90 S-4

more mail, Mike

90 S-4

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Mike Simard

Here are Joe's modified bearings. The grooving is 227 degrees which is similar to the other Porsche bearings as well as aftermarket ones. The groove stops where the oil hole ends. Those holes are good, the 928 block is unique in that an oil channel surrounds the outside of the bearing, I wonder if there would be a benefit in drilling some more holes along the groove? Well, I'm off on vacation, that gives me a week to decide whether my own bearings will be full or partial groove.

BC

I asked Taylor Machine to do the thrust bearing when I had them do the crank drilling. This is what I received back:

90 S-4

Groovy !!
Thanks Mike !!

BC

What did you end up doing Mike? Do you think the groove in mine is wide enough?

Fastest928

Too small.

Vilhuer

Both too narrow and shallow I think.

BC

Wonderful.

BC

Well, what machines do these grooves in the first place? The bottom end was this weekend's project.

Mike Simard

Brendan, I also think that groove is too little. Another thing to help oil flow is to drill a bunch of holes along the groove to draw oil in from the channel outside the bearing. The other Porsche bearings have multiple slots, anything helps. I'm going probably drill about 6 holes in mine. The groove width on Joe's is 6mm, it's depth is the same as the Porsches at 1.5mm. The easy way to make a groove is in a lathe and that's how yours was done. The reason I was able to make the partial groove is that I did them on a CNC mill which required making a somewhat complex fixture. If anyone wants their bearings grooved I can do it for $80 bucks when the work load permits.

BC

If I fed ex'd them to you do you think you would be able to get them done in the next week or so? Its that or I go back to Taylor machine and ask them to redo it. Thats in Whittier, about 1.5 hours north. Let me know.

BC

Looks like I can order the thrust bearings separately for 25 each half or so (If I couldn't get someone to fix these) from various people if I ask nicely.



Because I don't want to buy a whole new set.

Mike Simard

I think I could do them early next week but can't guarantee that, having more to do at the same time helps but nobody else has asked yet. Your shop should be able to make the groove wider and deeper, it would be a fully grooved bearing which should be a good thing, I just couldn't bring myself to do that to mine.

Here's what mine look like, I've added some holes.

BC

Thanks Mike. I will contact you privately with a day or so, otherwise I will just ship them since I have your address somewhere.