How do you true a spindle??

[norvalwilhelm]

am finally installing the new 14 inch front rotors. They have been machined as a unit and I know that all surfaces are true to each other.
The next step was installing the rotor on the hub. It is going to be going on and then marking one stud, torque the 5 lug nuts and then with a dial indicator check runout. I use a felt pen and mark on the hat the runnout with the rotor installed in that position, take it back apart, move one set of holes clockwise and do it all over agian remarking the runout with the rotor in that position.
I do this 5 times per side and try to get the least runout. Well without shims all positions show .008 runout?? This must be the hub runout??
I checked bearing play and found .004, this is the front remember.
I will take the .004 out of the bearing tonight and retry but this is the question.
I want to true the hubs themselves. I have the lathe and the dial indicators.
How do you set up something like that that rides on the bearings, not the outer housing. How could you do it???
How do I get my hubs faces trued??
With 14 inch rotors instead of 11 3/4 it really shows up. The calipers don't know the difference so any runout affects them regardless of the distance.

 

[AKRAY4PLAY]

Norval,
what if you pulled the spindle out and and jigged it up in a milling machine?? i think this would allow you to turn the hub and machine out the run-out from a horizontal position. just a thought, for a very interesting and tough question. Brian

 

[Ken Anderson]

All OEM rotors were machined after being riveted to the hub.

 

[norvalwilhelm]

All OEM rotors were machined after being riveted to the hub.

I expect more accuracy then the factory. If you met all their tolerance it is still possible to be outside their tolerances. Doesn't make sense??

The factory allowed wheel bearing play is .001-.008. If you take the .008.
The factory allowable runout on rotors is up to .005. Take the ,005.
The maximum the lip seal on the calipers will tolerate is .010.
Add the two factory tolerances together and you get .013. A sure way for brakes to pump air.
I set bearing play at .001 and keep my rotor runout to below .003 and that includes the bearing play.
Factory tolerances are not good enough.

 

[norvalwilhelm]

This is how I fixed the runout problem.

. Knock out the 5 studs then indicate the face finding the high spots. I would mark high or low at each of the 5 stud postions and then either set it up in the lathe to match these values and lightly skin cut the mounting face or take a grinder a lightly knock off the high.
I could start shimming at this point but would like to get closer without shimming.
As for the rotor and hat runnout, Both sides of the rotor and the mounting face internally of the hat is machined as a unit at the same time. The relationship of the hat and the rotor are then marked so if taken apart they always go together by lining up the marks.
I am fussy about puttings things together, drilling small dimples, filling in with red paint and then machining as a unit . This guarantees minimum runout.

The runout on the hub could be as little as .002 at most and still give me .008 on a 14 inch rotor. To remove the hub and just set it up on the lathe could easily introduce another error of this size.
I feel that knocking the studs out then using a dial indicator right on the hub face while mounted on the car marking the high and low then trying without removing the hub to knock this high spot off is the best. I could use just a light stroke of a file , re indicate and keep working until I get no runout of the hub face.
We are talking about so little runout that with a stock trued rotor I am below .003 but the extra distance really magnifies the runout.
I am at the point that all I need to do is finish this runout problem and bolt the front back together.
I am getting anxious to finish this part of the project.

I did finish the rotors this weekend and got the combined runout and bearing clearance to below .003.
I also posted on how I balance the rotors as the final step before polishing the aluminum hats.

 

[Hib Halverson]

To "true" the rear axle shafts or "spindles" you need to knock the wheel studs out of them, then chuck the axle in the lathe and true the brake disc mounting flange. I've had it done and, yep, even new axles often have run out.

if you true the axle flanges then set rear bearing clearance at .0015, you can end-up with the rear brakes working pretty damn well.

I've been through shims. They don't work that well or easily...if you can get them.

Don't use a grinder!! It's not near accurate enough.

A lathe and accurate cutting is the only way to get flange runout under control.

 

[norvalwilhelm]

It would be very easy to chuck something in the lathe and face it but sometimes even a good lathe can cut a .001 or .002 out just in the setup of the part. When you are looking for .003 absolute maximum 7 inches out .001 runout is not acceptable so the only solution is indicate what you have a do what you can for fix the problem.
I believe is shims for fine tuning, I make them myself and and an assortment of them in small sizes for fine tuning.
What is wrong with a .004 shim placed over a wheel stud and held on my the brake rotor and torqued down. It is not going anyplace, will not corrode and dissapear and will bring that last little wobble out.

 

[norvalwilhelm]

If you indicate the hub and find a spot that is say .001 high a little careful work with a fine file can remove that high spot bring your runout down to an acceptable level.
Removing the whole axle, chucking it in the lathe will not guarantee to improve on your existing runout.