Pedal questions

[BLS]

"So what to try now?"

This may be too simple, but if the rear master cylinder is good and will not move under force and the rear brake shoes are not against the drums at rest, then perhaps your rear wheel cylinders are frozen. Cars that sit have this problem. My new wheel cylinders with fresh brake fluid (meaning low moisture) were frozen after sitting for one year.

The pictures indicate to me that the rear master didn't move at all, which indicates a hydraulically locked system.

[Campbell Motorsport]

While you may have other issues with the brake system, per Steve Davis and my original post on this subject, until you have the balance bar 90 degrees to the pedal when depressed, the balance bar is not working as designed. See the attached diagrams from Tilton Installation instructions.

98-1250-600-Series-Balance-Bars.pdf (tiltonracing.com)

I still believe that you have the master cylinders reversed, the smaller on should be on the front. I used .625 front and .7 rear, I also used .7 front and ,75 rear for less pedal travel.

Larry Campbell
.

[HB280ZT]

Morning All,

As always thanks for the information. To start with I provided some bad information in an earlier post. The master cylinder setup I have on my Caracal D is a 5/8" master on the front and a 3/4" master on the rear. Sorry for the confusion.


From How it works portion of the Tilton instructions. "A common misconception is that changing the length of the master cylinder pushrod will alter how much force each master cylinder sees, or that it will decide which master cylinder builds pressure first. This is not true." Yet that is what it looks like in Diagram D with the one master to the left having a longer rod length compared to the other rod. Agree or not? I will even out my pushrod lengths when I get home tonight, but it will change nothing with respect to how my system is working incorrectly. Have tried it with no change to the outcome of pushing the pedal.


To set up the balance bar, thread each pushrod into its respective clevis the same amount. Sometimes this will lead to a “cocked” balance bar when the pedal is in the relaxed position, “no pedal effort”. This is acceptable as long as each master cylinder pushrod is completely free of pressure when the pedal is relaxed. (From Wilwood instructions)


When I adjust the balance bar it does not change the angle of the balance bar with relations to the master cylinders, like in the picture. The only thing that changes the angle to match diagram D on my car is to lengthen the rod on one master, like I have it now. The master closer to the throttle pedal is the front master and it has its rod adjust a bit longer.


No matter what I do to the system, when I push the pedal it will always look like diagram C never even like B. So from what Tilton says this is incorrect. This is what I am trying to fix. That and a need to update my pedal assembly so that I can use a Remote Brake Bias Adjuster while on the track and maybe a hydraulic clutch vice a cable operated clutch. I could have used the ability to change bias the other day at the track as it was raining and I could have used less front bias in the rain.


Trying to figure this all out gives me a headache. Yes my car does really good on the track but I know that the brakes are not working the way they should, possibly costing me time on the track.


R/--
Harry
FV#77 CFR

[FVRacer21]

Harry,

It just shows how complicated a "simple" brake system can be and how little things can throw you off.

It seems like you have hit most of the big items. Having the 3/4 on the rear is better and why there is almost no travel, but might not be the optimum set up - but hold that thought for now.

I would take the front drums off - put C clamps on the wheel cylinder and check the pedal travel. It should be virtually none. If not it could be a loose connection allowing air to get in, it could be a bad brake line that is expanding under pressure*, it could be a bad master, or just air in the line that does not want to come out.

*especially if the car had a history of a front accident

I am thinking it might be that your shoes are not properly seated to the drums. The drums could be beveled, the shoes might not be arced correctly, the backing plate might be bent, wheel bearings loose, etc.

Tape a piece of 100 grit sandpaper to the inside of the drum using double sided carpet tape. Then use a magic marker to draw a line on the face of the brake shoe and lightly move it back and forth across the sandpaper - if the mark goes away evenly, then the show if getting good contact. If it is only on the middle or ends, the show is not fitting properly (sometimes you can see this visually without the sandpaper).

I will not get to my car until the end of the week, but as everyone is saying, the angle on the bias bar is not right yet. But at this point we have to figure out why you still have a lot of travel on the front brakes.

My 2 cents

ChrisZ

[Hardingfv32]

Your issue sounds like the brake bleeding complications I have every winter re-assembling my car after upgrades. One of the circuits will have a bubble in it that will not come out. Acts just like what you have been describing. Just my thought on the subject. I waited until all other options were discussed to say anything.

Do not ask me how to get the bubble out. I have a well sorted brake system, so I can tell instantly when there is a bleeding issue.

Brian

[HB280ZT]

Morning All,

As always, thanks for the information. So to give you all more information concerning my current setup. I recently had all 4 drums turned and new brake shoes installed. As stated before I am running Porterfield R4 in the front and R4-S in the rear and they have been bedded in and worked very good on Sebring Club Course a few weeks ago. Like others I have had brake bleeding issues but have figure out a trick that helps with that. Most people pump and hold the brakes after 3 or 4 pumps. Well I have learned on my car that it takes as many as 10 pumps to get the air moving out of the system.


Now talking about the balance bar position when brake pedal is depressed. Are you all suggesting that I adjust the brake rod lengths on the master when the pedal is depressed so that I get the desired balance bar 90 degrees to the pedal?


So enough about the balance bar. I am still looking for ideas of how to update my pedal assemblies from the stock type VW pedals. I currently use the clutch cable setup on my car, but I am not against updating to a hydraulic setup if need be. The major issue with the Caracal D car is the small pedal area, about 9 inches. So putting something like the Tilton 3 pedal assembly in the car requires just a bit of cutting of the frame rails as it is 10 1/4" long. However, the 2 pedal or individual pedal setups that Tilton or Wilwood provide could be an option. Would like to see other peoples setup be it custom or off the shelf, pictures are requested.


Again thanks for the help.
R/--
Harry
FV#77 CFR

[Steve Davis]

Harry,
Have you had any luck with your pedals? I saw an ad for a FF Spectrum today (on this site) with a picture of the footwell and what is likely a custom pedal setup .. probably in about the same width footbox that you have to work with. You can see it at
https://www.apexspeed.com/forums/att...9&d=1637880071
or go look up the ad.. but this is the only pic of the footbox.

From this pic, you can see that the clutch pedal has been modified at the top to move the pedal contact point forward so that the base pivot can be far enough behind the brake pedal to clear the brake bias adjust cable.

Steve, FV80