IMS - Going with SKF hybrid

[Smallblock454]

Originally Posted by Silber

…worst case scenario with engine at max temp and 7000 RPM continuously.

The IMS isn't rotating at crankshaft 7.000 rpm. The camshafts are rotating at 3.500 rpm when the crankshaft is at 7.000 rpm (4 stroke engine). So because the IMS seems to have the same gearwheel diameter (didn't count the teeth, so i don't know exactly) as the cams i would say it rotates at around the same rpms as the cams and not as the same rpms as the crankshaft.

That means you have to look for an extreme high speed capable IMSB.

But it's important to take a look at the individual bearing specs.

I also would go with a sealed version.

And please remember that an engine in a car with acceleration, deceleration is not an engine on a engine stand. So if you have around max. 1g acceleration in changing directions, there is engine oil everywhere,

And if you want to reuse the center bolt, don't pull it with the cheapo "standard" tools some people like to sell for a lot of money. They are only OK if you replace the centre bolt anyway.

OK, enough IMSB talk for today. Think if you do a good research you'll find enough information to get everything right.

Regards, Markus

[78F350]

Originally Posted by Smallblock454

... And if you want to reuse the center bolt, don't pull it with the cheapo "standard" tools some people like to sell for a lot of money. They are only OK if you replace the centre bolt anyway.... Think if you do a good research you'll find enough information to get everything right.

Regards, Markus

I respect Markus's opinions, but Why not replace the center bolt? The original bolt design is flawed. During the replacement of the bearing it is simple to just put a new center bolt in (Silber sourced one easily with the Pelican kit).




As for the bearing selection, +1 to what Particlewave said. Thanks for posting, Silber, and looking forward to seeing the results.

[Smallblock454]

Originally Posted by 78F350

I respect Markus's opinions, but Why not replace the center bolt? The original bolt design is flawed. During the replacement of the bearing it is simple to just put a new center bolt in (Silber sourced one easily with the Pelican kit).

Hi 78F350,

for shure you can replace the center bolt if you want. My point was how to remove it if you want to reuse it. And if the one in the car is worn or the IMSB is worn, there is no other way as to replace it. The OEM one wasn't designed to be removed in the way it is done by pulling the IMSB with it and than reuse it. That was my point.

Another point is material quality, rigidity, durability, expansion. Maybe the replacement looks better, but that always does mean it is better. Shure, the after market manufacturers will know what they do, but bigger doesn''t always mean better. It has to fit the conditions and than has to be made better.

Regards, Markus

[Silber]

Originally Posted by Smallblock454

The IMS isn't rotating at crankshaft 7.000 rpm. The camshafts are rotating at 3.500 rpm when the crankshaft is at 7.000 rpm (4 stroke engine). So because the IMS seems to have the same gearwheel diameter (didn't count the teeth, so i don't know exactly) as the cams i would say it rotates at around the same rpms as the cams and not as the same rpms as the crankshaft.

That means you have to look for an extreme high speed capable IMSB.

The one i have chosen is very high speed capable, reference speed of 17k RPM.

However, I think you may have it backwards. Since the camshaft turns at half the speed of the crank, the RPM I have to worry about is 3500 max not a high rpm Max. That will make the grease last even longer and the bearing in general last even longer.

I am thinking since I'm going with the sealed bearing, the oil splashing around in the crankcase won't make too much of a difference. That is the hope anyway. I selected sealed because that will keep the high performance grease intact the longest AND keep small particles away from the bearing. I just cannot see putting an open bearing in the sump of the engine where all of the junk ends up. If you could do it oil fed without it being exposed to sump oil, that would be good, but you can't it's sitting smack dab in the sump, imho it will get particles in it if there are any there to float in.

I'm also thinking as my engine has 115,000 miles on it, and this SKF hybrid IMS bearing I am selecting has a calculated life of 350,000 miles, even if I went with half that, 175,000 miles, that puts me out to 290,000 miles on this engine. Basically a lifetime solution. I may just let it ride and see if I can get a lifetime out of the one bearing. This is assuming I don't find any more information out about the bearing that limits its lifespan compared to what I've seen so far in the documentation.

Then again, with how much I love preventative maintenance, if I am in there for some other reason I may just replace it if it is close to the hundred thousand mile mark.

And finally, thank you to all for the encouragement. It's nice to know that I am contributing, regardless of Final result.

Regards,

Silber

[thom4782]

Sealed bearings are great until...

Over time acids and other contaminants in the oil cause IMS bearing seals to degrade. When this happens, leaking oil causes the grease to wash out. When the grease is gone, splash oil isn't sufficient to lubricate the bearing because not enough oil gets through the seal to adequately lubricate the bearing. With too little lubrication, the bearing fails eventually.

BTW: if you don't buy what I've said, why do you think aftermarket suppliers like LN and TuneRS use unsealed bearings as their fixes to a design flaw?

[Gelbster]

Almost all reputable kits use a single seal bearing to facilitate splash lubrication.There has been a huge amount of discussion on this and few dispute its positive results.
Some diy guys removed both seals .They did not read the oil-in-the-ims-tube discussions.
The potential flaw in the 1RS IMSB proposal is filtration.That can be addressed by a filter upgrade.
But this is just one part of the total subject
The TuneRS kit has the oil line but you can choose not to fit it. If you check experience mentioned by JFP ,you;ll note some serious problems with using the supplementary oil line fed by the port on top of the camshaft cover.

Originally Posted by thom4782

Sealed bearings are great until...

Over time acids and other contaminants in the oil cause IMS bearing seals to degrade. When this happens, leaking oil causes the grease to wash out. When the grease is gone, splash oil isn't sufficient to lubricate the bearing because not enough oil gets through the seal to adequately lubricate the bearing. With too little lubrication, the bearing fails eventually.

BTW: if you don't buy what I've said, why do you think aftermarket suppliers like LN and TuneRS use unsealed bearings as their fixes to a design flaw?

[Silber]

Apparently according to Jake Raby, the inner seals on his bearings are leak free:

which ims bearing upgrade

I would assume with a high quality bearing the seals will be better than the OE porsche ones, but i need to do more research, perhaps combined with a freeze plug in the ims shaft to block thermal expansion and contraction the grease would remain intact.

This post does a good job explaining how oil will get sucked into the tube, though I'm not sure I agree with his solution.

https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/the-frugal-mechanic-meets-a-porsche-boxster/120457/page2/

Scroll about halfway down, look for a wall of text.

Silber