Brake Booster

[mark 39]

        Planning on up grading the brakes on '87MJ. I have a '95 XJ master cylinder but no BB. Will any of the later BB's ( WJ ZJ) be compatible, or do I need to use only a '95-'96 XJ booster?  Thanks for any info.

[cruiser54]

95 to 96 booster (with the 1/4" factory spacer plate on it) with master cylinder or 99 to 04 wJ Grand Cherokee master and booster.

[mark 39]

        Thanks Cruiser. Have a '95 XJ BB coming; was hoping I could mix and match parts I had. I can still use my MJ proportioning valve,right? I'm keeping the rear axle limiting valve.

[DirtyComanche]

If you don't have the spacer it just makes your pedal a bit higher...  Depending if you're into that sort of stuff, it might be what you want.  Oh, you'll have to roll the lip on the firewall too, but that's a 5 minute mod even to do it nicely.

 

Since you have a Renix be prepared to bojang all sorts of stuff to make the brake light switch operate correctly.  It's a very umm, odd, mechanism that it works on.  Basically the end of the push rod needs to be ground flat, but you have to get that accurate to about 10 thou or it either won't put the brake lights on, or they will stay on constantly...  And the switch isn't really adjustable.  I ground mine very carefully and only had to do a little fiddling with the non-adjustable switch, many guys wind up grinding too much and resort to using aluminum/stainless tape to build the surface back up.   I know other guys have gone to generic ('GM style') switches to avoid the hassle, and it's probably the route I would take if I ever do it again.

[cruiser54]

If you don't have the spacer it just makes your pedal a bit higher...  Depending if you're into that sort of stuff, it might be what you want.  Oh, you'll have to roll the lip on the firewall too, but that's a 5 minute mod even to do it nicely.

 

Since you have a Renix be prepared to bojang all sorts of stuff to make the brake light switch operate correctly.  It's a very umm, odd, mechanism that it works on.  Basically the end of the push rod needs to be ground flat, but you have to get that accurate to about 10 thou or it either won't put the brake lights on, or they will stay on constantly...  And the switch isn't really adjustable.  I ground mine very carefully and only had to do a little fiddling with the non-adjustable switch, many guys wind up grinding too much and resort to using aluminum/stainless tape to build the surface back up.   I know other guys have gone to generic ('GM style') switches to avoid the hassle, and it's probably the route I would take if I ever do it again.

I just did my first one with the gM switch. 

I had always ground the booster rod on the others. Same experience. Too much off, no brake lights. too little off, brake lights always on. 

[mark 39]

        Anyone have part# for GM switch? I have cruise control if it matters.

[DirtyComanche]

Anyone have part# for GM switch? I have cruise control if it matters.

I can look for a P/N later if I have time. It's a very generic switch, looks the same on my 76 K truck as on the 2014 Silverado I was under the dash of last week.

[cruiser54]

Here:

 

[mark 39]

       Thanks again for all the help.     Mark