Just when I though my bearing problems were over.....
 

3.0 Case - I test fit my intermediate shaft with new Glyco intermediate shaft bearings yesterday. Just the shaft, no oil pump.

With the new bearings snapped in place, the intermediate shaft lays in each side of the case and spins freely but when I put the case halves together, I can barely turn the shaft by hand.

I did make sure I had the #8 bearing in place to align the case halves, and checked the bearings for burrs etc. before installing them.

Another frustration with something that should be plug and play - anyone have any experience to share?

http://forums.pelicanparts.com/uploa...1563452886.jpg

I may have missed this on another thread, but how do you know the case is good?

Good question - I haven't measured the intermediate shaft bores but it's unlikely they're out of spec in any way.

The main bores measured out consistently in spec and there is no warpage on cylinder spigots, case mating surfaces, etc.

Other than that, it's a low mileage 3.0 case and there is no reason to suspect anything is wrong with it.

http://forums.pelicanparts.com/uploa...1563461628.jpg

bearings
 

Like the main bearings were a few years ago.Not all intermediate shaft bearings today are the same.New 996 are good but pricey.Ciao Fred

""" there is no reason to suspect anything is wrong with it."""

If I had a dollar for every time I thought this too, I'd be a rich retired man, living on an island in the Pacific, fishing every day and having cocktails in the afternoon, watching the sunset.

But alas, I woke up from my dream surrounded by all of this measuring equipment I have bought over the years for some unknown reason, realizing, this is where my retirement has gone.

What do the old bearings look like and did you test fit them after this snafu? I'd go back to the beginning for a look.

I agree with what you are saying about the tools. Expensive, and not necessary if we could be better with sharing or renting them. How many people have bought rod bolt gauges or micrometers for single usage? I’m one of them.

Edit: Neil Harvey does this for a living. I do not.

That's the plan today. They looked like the dogs breakfast, unfortunately. EDIT - Ok, dogs breakfast is a little harsh, just some strange wear patterns and one half of the thrust bearing looked like it had pock marks all over it. It literally looks like a dog chewed on it.

There is very little end play on the trust bearing when offered up to the int. shaft, loose from the case, and zero evident end play when laid in the case. I suspect an end play issue over a diameter/oil clearance issue.

Will update later, hopefully with my resolution. Searching for, ordering, waiting for, and paying (probably through the nose) for yet another part to replace one I've already got in hand is going to make me even grumpier than usual.

THIS.

Generally speaking, if you take a rotating part and you clamp it down on both sides, and it does not turn, you have two potential problems:

1) the bearing surfaces are too tight
2) the bore is warped

These are the only two solutions.

So when I put a Porsche case in my fixture, and I take my Renishaw probe and probe the mating surfaces and various other features, I usually find that the factory surfaces are not very flat, not very round, and not very consistent.

If the layshaft doesn't turn and the bearings are good, you've got a warped bore that can only be fixed by honing or even better, reboring it and then putting in the appropriate bearings.

Lay the IMS less the oil pump and it's drive tube in a case half with the new shells, give the shaft a rap on each end with a rubber mallet. Do the same on the other case. Check the float.

See my prior posts, I had this exact problem. My case halves when joined together and torqued were off by .007 or so at the intermediate shaft joint, where the bearing sits.

It was like this from the factory, case was like this from the factory. Put the old bearings in, and it spun. Old bearings were worn on the thrust surface mirror sides...

Ran like that 65,000 miles including track time with no issues...

Grab a micrometer, measure the thrust bearing flange thickness of the old vs new bearings. See if both flanges on the old bearing are the same thickness.

Checks your joint line, if your fingernail catches, that could be it...

Yep, may compress it enough to work...

If that doesn’t work report back...

Good advice - I did just that, and it didn't solve anything.

The solution (or actually the problem) was that the Glyco Aftermarket bearings are junk. I measured the bearing shell thickness, like you do, but it didn't occur to me to check the flange thickness. Today, when I did that, I was able to determine that one end of one flange was about .005" thicker than the rest of the flanges on the bearing pair.

The solution, then, was to (A) - throw the new bearings as far as I could, and (B) clean up the old ones (Date coded 2002 FYI) and re-use them. The wear on them was immeasurable and the bearing surface polished up nicely. The "dog chewed" surface, was probably pockmarks from shipping and were non-consequential.

I shudder to think how many sets of these bearings are churning away in rebuilds out there - contaminating the oil, creating heat, robbing power - all in small measures I'm sure but if I'd gone ahead without assembling the case around the intermediate shaft on it's own, I wouldn't have known. Even worse, as the motor warmed up, the clearance would get smaller and the problem progressively worse. Maybe that's just "break-in", but I'm happy to have a nice, free moving intermediate shaft.

PS - If I reached in through the sump cover hole and spun the IMS by hand, ,it would continue to spin for a revolution or two, on its own momentum.

This was, indeed, it, but it was the bearing not the case.

Thanks to everyone for their input!

Order the bearings in a Porsche box... they cost more but proper spec...

Glad it was something simple :).

See all the other threads on glyco bearings. Quality control ain’t great.

I suspect 99% of builders aren’t as anal as most on this board. We are all running around with micrometers... which is a good thing.

Look at how many of these bearings are sold... pelican shows a count. Thousands are installed... most folks aren’t aware of these variations...