I'm trying to figure out what is the best way to put discs on the 8.25 in my truck. I know there are people using the disc brake setup from a Grand Cherokee ZJ on the 8.25. But the ZJs use 5 on 4.5 bolt pattern and my ram has the 5 on 5.5 bolt pattern.

So is there enough meat in the ZJ rotor to have it drilled out to the larger bolt pattern, or can I convert my truck to 5 on 4.5 bolt pattern?

Has anyone done this before?

 

so why exactly do you want rear disk brakes?

 

Easier to work on. Better braking. Lighter.

 

i think all that is a matter of opinion. i think drum brakes are easy to work on. work great when properly maintained and weight about the same as a disk brake setup. to me it would not be worth the cost to do a conversion. if you want to upgrade the rear brakes you could buy larger wheel cylinders.

 

IMHO. Disks are better than drums. Disks are easier to work on. I have had to use heat on drum brakes just to get them apart or physically brake a drum that has welded itself in place. I have never had a problem working in disks. Disks have fewer moving parts and that is always a good thing.

The simple fact is that disk brakes are capable of providing better braking without the brake fade under heavy usage that you get with drums. If you have ever had to get the brakes wet you know that disks perform better wet and recover quicker than drums.

If you believe disks aren't better than drums please explain what the reason is that almost all manufacturers have gone away from drums to disk brakes and why disks have always been preferred in any performance application. I would also like to know of any after market conversion kits that go from disks to drums.

I do agree it isn't worth the price or trouble to convert or I would have them on my truck. Again just my 2 cents.

 

from what i have seen you still have to deal with drum brakes even if you get disk brakes. they still use them as park brakes.

i have never had a problem with getting a drum off a truck so i guess i look at it a bit different than you do Seal. i go through my brake system about twice a year and make sure everything is working properly so that it does not seize up and quit working.

i think gm still use drums on there newer truck

 

Wow. Even I don't go thru my brakes twice a year. No wonder you have never had a problem with drum brakes. I used to work at my fathers gas station as a PA. state inspector before I went into the Navy. I would estimate that I easily averaged about 2 full brake jobs a day and had to pull a front and back drum on every vehicle I inspected. Back then almost all brakes were drum. With the road salt caused corrosion a BFH was usually needed to get most drums off.

Thanks for making my point when you said Government Motors still uses drum brakes. Those same engineers also made the totally failed Volt.

If you want to learn to hate drum brakes all you have to do is work on the rear dual drum setup they use on vehicles like the Ford Explorer. What a nightmare. I have been told but can't verify that drums are still used for parking brakes because they more reliably lockup.

 

ya. with how expensive parts are here i try keep on top of maintenance. plus i would like to get my 81 to last the rest of my life.

i know Government Motors is a bad example. from what i read they are heading towards bankruptcy again.

the only truck i have worked on with rear disk brakes was my wood shops teachers 2nd gen with a cummins. there was drum park brakes under those large rotors. from what i have seen on rock auto they continue to use drum park brakes on there trucks with disk rear brakes.

 

I know the 99-06 chevys used disc brakes in the back. At least in my experience with my girlfriend's families 3 chevys in the past few years (I'll convert them to mopar before I convert my drums to discs).

In my experience, discs are way easier to work on. I can change my front brakes ten times faster than my rear brakes. I've never injured myself on a disc brake either. The only thing I like about drums is that they will last for 100,000 miles, instead of 20,000. That being said, I've only experienced noticeable brake fade once with my truck, and that was when 50 concrete pavers on my truck and trailer turned out to be more like 150. What's the moral of the story? Don't try to haul 6,600lbs without trailer brakes. That was far beyond what my truck is designed to do, so I'm not worried about it in normal application.

If I were to use my truck for something like autocross, or rally racing, or swamp-running, etc, where I needed either complete braking lockup every time, or instant performance in wet conditions, I would do a disc brake swap . . . and a truck swap.

There are after market kits to convert an 8.25 to disc brakes on ebay, but like you said, they are all for the jeep bolt pattern.

What about swapping to an axle that is already 5.5 with disc brakes? The only problem I see is finding one! Off the top of my head, I can't think of anything, but that doesn't mean it doesn't exist!

 

Another option is to get a rear end out of an '02 or newer 1500.
I picked one up here locally for $300.