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Discussion Starter #1 (Edited)
I touched base on this little job on the Trailing Arm post but I also use it for the fronts as well.
Brief history for you "youngsters" who never thought about a corvette brake job until you had to do it or you were recovering from the shock at what your local guy charged you to do brakes and they still failed a few weeks later.

When the rear spindles were assembled to the rotors they were turned as one and thus the surface was perpendicular to the axle centerline. It didn't matter is the spindle flange ranout .010" the rotor was secure with rivets and faced. The fronts were also riveted to the hub and faced. Leavng the dealership, new vettes had superior brakes in their day and still are pretty good. Taking the car to a road course and standing on them all the time is different, but for a street system they were exceptional.

As time went on, the pads needed replacement and then the story changed. Dealerships and local shops( including some corvette shops) would remove the rotors to turn or replace them. The finish off a lathe could be great but once the rotor was in place on the spindle the centerline was no longer perpendicular to the rotor face and they wobbled( runout).The calipers are 4 piston type using lip seals. Runout over .005 would cause them to turn into air pumps and then your brake pedal turns to nothing but air. Big problem.

30-35 years ago SS lined calipers hit the market and everyone thought they eliminated the vette brake problems. Thing is the calipers didn't resolve the runout and few understood what runout was or how to use an indicator for that matter.

So what you need to do it secure the rotors in place and dial in the runout, I like it under .002 but .003 is ok. Over .003' fix it- you're the one driving the car not the guy that just took your $1,000 and said runout is in spec- if he even said that.

You can re-rivet them- why, to be judged?

You can do as many have and just let the lugnuts hold them on? Not the way I like, although I have done that in years past on my cars.

You can bolt them on and they will stay where you set them. You will also be able to replace or service the PB without drilling out rivets.

Since I did rears on the TA post I'll do the fronts now. Follow along it won't take you long to get it and to have vette brakes that work great WITH lip seals in the calipers!:devil:

Here I have a front rotor off my 72. I center punched the rivet heads and will center drill them. Then use a 1/4" and 5/16 bit to drill just below the head. Use a cold chisel across the head and they will pop off and you can remove the rotor. With the rotor off you can drive out the bodies.




I then tap the holes 3/8-24 and countersink the rotor counterbored holes. If you buy aftermarket rotors be sure they have the rivet holes, not all do. REVISION: I no longer use new rotors with rivet holes. I prefer to drill a new bolt pattern to line up the holes better then relying on predrilled holes.

I paint them now as well.



Be sure to clean up all the mating surfaces. I use a 2" die grinder to touch them up.





The flat heads I use do not come beyond the flange to hit anything.


I have a spindle here that I will use for setup. I'll grease the new Timkens and install them. I setup the endplay for .002 by adjusting the spindle nut and facing it on a surface grinder if needed.




Bolt them on and tighten good. I'm not concerned about a torque rating here just equal and tight.


Setup a 1" dial indicator, set it at zero at the highest reading 360* around the rotor and read what you have for runout. Don't be surprised if you have
.010" See if a different tightening sequence changes the RO. If not then you have to shim the difference at the lowest stud. I use SS shim stock and a hole punch kit.





I witness mark the screws and mark the runout.






Maybe your shop does this, maybe not? You can do it at home with a little time and patience.

Good night Irene!!!
 

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man, keep this stuff comin' Gary! At this rate it's gonna be a busy winter :laughing:
 

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Darn good info Gary. Work like that is becoming a lost art. It's good to see that some people still care and have pride in what they do.
 

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Great post Gary. BTW people notice that Gary does not use a cheap
grade of indicator. If your going to do this or anything buy the "good"
tooling and parts.
 

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Discussion Starter #6
I have used the $30 chinese ones in the past and they don't last long before they start to stick. Since I have used these for years and have been doing unit blueprinting I can usually tell if the indicator is not acting correct. The problem is if someone is not experienced with them enough and gets a false reading- big problem. Think about setting up rear bearings to .0015" or diff gears to .005 backlash. The Starrett is the way to go look on ebay or a tool site- they run about $100.
 

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Thanks Gary for posts like these :D .

There priceless :thumbsup:

When it comes to "mechanics" I consider myself a Glorified Parts Changer.

One question though where do you get the SS shim stock?
I've never seen any of this before.
Can this be purchased at a typical parts house?
 

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Discussion Starter #8
You will need to go to an industrial supplier to get the shim stock. Local places usually don't have that stuff. Try McMaster-Carr or MSC online.
 

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Im printing out every one of these articles as you post them. IMO they are invaluable.



:cheers:
 

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where do you get the flatheads, and do you loctite 'em to make sure they don't come loose?
 

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Discussion Starter #11
You can get them at an industrial supplier like MSC or McMaster-Carr. I don;t loctite them, no need as there is no outward force on them. Hand tight is good.
 

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Gary helped me through the process on my car as well... Got my fasteners from McMaster.



I got this Brown & Sharpe dial indicator on eBay for $45 shipped... a steal.



Upon re-assembly I realized that my calipers were leaking... I wanted to drive BAD that weekend, and didnt have any seal kits.
Gary hooked me up... a quick 5 min ride to his house and he had two seal kits for me.

Bottom line.... Gary's the man.
 

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Good write up. Question on rotor runout.

I personally don't like using shims. What I do is find my high spot on the rotor(after I've rotated it in the different locations) and mark it with a magic marker. I than go 90* to the right and to the left and mark that as well. I than flip the rotor over and carry the marks to that side as well so I don't loose my place. On the inside of the rotor where it mates to the hub, I take the marker and fill in my high spot area which is 1/2 of the surface. Than I grind my high spot out w/a 3" angle grinder. It take a couple trys b/c I try not to take to much off at once. Do you see this as a problem or shimming the best?
 

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I going to catch **** over this opinion......

I been working on cars for some pushing 50 years now, feels like it anyway....

it just seems to me these C3 brakes are much to much toooo sensitive a design for reliable automotive use, I fail to see any advantage to them vs most any modern design....even single piston floating, and yes, IMO i'ts that bad.....when the only cure I have found in 12 years is to essentially change everything about the original system design from HB down to O rings/no springs, eliminating that pesky switch block also....in order to get what for NOW is the longest lasting without troubles set of brakes I have EVER had on this car.....adding the HB, then rebuilding the front 1/2 for a bad brake hose locking up the LF wheel, it's been over a year now in faultless heavy use driving....

ANY system with this sort of record that I have been through in 12 years with it, is just plain piss poor design...period.....

the inherent reliability sux, much too sensitive to runout, you get one good high speed stop on any rotor, say 80 to zero on a good hot day, IMO, you can get enough heat to warp any rotor by 5 mils......5 mills is too close a tolerance for any street car, and you guys are shooting for typically less than 1/2 that.....

IMO, the cure is to change all the calipers to a floating design of any pistons that work, and get over with it.....

I have pulled HS stops with other larger heavier cars time and time again, and never had ANY troubles with the brakes, crap, even Linda's little Escort we smoked the brakes 6 weeks ago..but GOOD coming down some mountain road....they fine...no pulsing, no pulling, no leaking, no problem...car stops fine....

IMO, they can do it for an little cheeep Escort, there is something the **** RONG we still stuck with these brakes today.....

some time I just may get enough time and 'tude' to go find a junkyard cure for this whole system, once and for all.....front and rear....


This in NO WAY is intended to slam Gary or anyone else about their work to make it right, I feel I am stating solid engineering facts about the basic design....


:crazy: :WTF :cheers: :huh:
 

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Discussion Starter #16
I think the best way is to do it is as the factory did and secure them then turn them. This is not practical for most though. I don't care for the rivets either. They were great in a mass produced job but the SFHs work as good and offer access without drilling out rivet heads. I don't like using the lug nuts alone to hold the rotor on. The runout will change when removing and retorquing the wheels, how much will vary. I've seen some close within .002-.005 and others out over .010"

I have found success with the procedure I use but yours would work. The concern I would have is indexing the rear rotors and losing the PB adjustment hole and someone grinding off too much. In short order someone could end up wrecking a spindle or rotor. With the shims you can replace and play around with them without any loss except time. For a shop to do it then it gets into labor costs but for a owner it shouldn't be a concern.

It works best with the tools and shims I show as they come in .001 increments and the hole punch really works nice for the ID of the shims. Others have had success with different materials so the end result of a secure runout .002 or better is what you want.
 

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One last question... Without a milling machine how would you recommend a guy gets those countersinks done? You think the same shop would do that after turning the rotors?
 

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I been working on cars for some pushing 50 years now, feels like it anyway....

it just seems to me these C3 brakes are much to much toooo sensitive a design for reliable automotive use, I fail to see any advantage to them vs most any modern design....even single piston floating, and yes, IMO i'ts that bad.....when the only cure I have found in 12 years is to essentially change everything about the original system design from HB down to O rings/no springs, eliminating that pesky switch block also....in order to get what for NOW is the longest lasting without troubles set of brakes I have EVER had on this car.....adding the HB, then rebuilding the front 1/2 for a bad brake hose locking up the LF wheel, it's been over a year now in faultless heavy use driving....

ANY system with this sort of record that I have been through in 12 years with it, is just plain piss poor design...period.....

the inherent reliability sux, much too sensitive to runout, you get one good high speed stop on any rotor, say 80 to zero on a good hot day, IMO, you can get enough heat to warp any rotor by 5 mils......5 mills is too close a tolerance for any street car, and you guys are shooting for typically less than 1/2 that.....

IMO, the cure is to change all the calipers to a floating design of any pistons that work, and get over with it.....

I have pulled HS stops with other larger heavier cars time and time again, and never had ANY troubles with the brakes, crap, even Linda's little Escort we smoked the brakes 6 weeks ago..but GOOD coming down some mountain road....they fine...no pulsing, no pulling, no leaking, no problem...car stops fine....

IMO, they can do it for an little cheeep Escort, there is something the **** RONG we still stuck with these brakes today.....

some time I just may get enough time and 'tude' to go find a junkyard cure for this whole system, once and for all.....front and rear....


This in NO WAY is intended to slam Gary or anyone else about their work to make it right, I feel I am stating solid engineering facts about the basic design....


:crazy: :WTF :cheers: :huh:

After reading this thread, my DRUM brakes are looking real good to me now. I have changed the shoes ONCE in 15 years. The drums are the original from 64.:smack :smack :smack :smack


This 64 is a daily driver.
 

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One last question... Without a milling machine how would you recommend a guy gets those countersinks done? You think the same shop would do that after turning the rotors?
You can also get the countersink bit (for metal, 3/4" I think) at the hardware store. Worked great with the drill press.
 

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After reading this thread, my DRUM brakes are looking real good to me now. I have changed the shoes ONCE in 15 years. The drums are the original from 64.:smack :smack :smack :smack


This 64 is a daily driver.

for all the bothers, I tell you what....DRUM brakes are not all that bad, really I drove many a car for hundreds of thousands of miles, towing, he enough speeds, and so forth....they were not sports cars either...talking 4500-5500 lbs of rolling Pontiacs B body cars....the drum brakes on my '60 vette never gave an instant of trouble either.....

frankly never did the brakes on my '87 vette, except the M/cyl--pads woopie doo....

Disc brakes are nice, don't get me rong, but for street driving, they just plain cheeper or they would n't be on the car.....wasn't for the Ebrakes having to be there by law the drums wouldn't be in the rear either in most cars....

way I remember it, it took a LOT to actually score up a drum and have it warp from overheating....

some day after my latest project, I going to do some junkyard fishing, but the lack of troubles recently has put that on back burner....

I still think a decent ALMINUM caliper set can be had for nothing out of a junkyard, which will work fine with stock shark rotors, give the same pad area, floating design and all they need would be a mounting bracket....woopie doo....something off a higher volume car, so cores are cheeep, and volumes are high enough to support the changeover as being cost effective too....
 
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