So, I just got my vbp o-ring pistons.

My biggest problem, or source of leaking I hope, was that the pistons were too corroded to seal between the piston and the lip seal.

I put new lip seals in the fronts about a month ago, so I know the procedure. This stopped them from (drip drip) leaking for about 24 hrs.

My questions are:
I know to use rtv where the dust boots go on the piston, and on the outside after installing the boot in the caliper, but do you use rtv on the inside. What I mean is where the metal ring of the boot goes into the caliper, do/should you use rtv there, or is there a reason why you shouldnt use it there?

My new pistons came assembled, should I take the o-rings off the pistons and wet them with fluid, or just dunk the dry assembled pistons in fluid before putting them in the caliper?

My calipers have been SS sleeved long ago, and Im planning on leaving the springs out.

Any other tips, or things I should do or not do to get these stupid things to not leak when I am finished would be much appreciated.

 

My first reaction is "why is he using RTV"...meaning something else is wrong if you've got to stop the bleeding with RTV sealant (it's like putting liquid band-aid on a cut that needs stiches...and you're wondering why it keeps bleeding). I assume you're using the new pistons in the seasoned SS calipers. I'm assuming the sleeves are smooth...you mention something about pitting but I'm assuming that was before you installed the new pistons.

You don't say where it's leaking from...could it be where the brake line enters the caliper? Is it all four or only one?

I did the same thing on my 78, replacing the pistons with O-ring pistons and using the existing SS calipers. I removed the springs and run silicone fluid instead of Dot 3 to avoid both the annual brake fluid flushing and concern re the affinity of moisture to Dot 3. Afterward, I drove over 2,500 miles to the 50th celebration in Nashville and than to Hershey and the car has sat for a year...no leaks! My point is you 've got the right idea but something else is causing the leak...just got to pin it down.

Now if the pistons were too corroded to reuse...something is causing that and you've got to figure out if that has been corrected. Moisture causes pitting due to the use of Dot 3 without the recommended annual flushing. You only have master brake cylinder, lines, calipers and pistons. If any single component has lost its integrity...it will eventually infect the remainder of components. My point...RTV is not the solution. I would re-examine those caliper sleeves and make sure they are pit free...if you're leaking from the caliper...something is causing the break in continuity between piston and sleeve.

BTW...yes remove the O-ring, coat with brake fluid and return to piston groove. Keep us posted.

 

I didnt use RTV on any parts when I converted to O-rings more than a year ago. Ive had no problems and have not had to bleed again since the initial install.

 

like the other guys said i don't use RTV any where, did you hone the SS sleeve before installing the pistons? why are you taking out the springs? these springs will keep the pistons fully expanded so that when you hit your brakes the maximum effort goes to pressing the brake pad against the rotor instead of pushing the brake pad out, i would rethink that...

 

He's just talking about RTV on the dust boot.
I assume to keep them better sealed for dust, not to keep fluid in.
I think we all know that won't work.

I agree, though - no sealer should be required.

If the new lip seals still leak, you had better check those sleeves
very well. You may have a scratch or pits.

 

I have done the O-ring conversion to both vettes.

No RTV needed.
Use the supplied grease to coat the o-rings before installing the pistons. Also apply to the rubber on the dust boot before installing them on the pistons. I did not dip the pistons in brake fluid before installing, only used the supplied grease and have not had any problems.

Mike

 

No RTV is needed, Mike is correct along with several others who posted.
We suggest leaving the spring in as bobs77vet said. Only the racers take the spring out, and that is on a rare occasion. A few racers have told me that if they take the spring out they can get maybe an extra 1-2 mph on top end but we do not suggest that for street purposes.

Tony
VBP

 

hunt4cleanair: just to clarify, I just got my new pistons/orings. I haven't installed them yet. The leaking was with the orig pistons and new lip seals. I just wanted to make sure I installed the new pistons/seals correctly, and didn't miss anything.

Ok, my orig pistons are pitted / corroded. I believe that fluid is leaking between the seals and the corroded bits on the piston causing the fluid to fill the area behind the dust boot, then they leak where the boot seals to the piston. Right now both fronts, and one rear caliper is leaking from the piston/boot and nowhere else.

My sleeves are smooth both visually and I can feel no scores or scratches in them.

The cause of the pitting (pistons) I believe is from a previous owner who tried to switch to dot 5 and did not properly flush the system first, so I had a lot of gunk around the pistons, and in the lines. The system has been flushed, and is now clean and clear.

I was not using the rtv as a "bandaid" to stop the leaks. I was using it with new lip seals/boots because I have read a lot of posts here that say to use rtv in the dust boot groove of the piston and to put some around where the boot seals to the caliper. I have also read here that GM started putting rtv on the piston/boot seal in 78'.
68-82 calipers are identical right???

I didn't come up with this stuff (rtv and springs) on my own guys, I got it here.

Quote from my Haynes manual:

On 1978 and later models, before installing the pistons into the caliper apply a bead of silastic sealant (rtv) to the boot grooves in the pistons (the groove closest to the concave end of the piston)
Same thing with leaving out the springs.

There are lots more posts like the ones above, but you get the idea.

I guess there are differences in opinion on these subjects, I have no stance on either, I just want to do it the right way and stop the leaks. Hopefully the new o-ring pistons will do it regardless of rtv and springs.

TONY.....VBP: Is the grease supplied with the o-ring pistons for assembly?? I assumed that it was the same stuff you got with new brake pads to stop squeaking between the piston and brake pad.

But if I read your post (the one you quoted) right, I should remove the rings, grease them before putting them back on the piston, and use the grease as assembly lube when installing the pistons in the caliper. Please let me know if this is correct.

 

TTT

Nobody??

Grease???
Tony?

 

"GREASE" as they put it is SPECIAL brake grease NOT chassis grease or wheel bearing grease or anti-squeek grease...use it sparingly OR use brake fluid...........ONLY!!
...redvetracr

 

Yes, never use any petroleum based products when rebuilding/cleaning brake system parts, use brake cleaner. I've used rtv to better seal the boots also, I've also used copper paste to keep moisture out.

 

The "grease" is Tef-Cone brake lube.
I got a little tube of it for each set of pistons, packaged in a bag w/the dust boots.

 

Not familiar with any grease, all I ever used was DOT5 fluid on the Orings when slipping them home...no springs, they are totally not needed...

GENE

 

there are many different opinions on how do to things on our vettes, there are also many different people who post ideas with varying degrees of knowledge.... its good to ask for and get opinions on how to do stuff.. for example you asked about RTV.... i didn't use any on my 77 ...however in your case the Haynes manual says to use it....so using it maybe was the right thing for you and your car even though I didn't use it on my 77... so what i'm saying is its ok to get varying answers but only you can sort them out and see whats appropriate....Having said that i do hold in higher regard posts from reputable vendors, their livelyhood depends on providing good quality stuff and they deal with it on a regular basis.... good luck on your repair...

 

Thanks, but getting different opinions is what im doing here, I know it's ok.

So -1 for rtv and +1 for no springs.

Still dont know about removing the o-rings from the pistons to lube/grease before assembly.

Guess I'll call vbp monday.

 

What is all this Cra* abought o-ring this and that. Why not just buy a set of rebuilt units from a good company and you are done for at least 8 to 10 years of trouble free braking. I have never had a problem with brakes on my 73 period.

 

OEM lips seals suck air-literally- and can develop a memory set from winter storage, allowing fluid leaks next spring, when you start moving your brakes again. Basically they just suck IMHO.

The O-ring piston/seals dont develop the memory effect it appears and they are much tighter in the bore, which helps to eliminate air pumping caused by slightly out of tolerance rotors.

Just use DOT3 brake fluid on your piston O-ring seals upon assembly, no special grease is required.

Make sure your mating surfaces of the two caliper halves are spotless and there is no paint on them either. Torque them to teh proper settings and you should have no problems-If the stars are in alignment

PS I beleive most trouble free caliper designs use O-ring seals, so there must be something to this.

Brent.....

 

Just got done rebuilding my calipers w/ VBP O-ring kits this weekend. Used the included grease on the O-rings, and on the inside of the dust seals to allow them to slip into the grooves on the pistons more easily. Went together tighter than a drum (no pun intended ), with the springs. I see what WESCH meant about the springs not being quite strong enough to push the O-rings. After a wire brushing and a couple coats of high-temp paint, I'm going to feel bad putting those great looking things back on the less-than-clean car!

-=Boston!=-

 

Thanks Brent/Boston.

Gonna get started tomorrow.
Keep your fingers crossed.
No leaks means I can start on something else.