I posted this issue a couple of years ago but cannot find the string of answers associated with my concerns. After the master cylinders were re-sleeved by White Post I found the pedal travel to be excessive. I have Willwood front calipers and it is this associated master cylinder that accounts for the excessive travel. IE- the travel of the front cylinder is about 3 times the distance of the rear master cylinder.
I have bled the system thoroughly and while the car stops fine and I’ve sort of gotten used to it…, It’s rather disconcerting going down a steep hill! I’m thinking about finding a larger diameter master cylinder for the front brakes but wondered if there’s something else I’m missing. Thanks for any thoughts.
This appears to be your original thread that you couldn’t find…
I still have full stock system so can only offer best guesses.
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You talk about bleeding by vacuum. I used a MityVac system for several years and believe it to have been a marginally effective system due to the aforementioned thread air leaks. Even after sealing the threads with their special thread paste I’d still get occasional bubbles so it was difficult to tell if I had a complete bleed or not. I switched to a pressure system and now get a 100% flush and don’t waste a lot of fluid in the process.
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Did you try switching the old larger front caliper pots to the rear? People have suggested it improves braking balance. But it would also have to bring fluid volume balance closer.
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Is the brake box, balance bar set up so that your booster activating and discharging correctly?
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How is your actual pedal set up? Is it up parallel to the clutch and it’s still sinking to the floor?
Hi David,
Thanks. Of course, I found it as soon as I posted my new one… Thanks again.
Hi Erica,
I pressure bled the system and the pedal is reasonably firm when the brakes finally take hold so I don’t think it’s air in the line. Interestingly, I did switch the larger original front calipers to the rear but there is still a big discrepancy in the travel between the front and rear master.
Im calling Willwood tomorrow to enquire about adding a residual pressure valve to the front system. Perhaps this will hold a little pressure and reduce the amount of travel.
Balance bar and brake/clutch pedal level are fine.
Wish me luck and thanks for your input./Mitch
Erica is right. “Vacuum bleeding” is rubbish.
Does the math add up with your master cylinders and Willwoods?
Whenever excessive pedal travel is an issue, always check the runout on the brake rotors and the play in the wheel bearings. Either will “knock back” the pads, resulting in excessive pedal travel.
I might be able to help as I have the same brake setup as you do on my '62 which works very well. The volume pushed by the two master cylinders seems to be similar as the balance bar remains at the same (near vertical) angle for full travel. I will see if I can track down the model details for my Wilwoods and then we can compare. Paul
Hi Erica, Sorry but i cannot agree with that statement. I think what you might have meant is that the MV device did not work for you. I have done numerous vacuum bleeds of partial and total brake systems with a vacuum pump. It was a refurnished high vacuum pump that was retired from a chemistry laboratory!!!
The MV itself is capable of developing sufficient vacuum to pull fluid out which is all it’s really intended to do. The issue is knowing when to stop. Between the plastic adapter which pops onto the fitting, and the potential for air leakage around the fitting itself, which is exacerbated by the age of the castings and wear to the threads over the years, getting some bubbles is an eventuality. So it becomes a judgement call on when to stop. I could pull an entire $15 bottle of fluid through every cylinder and never truly know whether the bleed is sufficient because an occasional bubble would still appear.
By reversing it and pushing fluid through the variables are removed and once a solid, bubble free stream has been pushed through for 10 seconds or so, I can be confident that it is fully bled.
I didn’t do that with Tweety, when I put Wilwoods on the front, and the brake balance was just fine.
I also just used the gravity bleed method, equally fine.
Have SNG English made fronts, stock 3.8 , 1964 brake set up and stock, but new, rear calipers. Also in my case, evertyhing seems to work just fine. They bragged about the quality and value of the fronts and I agree. My Asian, stainless rears caused trouble and needed replacement. The West Coast guys who sold the faulty rears stopped carrying them some time ago.
BTW, the “RAF” blue shocks visible.
Hello Larry,
At this point ,some 12 year after I installed the Wilwoods I wish I had kept the stock system. At the time which was very early in the restoration process, it seemed a good idea to replace the rather small Dunlops with something bigger and more modern. Thanks for the feedback/Mitch
Hi,
I was advised by Ray Livingston that the Wilwoods are only 35% larger than the stock units. I’m going to ut a dial indicator on the discs and see if there’s any noticeable run out.
I had my originals sleeved by a California outfit. They were junk - many things wrong with the job - including losing a master cylinder which they denied liability for (I had a delivery receipt from the post office which even included the time of day the parts were delivered). I wasn’t aware of the issues until I assembled the car literally years later. After goofing around trying to fix the foul ups I just got the new ones from SNG. Ditto for the new rears, but I “only” had to replace one. In that case the stainless bore had chatter marks which prevented a seal in the bore. Due to the time elapsed these foul ups cost us many hundreds of dollars and many hours in redo work (not easy to replace a caliper in the rear without removing the cage). I did test the rears before installing the cage, but my rig didn’t develop enough pressure to reveal the leaks.
Why? More characters to meet minimum requirements.
I wonder, too: I did the Wilwoods for the sole reason, that buying two new calipers was, at the time less expensive than getting one set of OE pistons resleeved.
It also happened that the Wilwoods were half the weight of the OE calipers, not that that made a sensible difference on the street. The Wilwoods worked as well as the OE calipers, so it wasn’t because of superior performance.
Hi Paul,
So, do you also have a very long brake pedal travel? I have a suspicion that my problem may be in the re-sleeved master cylinder as I had the Wilwood set up prior to having WhitePost re-sleeve both masters and the travel was fine. It’s always something… Thanks/Mitch
Hi Larry,
I hear you! I’m going to take the front master apart and see what it looks like. I had a problem w/one of the rear calipers that was also re-sleeved as it leaked like crazy upon installation. Fortunately, I tested it before I put the cage back in.