‘40 Ford pickup with TCI front end, GM discs on the front and Wilwood discs on the back. The master cylinder (1 inch GM if I recall correctly) at the stock location with a booster. I’ve bled this thing every way I know how, pushing the pedal, vacuum, and pressure bleeder. I have probably pushed 2 gallons through the system and haven’t seen a bubble since very early on. My wife opened a bottle of champagne last night and there weren’t even any bubbles in it! I took it to a shop and they thought one of the Wilwood calipers was bad so they capped it off and said I had brakes which I didn’t. I’ve replaced the caliper and bled it to death again and have a slightly stiffer pedal that still goes to the floor. I’ve capped off the calipers and have a good pedal with just the master cylinder. I added the front brakes and had a good pedal. I think it’s the Wilwoods but what? What am I missing? All suggestions will be appreciated. Sent from my iPad using The H.A.M.B. mobile app
Did you bench bleed the MC beforehand, do you have any inline residual valves (F&R)? What type of flexible brake line do you have to calipers, braided SS or OEM style as OEM won't take as much pressure as braided line? What diameter brake lines are you running, 3/16"? Do you have the correct brake pedal ratio and pre-load? Do you have sufficient vacuum source for booster? What type of fluid are you using? I originally used silicon (DOT5) however the pedal never felt right and was spongy so I drained and flushed the system installing all new seals and replacing fluid with older style fluid which is still there today. Are you using a particular type of fluid or mixing different types? FYI, silicon fluid is not hydroscopic and does not absorb water, originally introduced to give higher temperature performance over DOT4 fluid. Whatever you do, don't mix DOT 5.1 (Glycol-based) with DOT 5 (Silicone-based) or any other DOT brake fluid as each has a different boiling point. A few variables to consider.
I'd try pulling each caliper one at a time, blocking or clamping the piston so it can't pop out, tapping the caliper lightly to send any air bubbles to the top, holding the caliper with the bleeder at the highest point and bleed away. But that's only one possibility of many that others will no doubt weigh in on.
Have an adjustable push rod? It may be just a tad short and not opening one port or the other allowing pressure. Or too small of master to fill the calipers
Residual valves were not mentioned. Are they in there? Are they functional? Are they installed correct orientation ?
I have bench bled the MC, twice just to be certain. I have residual valves front and rear. Braided stainless to all four wheels, 3/16. Pedal ratio raises a question I’ll have to look into. This was a pedal and MC combo for the ‘40. I did shorten the pedal about two inches to put it at a comfortable position. Could be the problem. What is pre-load all about? I’m using Preston’s Dot 3, no mixing. Thanks for your input, I’ve got some homework to do. Sent from my iPad using The H.A.M.B. mobile app
They’re in there correctly. They seem to hold some pressure at the caliper based on what little brake actuation I’ve gotten. Sent from my iPad using The H.A.M.B. mobile app
The push rod isn’t adjustable unless shims are a possibility. The MC is 1” and should be adequate from what I’ve read. Maybe it isn’t. Sent from my iPad using The H.A.M.B. mobile app
All of the bleeders are at the highest point and I’ve whacked on them while bleeding. Sent from my iPad using The H.A.M.B. mobile app
Whew! When I first read the thread title I thought that Bubbles had quit working at the Deja Vu strip joint.
You shortened the vertical pedal arm behind the floor, or the horizontal portion outside the floor? If you shortened the vertical portion, that will alter the pedal ratio a lot. Might result in you having less plunge into the master, meaning not enough fluid going to the wheel cylinders.
There is very little fluid movement when one steps on the brakes, in my experience a spongy pedal is caused by air.... Sent from my iPhone using H.A.M.B.
I shortened it inside the cab. I still have 4 inches of travel till it hits the floor. Sent from my iPad using The H.A.M.B. mobile app
Wilwood calipers usually have 4 bleeders; there will be two pointing skywards irrespective of which side of the car the caliper is fitted on. You do need to bleed both upward bleeders on each caliper (doing just one side doesn't fully bleed the caliper), and they must be vertical, which might require them to be unbolted from the mount. Chris
Wilwood calipers must have the top bleeders vertical to bleed properly. This might require un bolting the top bolts and rotating the calipers. I had the exact same problem on my 37 and moving the calipers vertical and bleeding fixed the soft pedal. This requirement is on Wilwoods website. Sent from my iPad using H.A.M.B.
They’re vertical and I’ve bled both sides of the caliper. Sent from my iPad using The H.A.M.B. mobile app
The pedal need to return and have free play on the pushrod. on the down stroke The pedal needs to move the push rod about 1" It needs to meet both of those conditions
The master push rod and the little push rod between the booster as well could not be the right length Some times just a 1/4-1/2 turn on the pushrod is all it takes to get the peddle right Does the car stop with the low peddle? I know you have not seen air, but when you open the bleeders and some one is putting pressure on the peddle does fluid squirt out or just dribble ?
Did you use these through the front frame? They trap air that cannot be bled to the design. I originally was using them in my 34 but after reading of the issues trying to get air out of them I switched to under frame tabs.
There has to be adjustment in 2 places, #1 there should be a threaded rod and clevis at the pedal and booster cup going through a rubber boot with at least 1/4" play and #2 an adjustable rod and very small threaded pin like device on the end of that rod between the booster and the master cylinder cup. the clearance there should be only .020-.030. You need to be sure the master is returning fully so it can pick up a full load of fluid for the next application. If it's not filling it's not going to have enough to expand the calipers. I went bullshit trying to get pedal on my avatar pickup with 4wheel vette brakes till I paid attention to the clearances. Ralphie
Again very little fluid actually moves when applying brakes, IF that were the case the pedal would bottom out before it got hard, it would not be spongy it would be a low pedal....same as brakes adjusted wrong or so on. A spongy pedal is caused by air.... Sent from my iPhone using H.A.M.B.
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