Spongy Brakes

[Sieg]

Originally Posted by usa-69z

and i have moved it up (pivot point) approx 3/4 inch..

Up (closer to pivot point) on the pedal shaft reduces the leverage ratio!

[usa-69z]

Originally Posted by Sieg

Up (closer to pivot point) on the pedal shaft reduces the leverage ratio!

no the pivot point is at the top and the rod has moved up 3/4 " from the original position

i just measured im only getting just over 3/4 inch of push from my piston on the master then im hard on the floor... Wilwoods have 1.10" stroke so im underdone..
Now how to increase the stroke ?? i cant lengthen the rod and the pedal is against the stop in 'rest position'..any ideas?

[Vegas69]

You must be careful not to get your rod to far out of alignment, especially with a 7/8 Wilwood as the rod design is different than the 1". It will cause increased bore wear. It's doubtful it's causing your immediate issues but will cause long term problems.

When you bench bleed, you must make sure you have leak proof connections and your tubes are immersed in brake fluid. Otherwise, even the smallest leak will cause air to be trapped in the cylinder.

I have to agree with Chris and Tobin. I ran a 7/8 and 1" in my car. I always felt the 7/8 was a little to spongy for my taste. The 1" was great on the race track with some heat in the brakes. You had to treat the brake pedal like a red headed step child but the modulation was great. I learned to almost like them on the street. ha Where I agree with Tobin is on the 15/16th being the perfect size for a protouring car. When you want good drivability on the street and track with manual brakes, I think it's the right bore. Especially if you are running a realistic street compound. Clearly, your caliper bore sizes dictate but I've seen this discussion over and over in the protouring segment. Bottom line, if I wasn't a racer, I'd run a booster set up. Racer, a manual set up. As usual with protouring, you have to make a compromise.

[usa-69z]

thanx Todd,, the reason im running non assist is low vacuum with stack injection,, it was just easier and a cleaner look.. should my setup work with the 3/4 " max stroke i have regardless of bore size? Is this why im not getting it to bleed up properly? or because a 1" bore would it need less stroke?

[Vegas69]

Good morning, 3/4" of stroke isn't enough. If I recall correctly, the cylinder has just over an inch of stroke. Also, keep in mind that the higher you raise the rod, the shorter distance the piston will move with foot input. I moved my rod up the minimum amount by leaving just enough material between the factory and new hole in the pedal arm. I did this after switching to a 1". I'd put the rod in the factory position and see if you can get the brakes functional. Then you can move it up a hair.

[Sieg]

Originally Posted by Sieg

Up (closer to pivot point) on the pedal shaft reduces the leverage ratio!

Originally Posted by usa-69z

no the pivot point is at the top and the rod has moved up 3/4 " from the original position

i just measured im only getting just over 3/4 inch of push from my piston on the master then im hard on the floor... Wilwoods have 1.10" stroke so im underdone..
Now how to increase the stroke ?? i cant lengthen the rod and the pedal is against the stop in 'rest position'..any ideas?

My bad........old brain errored again.....sorry. You'd think after using a lever and fulcrum a couple of times last week it would be elementary.

I just measured my travel and it's 3/4" also. I don't think travel length is the solution. I'll assume there needs to be a certain amount of reserve piston travel in the master for safety. The Right Stuff calipers would be my primary suspect. Based on forum observation there's a lot of people running the 7/8" Wilwood with stock pedals with no problems, though this is the first system I can recall (for what that's worth now) using the Right Stuff rear calipers. I do recall issues attempting to use another style of OEM parking brake caliper, possibly a metric?

[Vegas69]

Stroke is 1.1". http://www.wilwood.com/MasterCylinde...inderList.aspx