CSX 4000 rear hub bearing

[Cobra75]

The bearing in rear driver's side hub began making noise. Discovered one of the spacers between the inner and outer bearing had disintergrated. Trying to find the specs on this spacer and the torque specs for pre-loading the assembly.

Anyone have suggestions as to where I can get this info? I have a reprint of the 1966 Ford Shelby Cobra Owners Manual, but it doesn't help.

Thanks for any advice.

[Cobra75]

ttt:

Amy...can you please direct me to where I can get information.

[computerworks]

Originally Posted by Cobra75

ttt:

Amy...can you please direct me to where I can get information.

Scott... I see this has been an open question for you for almost a month.

May be a dumb question, but have you tried just calling SA and asking them?

[computerworks]

...plus I just noticed that this thread is in the Shelby Enterprises Forum.

They are the engine house, not Shelby Autos.

I'll move the thread now.

ron
ClubCobra Moderator

[Rick Parker]

Contact Tom's Motorsports in Vegas.

[mickmate]

Shoot me a PM with an e-mail and I'll send you a page which tells you what you need.

[Tom Kirkham]

There is no spec per say. The bearing spacers are cut to fit to get the right preload. You said that you have a spacer that has disintegrated. I would bet that you meant shim. Do nut use shims they will disintegrate. Anyways what you need is a hardened spacer that is cut to fit. We had a whole stack of different size spacers so we could find the right dimension quickly. We then would make a hardened spacer on the lathe. If the spacer is not hardened the bearing will wear into the spacer and you will lose your preload. We were torquing the bolt to 150 ft-lbs. You also need to inspect the washer to make sure it is not dished. To set the preload we just used a press. It takes way to much time to put the bolt in and out to get the proper set up. Also be sure and Loctite the bolt. Now you know why we went to the Porsche bearing.

[Cobra75]

Originally Posted by computerworks

...plus I just noticed that this thread is in the Shelby Enterprises Forum.

They are the engine house, not Shelby Autos.

I'll move the thread now.

ron
ClubCobra Moderator

Thanks. I think I posted it in both locations, plus I emailed Amy. Phoning SA in the past has gotten me nowhere. Maybe it's better now.

[Cobra75]

Originally Posted by Tom Kirkham

There is no spec per say. The bearing spacers are cut to fit to get the right preload. You said that you have a spacer that has disintegrated. I would bet that you meant shim. Do nut use shims they will disintegrate. Anyways what you need is a hardened spacer that is cut to fit. We had a whole stack of different size spacers so we could find the right dimension quickly. We then would make a hardened spacer on the lathe. If the spacer is not hardened the bearing will wear into the spacer and you will lose your preload. We were torquing the bolt to 150 ft-lbs. You also need to inspect the washer to make sure it is not dished. To set the preload we just used a press. It takes way to much time to put the bolt in and out to get the proper set up. Also be sure and Loctite the bolt. Now you know why we went to the Porsche bearing.

Tom,
I'm not sure what the shim ("spacer" is the term used in the repro Cobra owners manual I have) was made of. Since the brakes were changed to Wilwoods from the original Girlings, the Shelby dealer that did the swap (no longer in business) may have changed the shim or not checked the preload. The "preload" in the manual is defined in an unintelligible number.

Can I convert these hubs with the Porsche bearings or will I need the entire hub assembly? I'd be willing to buy them from Kirkham.

Thanks for the reply. I've worked on several of your cars here at Cobra Inc. Your suspensions are amazing.


My next Cobra will be a 289 KMS/FIA .

[David Kirkham]

The spec is actually "12 inch pounds of torque" to rotate the bearing when the bearing is properly loaded by the hub bolt. If the shim is too tall, you will get less resistance. If the shim is too tight, you will get more--or even lock up the hub.

Interestingly, I had a long conversation with Carroll Smith right before he died about this very problem. He said it plagued the cars in the 60's--seems to still be a problem.

That is why the auto makers have come out with the Gen 1, Gen 2, Gen 3, and now Gen 4 hub assemblies. All four "gen-sets" are still in use today. The Porsche set up is a Gen 1. A while ago, we quit using the Porsche bearings as they were getting impossible to get a hold of. So, we switched to a Lexus bearing--also a gen 1 set up.

Unfortunately, you can NOT convert ORIGINAL hubs to the Gen 1 set up. There is no place to machine the lip into the upright as the seal area of the upright has been machined down to avoid the drive pin nuts.

Now, I am not really sure what Shelby is doing on your car as who knows what bearings they are using now. Take some pics and post them and I will let you know what I think--but I doubt they can be changed.

Your choices are buy a completely new Kirkham set up (you would not be the first)--expensive, but solves the problem completely. We have had NO bearing hub failures...and I hope it stays that way!

Option 2:

Get a local machine shop THAT IS REALLY GOOD to do the set up measurements. We did the set up measurements at 5 tons. You will need to make the spacers out of a HARDENABLE material. Then, they should be rough machined to size in the initial set up. You will have to make them TOO TALL because they will MOVE in heat treat and likely not be parallel when they come out. Then you will have to GRIND the shim FLAT AND PARALLEL to the required dimension. They will have to grind them to +/- 0.0005 inches. It is a nasty trial and error procedure. If you don't grind the shim parallel you will side load the bearing and it WILL prematurely fail...seen that one too.

It is a pain, but it can be done. The shims should be Rockwell 55 C when done. That means they must be heat treated and then quenched to get the required hardness so they will need to be made out of some good steel...not mush metal (I have seen that one too). Sorry to be the bearer of bad news. But there is a reason why no one does this any more. This is not the first time I have had this conversation and as long as people keep doing this it will not be the last.

I am happy to walk you through the procedure if you want in much more detail.

David

[amy B]

Originally Posted by Cobra75

ttt:

Amy...can you please direct me to where I can get information.

sorry, someone sent me a PM as well and I responded, if you email Gary davis or Gary patterson, they will help you

garyd@shelbyautos.com
garyp@shelbyautos.com


Amy