IMS center bolt

[WhiteyII]

I am about to rr my clutch,RMS and ims. I am making my tooling and my question is does anyone know the thread and size of the center bolt on the original? I need to get the correct coupling nut for my puller.
Thanks, Dave

[Homeoboxter]

Mine had an M8 1.0 mm center bolt, it`s a 1999 Boxster. I wouldn`t waste an original dual row bearing at such a low mileage though by pulling it out. Just a thought.

[WhiteyII]

Thanks appreciate the quick response. I’m changing it with low miles mostly due to the clutch..... which leads to the RMS. Which leads to the IMS. I would prefer to remove the inner seal on the IMS bearing but there’s no way to remove without pulling on the inner race which is fine to get it out but not to reuse. Too much stress/damage unseen to comfortably trust it after that. I see videos of guys “tapping” on the inner race driving it in that last 16th inch possibly damaging the bearing. This is done on the way out. I went back and forth on leaving it completely can’t go that either.......

[elgyqc]

Originally Posted by WhiteyII

... I would prefer to remove the inner seal on the IMS bearing but there’s no way to remove without pulling on the inner race which is fine to get it out but not to reuse. Too much stress/damage unseen to comfortably trust it after that. I see videos of guys “tapping” on the inner race driving it in that last 16th inch possibly damaging the bearing. This is done on the way out. I went back and forth on leaving it completely can’t go that either.......

Why remove the inner seal? I removed the outer seal to allow engine oil lubrication and other than that left the original bearing as it was. The car has been running for 2 years since with no problems.

[Homeoboxter]

Originally Posted by elgyqc

Why remove the inner seal? I removed the outer seal to allow engine oil lubrication and other than that left the original bearing as it was. The car has been running for 2 years since with no problems.

I agree. Removing the inner seal wouldn`t make any further difference.

[piper6909]

Originally Posted by elgyqc

Why remove the inner seal? I removed the outer seal to allow engine oil lubrication and other than that left the original bearing as it was. The car has been running for 2 years since with no problems.

Wouldn't the oil flow from the inside outward? Keeping the inner seal in blocks the oil flow. Maybe not completely, but it surely restricts it.

[elgyqc]

Originally Posted by piper6909

Wouldn't the oil flow from the inside outward? Keeping the inner seal in blocks the oil flow. Maybe not completely, but it surely restricts it.

The inner seal side of the bearing is in the IM shaft, so the only oil on that side is oil that has passed through the bearing and is trapped in the shaft. The good stuff is on the outside.
The PCA videos with Jake Raby explain in detail what is happening with the IMSB.

[WhiteyII]

I went in to my 23,250 mile 1998 Box and as the pictures show the dual row bearing was on its way. I pulled the seal on the bearing and found the bearing cage was broken but still in place and the balls just starting to go but races looked good.......there was surprisingly very little metal. When I pulled the bearing there was some in the tube but again very little, used paper towels on a set of magic fingers first with diesel fuel on the towel, I have a borescope and there is now nothing in the tube. I pulled the filter and it was spotless, dropped the oil and pan also spotless. The oil and filter had 500 miles. bought the car with 9100 miles in 2017. the oils been changed 4 times since I've had it with one being at the PDI. every filter has been cut and inspected with each. Did a 5000 mile cross country trip last July and changed the oil before I left and when I got home and inspected that filter as well, all have been spotless.
I know I'll be flamed, but I think I'm going to put it back together. I ordered a LN spin on filter and mag drain plug. I have a filter cutter so I'll change the oil at 50 miles first and inspect the filter, then 500 and then 1000mi. Your thoughts........

[elgyqc]

Originally Posted by WhiteyII

I went in to my 23,250 mile 1998 Box and as the pictures show the dual row bearing was on its way. I pulled the seal on the bearing and found the bearing cage was broken but still in place and the balls just starting to go but races looked good...
I know I'll be flamed, but I think I'm going to put it back together. I ordered a LN spin on filter and mag drain plug. I have a filter cutter so I'll change the oil at 50 miles first and inspect the filter, then 500 and then 1000mi. Your thoughts........

Very interesting. Seems to be the perfect example of IMSB failure in a car that has not been driven enough. I inspected the IMSB on a 2000 Boxster with 115,000 miles on it, I pulled the outer seal and verified the bearing, it was fine. I put a new o-ring on the flange and put it back on, it has been running ever since without problems.
Was there any grease left in the bearing... or oil?
I find your course of action reasonable. With the bearing seals in place it seems to me that very little metal would be circulating.

[WhiteyII]

No there was no grease whatsoever. Hey my tooling worked great..........

[Homeoboxter]

Originally Posted by WhiteyII

I went in to my 23,250 mile 1998 Box and as the pictures show the dual row bearing was on its way. I pulled the seal on the bearing and found the bearing cage was broken but still in place

Are you saying you found the cage like this after removing the seal? Looks like a perfect cut.

[WhiteyII]

Anybody know why you’re not supposed to use compressed air to blow the dust out
On your dual mass flywheel and no solvents “brakeclean”?

[elgyqc]

Today I pulled the IMSB flange off the engine that I bought on ebay last Juin (and that just arrived after being stuck at the border) and the bearing is perfect. I removed the outer seal to check it out... turns smoothly and there is no play. Unless closer inspection reveals something I will put a new o-ring on the flange and button it up. The engine is supposed to have just under 99,000 miles on it.

[WhiteyII]

Yes that's what I found when I pulled the seal for inspection. I certainly wasn't expecting
what I found. Anybody know what appears to be a patch/repair is in the photo?
Installed the new bearing, crankcase pan, RMS, flywheel and clutch today, tranny tomorrow.....can you help me understand why low mileage could have contributed to this failure? I don't get it, but glad I didn't like the feel of my clutch, that's why I went in to try and fix that and found what I found. Probably could have gone around the block a couple more times, you think.......

[Homeoboxter]

Originally Posted by WhiteyII

Yes that's what I found when I pulled the seal for inspection. I certainly wasn't expecting
what I found. Anybody know what appears to be a patch/repair is in the photo?

Weird... My guess is somebody has already tried to pull the bearing out using a bearing puller and one of the arms of the puller broke the casting. This would explain the unusual failure of the bearing, it may have got damaged at the same time. Is it the original?

[elgyqc]

Originally Posted by WhiteyII

.....can you help me understand why low mileage could have contributed to this failure? I don't get it....

I don't get it either, but reading on this and other forums it is often said that IMSB problems happen more often in M96 engines that have not been driven a lot and not driven hard. Is there data to back this up? I don't know.

This is from the LN engineering site.

"Remember, not driving your car or worst yet, not driving it like Porsche intended can make the problem worse. Although a greatly debated subject, most experts agree that more frequent oil changes with a quality 5w40 motor oil like Driven DT40 every 6 months or 5,000 miles is a good first step. Secondly, actually driving your Porsche more often and avoiding higher gears to keep the revs above 2500-3000 rpm is another good step to take to improve the life of the ball-bearing in the intermediate shaft. Although there is limited data, the general trend is that lower mileage vehicles with infrequent oil changes or driven light-footed (as in run at low speed/engine rpms) are most likely to suffer a failure rather than those cars that are driven hard and well-maintained."

[Homeoboxter]

Originally Posted by elgyqc

I don't get it either, but reading on this and other forums it is often said that IMSB problems happen more often in M96 engines that have not been driven a lot and not driven hard. Is there data to back this up? I don't know.

One possible explanation might be that the oil that gets trapped inside the IMS and hence in the bearing is overused and dirty as it`s not replaced with the oil changes. Also, the gas that seeps through the bearing during cooling-warm up cycles is crankcase gas, which contains CO2 and other potentially corrosive chemicals coming from burnt gas and oil. Now, if you leave your car unused for years, the bearing sits half way submerged in this dirty oil inside the tube. Being half way exposed to the oil for years may cause an uneven wear pattern which might lead to future failure?

This is just a theory that I just came up with, don`t take it for granted
But for this reason I added a "drain hole" to the IMS where the trapped oil can escape.

An additional note: my car had 100k miles and spent 11 years in a garage with the engine seized. The IMSB was original and in a perfect shape. But the oil it was sitting in was black and dirty.

[JFP in PA]

Originally Posted by Homeoboxter

But for this reason I added a "drain hole" to the IMS where the trapped oil can escape.

A better and permanent fix would have been to install a plug behind the bearing, as is done in all IMS Solution retrofits. The IMS shaft tube is weak enough without drilling drain holes into it.

[piper6909]

Originally Posted by Homeoboxter

One possible explanation might be that the oil that gets trapped inside the IMS and hence in the bearing is overused and dirty as it`s not replaced with the oil changes. Also, the gas that seeps through the bearing during cooling-warm up cycles is crankcase gas, which contains CO2 and other potentially corrosive chemicals coming from burnt gas and oil. Now, if you leave your car unused for years, the bearing sits half way submerged in this dirty oil inside the tube. Being half way exposed to the oil for years may cause an uneven wear pattern which might lead to future failure?

This is just a theory that I just came up with, don`t take it for granted
But for this reason I added a "drain hole" to the IMS where the trapped oil can escape.

An additional note: my car had 100k miles and spent 11 years in a garage with the engine seized. The IMSB was original and in a perfect shape. But the oil it was sitting in was black and dirty.

While we're on the subject of drilling and modifications; From my research, I believe the best, cheapest, and simplest way to keep fresh oil in the bearing is to tap a hole in the opposite end of the IMS shaft behind the oil pump and remove both seals from the IMSB. This way oil will actually circulate.

Full disclosure: I have not done any such mods to mine, nor have I changed the IMSB. But if I decided to do it, that's the route I'd go.

Yes, I'm aware of the DOF from LNE. While it's good, it's not the simplest nor cheapest. Plus, I'm a bit uneasy about having a pressurized external oil hose. My brother had an Audi with an external oil line. Unbeknownst to him, it ruptured and within seconds of the oil light coming on the engine was toast. The oil was pumped out that quickly.

[WhiteyII]

Like I said bought the car with 9000 miles, it had not been gone into
before this time. The repair history was oil changes and a belt. All done by Barrington
Porsche in Illinois. Yeah I’ve read all of Jakes stuff and I can assure you it’s driven
Like a Porsche and never “lugged” RPM is kept in the 3k area.