My ZF build

[6daze]

My Dana 20 finally gave up on me on a recent trailride It was not pretty. Anyway it is a good time to upgrade, right? I thought about just rebuilding the 20 but by the time it is built right I could buy an Atlas and be done with it. The Atlas will not bolt up to the three speed, so I needed a tranny too.

I had been looking for a ZF for while as I wanted to keep a manual trans and needed a low first gear. The ZF seemed like the perfect tranny. After a long search in the local junkyards I found a ZF for $500. It was out of the truck so I have no idea how many miles are on the thing. But, I spent so much time looking for one, I am giving it a go.

I ordered all the ZF stuff (clutch, cross member and hydraulic system) from BC Broncos, excellent people!

I have never swapped a tranny or transfer case before but am fairly mechanical and have some friends that are smarter than me.

So I figured I would document the build along the way, maybe it will help someone, I am sure I will have some questions!



Day 1:

I chose to modify the clutch pedal first. I had to remove the pedal from the truck to drill the needed hole. The clutch and brake pedals rotate on a common shaft behind the dash. It must be removed from the driver's side.

There are small retaining clips on each end of the shaft. I first removed these and removed the shaft using a hammer from the passenger side. The brake pedal, clutch pedal, shaft and a sleeve all came out. I took the pedal over to the vise and clamped it down. I measured down from the top 4.5" and center punched it.

Using various size bits, I worked my way up to 3/8”.

Now everything can go back in. I started with the brake pedal. I set in position, attached to the MC pushrod and put a spare bolt to hold it (from the passenger side). The bolt was long enough to hold the sleeve roughly in place as well. The shaft must go in from the driver’s side as it is “keyed” to fit one way. Holding the clutch pedal in one hand, start the shaft in the bracket, through the pedal, and into the sleeve. Keep sliding the shaft until the last bracket, towards the passenger side.

This where it gets tricky. The shaft has a flat spot cut into it that must line up with the bracket. Keep rotating the shaft until it lines up and goes through the bracket, install new cotter pins.

The attached pic is of the clutch pedal from the driver's side. I had not yet drilled the hole yet.

The second pic is the modified pedal.


Feel free to comment, give advice, etc, etc.

Mark

[6daze]

Day 2

Got back under the Bronco today and got some stuff done.

First I removed the pilot bushing. Using a grease gun, I filled the cavity with grease. I wrapped and old bolt with electrical tape so it just fit in the hole. I tapped the bolt with a hammer and out came the bushing. It was way too easy. I cleaned everything up and tapped in the new bushing.

Next up was the shield and flywheel. I had a local machine shop resurface my flywheel for $20. I put a little loctite on the threads and torqued them to 50 ft-lbs. Make sure you give it a wipe with brake cleaner to remove any grease or oil.

The new LUK disc and pressure plate went in. I used the alignment tool that came with the kit to keep it all straight. Again BC Broncos supplied the clutch kit. They were actually cheaper than the local stores and I knew I was getting the correct part. Bolts were torqued to 20 ft. lbs.

I did mark the correct mounting holes on the new pressure plate using the old one as a guide. The new pressure plate has several unused holes as it is a more universal item.

I moved over to the tranny and installed the new slave cylinder. The one that was in the tranny was replaced at some point and had two different sized bolts holding it in. I replaced them with 8mm 1.25 x 30mm bolts. I got them snug but not too tight as I didn't want to strip the aluminum housing. (14-19 ft. lbs.)

The slave cylinder came with the braided stainless line already hooked up and ready to go.

Next was the biggest challenge of the day. I don't have a tranny jack so I borrowed a adapter that mounts to the regular floor jack. Well once you have your tranny on the adapter on the floor jack, there is no way it is getting under the Bronco. I ended up jacking up one side of the Bronco with a high lift, laying the tranny on its side and sliding it under the Bronco. Should have just bought/rented a tranny jack!

That was enough for today, I need to mark and cut the tunnel before much else.

I included a pic of the break. That is about a 2 1/2 foot ledge that my left front tire is on.

Mark

[70EB]

Just finished installing my ZF a few months ago. Toughest part was getting the tranny up in there and aligned so that it would bolt up. Some clearancing of the tunnel was required. Used a tranny floor jack and definately expanded my vocabulary. Don't try and install it with the T/C attached (weight kept twisting the ZF to one side and did nothing to help line it up). Finally pulled the T/C off and muscled it up in there. Get/rent a friend to help. Doing this by myself was no joy.

Used all the BC stuff for mine and it fit great. Bleeding the clutch took a little bit (watch for the clutch to disengage - then your done) The pedal will only stiffen slightly, so it is a little deceiving.

Once you start it up, don't worry that you sound like a rock is loose inside the ZF - normal rattle.

I also made a simple adapter for the stock shifter to move it down and to the right a little. This keeps it out of your dash and out of your leg. (pics are on CB.com - 70EB screen name)

Make sure you have the correct application starter. I didn't and it made a hell of a racket. Get one for a manual or upgrade to one of Brzzzazz (whatever his name is) gear reduction jobbers.

Best mod I made. Still is a little noisy so I have to figure out some sound deadening under the floor. Geat low first gear and overdrive is a plus (5th is useless with my 33 MTRs and 3.50 gears - need to upgrade to 4.56). Great match for my 351W SEFI.

Good luck and let me know if you run into any sumbling blocks.

Bill

[crawlin68]

Great info! Keep it coming as you go. And don't be shy with the pictures.

[6daze]

Had to go back to work today so no Bronco progress...But since 68 asked for pics, here is my teaser...

[720Racer]

6Daze,


Thanks for posting this up. I'll be going through this pretty soon with my ZF, so this is a great referance for me. Love the pic's.



Galen

[6daze]

Tunnel hole question

I have read a bunch on where to cut my tunnel but I thought I would throw this out for opinions. I am thinking centered in the tunnel, 4 inches wide, 6 inches long. 2 inches on the sloped part, 4 inches on the flat (for length). What do you guys think? Cut a little and see? What about the body lift? Who has done it? I have the 1" in the garage ready to go if I need.
Here is the pic..

[Delta 4 Wheel]

Sweet write up. Keep it coming and complete so we can make it a sticky!

[720Racer]

Here's where mine ended up, i can get measurements tomorrow if needed. Might be a little "oversized" but I've got a plan for a little new sheet metal and the stock ZF boot.

[6daze]

Thanks 720, I found some other pics online, I think I will just cut a little at a time...I am also going to try without the body lift, just to see of it can be done. I think I want it anyways with the Atlas, fuel injection, explorer front dress, etc. It will be a good test to try without. Thanks for keeping me motivated.

[6daze]

Ok, I ran into my first problem. I cut a decent sized hole and I am trying to get the tranny up in place. But the shifter is not lining up at all. I can't find my camera of course so I will describe it the best I can. It looks like I need to cut the hole almost all the way back to the transfer case hole. Every picture I have seen does not have the hole cut that far back. Am I doing something wrong here? I can't push the tranny any farther foward as I am almost touching the clutch. I can get the stub in the hole I cut but there is no way that rectangular top piece of the tranny is going to clear. I am starting to worry that my hole will be too big (did I just write that?)
From my measurements it doesn't look like I need to cut the tunnel where it turns up.
Did all you guys set the body on after bolting up the tranny? What am I missing here guys?

[720Racer]

I did set the body on since I am in the middle of a frame up. Have you tryed loosening your motor mounts? If you can tip the back of the block down some, it should be eaiser to shove the ZF forward. I did cut a little where the tunnel goes up, but I don't think I needed quite as much room as I made. Unfortunately, but tub is on saw horses right now, but if you need some measurements, or a pic, let me know. I've got to run into town for a hour or so, but I'll be back by 7:30.


Oh yeah, I mocked mine up with a 2" BL. (see pic above)

[6daze]

I ended up just putting on the bodylift. I figured it was pointless to wait. It was pretty simple to do. I would recommend doing this before lining the interior. It took a while to cut that rhino lining out of the way to remove the bolts.

The atlas just showed up so I got to get to work. I guess I will loosen the motor mounts and tilt the motor back. Thanks for the pics...

[720Racer]

I ended up just putting on the bodylift. I figured it was pointless to wait......The atlas just showed up so I got to get to work. I guess I will loosen the motor mounts and tilt the motor back. Thanks for the pics...

I'm sure it's possible to install a ZF with out a BL, but it sure would be tight. What Atlas did you choose?

[6daze]

I went with the 4.3 with a 32 spline output shaft. That box is heavy! I will get some pics up in the am. It came to about $2300 shipped to my door. It took about 5 weeks to get though. pics to come...