79 CJ5 hydraulic clutch conversion - JeepForum.com
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post #1 of 33 Old 12-22-2011, 05:14 PM Thread Starter
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1979 CJ5 
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79 CJ5 hydraulic clutch conversion

Been thinking of doing this for a while but my jeep decided it was time.. The bellcrank to pushrod arm snapped clean off.

After limping it the remaining 10 miles home I pondered for a while my course of attack. Repair and reinforce my current parts, purchase a replacement bellcrank or upgrade to hydraulic clutch. Upgrade..... Everytime anything breaks that's what I have to do. Then I started thinking about how nice it would be to lighten my clutch pedal force by at least half.. No more leg cramping workouts in afternoon traffic. No more linkage to wear and fall out of adjustment.

First thing is parts. Slave is a 81-83 cj7 with gm 151. Bolted right up to my t15. It used the bottom and center hole vs. the top and center used by the stock linkage.

The master cylinder is one I had lots of previous experience with. A 88 yj. Also I got 4 feet of 3/16" brake line and a flex hose I had sitting around from some unknown previous project. Also a lot of brake fluid, a 1 1/2" hole saw and 4 5/16-18 bolts and nuts. Total parts cost- just under $100.

First step remove old parts and linkage. Mount slave and pushrod to tranny using 2 5/16-18 bolts 1" long using bottom and center hole. Next- unscrew fusebox and push to the side. Remove clip holding clutch pedal on. Slide to side taking care through this whole process not to dislodge needle rollers. I put a socket that fit snuggly in the center to prevent this.
Grind the 2 rivets holding the bracket to the pedal then knock them out.

Next measure then drill using the 1 1/2" hole saw the hole in the firewall for the master to mount. Using the master as a template mark and drill 2 5/16" holes to bolt it to the firewall. Once done bolt it to the firewall.

Next slide clutch pedal on. Align it to the correct height, then align the master pushrod and mark. Remove and drill the hole. It was a 7/16" for me. I then welded a nut on the other side. Install pedal then pushed to pedal. Check for proper travel with no binding and install return spring. Reinstall fuse box. Run brake lines and bleed. Test drive and enjoy the much lighter smoother clutch.

All in all took about 2 1/2 hours and minimal skill.. Very pleased. My leg is so much happier. Next up this weekend- install my yj booster and have power brakes...

1979 CJ5 MB OM602 diesel, dana 60/14b, T18, d300
1948 Willys CJ2a LS 4.8/sm465 dana 60's, 38's
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post #2 of 33 Old 12-22-2011, 05:29 PM
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1979 CJ7 
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Header clearance is the only thing stopping me fromgoin' Hydra. All the cool kids are doing it!
Good luck, I'm pulling up a chair

I've also learned that sometimes... when people don't agree with you .... its best to hold them down and kidney punch them till they agree with you
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post #3 of 33 Old 12-24-2011, 12:37 PM
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Great post. Did the same and is a big upgrade with relative ease compared to a lot of projects!


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post #4 of 33 Old 12-24-2011, 06:42 PM
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Yup pretty easy upgrade
...hutch, V8?

1980 CJ7,
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post #5 of 33 Old 12-24-2011, 07:15 PM Thread Starter
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1979 CJ5 
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Did power brakes today. Picked up a booster of eBay for $25 shipped. $15 in brake fluid and fittings and I can stop in a decent distance too. Without having to stand on the pedal.

Yes my wiring is a mess. Part of my list to do tomorrow. Lol..

1979 CJ5 MB OM602 diesel, dana 60/14b, T18, d300
1948 Willys CJ2a LS 4.8/sm465 dana 60's, 38's
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post #6 of 33 Old 01-01-2012, 01:33 PM
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Looking at making these same upgrades on my '76. Good information.



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post #7 of 33 Old 04-09-2013, 06:07 PM
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These are upgrades I definitely need to do. Just redid rear drums (wheel cylinders and shoes). Bout to do the front disc (not sure if they are even original to the jeep). But after the repairs I did, my brakes are still spongy and feel better after a cpl pumps. No air left in the lines (according to the clear fluid being pumped out) and I'm at a loss. The brake booster has been on my mind and the price u paid is excellent, but idk what parts I need, or what will even fit.

The clutch, it's on the floor and stiff as a board. Rumor is the original builder sold it for this reason. I got an idea for clutch parts... Any and all help is gladly received
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post #8 of 33 Old 08-10-2013, 05:35 AM
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Been doing research for this mod for my cj5. How do I find center for master cylinder on the firewall? The cj5 does not have dimple for it.
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post #9 of 33 Old 08-11-2013, 08:00 PM
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I just did this on my 74 with a 304 and T-15. Was so easy I'm sorry I waited so long. All the parts are available at Advance Auto. Search '81 CJ7 clutch master cylinder and slave cylinder and you'll find the whole setup. My local box had the master and slave in stock. I had to order the hydraulic line which came in a couple days later. My only other part was an adjustable pushrod kit from eBay. This is the kit:


The slave is a direct bolt-up to the T-15 bell housing. The master was slightly more complicated. Unfortunately I didn't take pics so hopefully my description will do. I used the existing wiring hole through the firewall as a starting point. I cut a new hole for the wiring to the outside of the current one and slotted between the two to move the wiring over without disconnecting everything. After that, I used an angle grinder and pneumatic die grinder to grind the original wiring hole inboard far enough so the pushrod on the master lined up with the pedal. Lots of trial and error and some time but got the job done. Once the master was lined up, I used the pushrod kit to attach to the same pivot point as the mechanical linkage on the pedal arm using a bolt and a couple brass bushings. For adjustability on the other end I used the pushrod from the old linkage. Hooked up the line, filled it up, bled it, adjusted the slack out of the linkage at both ends, and done.

The travel is perfect, clutch disengages perfectly, and there is enough play so the throw out bearing doesn't ride the clutch fingers when the pedal is out. Sounds a lot more complicated than it is. It's super easy even on the 5 and the parts are easy to come by. All in, I'm only out about $180.

If you've ever been stuck on an obstacle because the bell crank dropped out then you need to do this upgrade. Happened to me twice this summer and that was the last straw. Have done the trail that left me stranded twice since the upgrade and zero issues. Go hydraulic and don't look back.

Good luck.
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post #10 of 33 Old 08-14-2013, 09:58 PM
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Ok, started the conversion. At the suggestion of my nephew, made a template of the master cylinder(mc) base, then followed instructions found at http://extremecustomparts.com/attach...tructions4.jpg to locate where mc should go, I had to make a few adjustments for my application. Drilled holes and attached mc to firewall per instructions, attached slave cylinder (sc) to bell housing, needed to make adjustments again for my application. Took the old hose to local parts place, suggested sending to big city hose company. An online search for the hose returned a part number for omix ada 16919.24, available from several vendors online. If the local parts house cannot acquire, will be ordering online.
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post #11 of 33 Old 08-15-2013, 11:02 AM
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Did mine about a year ago and love it. The only thing I did as remove the return spring off of the pedal assembly under the dash. It make it very difficult to push in the clutch. Now its very easy and I seem to have more control over it.

Beat it to fit, paint it to match!

Wheel, Wrench, Repeat.
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post #12 of 33 Old 08-15-2013, 12:09 PM
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i got a question did you have to do any modification to the vaccum lines cus i though brake boosters ran off vaccum??
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post #13 of 33 Old 08-15-2013, 12:14 PM
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This doesn't have anything to do with the brakes or the brake boosters.

This is a conversion of the clutch from a linkage setup to hydraulic actuation.
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post #14 of 33 Old 06-05-2020, 09:24 PM
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Originally Posted by JoeDahero View Post
If you've ever been stuck on an obstacle because . . .
These words almost seem like prophecy now that I look at them. Iím resurrecting this seven-year-old zombie thread because I have new information to relay.

This spring before the lockdown I found myself once again stuck on an obstacle with clutch problems. The thing wouldnít disengage.

Ok now rewind seven years. At this time Iím driving the CJ every day as I recover from the hole the Great Recession has knocked in my life. Iíd already converted to power brakes because driving around a city of a half-million with manual drums on 32s is scary AF. Yeah I know thatís an anachronism since we didnít know what AF means back then. At any rate, Iíd done the booster in the most economical way possible since I was mostly broke at the time. Unbeknownst to me the kit I bought was for a 76+ CJ which made a difference in the booster bracket. The bracket was designed to interface with the pedal assembly under the dash, providing needed reinforcement to the firewall. On my 74, none of the holes lined up. So I modified it and made it work.

Despite this thread being about the clutch, the brake mod was my first mistake. The pedal bracket on the 74 isnít as stout as the newer design, and not designed to take the extra stress of the longer, heavier brake hardware of the booster kit.

Now back to the clutch. It turns out the clutch pedal linkage acting on the clutch master cylinder puts considerable stress on the firewall. This stress over time causes the firewall to flex more and more. In no small twist of fate, the stress the new hydraulic clutch puts on the firewall has precisely the same vector, at occurs at precisely the same time as the stress the brake pedal puts on the firewall. Over time, say seven years or so, all that flexing has weakened the pedal assembly to near the point of failure.

So there I was, front wheels up the side of a rock, about to make my next move up the obstacle, clutch pedal in and applying maximum force to the firewall, hard on the brakes also applying maximum force to the firewall. At this moment I hear a pop from under the dash. I donít think much of it at the time because rock crawling, but I notice moments later my clutch will no longer disengage completely. At this point Iím sure you can imagine how the rest of my day went. Iíll give you a hint: the grinding sounds were coming from both my transmission and my teeth.

Good news: I made it home. While investigating, I discovered the pedal bracket failure and a stress crack in the firewall around the clutch master cylinder. Fortunately, the engineers at jeep were good enough to solve this problem for us in the late 80ís with the redesigned pedal assembly on the late CJs and all new YJ.

After using some sheet metal to reinforce the firewall, I obtained and mounted a YJ style pedal assembly under the dashboard. The great thing about this bracket is that it not only mates to the booster bracket perfectly, it has additional bracket tie-ins for the hydraulic clutch master cylinder. This is the real money for this particular thread.

Bottom line: if youíve got an intermediate CJ and if youíre gonna hang a master cylinder off the firewall and if youíre gonna hang a brake booster off the firewall and if youíre planning on driving the Jeep seven years or more, youíre gonna need to reinforce the firewall somehow. There are certainly different methods of doing this, but replacing the pedal assembly for the YJ pedals is a pretty elegant solution and the additional upshots are the increased availability of parts and that the pedals are about 4Ē longer than the ones on the intermediate, increasing mechanical advantage over the master cylinder and making the clutch require less leg presses at the gym.

Hope this info helps somebody someday.

Sent from my iPhone using Tapatalk
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post #15 of 33 Old 08-04-2020, 03:40 PM
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Iím researching this project now. Thank for the information! I have a 78 CJ5 with a 304. The original owner replaced the T150 with an NP435. Iím not sure why he didnít complete the tranny conversion by going with a hydraulic clutch, but for whatever reason he didnít. My mechanical linkage failed me last fall while driving down the road. No muddling, flexing, climbing, just driving down the road. It was a quick repair, but I resolved then that a hydraulic clutch conversion was in my future. I wondered about the pedals, if the same assembly on my mechanic set up was the same as the hydraulic set. YJ pedals should be easy enough to find and I really like the fact the they help with locating the placement of the clutch master cylinder. That was a concern for me. I hope to do this conversion this fall since we generally park the CJ for the winter months and wonít be driving it. I know that the 80-91 CJ factory MC and S.C. are easy to locate and a heck of a lot cheaper the Wilwood, but what parts did you use, if you donít mind sharing.

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