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Wilwood disc brakes sticking

Posted: Mon Apr 08, 2019 4:40 pm
by redliner
Hey guys, I got my Stude out for the first time this spring and it seems the mastercylinder is not relieving the pressure very well when I let off the brakes. It takes quite a while ( 15 minutes?)for the pressure to be off (as far as turning the tires by hand.) I have A Wilwood M/C with Dynalight 120-6818 calipers on all 4 corners. Will this heal??? I hope cuz I hate messin with brakes. They haveworked fine for 5 years or so. Easy fix? I hate tearing into them....

Re: Wilwood disc brakes sticking

Posted: Mon Apr 08, 2019 9:40 pm
by BOOT
If you open the bleeder do they let up? If so could be bad soft lines

Re: Wilwood disc brakes sticking

Posted: Tue Apr 09, 2019 2:01 pm
by redliner
BOOT wrote: Mon Apr 08, 2019 9:40 pm If you open the bleeder do they let up? If so could be bad soft lines
I pulled the M/C and sent it back to Wilwood. The brakes would free up when I cracked line at M/C and the M/C is still under pressure.

Re: Wilwood disc brakes sticking

Posted: Tue Apr 09, 2019 11:38 pm
by pdq67
Please note this!!

Make sure your M/C pushrod CAN'T fall out if it's piston sticks!

If it does, the pushrod MAY fall out and then you won't have any brakes!

I used a big P/B M/C on my car and fabbed a retainer that holds the pushrod if the piston ever sticks!

Power M/C's have shallow piston holes that the pushrod may fall out if stuck and non power M/C's have deep holes in the piston so the pushrod can't fall out!

Please check this closely!

pdq67

Re: Wilwood disc brakes sticking

Posted: Sun Apr 14, 2019 10:06 am
by redliner
pdq67 wrote: Tue Apr 09, 2019 11:38 pm Please note this!!

Make sure your M/C pushrod CAN'T fall out if it's piston sticks!

If it does, the pushrod MAY fall out and then you won't have any brakes!

I used a big P/B M/C on my car and fabbed a retainer that holds the pushrod if the piston ever sticks!

Power M/C's have shallow piston holes that the pushrod may fall out if stuck and non power M/C's have deep holes in the piston so the pushrod can't fall out!

Please check this closely!

pdq67
I think I did this when I built it but will double check, thanks!!!

Re: Wilwood disc brakes sticking

Posted: Wed Jul 31, 2019 11:56 pm
by 62ChevyII
Redliner, did you ever figure this problem out? I'm having trouble with my Wilwood Dynalite calipers sticking too...

Re: Wilwood disc brakes sticking

Posted: Sat Aug 03, 2019 2:52 am
by Baprace
redliner wrote: Tue Apr 09, 2019 2:01 pm
BOOT wrote: Mon Apr 08, 2019 9:40 pm If you open the bleeder do they let up? If so could be bad soft lines
I pulled the M/C and sent it back to Wilwood. The brakes would free up when I cracked line at M/C and the M/C is still under pressure.
I think the pushrod to mc needs a little end play, if the rod is too long the mc cannot relieve the brake pressure, you don't need much end play .015 should be enough when every thing is up to temperature. One last item you need a disc brake mc with disc brakes, a drum brake mc will cause the same problems when used on disc brakes.

Re: Wilwood disc brakes sticking

Posted: Thu Sep 19, 2019 1:21 pm
by chimpvalet
A fellow who hosts technical forums over on Yahoo has had big trouble with Wilwood M/C's and puts it down to use of plastic for the retainer on the stem of the internal check valve. IIRC his problem was complete loss of pedal which he attributed to the soft retainer flex causing the stem to cock in bore and thus preventing the check valve from seating at the fluid reservoir entry port. He machined up that retainer "hat" in brass as a solution. FWIW

Cheers

Re: Wilwood disc brakes sticking

Posted: Tue Sep 24, 2019 1:37 am
by HS Nova
Gentleman, you are aware the Wilwood has a recall on some master cylinders. You might want to call them first and see if your master cylinder is affected.

Re: Wilwood disc brakes sticking

Posted: Tue Sep 24, 2019 11:50 am
by chimpvalet
Was not aware of a recall, thanks for bringing that to our attention.

Re: Wilwood disc brakes sticking

Posted: Tue Sep 24, 2019 9:32 pm
by HS Nova