

At 40k miles pull pelican parts bearing and verify that oil has not washed out the grease, at that time install suitable steel SKF, FAG, NSK bearing of high quality. Thereafter every clutch change.

why?

My theory is that Porsche got the spec of the bearing right, assuming no grease washout. The laws of physics tell me that the "lung effect" (discussed above) is the most likely reason oil and grease are getting exchanged in the bearing. So, if you stop this effect, the bearing Porsche specified will be more than suitable to get from clutch change to clutch change (100k or so miles)

So the permanent (in my mind) IMS method is:

1) install freeze plug in end of IMS shaft, install pelican bearing (uprated bolt is critical)
2) change bearing every time you change clutch (plain steel bearing is like $10, uprated bolt should last through as many clutches and bearings as an engine could go through.)

I am advocating that the IMS problem can be resolved for essentially $3. A freeze plug is the missing component. I have no financial incentive from Pelican Parts or the Freeze plug manufacturers, just a fellow hobbyist with a theory that I intend to prove to be correct.

$185 initial outlay, assuming you can borrow special tools, then an extra $10 every time you change the clutch is a LOT more palatable than thousands especially if it is just as effective at preventing catastrophic engine damage. I actually think a 2rs (double sealed) bearing without thermally caused oil intrusion will be more effective at preventing catastrophe as metal particles will be kept out of the bearing, allowing it to lead its full rated life EVEN IF you end up with metal particle or two in the oil.

If someone asked, I would say that the factory bearing with no freeze plug is highly suspect and should be changed, it almost certainly has oil washout, and is not to be trusted.

regards,

Silber

07-27-2017, 07:22 AM	#1
Silber Registered User Join Date: Aug 2016 Posts: 166	IMS - 2rs + freeze plug All, Starting a new thread so that the waters are clear. Was originally going to go with an SKF Hybrid, later determined to be unsuitable, as discussed here: IMS - Going with SKF hybrid Came up with a theory that the grease washout in the IMS bearing was caused by the "lung effect:" IMS - Going with SKF hybrid So my new plan is as follows: Acquire dead IMS shaft for testing. Plug the end with a freeze plug, measure that this causes no deformity of shaft. install a pressure gauge on the air space inside, then heat to 300 degrees, see how much pressure we get. Once I have that number, take compressed air and double it to make sure the freeze plug will hold. then, discard test shaft and install pelican parts bearing, as supplied by Pelican, with the addition of a freeze plug on my vehicle in situ. At 40k miles pull pelican parts bearing and verify that oil has not washed out the grease, at that time install suitable steel SKF, FAG, NSK bearing of high quality. Thereafter every clutch change. why? My theory is that Porsche got the spec of the bearing right, assuming no grease washout. The laws of physics tell me that the "lung effect" (discussed above) is the most likely reason oil and grease are getting exchanged in the bearing. So, if you stop this effect, the bearing Porsche specified will be more than suitable to get from clutch change to clutch change (100k or so miles) So the permanent (in my mind) IMS method is: 1) install freeze plug in end of IMS shaft, install pelican bearing (uprated bolt is critical) 2) change bearing every time you change clutch (plain steel bearing is like $10, uprated bolt should last through as many clutches and bearings as an engine could go through.) I am advocating that the IMS problem can be resolved for essentially $3. A freeze plug is the missing component. I have no financial incentive from Pelican Parts or the Freeze plug manufacturers, just a fellow hobbyist with a theory that I intend to prove to be correct. $185 initial outlay, assuming you can borrow special tools, then an extra $10 every time you change the clutch is a LOT more palatable than thousands especially if it is just as effective at preventing catastrophic engine damage. I actually think a 2rs (double sealed) bearing without thermally caused oil intrusion will be more effective at preventing catastrophe as metal particles will be kept out of the bearing, allowing it to lead its full rated life EVEN IF you end up with metal particle or two in the oil. If someone asked, I would say that the factory bearing with no freeze plug is highly suspect and should be changed, it almost certainly has oil washout, and is not to be trusted. regards, Silber __________________ 2002 Boxster S - Silver/Boxster Red Coilovers - LSD - CAI - High Flow exh. - F&R Adjustable Sways LN 3.2 to 3.8 - parts acquired, pending assembly and tuning Last edited by Silber; 07-27-2017 at 07:25 AM.