33 Hot Rod Brake Issue

[Dgc333]

I have posted this same issue on the 33 Hot Rod Facebook page. I am hoping I can get some more suggestions here.

Anyway, to the issue. The brakes are down right dangerous, I can not lock them up even with two feet on the pedal. I have driven my 68 Barracuda with manual disk brakes for almost 20 years so I know what to expect in the way of effort required. They certainly take more effort than the manual drums the car originally had but they never felt inadequate and would easily lock up. The Hot Rod brakes will slow the car gradually but if there was ever a panic situation I would not be able to stop. Hence my driving has been limited to the neighborhood.

What I have for brakes on the hot rod are the Mustang GT dual piston calipers as supplied by FFR. The master cylinders are 3/4" bore Wilwood that were supplied with the kit. The rear calipers are single piston Mustang units with solid rotors I sourced for a 94 Mustang GT. The pads were generic ceramic items.

I initially set up the master cylinders with the bias bar centered and the push rods adjusted to the same length. My initial bleeding of the system was with a vacuum bleeder. I pulled fluid through each caliper until I saw no air. I then followed Wilwoods procedure and did the right front/right rear then the left front/left rear. I saw no additional air bubbles.

The first time I backed out of the garage the brakes would barely stop the car at walking speeds. I lengthened the front mc push rod and adjusted the bias bar more to the front. This made a slight improvement but driving in the neighborhood I needed engine braking to slow the car.

Here are the suggestions from the Facebook forum that I have done. Each of these have made an incremental improvement that I can now comfortably drive in the neighborhood but still can't lock the brakes at anything over 15 or so mph. Engine braking is still much more effective at slowing the car than the brakes. Also, the parking brake can lock up the rear calipers.

1. I replaced the ceramic pads with semi metallic Raybestos brand.
2. Pressure bleed the brakes. I got no air doing this.
3. Reverse bleed the brakes. I initially got a few bubbles in the reservoir with each caliper but several more ounces of fluid did not produce more bubbles.
4. Add more bias to the front brakes.

It was suggested that I swap to 5/8" master cylinders to increase pressure at the calipers. I have not done this yet. I stopped by FFR and asked them and was told that they used to supply 5/8" mc but switched to 3/4" because the smaller bore wouldn't move enough fluid under all conditions. While at FFR I tried the brakes on cars in the showroom with both Mustang calipers and Wilwood calipers. The pedals all felt very hard compared to mine suggesting I still have air in my system.

Any additional suggestions will be very much appreciated.

Dave

[michael everson]

Since it sounds like your near FFR perhaps you could bring it by my shop in Norton so I could take a look at it for you.
mike

[RoadRacer]

Hey Dave,

A lot of the same people here, but this is the better place than FB, where you also get bad advice more often

Given this: "The pedals all felt very hard compared to mine suggesting I still have air in my system." it does seem likely that you still have air trapped. Bleed bleed bleed. Depending on how you routed your lines at the rear of the chassis there are definitely places to trap air.

You should 100% go and see Mike. ^^

[Dgc333]

Since it sounds like your near FFR perhaps you could bring it by my shop in Norton so I could take a look at it for you.
mike

I would love to, I am in Pembroke. Only issue is the car is not registered, I will have to borrow a trailer to get it over there. I have been meaning to give you a call to ask about fitting the doors.

BTW, Kevin Cox introduced us one Sunday morning at the Rebels & Rods cruise in Plymouth.

[Dgc333]

Well I called Wilwood tech support and was told that in some systems the only way to get all the air out is to do a three person bleed. One pumping the pedal, one in a front caliper and one on a rear caliper. Wildwood told me their video procedure, power bleeding or vacuum bleeding do not generate enough pressure in some systems to flush out trapped air. They also said to make sure the push rods are adjusted to get full stroke on the before the pedal hits the floor.

A couple buddies came over today and we went through this procedure. After pushing a quart of brake fluid through the system we got a nice firm pedal. I can lock up the brakes and the car hauls down from speed nicely.

[RoadRacer]

I love it when I finally work out who is who between here and FB. It's only when you see posts on the same subject the penny finally drops

[Just 1 More]

I love it when I finally work out who is who between here and FB. It's only when you see posts on the same subject the penny finally drops

Is there a good FB page just for the 33?

[RoadRacer]

Is there a good FB page just for the 33?

I’m in this one: �� Look at this post on Facebook https://www.facebook.com/share/7wzoN...ibextid=K8Wfd2

[frankeeski]

Is there a good FB page just for the 33?

Your problem isn't just related to the 33. If you want a facebook page that is more concerned with the quality vs number of members go to https://www.facebook.com/groups/251681411988299 We have group experts that can answer your questions. Most of us have experience in all of the F5R platforms.

I will say, if you are certain you have gotten all of the air out of the system and are still having issues, you most likely have glazed the rotors. My advice would be to take the rotors and have them turned to just clean the surface and then go with a more aggressive pad compound from Porterfield or Hawk.

[Mastertech5]

Some of us don't do Facebook.