Master Cyl Swap from 90 Cherokee

[pflaming]

Gonna try a couple of things and if they don't work, I'll pull the MC again and get a kit.

Well, "nothing ventured, nothing gained."

[NiftyFifty]

Oh ok, deffinately a different set up then, I can't see any reason why it should work then, but as I say make sure you do a manual bleed if that doesn't cure then your back to the wrecker

Was supposed to say "shouldn't".... Stupi iPhone auto correct :@

You didn't adjust the valve at all right?

[pflaming]

I did not mess with the valve. I just have a hard time accepting MC failure. The donor vehical had less than 100K miles, and was rust free, i.e., probably a "valley" car.

[NiftyFifty]

It was full of brake fluid when you got it? If it was dry it may have dried out the deals internally. Did you make sure your push rod is doing the full stroke of the mc?

Just tossing ideas out there...

[pflaming]

I tried two things: (1) I put fluid in the sprayer and put the line under pressure, (2) I went to the brake pedal and gently gave it 3/4 pushes, slow and steady and (3) EURIKA!!! I got pedal,nice and strong at about 2/5 down. Maybe the fluid in the sprayer changed (one post said it was IMPORTANT and it obviously is) the game.

It is not difficult to make that pressure system. I drilled a hole in then lid, used two brake nipples, then a fitting with a 1/4" stub and connected that to the sprayer.

"Happy days are here again" and I'm not a Democrat:)!!!!!!!!!!

ps. I kept the sprayer 'trigger' so I could apply presure as I wished.

Edited July 27, 2012 by pflaming

[ggdad1951]

glad it worked for you! Did you do that trick I told you about for the tube that goes into the MC?

Thats seems just like the same cheapo sprayer I used for mine.

[pflaming]

ggdad: Yes, worked fine. Well, I took it around the block. I can stop but they are VERY SPONGY, so some air must still be in the line(s). As I was driving I pumped the brakes to get things to 'seat' in. Back in the shop, I did a quick check of the connections and did not see any leaks and the MC reservior was still full.

So will do a repeat bleed tomorrow.

"Close, but no cigars!"

[NiftyFifty]

You kids and your fancy bleeders... I did mine the good old fashioned way once 3 years ago and haven't touched them since

Glad your on the home stretch, soon you'll be stopping on a dime!

[pflaming]

"You kids and your fancy bleeders" Thank you for the compliment, but I'm as old as dirt!

Some observatons: (1) There are slight differences between mine and 4mula-dixs' MC and valve; (2) They have a mixed and matched metric and SAE fittings, so take note; (3) Space is still tight for the replaced MC, about 1/2" between the MC and the steering gear box; (4) if you use a fabricated mount, make the mounting bolts for the MC as short as possible, then the MC will mount with the new mount on the housing, (drilling new holes in the housing will give you another 1/4"; (5) if you carefully cut off some of the post that comes from the pedal, you can put that in after the MC is mounted, otherwise, it must come in before the MC does; (6) location of the proportioning valve is a personal thing, I put mine in close, but that means two short lines with 90 degree bends and that is tricky to get the fittings to start; (7) I mounted the brake light switch in line and that hasn't been tested yet; (8)with the proportioning valve and the "T" for an inline brake switch, there is a lot of tubing and fitting work involved; (9) I would suggest all 3/16" lines to the front for sure, so much easier to work with, I now have all new lines; (10) my valve has an electrical 'low fluid" senser, so I have to buy some sort of light and mount it on the dash, that's a nice feature; (11) there are a number of manufacturers for this MC, mine is a Bendix; (12) if you have a hoist and experience with plumbing it's not a very hard swap, I'm on the floor with the truck on a winch and stands and that gets very tiring.

I'm glad I did it, once debugged (a friend is coming over today to help) this will be a very good safety upgrade; discs up front, larger - newer brakes in the rear and a new dual MC, and new lines.

I trust these few comments will be helpful to someone.

Edited July 28, 2012 by pflaming

[jboymechanic]

4mula-dlx,

 

Do you have the part numbers for the master cylinder and valve you used in your conversion?

Edited August 6, 2013 by jboymechanic

[RobRobitaille]

Is a proportioning valve needed with 4 wheel disk brakes?

[Don Coatney]

Is a proportioning valve needed with 4 wheel disk brakes?

Most likely yes.

[Plymouthy Adams]

check with your distributor of the swap kit or the donor car you are grabbing the parts from...these should stay matched..

[pflaming]

Six month follow up: brakes still work GREAT! I had a lower pedal than what I liked and had to do quick pedal pre pedal for a good pedal. Then a month or so ago I had the truck on a rack. A mechanic was helping me and said, "Your rear brakes are not tight" I replied how do you know" ". . . because I can spin the wheels". 

We tightened the rear brakes (97 Cherokee) and the pedal came up to where it should be. So check those rear brakes!

[Plymouthy Adams]

you could have done the same thing by backing up and hitting the brakes now and then...

[pflaming]

Ply: you mean this old truck actually has a reverse?  I thought this was a THREE SPEED, Gotta try it! 

Edited November 18, 2013 by pflaming

[Jeff Balazs]

Yes. And I think it should be an adjustable proportioning valve on any retrofit or upgrade.

 

If you stop (no pun intended) and think about it.....it is really the only way you are going to get the correct amount of front to rear braking adjusted properly on your particular vehicle. There are M/C's out there that have proportioning valves built in to them but they are really built for specific applications. They offer little or no provision to make any fine adjustments.

 

Wilwood makes a nice adjustable valve with a brake light switch......and I am sure there are others. If you use this with a M/C that was made for the same model vehicle as your rear discs came from you should have a pretty easy system to balance. Run all new lines and use new or freshly rebuilt components and the braking system should be about as good as it is ever going to get. I am really happy with the 4 wheel disc brakes on my Pilothouse......best money I have spent on it.

 

Hope this helps, Jeff

[RobRobitaille]

I am using a 98 explorer rear diff but the master cylinder is too long to fit behind the steering box. trying to decide if I should use a Jeep m/c or move it to the firewall and use the brake booster as well with a hanging peddle for the brakes.

 

Any advice? 

[Jeff Balazs]

You could probably use a 2000 - 2004 Grand Cherokee M/C like I did. The wilwood or similar valve will allow you to fine tune it. Then you can fit it to the existing pedal arrangement. No need for a booster......works great just like that. You get better pedal feedback that way in my opinion.

 

Jeff

[RobRobitaille]

Great Advice Thankyou

[NiftyFifty]

Hey guys, I've run this mod for 3 years now and its still working great! I haven't had to change any components so far and the last two seasons the truck has logged some pretty decent miles. I don't have any part numbers, but I could dig up next spring if needed as the truck away now for winter. With my set up I'm basically running what a stock Cherokee would for brakes with a jeep rear diff and the front disc conversion and I've never felt the need to get an adjustable valve. I looked at a few newer Cherokee MC's but they did seem to get a bit bigger in the reservoir and possibly different for the prop valve. I still highly recommend this swap and if you can't find the exact parts I did the basic ideas stay the same as long as you have the room

[stewdecky]

Do you guys think this would work on a '46?  I have a ford rear end and stock front but looking to use Charlie's kit to go with disc brakes up front.  I have 1/4 line, can I use  3/16 up front and 1/4 to the rear drums or will I have to go 3/16 everywhere?

[Dave72dt]

You can. I would seriously consider adding in an adjustable proportioning valve.  two different line sizes is a method that's been used to proportion brake application.  For simplicity, I'd go with 3/16 throughout.  It'll probably match up better to the Ford rear wheel cylinders and the caliper hoses without adding in multiple adapters.  JMO

[vance1234]

4mula-dlx, does yours have a proportioning valve on it?  I looked at a 1990 Cherokee master cylinder but it looks different than the one in your pictures.  Yours looks more like a 1995 Cherokee master cylinder.

[NiftyFifty]

Ya, I've heard that before, but I think there was differences between American models and Canadian models...only reason I can come up with the difference. I know what mine came off of, as I have the receipt still in my pile and I double checked when someone asked me that before. Mine also came off one with ABS, but that part didn't affect the master in any way. The proportioning valve is the stock Jeep one, just cut the lines and took the whole unit, as I was sure it would work well with my set up. I can't howver say with a 100% that someone hadn't changed the one out of the jeep I removed mine from with a newer model..but I do have 1 more port in my valve that some other don't either.