jr73

I will be buying new rear spindles for my 73. Has anyone found when checking their new spindles that they have excessive runout? Is this something suspension experts look for and and correct? For the record I will be buying U.S. made spindles and assume they will be concentric but just wondering if anyone out there has found less than desirable specs.

imariver

I do not know what the acceptable run-out is, (if any) on these spindles, but I did check mine the other day and found .0045 from true center, or a total of .009. These are brand new spindles and the shop that rebuilt the trailing arms in the first place, has them back to correct this.
This much run-out equated to about .0190 total at the rotor

jr73

I think thats a lot. I wonder if you can see a slight wobble in the tire going down the road. It would be interesting to know if anyone has removed the studs and machined a few thousandths off the outer face to true it up.

Mike Ward

Do like the factory did and finish machine the rotor face after installation on the spindle.

jr73

thats a good idea

redvetracr

If I was you I think I would track down Mike Dwyer aka tracgogg2 and ask him which spindles are actually made in America and which ones come in boxes made in America

doorgunner

Can you imagine the amount of run-out/wobble/vibration at the tire tread.

A decent machine shop should be able to "skim" the spindle face with the studs removed to less than .001 total runout...
then reinstall the studs...put the rotors on and torqued properly....
and "skim" the rotor faces true to the skimmed spindle hub---scribe an index mark on the spindle hub & rotor face for future maintenance (not exactly the best way...but would be half the cost of the "right" way).

jr73

one of our sponsors here "Zip" sells an American made spindles $149 http://www.zip-corvette.com/ProductD...GR-SR&CTitle=&

jr73

hey Doorgunner not sure if my PMs are working, did you get my PM?

doorgunner

No.....I'm getting bad service from my internet provider lately too!

Mike Ward

No worse than what came off the factory assembly line. No need to reinvent the wheel here.

jr73

I know, I hope Im not getting carried away here, but like you said above the factory machined the rotor after it was mounted on the spindle. That would take care of it right there. How many guys are putting in new spindles then new rotors and letting it go. You've got to feel that in the brake pedal.

Sunstroked

I had a machinist do exactly this when I rebuilt my T/A's. It didn't make any difference as the rotor bolts up to the spindle, if the rotor hub is not perfectly square to the rotor facings you have gained nothing. I really think machining the rotor once mounted to the spindle is the only way to fix the rotor runout problem.
Now, the real question, who has the capability to do this? Who are you guys using?

Sayfoo

[QUOTE=jr73;1586300085]I think thats a lot. I wonder if you can see a slight wobble in the tire going down the road. It would be interesting to know if anyone has removed the studs and machined a few thousandths off the outer face to true it up.

The rotor runout is more important than the tires. If you don't get the runout down, you will always have brake problems.
Have you looked at run out corrections shim plates. Worked for me.

jr73

I will just take mine to work. I have an unfair advantage, I'm a machinist.

Sunstroked

Pretty much what GM did. I should have had my buddy do the same, I figured truing up the spindle face would be all I needed. Live and learn.

doorgunner

AAAAHAA......someone who understands everything that needs to be done. Could you explain to the members how to use a dial indicator to index a rotor on a spindle hub to eliminate run-out without having to do any machine-work?

Mike Ward

Followed by the aww sh*t moment when we realize that the rear rotor will only fit in one position and still have the adjustment holes for the parking brake line up.

doorgunner

ROOKIES......what are we gonna do with 'em!?

(machine a new "hole"!)

Keep an eye on me, M.W. ..........I need all the help I can get.

tracdogg2

There are only 2 stock design spindles made in America, and they are both made by the same company. But sold by several companies.
The "good" spindles have less than .0005 runout.
Everyone is assuming the problem with original spindles is just runout. The machining from the factory is horrible. The face is not perpendicular to the shaft and it is not flat. Then add years of rust build-up, improper wheel tightening, and those curbs that somehow jump out in front of you, just make it worse. I have machined hundreds of spindles and none of them are flat. The case-hardening on the face is very uneven. When GM trued the rotor after is was riveted to the spindle they did not true the wheel surface.
The company that made the original spindles had to do so under GM guidelines. By the mid-seventies quality dropped severely. That same company makes the new replacement spindles with far better quality. The hub face is now flywheel cut, not lathe cut. The flange is thicker and more uniform.
Mike