J
jloran
Guest
I just brought a 77 that needs complete break overhaul, but can't get the rear rotors off. Any suggestions would be welcome!
Hi Jloran, If the 77 is the same as my 72 the rear rotors were held on to the rear spindles with rivets. They are in between each wheel stud. That is the way the factory put them on. The shop manual (GM) said to drill them out to remove the rotor and that the wheel lug nuts are enough to hold everything together after any work is done back there. I am going to say something that I KNOW I do not know enough about: The rear spindles are on wheel bearings which I think are pressed on to the spindles, the races are pressed into the bearing carries which are bolted to the control arm. There is a total run out # for the assembled spindles and bearings .008 on my 72. I would think when the rotors were riveted that this run out was taken into account, otherwise the rotor would wobble too much??? I don't have the car or the GM shop manuals any more. I know after replacing my rear rotors I had problems with bubbles in the brake system. I know I did something wrong. I don't know what, I had a recurring bubble situation in the brake fluid. I gave up and went to local chevy dealer (they sold a lot of vettes) and their diagnosis was bad rear spindle bearings. I had them change the spindles and the bearings and the control arm bushings & re-align car and my problem went away. I am convinced I must have done something wrong. I'm just saying do some research. tom
GTR1999
Well-known member
To remove the rear rotors you have to drill out the rivets.The rear rotors are riveted on the spindles then they were turned together to have no runout in the rotor. If you have more then .005" runout you will have air in the system and will not get a good pedal.
Question is what do you have to do?:
Replace pads,rotor,leaks, parking brake?
If the rotor is ok then leave it alone. Replacing or turning it on a lathe may INCREASE your problem if you have runout over .005"
Removing rotor:
1- mark the stud to rotor location so you know where you started.
2-measure the rotor runout with a dial indicator with the caliper off. Should be under .005" better if between .000"-.003"
3- center punch,center drill the rivet heads.
4- step drill up to 5/16" drill size. Drill just beyond the rivet head about 1/4" should be ok.
5- use a cold chisel to remove the rivet head
6-compress the parking brake shoes if you can
7-remove the rotor
8- grind flush the rivet bodies,don't hammer on them because the flange is part of the spindle and bearings don't like to get hammered on.
9- install new/old rotor and start with the marked position.Don't be surprised f the runout is not the same.You may be able to index the position but keep the PB shoe hole open to the star wheel
10- Shim as required in between the rotor and spindle flange to get the runout under .003"
The rear bearings are pressed on the spindles and must have endplay under .003" The GM book calls for up to .008" but the higher numbers will give you bleeding problems with a constant soft pedal. I can tell you how to rebuild the rear bearings but that wasn't your question.
Also don;t overlook the rubber hose for each caliper. They swell closed and lock the caliper. I know of one car that burned up because the caliper was locked up and over heated.If you have original hoses invest the $10 and replace them,if they are several years old do the same.
Question is what do you have to do?:
Replace pads,rotor,leaks, parking brake?
If the rotor is ok then leave it alone. Replacing or turning it on a lathe may INCREASE your problem if you have runout over .005"
Removing rotor:
1- mark the stud to rotor location so you know where you started.
2-measure the rotor runout with a dial indicator with the caliper off. Should be under .005" better if between .000"-.003"
3- center punch,center drill the rivet heads.
4- step drill up to 5/16" drill size. Drill just beyond the rivet head about 1/4" should be ok.
5- use a cold chisel to remove the rivet head
6-compress the parking brake shoes if you can
7-remove the rotor
8- grind flush the rivet bodies,don't hammer on them because the flange is part of the spindle and bearings don't like to get hammered on.
9- install new/old rotor and start with the marked position.Don't be surprised f the runout is not the same.You may be able to index the position but keep the PB shoe hole open to the star wheel
10- Shim as required in between the rotor and spindle flange to get the runout under .003"
The rear bearings are pressed on the spindles and must have endplay under .003" The GM book calls for up to .008" but the higher numbers will give you bleeding problems with a constant soft pedal. I can tell you how to rebuild the rear bearings but that wasn't your question.
Also don;t overlook the rubber hose for each caliper. They swell closed and lock the caliper. I know of one car that burned up because the caliper was locked up and over heated.If you have original hoses invest the $10 and replace them,if they are several years old do the same.
If it's not orginal/riveted - it may be rust. If so they make pullers that you can rent that pull the rotor from the edges and push against the hub. It could be rusted at the hub (spray penetrating oil on and let it sit for quite a while - they take time) or the stupid parking brakes.
Similar threads
Corvette Forums
Supporting Vendors
Dealers:
