So the O-ring keeps the pads at the ready, right in contact with the rotors?

 

That was the plan.

 

Does it hurt to leave the springs in even with O-ring calipers?

 

Don't know why it would....
If you have a big runout problem the pad is still gunna knock the pistons back, it's just that the o-ring style tends not to pump air into the system like lip seals.

 

there is a small amount of elasticity in the o rings. So when the rotor moves around a few thousandths the o ring position relative to the bore does not change although the piston moves these few thousandths. When called on to move more than that,,, the friction between the O ring and wall is overcome and the position of the o ring changes in the bore.

So the o rings are acting like springs but only for a few thousandths.

 

I personally don't think I would go out of my way to remove them, but I guess if I were rebuilding and using O-rings I would consider leaving them out. I just don't see a benefit when leaving them won't hurt anything.

 

Yeah, I'm in the process of rebuilding my front calipers and everyone seems to agree to leave the springs in when using OEM piston seals. Vette Brakes even told me they help keep the pistons straight in addition to keeping the pads slightly touching the rotors. I don't remember where I saw that paper about not needing them by obviously it was .

 

One of the reasons that AP, Willwood etc. don't have springs behind their pistons is that they are designed to be used with a residual pressure valve. These valves trap a small amount of line pressure when you let off the brake pedal. That is what keeps those brake pads in contact with the rotors.

On the Corvette, the springs do that job.

RGDS

Bob

 

Thanks for the info, Bob.

 

That clears up a lot of questions.

 

Everyone is missing one very important fact. The corvette calipers along with all the 4 piston calipers from the 60's used a lip seal on the piston that seals against a cast iron bore. The side area of the piston is very short and allows the piston to **** in the bores. The purpose of the springs were to keep them against the pads to hold them straight. The early C2 calipers had a shaft extending from the piston into a smaller bore to hold them straight. All brake systems, drum and disc, use residual pressure valves in the master cylinder. Drums are 10#, disc are 2#.
Except corvette all calipers were changed to a stainless steel piston and a square cut seal that fits into a groove in the bore in '70-71. Corvettes changed to this design in '84. All calipers one, two or four piston now use this design. Lip seals create a tighter seal as more pressure is applied. The drawback is they also act as a one-way valve so minimal runout is vital to prevent air pumping into the bores. Oring conversions prevent pumping but the springs should still be installed to keep them pressing against the pads. Under extreme pressure it is also possible for the fluid to be forced between the Oring and bore. Current square cut seals cannot bypass due to their design. They also act as a reaction seal to pull the piston away from the pad when the pedal is released. This effect along with the length of the piston eliminates the need for springs. Residual valves are still needed to keep the lines and hoses full of fluid. Nascar installs springs between the pads to push them away from the rotors for qualifying only, not during the races.
Mike

 

Wow that was amazing. Good job bud.

 

Not quite.
Residual valve are for drum brakes (rear) not for disk brakes.
Adding a valve to disk brakes will create a serious drag.

Pacha

 

define serious.

I have them and they don't create that much drag.. Recently when driving in ice and snow thought it may be a problem but still not sure.

 

When I installed the Zero Tolerance pistons 15 years ago I omitted the springs per instructions. It was obvious they would way too weak to overcome the friction of the O-ring anyway.
That said, has anyone used a heavier spring with o-ring pistons?

 

Are your calipers still with the original seals; fifteen years old and never a leak?

 

the springs are to keep the pistons from rocking in the bores, keep them in

 

They are aftermarket O-ring pistons by Zero Tolerance. They recommended the springs be left out.
The friction of the o-rings on these pistons is more than the stock springs could overcome anyway (i tried them in)
I do think they should have springs as when I removed my calipers to re-do my trailing arms, i checked them and one piston was cocked in its bore. I just need to track down a heftier spring to do the job and not so heavy as to cause excessive drag....

 

I left the springs out just to make it easier to slip the pads in when doing the final assembly. Seems that, for one reason or another, I'm often pulling the calipers. With springs installed, this was always a three-handed hassle.
My '81 is a daily driver and, after two years with new brakes and no springs, not a single brake problem...

 

Thanks for the info but I'm wondering if you've had these Zero Tolerance calipers installed for 15 years without any leaks.