Case Throughbolt washer bevel

Walt Fricke · 06-01-2010, 07:07 PM

When Porsche enlarged the spigots for the 2.7s, they had to bevel the tops of the case throughbolt washers (at least the ones right next to the cylinder spigots). They did this because the washers stuck up a bit over the spigot top, and interfered. Earlier engines just had flat thick washers, with the bevel in their IDs.

I have a case from a 1977 930. I bought (at some expense) the late style through bolts with the 1.00 thread, the better to enjoy the more even torquing (or so the factory explained the change). Somehow I was one short of bevel topped washers. I had purchased four new ones, but they came as flat (with ID bevels) washers. What to do?

Well, two go behind the oil cooler, and one is out of the way anyway. So I put one by a cylinder.

It sits below the spigot face.

At this point (I now have a short block) it would be easy to hunt up a beveled washer and use it. Lighter, too! But is there going to be any problem just using the flat one I have?

I haven't measured, but there is definitely some height differential here (washer is lower) you can't see too well in the photos. It has been so long since I rebuilt my SC motor that I can't remember what its washers were.

Walt

Flat6pac · 06-02-2010, 03:53 AM

Walt,
I have a couple you can have, just PM an address and I ll get them out.
Bruce

Cipotifoso · 10-22-2010, 09:34 PM

I've got a different dilemma(?). I was cleaning up my throughbolts/washers/nut hardware and noticed one washer different from all the others. It looks like it was spiral ground(?). It does however, have a smaller/narrower bearing face for the nut or bolt head (could that pose a problem?).
- Is this meant to go in a particular location?
- Is it from a different OEM supplier?
- Or, could it be a shop-ground non-beveled washer like Walt got?

Dave

Cipotifoso · 10-23-2010, 07:32 AM

Here's another picture from a different angle...

Henry Schmidt · Henry Schmidt's Garage

Over the years we have ended up with a plethora of early, flat style washers and as engine got larger we discovered a need for beveled washers.
In response to this dilemma we made a little fixture to bevel the washers on the lathe.
If you need some, we have plenty
The case through bolts are actually better in two ways. Fine thread, for improved torque consistency and they are larger in diameter to offer more rigid case clamping.
Larger diameter and fine threads? Where have we seen that before?
Hint, think head studs.

Henry Schmidt · Henry Schmidt's Garage

Quote:

Originally Posted by Cipotifoso

I've got a different dilemma(?). I was cleaning up my throughbolts/washers/nut hardware and noticed one washer different from all the others. It looks like it was spiral ground(?). It does however, have a smaller/narrower bearing face for the nut or bolt head (could that pose a problem?).
- Is this meant to go in a particular location?
- Is it from a different OEM supplier?
- Or, could it be a shop-ground non-beveled washer like Walt got?

Dave

The beveled washer with the inconsistent look was spun on a grinder.
Put a washer on a dowel like a Philips screwdriver, add a slight amount of tension and apply it to the grinding wheel allowing it to spin while it grinds. Ask me how I know?

Walt Fricke · 10-23-2010, 10:01 AM

Cipo

I'd go with your shop ground guess. If Henry did this kind of thing, others could also. If I had a lathe, maybe I'd have thought of doing that. Looks like it should do its job.

Shows the case has been apart before.

Walt

Cipotifoso · 10-23-2010, 10:47 AM

Thanks Henry and Walt for your replies.

Walt - I know the case has been apart at least once, however; this time it should go together correctly. I hope that paying attention to all the small details will ensure this.

Dave