4 wheel disc brake Q:

Anyone running 4 wheel disc? I am setting this up and wondering about power/diaphram vs manual MC. I am hanging a pedal and have plenty of room on the fire wall for a diaphram/power assist. My set up will use (4) 3/4T calipers on F&R D44s. I am affraid a power disc set up would be too much stopping power in the 2300 lb CJ and cause the big brakes to lock up too easy.

So the question is "how much pedal pressure does it take WITHOUT a diaphram/power assist?"...and "is it comfortable driving a non-power assist 4 wheel disc set up?"

Thanks,

 

I've got non power assisted 4 wheels discs on my stock axles and stock MC and it stops very well. Offroad I can hold on steep hills for a long time without problems. I previously had a hydra-boost hooked up inline with my stock MC and drums and that was a noticeable improvement over stock. The discs are much better than that even.

 

Just went to power assist and so far it worlks really well. I have not had it off road yet but on the street it is a huge improvement over manual.

 

I don't have any assist on my 4 wheel discs and pedal pressure isn't a problem.

 

Same here! Without assist, use organic pads, not metallic.

 

Most definitely!

I have 4 wheel disc on the '59 '5 for more than 12 years, don't remember exactly how long. 1/2 ton GM calipers and still have the single reservoir, under floor manual m/c. Stops great! I won't ever go back to drums except on the '57 restoration project....

 

No power. Stops fine.

 

They will obviously work without power, but power is sooooooooooo nice, especially in the rocks. I guess if I were doing it and using a firewall mounting/hanging pedal anyway, a booster would certainly be included-very little extra work.

I used a 7/8" Chrysler booster/master for the 82-84? Shelby versions of the 024/TC3 with 4 wheel discs. Made a light, compact installation.

 

I have also heard that the pedal ratio requirements are different for PB vs MB. The hanging assembly I have is from a 79 waggy that had an auto tranny (which I am going to run as well) I have read that PS uses a 3.1 pedal ratio and MB needs a 6.1 ratio?

Any inputs on the single (brake only) hanging pedal set up and ratios?

BTW that's a really nice looking MC/booster assembly, where did that one come from?
thanks

 

I have pedals from both manual and power applications and the pedal length, pivot points, etc. are identical. The only difference I've found depending on year is the bolt up for the power booster vs. the master cylinder. Many CJ's did have a bellcrank style linkage between the booster and firewall but with the right booster it's not necessary imho. I can't remember if the bellcrank linkage changed ratio or not and I don't have one to look at. Maybe someone else can chime in on that. I know the YJ Wrangler booster I have on the '6 project did not have that.

 

Here is a link to a very good write up on Pirates called The Brake Bible. If you look at the table of contents - Brake System Design, the article in step 9 discusses pedal ratio.

http://www.pirate4x4.com/tech/billavista/Brakes/#BrakeSystemDesign

 

X2, what a difference! I have not had a chance to try it in the rocks but it works great on the street. I used Cherokee booster, M/C and pedal. Almost forgot, only running front disc and rear 10".

 

Wow, now there is the mother-load of brake sys design data! thanks I will digest it all in due time.

 

I used a Willwood master cyl. and hanging pedal from Summit Racing and plumbed a adjustable limiting valve in the rear port and it works great.