Power brakes in a low hood flatty

I finally got sick of my crap brakes in the Jalopy. I have 11" drums and hanging pedals, but the MC was too small for them. I was working on my TJ and looked at the MC on that and thought, "huh, that might fit!" I scored a real nice one from the local pick-a-part.

The firewall was so hacked up that I couldn't use it. So I chopped that area out with the plasma cutter.



I made a new plate up with all my holes and everything. And perfect! That thing fits in there just right with just enough room left for the clutch MC to squeeze in. Tomorrow, I'll finish the plumbing and see how well they work!

 

Can't wait!

 

Cool! This is valuable information. Curious if any issues arise, using a disc brake (or is the TJ disc/drum) set up on a drum brake vehicle.

 

This one came out of a grand cherokee actually. They look the same. I think it should work with drums, because disc needs more fluid flow, right? Wouldn't that just mean it will engage the drums faster? I like too how the proportioning valve is mounted right on the unit.

 

Drums need a 10 lb. residual pressure valve for proper operation. Discs only need 2 lb. You might think of adding some.\

http://www.summitracing.com/parts/wil-260-3279/overview/

 

I think the rears were drums. I'll see what it does, but I'll probably end up having to get one or two.

 

FYI, I think you'll need some conversion fittings for the lines. Newer Jeeps use metric bubble flares and older ones use standard SAE double flares.

 

running a yj power unit on the wife's drum/drum 76 seems to wear the drivers shoes faster than the right but works fine.

 

Ok, I got it hooked up. What exactly is the purpose of those residual pressure valves? They are barely working. I'm not sure if it is air or I need those valves.

 

Ok, I answered my own question. It definitely needs two residual pressure valves. That is what my problem is it sounds like.

 

The residual valves do exactly what the name implies...they keep a pre-determined amount of residual pressure in the brake lines. If you have drum brakes, they will require a 10 pound residual valve.
Disc brakes only need about 2 pounds of residual pressure. A firewall mounted MC usually creates enough residual pressure for disc brakes. Your MC may already have residual valves. You will have to check that out first.

 

How do you check for that? I see lines going from the MC to the proportioning valve and that's it. Would they be built into the MC? I wish I remembered what the Grand Cherokee had for brakes. I bet it was 4 wheel disc. I have 4 wheel drums.

 

It could be built into the MC or in the combination valve, not sure on yours. Maybe someone can chime in that knows.

 

My 2000 Grand Cherokee Laredo had 4 wheel discs.

 

As you, I have 4 wheel 11" drum brakes on my '45 flat fender. I also wanted to install power brakes and used a mid 80's S-10 booster, master cylinder and combination valve. Actually, I modified and used the entire brake/clutch pedal assembly and gained the hydraulic clutch in the process. With this set up, I have not had any problems and the brakes work very well. The residual pressure valves mentioned earlier are normally associated with brake systems where the mc is frame mounted not firewall mounted. In my case they were not installed or needed. If you are interested, a good read on the subject can be found at: http://www.pirate4x4.com/tech/billavista/Brakes/ . I used this information as a resource when I did mine and have not had any problems.

My install [/IMG]

 

Well, after getting the leaky wheel cylinder replaced and adding two 10psi residual pressure valves, WOW, they work superb!!!!! Pedal goes half way to the floor with normal braking and then if you really stomp it, you can lock up all 4 wheels!

 

Good deal. Thanks for the thread.Looks like things are getting tight in the engine compartment.

 

Yeah, it is starting to get tight. At least I don't have OBA or a welder, but I can probably make room for that.