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YJ/CJ brakes

Posted: Sun Oct 15, 2023 1:56 pm
by HBP40
For the folks who run YJs and CJs, I made a little bit of a snap decision recently and I picked up a CJ (kind of). Has YJ frame, waggy 44s front and rear, amc 360, tf727 and dana 300. CJ nose is about all thats CJ on it.

In low range, this thing feels like its going to drive through the brakes, a lot more than normal. Disc brakes all around (15 inch wheels though), and it has the hydroboost so when its rolling and I stomp the pedal, it’ll lock everything up. But normal braking gives you that feeling like ehhh is it going to stopppp…

It has been a long time since I’ve driven an older rig so maybe a lot of it is ‘driver mod’ needed.

So, what do folks run for brakes? I feel like a bigger rotor and dual piston calipers would be the next move…

A manual swap also isn’t off the table… shifter on the 727 sucks (if the 727 stays Ill get a new one, theres a cost), only a 3 speed, driveshaft packaging to get a flat belly is another cost/issue.

Anyway, be curious what other folks think who have experience with these. Thanks


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Re: YJ/CJ brakes

Posted: Sun Oct 15, 2023 4:36 pm
by KenCal
Sounds like a fun ride a ride Scott. Did you bleed the brakes and is the brake fluid a dark color?

Re: YJ/CJ brakes

Posted: Sun Oct 15, 2023 7:14 pm
by Kurt
In my 92 YJ I run a Dodge master cylinder with a TJ brake booster and manual line locks.
D60's, 4 wheel disk brakes, stock twin cylinder brake calipers up front and singles in the rear. Works well.

Re: YJ/CJ brakes

Posted: Tue Oct 17, 2023 1:41 pm
by HBP40
Yeah Ken - could def need a bleed, I haven’t turned a bolt on this thing yet, haven’t even made it to the RMV. Theres a couple notes from the shop the previous owner had the hydroboost put in that make me think the system needs some adjustment. But good point, thats where to start.

Kurt - I remember the line locks from when I rode with you fall crawl 2022, liked how you have that set up. That dodge master, TJ booster setup is pretty much what I’ve read/heard about as a good ‘go-to’ but thats all internet posts haha good to hear a real person has the same recommendation!


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Re: YJ/CJ brakes

Posted: Tue Oct 17, 2023 2:04 pm
by BlackNBlue-ISH
I don't know anything about the brake issue, but I do have a 727 sitting in my garage I have no plans for. Just need to take the D300 off of it first.

Congrats on the new project!

Re: YJ/CJ brakes

Posted: Tue Oct 17, 2023 5:36 pm
by MDSRACING398
Converter could be to tight. Be ready to throw into neutral until figure it out.
Check and see if they removed proportioning valve. That gave me fits on cj.
I had good luck with late 70's early 80's Corvette booster and Master. Also if it was wheeled or sat long time check the brake pads.
Make sure have good vacuum going to booster too.

Re: YJ/CJ brakes

Posted: Thu Oct 26, 2023 11:37 am
by HBP40
Found some more invoices from previous owner. Per the install folks vacuum was good, they did put in a GM disc/disc proportion valve. Looks like fluids flushed and calipers/pads/rotors were ok. Looks to be done spring of 2023 so not too long ago.

The install guy noted in the future should upgrade from the single piston caliper.

Finally getting the reg/title done today so hopefully I can spend a little more time on it soon.

Appreciate the feedback, I got some things to double check


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Re: YJ/CJ brakes

Posted: Thu Oct 26, 2023 12:40 pm
by MDSRACING398
Extend the brake pedal longer or out farther so has better ratio of throw helps too

Re: YJ/CJ brakes

Posted: Thu Oct 26, 2023 1:40 pm
by HBP40
That actually might help a lot, they converted the 727 from the original manual, still using the old ‘small’ brake pedal…


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