"More Boost"
Major Member
- Joined
- Feb 13, 2005
- Messages
- 522
im probably reaching here, but u havent changed the brake pedal assm. out recently have you?
Brake drag with S-10 brakes
- Thread starter LOT
- Start date
Welcome!
By registering with us, you'll be able to discuss, share and private message with other members of our community.
if this directed to me?
If so, no it is the same brake assembly that came on car. Car is an 85 with factory hyd. boost. The S-10 calipers are NOT aluminum. The factory calipers must be designed for the pressure the hyd. boost puts out as I never had drag with the factory setup. Back to the piston size on hyd. boost---Going through NAPA book on master cyl.--the vans take a 1 1/8 bore piston--more pressure. Make sense as the van is heavier. I can't think of a GM vehicle smaller than the G body that came with hyd. boost. The G-body deisel had hyd. boost but they take the same piston size (actually calls for the same master cyl.) as my car. I see no reason why the S-10 brakes will not work with the Power master assuming the car has the correct master cyl. (15/16 piston). 85 car with hyd. boost and 87 with Power Master have the same brakes all around. The reason the hyd. boost feel and stop better is the added pressure. Now I add the S-10 calipers and the brakes are unbelievable great. Just more pressure then the S-10 were designed for as they are dual piston. Enough pressure to cause the calipers to flex. The GM engineer told me that when they went to aluminum calipers they had the same problem and had to totally redesign the calipers. I have not given up YET, close, but not yet.
If so, no it is the same brake assembly that came on car. Car is an 85 with factory hyd. boost. The S-10 calipers are NOT aluminum. The factory calipers must be designed for the pressure the hyd. boost puts out as I never had drag with the factory setup. Back to the piston size on hyd. boost---Going through NAPA book on master cyl.--the vans take a 1 1/8 bore piston--more pressure. Make sense as the van is heavier. I can't think of a GM vehicle smaller than the G body that came with hyd. boost. The G-body deisel had hyd. boost but they take the same piston size (actually calls for the same master cyl.) as my car. I see no reason why the S-10 brakes will not work with the Power master assuming the car has the correct master cyl. (15/16 piston). 85 car with hyd. boost and 87 with Power Master have the same brakes all around. The reason the hyd. boost feel and stop better is the added pressure. Now I add the S-10 calipers and the brakes are unbelievable great. Just more pressure then the S-10 were designed for as they are dual piston. Enough pressure to cause the calipers to flex. The GM engineer told me that when they went to aluminum calipers they had the same problem and had to totally redesign the calipers. I have not given up YET, close, but not yet.
regal81455
Member
- Joined
- Oct 20, 2008
- Messages
- 419
master cyl.
Either the GM engineer misunderstood my ? or I misunderstood his answer. I was under the impression that a master cyl. with a smaller bore would drop my pressure. It appears I was wrong--a larger bore will drop pressure. That being the case, an Astro van with hyd. boost calls for a master cyl. with a 1 1/8 or 1 3/16. Don't remember, but tomorrow I will see if any of the local discount stores have one in stock. If so I will install and check pressure. Might work.--Lee
Either the GM engineer misunderstood my ? or I misunderstood his answer. I was under the impression that a master cyl. with a smaller bore would drop my pressure. It appears I was wrong--a larger bore will drop pressure. That being the case, an Astro van with hyd. boost calls for a master cyl. with a 1 1/8 or 1 3/16. Don't remember, but tomorrow I will see if any of the local discount stores have one in stock. If so I will install and check pressure. Might work.--Lee
RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
- Messages
- 2,234
Correct on needing a larger bore M/C to lower the line pressure. Some of the Astro vans actually ran a 1-1/4" bore M/C when used with HydroBoost. Check out the '95 MY Astros.
Once the caliper is OK with the pressure, can then further adjust the braking with the pad compound.
RemoveBeforeFlight
update
Got the 95 Astro van master cyl. with a 1 1/4 in psiton. It did exactly as I wanted it to. My pressure dropped from 1500 to 1250--brakes still drag !!!!!! %$#@&$$$$$$$ I guess I need to get someone to help me. Apply brakes starting @ 700 psi and each apply increase 100 psi untill I reach the dragging point. I now wonder if my calipers are ruined. @#$%^& $$$$ pit.
Got the 95 Astro van master cyl. with a 1 1/4 in psiton. It did exactly as I wanted it to. My pressure dropped from 1500 to 1250--brakes still drag !!!!!! %$#@&$$$$$$$ I guess I need to get someone to help me. Apply brakes starting @ 700 psi and each apply increase 100 psi untill I reach the dragging point. I now wonder if my calipers are ruined. @#$%^& $$$$ pit.
Similar threads
