Brake Questions

[Tritium007]

Ok guys, the summer has been great. I had some good cruising, but the brake pedal has now decided to go to the floor. After looking over some websites, I have a few questions. Should it be expected that all remanufactured calipers are stainless steel sleeved now or do I have to ask? Is there an advantage to the o-ring design and what function exactly do insulators perform for the brake assembly? I have an '81 and suspect that the calipers are all original although I have records that they have been rebuilt over the years, so I'm assuming that they are not SS sleeved but I have'nt taken anything apart yet to see if they had been converted to o-ring pistons at the last rebuild. Do I rebuild and convert to o-ring pistons and can that even be done on original calipers? OR, do I replace with remanufactured calipers upgraded with o-rings and SS sleeves? Any recommendations on who the buy from? I don't plan on any performance upgrades but I feel strongly enough about my investment to make sure she stops when she needs to. Any insights are welcome.

Thanks,
Mike

 

[GaryS]

Ok guys, the summer has been great. I had some good cruising, but the brake pedal has now decided to go to the floor. After looking over some websites, I have a few questions. Should it be expected that all remanufactured calipers are stainless steel sleeved now or do I have to ask? Is there an advantage to the o-ring design and what function exactly do insulators perform for the brake assembly? I have an '81 and suspect that the calipers are all original although I have records that they have been rebuilt over the years, so I'm assuming that they are not SS sleeved but I have'nt taken anything apart yet to see if they had been converted to o-ring pistons at the last rebuild. Do I rebuild and convert to o-ring pistons and can that even be done on original calipers? OR, do I replace with remanufactured calipers upgraded with o-rings and SS sleeves? Any recommendations on who the buy from? I don't plan on any performance upgrades but I feel strongly enough about my investment to make sure she stops when she needs to. Any insights are welcome.

Thanks,
Mike

If your pedal is going to the floor you probably don't need new calipers, just a master cylinder rebuild. Without any corresponding brake issues, such as pulling to one side during braking or leaking, then this is almost certainly a MC issue. The good news is that MCs are very easy to rebuild; the bad news is that finding a MC rebuild kit is somewhat difficult. Most McParts stores want to sell you a rebuilt MC. When I had these identical symptoms in my 77 Buick, the MC was cheaper than the kit! SInce this wasn't a collectible car, I just replaced the MC. Btw, this is a really easy DIY job.

Gary

 

[Ripp 73]

Or Booster?

While the Master Cylinder could be the culprit, I would also question the Power Booster. I originally thought I had a MC issue until I noticed that I was blowing air out between the Power Booster and the MC. This told me I had a hole in my diaphragm. Again, this is a fun DIY project if you don't mind hanging upside down to get under your dash. Let us know what you find.

 

[Tritium007]

Thanks guys. I do have some caliper leakage issues. I pulled the front right off and had fluid on the inside pad. I suspect the others will have some leakage also. They were all rebuilt in the fall of 1987 and the RR was done again in May of 2001. How can I check the power booster if I've already removed one of the calipers?. I've seen a VBP kit that includes calipers and an MC for not much more. Would you go with the lip seal or the o-ring calipers. Are the rotors friction fit on the hubs?:confused I can't seem to get them to move. Did I mention I hate the whole core charge concept? :L

Mike

 

[gmjunkie]

Thanks guys. I do have some caliper leakage issues. I pulled the front right off and had fluid on the inside pad. I suspect the others will have some leakage also. They were all rebuilt in the fall of 1987 and the RR was done again in May of 2001. How can I check the power booster if I've already removed one of the calipers?. I've seen a VBP kit that includes calipers and an MC for not much more. Would you go with the lip seal or the o-ring calipers. Are the rotors friction fit on the hubs?:confused I can't seem to get them to move. Did I mention I hate the whole core charge concept? :L

Mike

If Rotor's are Org. they are most Likely Riveted!! and you have to drill them out!! You can take them off with out drilling the Front with out too much Trouble!! Rear are a pain in Azzski!! junk!!

 

[Ripp 73]

Yup, if they are the original rotors you have to drill them out. A PIA but it can be done. It does not sound like it is your booster that is wrong, but its hard to say. A way to check would be to have one person hit the brake pedal and another person at the booster listening and feeling for air. Maybe at this point you want to just take the MC off as it is only two bolts if I remember correctly. I have one other question for you, was there any pulling to one side when you would hit the brakes? Or do you hear any sqeaking that goes in time with your speed that could sound like a caliper sticking to a rotor?

 

[Tritium007]

I don't remember any significant pulling when braking. I hadn't had to brake hard enough to see a difference. A couple weeks ago I found a very small puddle of fluid near the rear of the car and started thinking brakes. Front leaks evident shortly thereafter. I got the left front off this afternoon and worse than front right. I don't think there would be any pulling with all the fluid there was on the inside of the rotor. Pads were lubed up pretty good on the inside both front wheels. I was going to replace the hoses with SS braided as I thought the ones on there were original, but noticed they had dates from 5/99 and looked pretty good. I am definitely going to either rebuild or get remanufactured calipers, new pads, and turn rotors (I hope). May replace the MC if the budget allows and I don't need new rotors. Trying to get all the rotors off to avoid core charges. Just not sure which rotors to buy and from who. I suppose this is the time to repack the front bearings also? I appreciate you folks feedback.

Mike

 

[purpleRac3r]

Well, since you're going to have the calipers & MC off anyway, you might as well replace the hoses - call it cheap (ish) insurance. Remember, the next weak link will always be the next to fail. As for the calipers, o-ring SS are the only way to go in my book. The original lip seal pistons tend to pull away from the cylinder bores if they sit inactive for any length of time. This causes leaking. SS sleeves sleeves are more wear-resistant and won't rust which will also cause leaks. I don't think you can even get them without SS sleeves, anyway. I opted for a set of VBP calipers with the piston insulators (that's a reinforced plastic disc attached to each piston to reduce heat reansfer to the fluid - a helpful thing since I autocross my '74). The Beast now stops better than ever. I pulled .88 braking g's at the last autocross according to my G-Tech performance meter.

 

[Tritium007]

Thanks purple man. This stuff adds up quick, but I knew that when I decided to finally take the plunge and get a vette back in April. The car had probably sat for long periods since it only has 56K on it. The cylinders are most likely pitted and couldn't be honed enough to last. Good thought on the hoses. I really would like to bleed'em only once if I can. Here's a photo of the rotors. Are the rivets under those what looks like plastic round covers between the studs?

Mike

 

[Ripp 73]

YuP, those are the rivets. Just take your time and don't chew through too many bits. I would recommend a drill that plugs into the wall as opposed to a battery powered one. Just imagine, 25 years on the same rotors... Do you think rotors in the new Corvettes will last that long? I replaced the ones on my 76, 29 years on one set of rotors. Just amazing.

 

[Tritium007]

Thanks Ripp. Do you need to re-rivet the new rotors? I saw that mid-america sells a rivet kit. Of course I'll try to get them turned first and see if there's enough metal left. If not....add to shopping cart! :L

Mike

 

[purpleRac3r]

I think those rivet kits are for the restoration crowd more than anyone. They were installed at the factor to facilitate quicker assembly (so I've read). I didn't put them on my '74 when I replaced rotors, and have had no trouble - the wheels hold them in place just fine. If you do replace the rotors, might I suggest a set of slotted ones? I know this really begins to add up (my brake job last year ran about $1200 without a MC), but they really facilitate stopping. They seem to reduce fade in hard-brake situations (like my autocrossing). You could also go with dimpled rotors. I'd shy away from actual cross-drilled rotors for the C3's - I've heard they tend to crack a lot. I guess it has to do with the relative small size compared to the newer cars.

 

[Tritium007]

I know this really begins to add up (my brake job last year ran about $1200 without a MC), but they really facilitate stopping.

Let me see how long I can survive on Ramon noodles first. :L I'm competing with pedicures and Mary Kay expenses here (important stuff).

Mike

 

[JohnZ]

If the rotors are still at or above minimum thickness and aren't badly scored, cracked, or damaged, leave them alone; they were riveted to the hubs during manufacturing so the rotors could be finish-machined on the spindle bearings to minimize lateral runout, and drilling out the rivets and replacing them opens up another whole can of worms for lateral runout problems.

If the pedal indeed "goes to the floor", the master cylinder piston seals are shot, unless brake fluid is really pouring out somewhere - that condition has nothing to do with the booster.

 

[Tritium007]

OK, I'll bite. Check your email Alan

JohnZ: Do I have a problem? I got all the calipers off now. The RR caliper appears to be the only one that wasn't leaking appreciably, but it is the only rotor that has had the rivets drilled out. I still need to mic the rotors. Is it a problem to replace one rear rotor if necessary and do you think it needs to be re-riveted? None of the rotors appear to have any scratches, scores, gouges, cracks, etc. They're all just dirty and slick with brake fluid.

Thanks,
Mike

 

[JohnZ]

Functionally, they don't need to be riveted, as the wheels will hold them on just fine; if they've been removed before, it was probably done to work on the parking brake mechanism. What's important is to re-install them indexed EXACTLY in the same position on the wheel studs they were in originally so the lateral runout isn't disturbed.

If the rotors mic OK, I'd leave them alone (just clean them up and remove all traces of brake fluid), and just replace all the calipers (with SS O-ring calipers) and flex hoses, and the master cylinder. If you only replace one caliper, the others won't be far behind, and why do the job twice? Don't skimp on your brakes - they're all that stands between you and a fixed object.

 

[gmjunkie]

Don't skimp on your brakes - they're all that stands between you and a fixed object.

Or Fixen Your Object!! junk!!

 

[Tritium007]

Thanks John and to all for your insights. I'm planning on getting the VBP kit that includes the 4 o-ring ss sleeve calipers, hoses, rear lines, and MC. I'll probably get the power bleeder as well. Does anyone know the specs for the rotor tolerance?

Mike

 

[gmjunkie]

Thanks John and to all for your insights. I'm planning on getting the VBP kit that includes the 4 o-ring ss sleeve calipers, hoses, rear lines, and MC. I'll probably get the power bleeder as well. Does anyone know the specs for the rotor tolerance?

Mike

Stampt on Rotor somewhere,I think back (min. thick. XXXXX) If you can still read it!! junk!!

 

[JohnZ]

Minimum thickness service limit on the rotors is 1.215"; they were 1.250" new.