When you put the dial indicator on the spindle to check for runout make sure you only check the machined surfaces. Any cast surface will not show you accurate runout even on a new one. If you know someone who has a metal lathe they can chuck it up and rotate the spindle and watch the indicator for runout. That would be the best way I know to get a true reading on the spindle.

 

I like to have the spindle turned down to establish a .002" friction fit with the bearings. Makes reassembly (and subsequent disassembly) much easier. This is a very controversial procedure on this forum but it works for me.

 

How tight did GM make these fits? I wonder why they felt it needed to be so tight, especially compared to the front bearings.

 

The reason WHY is very well documented and documents a fundamental engineering error made by GM on the new '63 Corvettes. The original design had a fit similar to a front wheel bearing. If it works well on the front, why not on the rear, right? Nope.

The difference is that the rear spindles rotate, the fronts do not. In both cases, the inner bearing races are loaded 'upwards' on the spindle by the weight of the car. If the clearance is .001" loose fit, that 'gap' will be at the top of the spindle. In the case of the fronts, since the spindle does not rotate, there's no continuous motion between it and the bearing race. The opposite is true on the rears since they rotate and the inner race is constantly being moved in the vertical plane an amount equivalent to the clearance.

Given enough time, the constant motion heats and wears the sides of the bearing races, shims, etc. etc. and the race will be 'free' enough to occasionally turn on the spindle along with the bearing. In some cases the spun bearing causes enough friction to overheat the whole assembly and the spindle sheared, releasing the entire wheel.

GM issued tech service bulletin DR#599 on June 10 1963 introducing the scheme that existed to the end of C3 production in 1982.

In addition to the 0.0005" tight fit bearing, a belts and suspenders 100 ft/lb torque was specified for the spindle nut.

End of bearing problems in that respect.

Now you know why I shake my head every time some shade tree expert undoes all the engineering improvements by making the bearing a slip fit again.

 

That is the best explanation I have ever heard of why the General made the rear wheel bearings so tight. It makes perfect sense. However, I still say they don't need to be as tight as they are. There is no reason why we should need a 50 ton press to disassemble these things. All of my cars have had the spindles turned down and I have never had a failure in 25 years of Corvette ownership.

 

We agree with Tracdogg2, 99% of all original spindles have face run out so we face them on our lathe or OD grinder.

Probably one out out every 30 caliper brackets we check are junk because someone used the threaded rod method removal of the spindle and bent the ears. A bent caliper ear will make the caliper mount crooked then it will not ft over the rotor.

We have had customers lose a wheel or come close to it... because the undersized spindle outer bearing heated up. It is metal to metal spinning with "NO" lubrication. Imagine you engine crank with no lubrication. The inner bearing journal is designed slip fit with no lubrication which often leads to a scored surface. (junk)

We also see spindles where a torch was used previously to remove the bearing and left a deep torch gouge on the bearing journal. (junk) The mechanic got the job done but poor customer is riding on unknown borrowed time.

 

The tight fit plus the 100 ft/lb. torque was a belts and suspenders approach- but it does follow industry engineering practices on how to make sure a race never ever slips again.

The other element is that GM declared the bearing assembly to be 'sealed for life' meaning that there would be no reason to ever disassemble it again.

It was in sometime in the '70s (IIRC) that GM reversed themselves and declared a service interval of around 35K miles for inspection and regreasing/replacement.

They never thought that these cars would still be around half a century later.

 

I believe the original "slip fit" spindle nut spec was around 50# .

 

I used 4 lengths of threaded rod, through the spindle support/mounting holes, with a 1/2" steel plate on the other end (drilled 4 holes), then tightened down the nuts (evenly) on the rods and pushed/pressed out the spindle. No press involved.

It created a lot of tension on the rods, however they stood up and pressed out the spindle.

 

Good method. The threaded rod is easy to get but the 1/2" plate can pose a problem if there is no steel distributor in ones area. Where did you get the plate?

 

The plate came from a friend who was a Boilermaker working in a large shop that repaired Locomotives.
It came drilled, ready to go.

Also there is a local shop, "Metals 'R' Us", they seem to have just about anything you want.

 

Everything Mike Ward has said is correct. Mike doesn't like replacing rotors or trueing spindles unless it is absolutely needed. But here's something else to think about. If the spindle face is crooked, which they all are, then the wheel mounting surface is also crooked. Spread that out over a 26 in. tire and you will have some tire wobble. How much? Who Knows. It depends on how bad the spindle is. The only way to fix it is to true the spindle. This usually requires replacing the rotor. But if you want a good laugh, and you know someone with a lathe, take an old rotor and have them reface the surface the mounts to the spindle face. You will be amazed how bad they are.
Mike

 

To clarify- I don't like seeing people inadvertently induce rotor run out problems by doing a half-a** brake job.

Do it properly or not at all.

People just love to spend money on recently acquired cars. It somehow makes them feel good to see shiny new parts and brake rotors seem to be a particular favourite. This an innocuous act on Honda Civics or similar where rotors were designed to be a field replaceable throw away item, but not at all true on C2/C3 brakes.

The vast majority of C2/C3 rotors don't need replacing or turning at all- the act of doing so is a frequently an unnecessary up sell or a CYA practised by brake shops to limit come backs.

Mike- we all know that GM finish machined the rotor surfaces after mating the rotor and spindle or hub, which makes them a matched set. I have some information that says that wheel mounting surface on the rotor was also machined at the same time. This would negate the wheel wobble you allude to.

 

That would require the rotor hub face to be machined after it was riveted but before the wheel studs were installed. Since the equipment that installs the front wheel studs in the hub leaves 4 indentations in the hub surface I would expect to to see the same in the rear rotor hub surface. I'll check that out first chance I get. You may very well be correct.
If that was done then just installing a new rotor on a crooked spindle may induce tire wobble, a symptom that wasn't there prior.
Mike