Disc Brake Master Cylinder Delima

[mtrdud]

I just finished converting my 74 FJ40 to front and rear disc brakes. I purchased an AISIN four wheel disc brake master from JT Outfitters. The master cylinder bolts up fine but as you put it on there is pressure being applied. I'ver done several searches and tried some tips such as tightening the adjuster all the way in. By this I am referring to the small rod that goes into the booster on one end and into the master cylinder on the other end. I have also tried to adjust the brake position from the inside. I have the thin booster also. I still need about 1/4" or so to take the pressure off. Can the adjusting rod that goes into the booster/master cylinder be shortened? I have also read about shortening the other brake rod. Any suggestions?

 

[dgangle]

Shorten the rod some more, either by adjusting, cutting or grinding. A good check is to jack up a wheel and turn it. You'll feel if it's dragging. This MC won't have residual valves so disregard that. By the way, exactly what application is that MC for? I bought the same thing from another vendor and have been unable to resolve front to back proportioning issues, even with an adjustable prop valve.

 

[mtrdud]

I'm not sure what exactly it is for. Are you talking about the short rod that goes between the master cylinder and the booster? It appears that the one from the pedal fits into the short one. I though about grinding it some but I was not sure if that would do the trick. If the long rod from the pedal fits inside the short one wouldn't have to drill into the short one to make it deeper as well? I have tightened it all the way and I still need about 1/4" and it is dragging when bolted up that way. Another idea - what about a spacer of some sort??

 

[Poser]

T H I S may help...it is in the FAQ.

 

[rabid]

I just ran into this same problem when puting on a master adapter on my 67. I adjusted the rod from the booster to the pedal 800 different ways. I tried several different boosters, etc.

What I had to do was turn the little 8mm acorn nut on the end of the booster al the way back. It is adjustable there as well (or so it seems) and needed to be all the way in in my situation. You can tell when you bolt on the master that you have to force it on a bit..if so, then the piston is being pushed in before you even get it bolted down. I have not driven my truck yet since the swap, but it seemed to be the problem. If that does not work, a lot of mini masters had a little (actually not so little, maybe 1" or beter?) aluminum spacer betwwen the booster and master. Maybe snag one of those from a boneyard?

 

[mtrdud]

Poser,

I read that one all the way through last night and I thought I had it all figured out. Today is when (after adjusting the small bolt) that I realized I needed another 1/4" or so. What is the best option to get that distance? Grinding? If so where? Spacer?

 

[andrewfarmer]

Poser,

I read that one all the way through last night and I thought I had it all figured out. Today is when (after adjusting the small bolt) that I realized I needed another 1/4" or so. What is the best option to get that distance? Grinding? If so where? Spacer?

Assuming you're talking about the rod from the pedal, on my 40 wwhen I fitted a 60 booster, I had to cut the rod so short I could not use the locknut (loctited instead) - worked fine.

 

[Trollhole]

does it look like this.

If so it's a 95 TLC from an 80

 

[mtrdud]

It looks like that but both connections are on the right side.

 

[mtrdud]

I meant on the right side as you are facing the firewall of the cruiser.

 

[Trollhole]

Very similar. I wonder what the difference is?

 

[snailwagon]

Difference is abs vs. non abs. The picture of the one with 2 side ports is non abs. Ports are reversed on the abs model.

I too have never been able to resolve my front to rear bias problem, even with two proportioning valves.

 

[mtrdud]

I Finally Got It!! (i Think)

I finally got this to work. I took the shorter rod (the one between the booster and the master) and ground it on one end to the right length, drilled inside it to let it slip over the other rod (the one from the pedal into the booster), I tightened the front acorn nut all the way in. It fit perfect and stops real good with no dragging. I don't see a proportioning problem at least yet. I did notice that when me and my son bled them that the front calipers have a lot more pressure than the rears which I would expect. I guess I will see how it progresses but four wheel disc brakes is WAY WAY better than drums. Thanks for the help guys!

 

[Poser]

Glad you were able to modify your pieces to make it work!

 

[WES1977]

JTO RDB master cylinder

Which vehicle is it from?

I want to buy the electric connector for it.

I also want to know what it is from so I don't have to go through JTO anymore.

 

[dgangle]

Which vehicle is it from?

I already asked this and he said he doesn't know. See posts 2 & 3. Methinks it's a 94 V6 Minitruck.

EDIT:
deleted double post

 

[WES1977]

I already asked this and he said he doesn't know. See posts 2 & 3. Methinks it's a 94 V6 Minitruck.

Who is he? I think on post 3 he misunderstood your ? I want to know if anyone knows. I'm going to get the numbers off my master cylinder and see if I can find out what a part # is or something. Ok this my sound stupid but what is a minitruck?