Power drum brakes
rlitavecz
Jeeper
- Posts
- 141
- Media
- 2
- Thanks
- 0
- Location
- Merrillville, IN
- Vehicle(s)
- 1973 CJ-5 258 w/7120 head, Comp Cam, Howell TBI, HEI, stock T15 trans, Dana 20 tc, Dana 30 & 44 axles 3.73 gears, Lock Right both ends
I installed a power booster on my 73 CJ5 this weekend. I purchased a 7" single diaphragm booster on Ebay and used my stock master cylinder and drum brakes. The brakes are in good shape and they are the 11" x 2" drums, so I didn't want to spend the money to convert to discs.
I cut the shaft that connected the pedal to the master cylinder and welded a 3/8" sae coupling nut to connect to the new booster. I had to cut the input shaft on the booster to get the correct pedal free play. I made a template from cardboard to drill the new holes in the firewall. The top 2 bolts also hold the pedal assembly inside the vehicle. The center hole had to be enlarged using a rotary file to fit the boot from the booster.
With the new booster mounted, I cut a spacer to fit in the master cylinder from what was left of the original shaft. It ended up just over an inch long. There must be a small amount of freeplay between the booster shaft and the master cylinder piston. I bent the brake lines to allow the master cylinder to bolt in place. Eliminate the boot at the master cylinder. I never removed any lines and did not have to bleed the system.
I installed a 3/8" hose barb in the intake plenum and ran a hose to the booster.
The brakes work great! I estimate about 25% reduction in pressure needed. I would guess that an 8" booster would work better, but I am not sure is room. I have to change out my air filter to clear the master cylinder (14" x 3"). I will try a 2" spacer and a shorter filter. I may have to use a 10" x 3" to clear the brake assembly. The booster was only $63 in chrome. I could have gotten a gold anodized one for $54. Chrome is faster!
I cut the shaft that connected the pedal to the master cylinder and welded a 3/8" sae coupling nut to connect to the new booster. I had to cut the input shaft on the booster to get the correct pedal free play. I made a template from cardboard to drill the new holes in the firewall. The top 2 bolts also hold the pedal assembly inside the vehicle. The center hole had to be enlarged using a rotary file to fit the boot from the booster.
With the new booster mounted, I cut a spacer to fit in the master cylinder from what was left of the original shaft. It ended up just over an inch long. There must be a small amount of freeplay between the booster shaft and the master cylinder piston. I bent the brake lines to allow the master cylinder to bolt in place. Eliminate the boot at the master cylinder. I never removed any lines and did not have to bleed the system.
I installed a 3/8" hose barb in the intake plenum and ran a hose to the booster.
The brakes work great! I estimate about 25% reduction in pressure needed. I would guess that an 8" booster would work better, but I am not sure is room. I have to change out my air filter to clear the master cylinder (14" x 3"). I will try a 2" spacer and a shorter filter. I may have to use a 10" x 3" to clear the brake assembly. The booster was only $63 in chrome. I could have gotten a gold anodized one for $54. Chrome is faster!
