IXLR8

Next month I'll have my distributor out for a "preventative maintenance" overhaul.

I'll finally get to dimension and post the bearing size which in countless searches, hasn't been yet.

Gunter

Same here, Alex.

I plan to install a new belt on the spare DD more slowly taking measurements of the bearings for future reference. Usually, bearings have a number on the side of the races but these bearings might be too small?
Anyway, dimensions can also be used to find new ones. In the Spring, I'll go to Kaman Bearings in Trail and see if SKF, ***, Koyo or ? has something that will fit exactly. I suspect that they're just sealed single row ball bearings. Once we get the right part numbers, the mystery might be solved.

I can see how a frozen bearing will make the small tooth belt work so hard that it'll eventually either break or jump teeth. With 60k Miles (or 100k Kms) I believe that along with a new belt, the bearings should be changed for piece of mind.

Rinty

I had my distributor rebuilt last year, at 50,000 miles. But no prior issues.

Mike J

Sounds like a solution Guy, but how how accurate was the 0.5mm? I suspect the bearing/shaft has a bit of a snug fit, and I would be a bit apprehensive about being out of round, since that causes a vibration in the distributor. What that considered a tight and appropriate fit?

Cheers,

Mike

Gunter

Out of round and/or the shim moving would be a concern.
I'll get in touch with Bosch and report back.

IXLR8

I'm one to take note of numbers and dimensions. I keep files on stuff like this as well as Porsche-Beru-Bosch, etc part number cross references. It makes the hunt for information and data/specifications at least a bit easier. And if I don't need the info at the moment, maybe someone else on the net does.


Yes, bearings have standard numbers and any suffix usually describes the seals and other details. They also come in various "fits", by that I am referring to the "play". But in this case, I believe a deep groove ball bearing with double sided rubber seals is what we are looking for.

Once I have the exact dimensions, I will have my co-worker check if they are available. He works with bearings in the tribology department; that is all he does...bearing failure analysis.

It has been said that they were specially made for Porsche/Bosch which I find hard to believe. Manufacturers usually take off-the-shelf bearings.



There is very little load on them considering their size and RPM (half engine speed). The belt will fail due to age more than wear in most 993 cases.

Same here. I will as a minimum check them.

By the way, the Bosch number for the distributor is: 0 207 503 004, other script under the part number is: PHFXZ 6x2

IXLR8

And if for some reason they are no longer available, I will get in touch with our machine shop to discuss ways of machining/grinding the inside bore of the bearing.

Mike J

I thought the ID was too large on the bearing that Guy quoted? You mean machine a collar or ?

IXLR8

I thought there were two bearing possibilities; one with a larger ID where a shim was needed and another with a smaller ID which needed to be ground to size.

I'll soon know.

Machining a collar would be a possibility as long as the wall thickness was say 1 mm. There is a 15 mm bearing with a 32 mm OD with thicknesses of 8 or 9 mm.

cosmic_993

Im at 72K miles on my 96, original belt. but a new one is waiting on the bench

Gunter

Sounds good, Alex.
Small correction: The Bosch number is 0 237 503 004 and the Porsche ID number is 930.602.015.01 for the dual distributor. The tooth belt is 930.602.134.00 and available from Porsche AFAIK.

The right size bearing would be best but, we'll see................................

briefescape

The reason the bearings crap out was moisture got in and the bearings had lots of rust ( maybe from when I power wash the engine while it was out ? ) Notice it only when replacing belt , there was no indication beforehand I guess just lucky that I decided to do the distributor maintenance when I did .

As far as the fix , the sleeve ( collar ) it was cemented to the shaft it is not going anywhere . I`ve done 1.5 season approx . 10k km and all is well .

Cheers Guy

Renaud Bizet

When you are ready to change it let me know, I would like to see how it is done as well.

Thanks !!!

Luftd993

When I enquired at a p-car specialist about a replacement belt he described broken belts on a 993 as rare and suggested a complete new unit in a couple of years as the bearings might be starting to wear and new caps would also be good.
He could not source the non standard size bearings used by Bosch.
I found some information on a couple of German Porsche forums and the bearings were listed as INA-Schaeffler Germany 7201 BE 2RS (AH01 F0329, K0807, F0831, special order production numbers) The bore size is 12.45mm, 32mm OD and 10mm deep.
Not available from Bosch and Schaeffler will not sell them either.
This is what INA Schaeffler do have available 7201-B-2RS-TVP angular contact ball bearings.
http://medias.schaeffler.com/medias/...P;bF89aeEIqQ15
I know this size does not tally with what Guy has posted so will have to wait for Alex to report back in the true spirit of the Rennlist with his dimensions and a possible fix that might save us DIYers money. (Unless he develops a commercial interest!)

Gunter

Interesting.
Are the OEM bearings actually angular contact bearings?
Or just regular ball bearings?
Angular contacts are used when, aside from a radial load, an axial load factor is present like on most wheel bearings which are usually double-row as well.

If the distributor bearings are angular contact, they may have to be installed correctly to respect the axial load-factor.