Trying Hydroboost, much needed advice PLEASE
- Thread starter BillySS
- Start date
t5montecarlo said:
The manual brake master from a g-body is an option. Only drawbacks are that it's heavier because it is made of cast iron and there is no pushrod retention hole. A retainer would have to fabricated to make sure the pushrod doesn't fall out of the back of the master cylinder and cause a total loss of the brakes.
malibudave1978 said:
I honestly can't say. Any manual brake setups I've ever been involved with were full-on race setups with individual front & rear masters.
Tommy
I am having problems with my system also. I converted using a reman factory Gbody manual master cylinder, and an adapter plate from a manual brake S10. My brakes are all factory front disc, and the factory rear drum brakes on my Chevelle 12-bolt. All brake parts are new including the front calipers, soft lines, rotors, and brake pads...the rears are all new also including the wheel cylinders, hardware, and brake shoes. Used the upper hole in the brake pedal and modified the pushrod. My problem is my pedal is slightly spongy feeling. When I bleed out the brakes the pedal gets nice and firm, but when I drive the car it just does not stop very well. I have bled the system at least 4-5 times and these is no air coming out just straight fluid all 4 corners. Even double checked the rear drum brakes made sure they are adjusted properly with a slight drag. Any suggestions would be helpfull. I honestly am a bit worried that this thing will not stop fast enough at any kind of speed.
malibulvr said:
It is my opinion, that the front caliper bore on stock g-body, s-10, and third generation camaro/firebird with the 10.5” rotors are too small even for a stock g-body 7/8” bore master cylinder. The bore of the caliper is 2.38”. Even with the small 7/8” bore master cylinder I think that the master cylinder cannot get enough pressure to apply the brake pads to the rotors sufficiently. With the upgraded 2.75” big bore metric calipers, the 7/8” bore master cylinder is just adequate.
There is also an issue with low drag calipers that came on s10, third generation camaro/firebirds, and 1981 to 1987 g-body cars. These cars used quick take up (step bore) master cylinders to compensate for the extra volume of brake fluid need to have these calipers operate effectively.
http://www.mpbrakes.com/technical-support/troubleshooting-disc-drum-07.cfm
Spongy brakes for our cars, with a good working system with no air in the lines are cause by master cylinder too big, calipers too small, low drag calipers on the newer g-body, or a combination of these.
I don’t know if the new calipers you bought are low drag or not, but the bore size, in my opinion, is still too small.
On my dad’s 1980 El Camino, I retrofitted his car with manual brakes. I made a 1/8” thick aluminum plate made from 6061-T6 aluminum to position the master cylinder in the stock manual brake location (top two bolt holes). I upgraded the front calipers to the 2.75” big bore calipers, 7/8” diameter rear wheel cylinders for the stock rear drums, and Russell braided brake lines replaced the decades old stock rubber lines. His Elco came with the stock 24mm (.945”) aluminum strait bore master cylinder that has never been replaced. It stopped the car, but it would not lock up the front brakes. I am in the process of testing smaller master cylinders. I am trying to retrofit a mopar 21mm (.827”) master cylinder to the system, but the outlets for the brake lines are 3/8-24. The difficulty is trying to find adapters to go from 3/8-24 to1/2-20 and 3/8-24 to 9/16-18.
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