YJ Dual Diaphragm Booster Question... - JeepForum.com

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post #1 of 18 Old 03-02-2016, 05:40 PM Thread Starter
rixcj
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YJ Dual Diaphragm Booster Question...

Hi guys...

I'm installing a YJ dual diaphragm power brake booster setup in a CJ5 that I'm building.

I installed a YJ power brake booster (not a dual, though), in my current CJ5, and just used the original CJ power brake / clutch pedals.
The brakes work great.

Now, I've read that it's recommended to use a YJ brake / clutch pedal setup. How much of a difference would it make on the dual diaphragm booster? Should I use the YJ pedals?

If so, do the pedals have to come from specifically from a dual diaphragm jeep, or will any Yj power brake pedal setup work.

I've googled this, and all that I found out was that there are newer and older YJ pedals available, but I'm not sure what the differences are, other than the brake light switch.

I just want to make sure that I do this right. I'm the cautious type....

Thanks.

Rich




'79 CJ5, AMC 360, t-18/d20 twin stick, dana 30/amc20(Mosers), Edelbrock Performer intake, Holley 600, ps/pb, DUI HEI, 'glass tub/1pc. tilt nose, 33x12.50 BFG AT's.

There's a fine line between "hobby" and "mental illness".
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post #2 of 18 Old 03-02-2016, 06:57 PM
Dadamsnv
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Sub'd for the answer.

I too did the regular YJ booster with my stock power brake stuff. I never swapped pedals.

I'm looking for a Scout II Dana 300. Drop me a line if you have any leads. Thanks
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post #3 of 18 Old 03-02-2016, 08:25 PM
skizriz
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Some good info on this thread that may help you out.
http://www.jeepforum.com/forum/f8/me...e-swap-377653/
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post #4 of 18 Old 03-03-2016, 03:54 AM Thread Starter
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Thanks Skiz..

That article had a lot of good information, and a lot of time was dedicated by the OP. Sad thing is, is that in the end, he asked a question but didn't get much for answers. Only 2 responses, one of them being a question....

I'll probably make a CJ pedal setup work, somehow...

Rich

'79 CJ5, AMC 360, t-18/d20 twin stick, dana 30/amc20(Mosers), Edelbrock Performer intake, Holley 600, ps/pb, DUI HEI, 'glass tub/1pc. tilt nose, 33x12.50 BFG AT's.

There's a fine line between "hobby" and "mental illness".
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post #5 of 18 Old 03-03-2016, 06:56 AM
JohnnyRotten
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I swapped out my old manual brakes for a 95 YJ booster. Not a double, but it will lock up my 33s at will. The only thing I had to do was make an adjustable push rod for the master cylinder. I used the good ole 79 pedals.
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post #6 of 18 Old 03-03-2016, 07:05 AM
skizriz
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I believe that was the big problem I had with my YJ swap, although it was only a single, not enough throw from the pedal. Brakes worked well, just no feel and too much travel.
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post #7 of 18 Old 03-03-2016, 08:11 AM Thread Starter
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Quote:
Originally Posted by JohnnyRotten View Post
I swapped out my old manual brakes for a 95 YJ booster. Not a double, but it will lock up my 33s at will. The only thing I had to do was make an adjustable push rod for the master cylinder. I used the good ole 79 pedals.

I did the same thing on my current jeep....Wrangler booster w/ CJ pedals and extended adjustable push rod. They stop great.


I just wasn't sure if the dual diaphragm made a difference, pedal-wise.


Seems like it won't...


Rich

'79 CJ5, AMC 360, t-18/d20 twin stick, dana 30/amc20(Mosers), Edelbrock Performer intake, Holley 600, ps/pb, DUI HEI, 'glass tub/1pc. tilt nose, 33x12.50 BFG AT's.

There's a fine line between "hobby" and "mental illness".
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post #8 of 18 Old 03-03-2016, 09:36 AM
grapehead
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I've got a yj single booster with stock CJ pedals and it works great with 39s, other than I think I need to check the pushrod length, it seems to be dragging the fronts.
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post #9 of 18 Old 03-03-2016, 05:41 PM
only in a jeep cj
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Quote:
Originally Posted by rixcj View Post
I installed a YJ power brake booster (not a dual, though), in my current CJ5, and just used the original CJ power brake / clutch pedals.
The brakes work great.
I read mixed results from that combo works fine to the pedal was too low to adjustable rods and fab work was needed.

Quote:
Originally Posted by rixcj View Post
Now, I've read that it's recommended to use a YJ brake / clutch pedal setup. How much of a difference would it make on the dual diaphragm booster? Should I use the YJ pedals?
Yes,use the YJ pedal as it will put the pivot point at the right height on the pushrod and maintain proper travel length and leverage.

Quote:
Originally Posted by rixcj View Post
If so, do the pedals have to come from specifically from a dual diaphragm jeep, or will any Yj power brake pedal setup work.
No, the pedals from either single or dual systems are the same.

Quote:
Originally Posted by rixcj View Post
I've googled this, and all that I found out was that there are newer and older YJ pedals available, but I'm not sure what the differences are, other than the brake light switch.
There are different YJ pedal units, mainly the pre and post 91 when there was a change to the size of the clutch master and the stud diameter on the pedal where its push rod attaches. The later master with the wider spaced mounting bolts use the smaller diameter stud pedal. Also, although the CJ and YJ seperate pedals interchange in the hanging assemble. The tabs for the brake switch are in different locations and it just way easier to swap the whole pedal assemble/hanger as it bolts right to the CJ firewall.

Quote:
Originally Posted by rixcj View Post
I just want to make sure that I do this right. I'm the cautious type....
Almost all the folks who mix n match CJ and YJ pedal and boosters end up cutting or making an adjustable push rod between them to compensate for the differences that they didn't know about when they did the swap. IF you want the end result to act and preform like a factory YJ set up, just make it easy and swap it all in at once.

Ed
1975 CJ-6 1983 CJ-8
1986 CJ-7 Laredo 1986 TJ-7 Trail Jeep
2003 Inca Gold TJ Rubicon
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post #10 of 18 Old 03-03-2016, 05:50 PM
only in a jeep cj
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Quote:
Originally Posted by rixcj View Post
Thanks Skiz..

That article had a lot of good information, and a lot of time was dedicated by the OP. Sad thing is, is that in the end, he asked a question but didn't get much for answers. Only 2 responses, one of them being a question....

I'll probably make a CJ pedal setup work, somehow...

Rich
I've learned a lot and done a lot in the last 9 plus years. Ive learned that TJ boosters make a great swap into CJs with large tires. I needed to holding power on rock climbs, etc. Its a combo of a TJ booster/master, a YJ firewall bracket. and YJ pedal unit. Mods include re flairing the two master lines to the TJ fittings and I cut and welded the booster rod to match the YJ length. So why am I saying all of this? Because I never got my hands on a YJ dual booster and my friend swears that the YJ dual and the TJ boosters ARE the SAME other than the rod length for the different applications. It was his CJ that we converted and the stopping power difference is VERY noticeable.

Ed
1975 CJ-6 1983 CJ-8
1986 CJ-7 Laredo 1986 TJ-7 Trail Jeep
2003 Inca Gold TJ Rubicon
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post #11 of 18 Old 03-03-2016, 08:00 PM Thread Starter
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Thanks for sharing your experiences, Ed. It's no problem for me to fabricate an adjustable push rod. I'd have to do that no matter which pedal setup I choose, because I have a fiberglass tub which has a 1/2" thick firewall.

Rich

'79 CJ5, AMC 360, t-18/d20 twin stick, dana 30/amc20(Mosers), Edelbrock Performer intake, Holley 600, ps/pb, DUI HEI, 'glass tub/1pc. tilt nose, 33x12.50 BFG AT's.

There's a fine line between "hobby" and "mental illness".
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post #12 of 18 Old 06-30-2016, 12:25 PM
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A little revival here... I too put in a YJ single and kept the CJ pedals. I cut the end off the CJ rod and threaded both sides and used a 2" long threaded nut deal, I forget the name of the thing, any how I am not getting brakes till pedal is halfway through its travel and when it builds pressure it is VERY quick... Like just barely tap or else its braking like you're about to rear end somebody... and it locks up the rear before front, isn't that backwards?

I have new prop valve(CJ) and all new lines, calipers, and shoes and pads.

What should the length of pushrod be?

80 CJ7-304/T176/D300 HEI hdrs-WT D30/D44 4.56s, lockright/spool-SOA YJs W/RE AAL-35 MTRs beadlocks
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post #13 of 18 Old 06-30-2016, 02:38 PM
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Quote:
Originally Posted by only in a jeep cj View Post
I've learned a lot and done a lot in the last 9 plus years. Ive learned that TJ boosters make a great swap into CJs with large tires. I needed to holding power on rock climbs, etc. Its a combo of a TJ booster/master, a YJ firewall bracket. and YJ pedal unit. Mods include re flairing the two master lines to the TJ fittings and I cut and welded the booster rod to match the YJ length. So why am I saying all of this? Because I never got my hands on a YJ dual booster and my friend swears that the YJ dual and the TJ boosters ARE the SAME other than the rod length for the different applications. It was his CJ that we converted and the stopping power difference is VERY noticeable.
I promise you that tj booster is the exact same booster as the on from the yj. The mc are even the same part numbers.only difference is the rod length on the boosters. Because the 4th mounts the booster directly to the fire wall and the yj uses an adapter bracket.

Glad you are suggesting my tj booster idea though. Seriously for the stupid money a used yj dual diaphragm goes for you can buy a booster bracket from a yj and a used tj booster and still have like 150 bucks to spare.

1985 CJ7 Laredo, 4.0, NV3550, D300, 3.31 AMC 20 w/trac loc
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post #14 of 18 Old 09-13-2016, 12:43 PM
robblue6412
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Quote:
Originally Posted by rixcj View Post
I did the same thing on my current jeep....Wrangler booster w/ CJ pedals and extended adjustable push rod. They stop great.


I just wasn't sure if the dual diaphragm made a difference, pedal-wise.


Seems like it won't...


Rich
Rich,
I am just starting this process with my 80 CJ7. How did this approach work for you? I am also leaning toward using a YJ booster/MC with CJ pedal and lengthening the push rod. Did you use the YJ or the CJ booster bracket with this setup?

I've been reading a lot of different forums where its being said that the pedal travels a bit and then, bam the brakes lock up. seems to me that this is caused by the incorrect pedal height. Did you have any issues like this?

Also, I noticed that YJ's came with 2 master cylinders: the traditional cast iron MC on the 4cyl and the plastic reservoir on the 6 cyl. which MC did you use in your CJ?

thanks much for your thread,
Rob
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post #15 of 18 Old 09-13-2016, 06:15 PM Thread Starter
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Quote:
Originally Posted by robblue6412 View Post
Rich,
I am just starting this process with my 80 CJ7. How did this approach work for you? I am also leaning toward using a YJ booster/MC with CJ pedal and lengthening the push rod. Did you use the YJ or the CJ booster bracket with this setup?

I've been reading a lot of different forums where its being said that the pedal travels a bit and then, bam the brakes lock up. seems to me that this is caused by the incorrect pedal height. Did you have any issues like this?

Also, I noticed that YJ's came with 2 master cylinders: the traditional cast iron MC on the 4cyl and the plastic reservoir on the 6 cyl. which MC did you use in your CJ?

thanks much for your thread,
Rob
Hey, Rob....

I installed a YJ power brake setup in my current CJ5. It uses a cast iron MC....



I also used the YJ booster bracket. The push rod is adjustable. my CJ also has a fiberglass tub, which has about a 1/2" thick firewall, so that gives me a need for the rod adjustment, too.

I also moved the MC brake lines from the inboard side of the engine, to the outboard side...




My brakes couldn't be any better. They are very smooth.

I'm going with a YJ dual diaphragm booster / MC (plastic) on a second CJ5 that I'm building.

Hope this helps.

Rich

'79 CJ5, AMC 360, t-18/d20 twin stick, dana 30/amc20(Mosers), Edelbrock Performer intake, Holley 600, ps/pb, DUI HEI, 'glass tub/1pc. tilt nose, 33x12.50 BFG AT's.

There's a fine line between "hobby" and "mental illness".
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