turbo nasty
Turbo Dojo / MNTR
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- Jul 19, 2001
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- 9,478
Leo you are gonna be real happy after all of this and the troublesome sealed bearings in those spindles start making noise. Hope it works out for ya tho either way
Brake drag with S-10 brakes
- Thread starter LOT
- Start date
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Scott, you are correct and you may be correct on the pressure idea.
I could sing it for you. Yes, I did install the brakes later--I am going to get a 3000 lb. gage today. It may be that there is more pressure than the brakes were designed for. If I regulate the pressure down then my brakes may suffer. Something has to give. See you soon. Do you want the # for motel in Tenn? that we are using. I know you said you were doing your own reservations.
I could sing it for you. Yes, I did install the brakes later--I am going to get a 3000 lb. gage today. It may be that there is more pressure than the brakes were designed for. If I regulate the pressure down then my brakes may suffer. Something has to give. See you soon. Do you want the # for motel in Tenn? that we are using. I know you said you were doing your own reservations.
bearings
Luckly I was able to get @ a steal on a new set of GM bearings that I have setting on shelf.
Luckly I was able to get @ a steal on a new set of GM bearings that I have setting on shelf.
turbo nasty
Turbo Dojo / MNTR
- Joined
- Jul 19, 2001
- Messages
- 9,478
Good...your ahead of teh game. Unfortunately they tend to go out. Kinda like a br sw on the PM brake system. Inherent to them
Just talked to a local guy who has a 3000 lb. brake gage just for this. He is bringing it into town tomorrow. Thanks anyway. Here is the room info
Comfort Suites
2431 Williams Street
Chattanooga, Tn.
423-265-0008
I believe they have double bed suites with an extra rollaway bed.---Lee
Maybe
I have yet to hear from the GM brake engineer--hopefully soon. With the help of our good friend (John Bruce) We installed a 3000 lb. gage @ the end of hard line where flex line joins. With eng. off I could push 600 psi to calipers. With eng. running and @ idle or 2000 RPM--didn't matter --we got 1500-1600 PSI. I still would like to know FOR SURE what I should be seeing for those calipers, not the Hyd. boost specs but the S-10 specs. I ask my GM parts guy in In. to check with some mechanic but he was unable to get the psi info I need. That info is out there somewhere. Google search has yet to turn up what I'm looking for. I did call Wilwood tech and the gentleman there said that with 1500 psi on the back side of piston fluid would eventually push by the square o-ring and start leaking as that was starting to happen. There was fluid between the o-ring and dust seal. He said that they design their dual caliper piston for 1000 psi. They sell a PRV (pressure reducing valve) as does Jegs and Summit but the range is 100-1000. I will be looking for one with a larger high # say 1500 or 2000 psi. All you thumb suckers, wish me luck.--Lee
I have yet to hear from the GM brake engineer--hopefully soon. With the help of our good friend (John Bruce) We installed a 3000 lb. gage @ the end of hard line where flex line joins. With eng. off I could push 600 psi to calipers. With eng. running and @ idle or 2000 RPM--didn't matter --we got 1500-1600 PSI. I still would like to know FOR SURE what I should be seeing for those calipers, not the Hyd. boost specs but the S-10 specs. I ask my GM parts guy in In. to check with some mechanic but he was unable to get the psi info I need. That info is out there somewhere. Google search has yet to turn up what I'm looking for. I did call Wilwood tech and the gentleman there said that with 1500 psi on the back side of piston fluid would eventually push by the square o-ring and start leaking as that was starting to happen. There was fluid between the o-ring and dust seal. He said that they design their dual caliper piston for 1000 psi. They sell a PRV (pressure reducing valve) as does Jegs and Summit but the range is 100-1000. I will be looking for one with a larger high # say 1500 or 2000 psi. All you thumb suckers, wish me luck.--Lee
Free @ last !!!!
Installed a PRV right off master cyl, started car and gage reads 600 psi-- inceased pressure to a max. of 900 as that is the max. range of PRV. Running knob in any farther shuts PRV OFF!!---O pressure. Back knob off and test drive. Come back and raise car and wheels turn free. Brakes are not as good as @ 1500 psi. Those brakes spoiled me. Plan is to find another PRV that has @ least a 1500 max range. Install and see what is the max. pressure before drag comes back. So it looks like Hyd. boost and S-10 brakes don't play together well, @ least I could'nt get them to.
Installed a PRV right off master cyl, started car and gage reads 600 psi-- inceased pressure to a max. of 900 as that is the max. range of PRV. Running knob in any farther shuts PRV OFF!!---O pressure. Back knob off and test drive. Come back and raise car and wheels turn free. Brakes are not as good as @ 1500 psi. Those brakes spoiled me. Plan is to find another PRV that has @ least a 1500 max range. Install and see what is the max. pressure before drag comes back. So it looks like Hyd. boost and S-10 brakes don't play together well, @ least I could'nt get them to.
RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
- Messages
- 2,234
Interesting problem and an even more interesting reason. I never would have thought that the excess pressure would deform the seal so that it didn't pull back the piston.
The reason I posted is that my understanding of hydroboost systems is that they use a 1-1/8" bore M/C. This provides good volume but at a lower pressure.
Not sure what bore M/C is on the car now, but a 1-1/8" M/C may be a better choice then running a pressure reducing valve.
RemoveBeforeFlight.
The reason I posted is that my understanding of hydroboost systems is that they use a 1-1/8" bore M/C. This provides good volume but at a lower pressure.
Not sure what bore M/C is on the car now, but a 1-1/8" M/C may be a better choice then running a pressure reducing valve.
RemoveBeforeFlight.
more info
I got the return call from the GM engineer. It looks as if the 1500 psi is more than the S-10 brakes were designed for. The square o-ring it not deforming (I should hsve worded it better)--it is being twisted outward toward pads as it is designed to do. It is returning to its original shape as it is supposed to do. The excessive pressure is pushing the pistons a small amount farther than they should go. The square o-ring is returning back to its original shape as it should but since going too far this leaves the piston a little short of releasing pads. He also mentioned that they design a brake system for a certain amount of caliper flex @ a max. pressure. I am probably getting excessive caliper flex which would contribute to the problem. He did also mention master cyl. bore size. I have a list of ? and plan to call him first of next week. This all makes sense as I can free brakes with screwdriver--drive car normal --raise car and brakes are free--power brake car --raise car and they drag. Thanks to all who have helped. I will keep posted.
I got the return call from the GM engineer. It looks as if the 1500 psi is more than the S-10 brakes were designed for. The square o-ring it not deforming (I should hsve worded it better)--it is being twisted outward toward pads as it is designed to do. It is returning to its original shape as it is supposed to do. The excessive pressure is pushing the pistons a small amount farther than they should go. The square o-ring is returning back to its original shape as it should but since going too far this leaves the piston a little short of releasing pads. He also mentioned that they design a brake system for a certain amount of caliper flex @ a max. pressure. I am probably getting excessive caliper flex which would contribute to the problem. He did also mention master cyl. bore size. I have a list of ? and plan to call him first of next week. This all makes sense as I can free brakes with screwdriver--drive car normal --raise car and brakes are free--power brake car --raise car and they drag. Thanks to all who have helped. I will keep posted.
RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
- Messages
- 2,234
OK, now I got it, caliper flexes which allows the piston to extend. This extension of the piston is the same as when the pads wear, it slides through the seal a fraction to take up the gap.
Release brakes, caliper relaxes from it's flex, allowing the seal to retract the piston. However, this just compensates for the caliper flex.
Then there is nothing left of the seal flex to pull the piston/pad back off the rotor and it drags. Who'd had thought?
I recall reading your (this) thread a week or so ago and was stumped.
RemoveBeforeFlight
valve
I assume you are talking about the valve I bought from the local speed shop that stopped adjusting @ 900 psi. I have removed it from can and will not be reinstalling it. Do you want it?
I assume you are talking about the valve I bought from the local speed shop that stopped adjusting @ 900 psi. I have removed it from can and will not be reinstalling it. Do you want it?
regal81455
Member
- Joined
- Oct 20, 2008
- Messages
- 419
any updates Lee?
As of now
I firmly believe the hyd.boost and S-10 brakes will NOT work in combination with my current master cyl. Doing some checking I have found that my car came with a 1 1/16 in dia. piston in the master cyl. I have changed it in the past but believe it has the correct bore dia. piston. Doing the math--if I can find a 15/16 in. dia. piston master cyl, it would drop my pressure just short of 20 percent. So I believe going from 1500 psi to 1200 would cure my problem. Now comes the problem of finding a master cyl. that will bolt up to the hyd. system. The 87 Powermaster unit take a 15/16 in. piston master cyl. but WILL NOT bolt up. My last chance is to try to contact Cardone who are the only reman. company doing this. And see if such a master cyl. exist.
I firmly believe the hyd.boost and S-10 brakes will NOT work in combination with my current master cyl. Doing some checking I have found that my car came with a 1 1/16 in dia. piston in the master cyl. I have changed it in the past but believe it has the correct bore dia. piston. Doing the math--if I can find a 15/16 in. dia. piston master cyl, it would drop my pressure just short of 20 percent. So I believe going from 1500 psi to 1200 would cure my problem. Now comes the problem of finding a master cyl. that will bolt up to the hyd. system. The 87 Powermaster unit take a 15/16 in. piston master cyl. but WILL NOT bolt up. My last chance is to try to contact Cardone who are the only reman. company doing this. And see if such a master cyl. exist.
turboc87gn
Darkside in Detroit
- Joined
- Oct 2, 2008
- Messages
- 2,766
Im wondering if the astrovan hb will have the same prob? I used that one but i haven driven my car yet since i added it? What about the stock calipers they are a lot more old school than the the s 10 calipers but they are also arent aluminum...Im using wilwood bolt on replacements I guess ill know soon hopefully someone else can chime in....
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