Brake booster/master cylinder swap

[rustys76]

I have a 76 wagoneer, with 35's, that doesnt like to stop quickly when needed. i have read some posts about a dule diaphram booster that helps. i have access to a booster and master cylinder from a 91 grand wagoneer. worth swapping the booster? booster and master cylinder? thanks for any help.

[Tad]

Yes, swap both.
The older system was adequate but the dual diaphragm setup is better.
Not as good as a hydroboost swap for larger tires but a definite improvement.

[husker77]

What year did they switch to the dual diaphragm booster?

Is it a bolt on deal?

[Tad]

I am thinking 83-84?
My 82 did not have it, the 86 did.
Didn't save much from the 85.
There might be a few differences I am not aware of.

[ScottsMojo]

I am thinking 83-84?
My 82 did not have it, the 86 did.
Didn't save much from the 85.
There might be a few differences I am not aware of.

Tad I think you are right, I think it was 84. I did this swap last summer and it makes a big difference. A couple things to note, the rod length that attaches to the brake pedal appears to be longer on the newer units which will place your brake pedal further from the floor. I am long legged and this bothered me so I made a 1/4" spacer that mounted between the booster brkt and the firewall.

The only other "issue" is the lines are "backwards" from the 70's models. You will have to move the "front" line to the rear and vice versa, but the good news is in you can do this with the stock lines without any problem.

Good Luck!

[husker77]

So the master cylinder needs swapped also? Or is that part optional?

[Tad]

So the master cylinder needs swapped also? Or is that part optional?

I always prefer HB, but yes, I think you need to do both.

[husker77]

Ideally yes, but it is a lot more involved and expensive.

[rustys76]

I did notice the lines were oposite on the newer unit. I will change the whole thing. Thanks for all of the input. You guys are awsome.

[ScottsMojo]

So the master cylinder needs swapped also? Or is that part optional?

I personally would not use the old MC with the new booster. The master cylinder and the booster are designed to work together.

[FSJ Guy]

Grab the whole assembly. MC, booster AND the brake pedal assembly.

[sgtpoliteness]

Blake and Ethan - this is something I might be interested in until I convert to HB. Next time we're out at the yard let's look!

[FSJ Guy]

There are two (IIRC) FSJ's at the Denver U Pull n Pay and one in Co. Springs. I'm sure the brake assemblies are still there. Heck, no one ever pulls those things. Also, IIRC, you need a 15mm deep socket to pull the MC or brake booster from the firewall.

[rustys76]

OK, i finally finished the new booster and master cylinder install. i opted for the 1/4 inch spacer on the fire wall, worked out good. i drove it for the first time last night and have a couple questions: 1.The pedal travels further than with the old master cylinder/booster setup. it does stop but alot of travel first. i bleed it again, no air in the system. thoughts, normal? 2. back brakes lock up now with heavy braking, i heard they make a proportional valve you can dial to your preferance so the rear brakes dont lock so soon. any thought would be good. thanks

[FSJ Guy]

Did you bench bleed the new master cylinder? It MUST be bleed on the bench or it will still have air. BTDT.

[rustys76]

I went back and bench bleed it to make sure i didnt miss any air. I also adjusted the back brakes to eliminate that as an issue. still has more travel than the old unit. is it possible that is normal operation for the new master cylinder/booster set up?

[44bz]

I recently added a dual diaphragm booster and disc/drum MC to my previously manual braked J2000. I installed everything and had a mechanic do the fine tuning. He said that he adjusted the pushrod between the booster and MC to firm up the pedal and take some of the excess travel out. Maybe that would work for your issue too?

[chevelleguy]

I was thinking of that too. It has probably been 20yrs since I have had to lengthen a MC pushrod, and I can't even remember what kind of car it was on, but I am sure that it was after replacing the booster with a new one. Just make sure you don't make it too long or you will be applying the brakes all the time.

[rustys76]

That had crossed my mind as well, but i thought i would pick some brains before i went down that road.

[rustys76]

So, I made a new rod an 1/8th inch longer and it works much better. Thanks for all the help.