C2 Brake caliper lip seal question

[Lawrence S.]

When rebuilding a rear caliper on a 67 do you install the hydraulic lip seal in the bore first then push in the piston or do you install it on the piston then put the piston in the bore with the seal installed. I just rebuilt one rear caliper for the first time and installed the hydraulic seal on the piston first then had to hit the piston with a socket to get the piston in the bore with the seal on the piston. Well the job is a bust. And I think I know the answer to my question but wanted to find out from someone who has actually done it.

Thanks

Lawrence

[Gene M.]

Re: C2 Brake caliper lip seal question

Well, I'm pretty sure you just destroyed that seal. I suggest you get somebody right along side you that is experienced in doing this to demonstrate the procedure. I would be clueless in how to describe the procedure of loading the piston with new seal in the bore without damage to it. A thin mylar lubricated sleeve to act as a "ring compressor" going in helps. Make sure bore and seal are well lube with brake fluid. Good luck.

[Lawrence S.]

Re: C2 Brake caliper lip seal question

Yep I agree the lip seals are history. Must be a technique...frustrated...

[Gary R.]

Re: C2 Brake caliper lip seal question

You have to install the seal on the piston before installing it in the bore. Lube it with brake fluid and roll in the seal edge 360* to slide it in the bore. The spring goes behind the piston and the boot holds it all in. I smear a LITTLE RTV on the OUTSIDE of the boot to caliper. Don't forget the O-Ring that goes in between the halves. The bolt torque for the front is 130 ft/lb while the rear is 60- the manual doesn't show that difference.

https://www.youtube.com/watch?v=H6r3eJ5BaTQ

NOTE THE ANGLE OF THE SEAL IN BORE

[Larry M.]

Re: C2 Brake caliper lip seal question

Yep I agree the lip seals are history. Must be a technique...frustrated...

As has been already said, lip seal first goes on piston, and then piston goes into caliper. Need some lube, possibly use a bit of silicone grease. I have done it with no special help or tool, but CSSB Inc. I believe still sells a compression tool to assist in this job. Not very expensive. I have the tool, but have never used it yet, so I can't comment on how well it works. I bought it for the next caliper/brake job.

http://www.cssbinc.com/1965-82corvettelipsealpistoninstallationtool.aspx

Similar made steel compression tools are used for installing engine piston rings.

Larry

[Greg H.]

Re: C2 Brake caliper lip seal question

Hi Lawrence,
I recommend that you NOT install lip seals in your calibers. The best repair for leaking brake calibers is replacing the soon to fail new original designed lip seals with O - ring seals.

[Lawrence S.]

Re: C2 Brake caliper lip seal question

Thanks guys.
I had already seen the youtube video but it does not speak specifically to installing the seal into the bore which is my problem. I did install the seal on the piston first. (thankfully) but I guess I did not lubricate it enough to slip into the bore? I bathed it in brake fluid along with all the other parts, however. When I tried to slip the piston with the seal into the bore it just would not go? Thus the socket on the piston and the hammer. I guess I need to massage the seal into the bore gently with a "tongue depressor" screwdriver per the video. This is where I screwed up. I did not recall that detail from the video. I will get it another shot tomorrow or Monday.
As always thanks so much for the comments.
Lawrence

[Joe L.]

Re: C2 Brake caliper lip seal question

As has been already said, lip seal first goes on piston, and then piston goes into caliper. Need some lube, possibly use a bit of silicone grease. I have done it with no special help or tool, but CSSB Inc. I believe still sells a compression tool to assist in this job. Not very expensive. I have the tool, but have never used it yet, so I can't comment on how well it works. I bought it for the next caliper/brake job.

http://www.cssbinc.com/1965-82corvettelipsealpistoninstallationtool.aspx

Similar made steel compression tools are used for installing engine piston rings.

Larry

Larry-------


The best way to install the pistons with the seals is to use the compressor tool. Doing it any other way (and I've done it the other ways) risks damaging the seal, especially the all-important lip of the seal. Using the tool, properly centered, the pistons slip right in with no damage to the seal.

[Lawrence S.]

Re: C2 Brake caliper lip seal question

As has been already said, lip seal first goes on piston, and then piston goes into caliper. Need some lube, possibly use a bit of silicone grease. I have done it with no special help or tool, but CSSB Inc. I believe still sells a compression tool to assist in this job. Not very expensive. I have the tool, but have never used it yet, so I can't comment on how well it works. I bought it for the next caliper/brake job.

http://www.cssbinc.com/1965-82corvettelipsealpistoninstallationtool.aspx

Similar made steel compression tools are used for installing engine piston rings.

Larry

Larry,
Did you just use your hands to insert the seal in the bore with grease? I don't have the luxury of time to wait for the compression tool to get shipped here. I want to get this fixed asap.

Thanks

[Michael W.]

Re: C2 Brake caliper lip seal question

Grease does not belong inside a brake caliper. Brake fluid only.

[Joe L.]

Re: C2 Brake caliper lip seal question

Larry,
Did you just use your hands to insert the seal in the bore with grease? I don't have the luxury of time to wait for the compression tool to get shipped here. I want to get this fixed asap.

Thanks

Larry-------


To be brutally honest, if you're considering using GREASE as a lubricant when installing brake caliper pistons, you might be better off having someone else more experienced do this job for you. No petroleum products of any kind should be getting anywhere near brake system components. That's fundamental and part of basic knowledge that folks working on brake systems should have.

The only lubricants that should be used in brake system assembly operations are the brake fluid destined to be used in the system OR special brake assembly lube compatible with the brake fluid to be used. The latter can be hard to find.

[Larry M.]

Re: C2 Brake caliper lip seal question

Larry,
Did you just use your hands to insert the seal in the bore with grease? I don't have the luxury of time to wait for the compression tool to get shipped here. I want to get this fixed asap.

Thanks

Larry:

It has been a number of years since I last did this work, but I used DOT 3 brake fluid and a very small and dull blade screwdriver to push the lip seals (and pistons) into the caliper bores. Took a bit of time and care is needed to avoid damage to the lip seal.

Regarding the term "grease" that I used in my earlier reply, you will see that I stated to use "silicone grease" and not any kind of common chassis or petroleum-based grease. Mike and Joe are correct in that any petroleum based product in not compatible with brake elastomers or rubbers. Brake elastomer materials are generally EPDM rubber. Compatibility charts that I have from Parker and others show silicone grease to be compatible with EPDM rubber.

Commercial rebuilt brake calipers that I have seen often have a light coating of silicone grease or silicone assembly lube around some of the rubber parts. Since I now use and recommend DOT 5 Silicone Brake fluid, I personally do see not an issue with using a VERY LIGHT FILM of silicone grease on the lip seal and top of the caliper bore for assembly, followed later by a flush and refill of the brake system with DOT 5 silicone brake fluid. One example of silicone grease is the silicone di-electric grease used for high voltage electrical connections in auto and other applications. However, if you do not feel comfortable with this, then stick to using brake fluid for assembly lubrication that is currently in your cars brake system...........ie DOT 3, DOT4, or DOT 5 (silicone). That way you cannot go wrong.

Example: http://cpc.farnell.com/1/1/42871-dow...mpond-dc4.html

Larry

[Michael W.]

Re: C2 Brake caliper lip seal question

Is the silicone grease compatible with DOT 3 or 4 fluid?

[Lawrence S.]

Re: C2 Brake caliper lip seal question

I bought new seals and successfully rebuilt the caliper. I used a very small amount of synthetic grease to get the seals in the bore being careful with a small straight blade screwdriver.

[Larry M.]

Re: C2 Brake caliper lip seal question

Is the silicone grease compatible with DOT 3 or 4 fluid?

Mike:

I don't know where to go to find the specific information to answer your question. Maybe if I search long enough..........

I don't forsee a problem if one uses a light film of silicone grease on EPDM rubber brake parts and then puts DOT3/4 in the system. The big issue to me is will a bit of the silicone grease degrade EPDM.........and the material of construction charts from Parker (o-ring) and others say NO.

The internet is full of stories and testimonials of various auto mechanics using silicone grease versus brake fluid for lubrication during rebuilding brake systems, and I am almost certain that these brake systems are DOT3/4 systems and not DOT 5. DOT 5 is not used routinely except for some of us old car guys and in the military. Also, as I mentioned earlier, some commercial rebuilt calipers I have seen have had what I believe is silicone grease on them. Certainly it was not petroleum grease. It was clear and had the silicone feel to it.

If you and others are uncomfortable with this, simply continue to use brake fluid. I have done this for years myself. Now I think I found a better way, especially for my cars that use DOT 5.