Brake caliper O-rings per SL-00047 leaking

[seagull]

The o-ring seals in my wheel calipers (Matco) are the standard ones, (MS28775-222). They have 1600 hours on them and as preventative maintenance I decided the change them per SL-00047. I have the high temp ones from Van’s, (U-00025) Viton. When I installed them they leak.
I reinstalled several times and no joy, still leak. I put the old ones back in and the leak stops. I have (4) of the high temp Van’s ones and they all leak. I tried both left and right caliper with the same results. The o-ring dimensions are identical to the old ones.
Any idea what is going on?

 

[Walt]

I've always sourced my Grove brake parts directly from Grove, never had any issues.

 

[seagull]

My error, they are Matco, I edited the original post.
But they still leak with the U-00025 Viton o-rings.

 

[seagull]

I spoke to George at Matco today, he said "Take care when using the Viton seals. In order to have a material that is equivalent to the low temperature dynamic temperature limit of as the Buna-N material, it takes a very special (read as very expensive) type of Viton". He didn't know what Van's sells.

Today I was able to source O-rings locally using the spec that Van's lists and picked up (4) for $4.40 ea. I installed in both sides with no leaks.
Using a magnified inspection I can't see anything different in the Van's supplied ones, but they leaked and the new ones don't.

The only thing I can assume is the Van's ones, bought about 6 months ago were possibly mis-labeled.

 

[graywoodworking]

The o-ring seals in my wheel calipers (Matco) are the standard ones, (MS28775-222). They have 1600 hours on them and as preventative maintenance I decided the change them per SL-00047. I have the high temp ones from Van’s, (U-00025) Viton. When I installed them they leak.
I reinstalled several times and no joy, still leak. I put the old ones back in and the leak stops. I have (4) of the high temp Van’s ones and they all leak. I tried both left and right caliper with the same results. The o-ring dimensions are identical to the old ones.
Any idea what is going on?

Yesterday I swapped the o-rings out with new ones supplied by Van's (purchased over a year ago). I haven't re-installed the calipers yet. Now I'm having second thoughts. Has anyone else had issues with the Viton o-rings leaking? My brakes are Grove 30-4M.

 

[seagull]

Yesterday I swapped the o-rings out with new ones supplied by Van's (purchased over a year ago). I haven't re-installed the calipers yet. Now I'm having second thoughts. Has anyone else had issues with the Viton o-rings leaking? My brakes are Grove 30-4M.

I replaced the caliper seals, o-rings, without bleeding the system. It takes a second person to depress the brake pedal to push the puck out. If you hold the caliper slightly above its lowest point no air can enter the system while you exchange the o-ring. After putting the puck back in put a c clamp on the puck so it can’t escape and have the other person push the brake pedal. The puck is stopped by the clamp and you can check for leaks. It is fairly easy and you can check the system before a complete reassembly.

 

[graywoodworking]

I replaced the caliper seals, o-rings, without bleeding the system. It takes a second person to depress the brake pedal to push the puck out. If you hold the caliper slightly above its lowest point no air can enter the system while you exchange the o-ring. After putting the puck back in put a c clamp on the puck so it can’t escape and have the other person push the brake pedal. The puck is stopped by the clamp and you can check for leaks. It is fairly easy and you can check the system before a complete reassembly.

I already removed the caliper because I was changing out the gear leg brake line for a new flexible one. I'm concerned about the new Viton o-rings leaking. Were yours OK?

 

[seagull]

The ones from Van’s leaked, but the ones I got locally did not. I could see nothing irregular about the Van’s ones, no scratches or nicks to explain the leak. They feel exactly the same as the “good” ones. I took the spec off the Van’s part listing and gave it to the local supplier.