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Keyav8r

Rear Disc Brake Conversion

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I’ve seen several posts about rear disc brake conversions for D35 axles using ZJ components.  What ZJ model years work for this and are there any that offer better compatibility?  

From what I’ve seen, I need to get brackets, calipers, rotors, brake lines and e-brake cables.  Anything else?  

And, do the wheel studs have to be changed because the rotors are thicker than the drums?  Will the axle shafts interchange to provide the longer wheel studs?

Looks like the local PnP has several ‘96 and ‘98 models on the yard.

 

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I've done the ZJ disc conversion on a 95 YJ with a D35.  I used new components and matched to a 1996 ZJ when doing it.  Ithink all years work fine, you want a non-ABS setup.

 

You need longer wheel studs.  I have no idea about swapping the axle shafts but assume that would work.  The stud length and size you need is identical to what's on the front brakes.  I used front studs on my YJ axle and it worked great.  Studs press/hammer in and out easily.

 

Crown makes new ebrake cables with the right ends on them in various lengths using the RT Offroad brand name.

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Dorman #610-449 wheel studs will work fine too Fred. They do make "upgrade" axles for the D35 for ~$100/ea, but IMO it's not worth it. If you find a D44 later to swap the disks over will only require different backing plates, which you will need anyhow since you now have a c-clip D35. 

 

Wish OME made rear springs for the MJs. Nick, bet that YJ really rides nicely with them. 

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1 hour ago, HOrnbrod said:

If you find a D44 later to swap the disks over will only require different backing plates, which you will need anyhow since you now have a c-clip D35. 

 

Wish OME made rear springs for the MJs. Nick, bet that YJ really rides nicely with them. 

 

For the D44 swap the backing plate may just need need to be grinded out a bit to fit the larger D44 tube, maybe not, depending on the plate.  Plus he'd need TJ axel retaining brackets for a disc D44.  Everything else swaps over.

 

When I get the YJ on the road, I'll let you know how it rides.  It has 036R springs on all four corners, which are listed as rear heavy duty leafs.  They are giving me about 3.5" of lift.  Drivetrain and frame are 100%.  Working on the tub now.

 

I'm a huge OME fan, and am equally disappointed they don't have an MJ rear spring.  Will likely use OME fronts and Hells Creek or Alcan rears on the MJ.

 

I just put an OME lift on my JKUR and it rides way better than stock.  Like butter.  Soo good that I just bought one for me wife's TJ, pending install.

 

Ok, back to ZJ disc brakes... 

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1 minute ago, kryptronic said:

For the D44 swap the backing plate may just need need to be grinded out a bit to fit the larger D44 tube, maybe not, depending on the plate.  Plus he'd need TJ axel retaining brackets for a disc D44.  Everything else swaps over.

 

He has a 91, so the D44 axle flange will be a different bolt pattern than the non-c-clip 35s. I went through that mess when I swapped my Explorer disks from a 35 to a 44. Everything else will work with the correct preload spacers.

 

Since they never sold MJs in Oz OME never made rear leafs for them. Bastids. I have all OME stuff on my MJ too with General Spring MT rear leafs. Rides/handles real well, but still would rather have OME springs in the back. Wonder if anything else they made is close. Alcan makes nice springs too. 

 

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Thanks for the input gentlemen.  I think I’ll start this project as soon as my MJ fund gets built back up a little more.

Recently changed the diff lube because the cover was leaking.  When Rich had it done (before I bought the truck) the shop just used RTV as a gasket and it didn’t hold.  While I had the case open I pulled the axles to check the bearings and replace the axle seals (driver side had leaked on the brakes) so that part will be old hat.

Is it safe to assume the caliper location will be correct without any spacers on the brackets?

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14 minutes ago, HOrnbrod said:

He has a 91, so the D44 axle flange will be a different bolt pattern than the non-c-clip 35s

 

Is it a non-c-clip D35?  I assumed it was c-clip, thinking non-c-clip stopped in the 80s.  My 91 has a stock c-clip D35.  Regardless of what it is, I think you're right about the bolt holes needing to be enlarged/moved during any future swap to a D44.

 

18 minutes ago, HOrnbrod said:

Since they never sold MJs in Oz OME never made rear leafs for them. Bastids. I have all OME stuff on my MJ too with General Spring MT rear leafs. Rides/handles real well, but still would rather have OME springs in the back. Wonder if anything else they made is close. Alcan makes nice springs too

 

When I actually start my MJ build I'm going to research this heavily.  OME is excellent with their R&D and they are known as the best of the best for the applications they support, and that's led me to pick them for three different generation wranglers (JK, TJ, YJ).

 

Now you've got me thinking on OME rear springs for the MJ.  Need to expand my thinking.  I had an 88 Land Cruiser FJ62 with OME springs.  I loved that beast.  It was the "when you absolutely, positively have to get the serum to the villagers" model.  They might just have a similar truck application.

 

Alcan has a very detailed quote process I was impressed with.  Seems like those are tuned to the truck as well as what you do with it. Hells creek knows MJ springs.  The general MTs are proven.  There are good choices out there.

 

Truly sorry for the thread hijack.  

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17 minutes ago, Keyav8r said:

Is it safe to assume the caliper location will be correct without any spacers on the brackets?

 

Yes, it will be correct.  If everthing doesn't line up perfectly, there's something wrong. 

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16 minutes ago, kryptronic said:

Is it a non-c-clip D35?  I assumed it was c-clip, thinking non-c-clip stopped in the 80s.

 

89 and below MJ D35's were non-c-clip. The Dana 44 backing plate bolt hole spacing was the same as the non-c-clip D35s. I had to get new backing plates when I put in the D44 from TeraFlex because I used Ford Explorer disk brakes. 

 

Which axle flange bolt pattern do the ZJ the backing plates use? Never worked with them.

 

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14 minutes ago, HOrnbrod said:

 

Which axle flange bolt pattern do the ZJ the backing plates use? Never worked with them.

 

ZJ brackets are drilled for a c-clip D35.  I used new backing plates available from Crown designed to work with both D35 variants, the D44 and the Chrystler 8.25.  So they're all somewhat similar in profile I would guess.

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94 to 98 ZJ.

Longer wheel studs.

Get the longer mounting bolts for the caliper mount from the donor.

 

Or, contact BigDavid on Cherokee Forum and he sends you the kit. 

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@Keyav8r I had planned on doing the ZJ swap for my truck but went the Teraflex route instead. I still have brand new slotted and drilled rotors, pads, hardware, etc. and I'd be happy to make you a deal on them. You'd just need the plates, calipers and lines I think. 

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we have 3 disk brake conversion writeups in the DIY list.  could you guys skim through them and see if any info needs to be updated?  thanks! :D 

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1 hour ago, Pete M said:

we have 3 disk brake conversion writeups in the DIY list.  could you guys skim through them and see if any info needs to be updated?  thanks! :D 

 

The kj disc brake write up is good, could use a bit more info and definitely some pictures. I have some pictures from when I did my swap that I can give you 

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add in a reply to the thread and I'll move the pics up later on.  :thumbsup:  

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