model 20 brake conversion

Is there any write ups or articles on drum to disc brake conversions for the model 20 rear ? Any help would be greatly appreciated.

Chris  

What kind of issues are you trying to resolve by converting your rear to disk brakes?

There are advantages to disk, that's for sure. But they may not help your specific desires. If your drum brakes are in good working condition, you won't notice much, if any difference for normal street braking performance.

Front brakes provide 60-70 percent of the braking force during normal braking, and can be as much as 90 percent during hard braking. That's because of the load transfer to the front of the vehicle during braking.

It is actually quite easy to exceed the rear axle's capability for braking. Then you just get lock-up.

Disc brakes are easier to maintain, don't require adjustment, and are not affected by water and mud. So, if you're having problems in these areas, disks may help you. But if you want better braking performance on the street, concentrate on bigger/better front brakes. They'll give you a real bang for your buck.  

I'm running disks on my AMC 20.  Also, installed a proportion valve to prevent lockup on the rear.  Works great so far.  Wish I had a link to steer you to my parts list.  Got the info on the web.  In fact, if I remember right, that valve was a suggested part for my disk brake kit.  Good Luck!!

http://rides.jpmagazine.com/ride/1064769/tinymay/1982/jeep/scrambler/index.html  

TSM has the best kit.HERE  

Jp Editor:
TSM has the best kit.HERE



Those require Warn full float hubs which are not available anymore.  

Jp Editor:
TSM has the best kit.HERE

ftgiles:


Those require Warn full float hubs which are not available anymore.

Not true. There are kits for both.

'76-'86 Jeep CJ 5 - 7 & 8 Model 20 axle fits two piece & one piece axles. Kit includes: brackets, bolts spacer plates and new  11 9/16" vented rotors.  

Oh, I see they have two kits, but $600 plus, to upgrade a Model 20 rear? Just doesn't seem like a good return on investment to me.

I think he's having some other braking issues and mistakenly looking to rear disks for the solution??  

ftgiles:
Oh, I see they have two kits, but $600 plus, to upgrade a Model 20 rear? Just doesn't seem like a good return on investment to me.

I think he's having some other braking issues and mistakenly looking to rear disks for the solution??

Well, most of the price is in calipers and rotors. They are not cheap parts.

Could be...but I can only answer his question and not guess as to why he is asking it.  

Thank you for all your response's, The omly issue I'm having is the brake pedal is close to the floor board I've had a mechanic look at it and doesn't know why the pedal is so low. I thought if I went to disc brakes would help. I'm also running Mickey Thompson's 36x15.50x15 claws just might be to much tire for the brakes don't know.  

Does it go to the floor when you press the pedal or does it just stay there?

If it goes to the floor: Check the rear brake shoes to see if they are worn. If not adjust the rear drums so they have just a little bit of drag. You should still be able to spin the wheel by hand with the Jeep jacked up.

If it stays there: Adjust the pedal height from under the dash and see if there are any missing return springs.  

The brake pedal is find all the springs all there it has all new brakes / rotors etc. the pedal use to grab high now for some reason it grabs low I've bleed the system with the exception of the master cylinder. I don't know how to do that task.  

Is it a new master cylinder? If not there is no real need to bleed the master separately.

If all the air is out of the system... It could be one of two things. The pads and shoes have not seated yet (how many miles since you did this 4-wheel brake job?). Or, the rear drums need to be adjusted.  

It's around 1,500 to 3,000 miles ago it's not a daily driver and I didn't replace the master cylinder.  

If the brakes can be pumped up, and the pedal will remain firm for a period of time, then you have air or contaminants in your brake system.

If the pedal becomes soft after a period of time or you can't pump them up, you have a leak. The leak can be internal or external. If the fluid reservoir gets low, you have to find the leak by looking at everything. Don't forget to look around the pushrod on the master cylinder. If the reservoir does not get low, you have an internal leak. That would be a bad master cylinder.

If you replace the master cylinder, it must be bench bled before you install it. It can be very difficult to get the air out of the master cylinder after it is installed. You also might want to try bench bleeding the master cylinder and then bleeding the entire brake system again if the system has lost all its fluid at one time.

What has been the condition of the fluid? If the system has been poorly maintained or opened and left open for a period of time, there could be contaminants in the system. The contaminants will have an abrasive effect on the seals and bores, accelerating wear in the master cylinder, calipers, and wheel cylinders.

In normal use, the master cylinder piston only moves about a half-inch or so every time you step on the pedal, even when you step hard. However, total travel is over an inch when the pedal goes to the floor. This means that there is about a half-inch of master cylinder bore that never gets used during normal braking. With poor brake system maintenance, goop, gunk and corrosion builds up in this unused portion. Then, when you bleed the brakes with the pedal-pump method and the pedal goes to the floor, the rubber seals on the piston will be damaged by this buildup.