Disc Brake Upgrade on an '88 Non-C-clip Axle

[Salvagedcircuit]

Hi. I've been itching to do a rear disc brake conversion on my 1988 Jeep comanche, but I have held out until I have completed my research on brake conversions.
My comanche has a rear dana 35 non-c-clip style axle. Mine has the bolt access hole in the brake drum axle flange, and I can see the retainer plate and bolts behind it. Its definitely a c-clip axle.

My use case: My comanche is my work truck. I plan on picking up building supplies, towing and various other truck activities. Not planning to rock crawl with it. I'm trying to improve brake response and reliability and to me it makes sense to switch over to disc brakes.

At this point, the vehicle is 34 years old and still has the original rear corrugated brake lines, stock drums, stock front disc brakes, dana 30 front axle, dana 35 rear axle and the stock brake booster. It's at the point where it makes more sense to replace components than to refurbish.

I plan on making my braking system reliable because I would like to make this my daily driver. You just don't see any of these on the roads anymore by me and I would like to change that.

However, the non-c-clip axle is throwing me a curve ball. There are not many bolt-on disc brake options for the trapezoidal bolt pattern on the retainer plate that is used on the XJ and MJ from '84-90. The only one I could find is from teraflex, the Teraflex 4354410:
https://teraflex.com/1987-90-yj-1984-90-xj-rear-disc-brake-conversion-kit.html

My question to you guys is this: is it easier to remove the entire rear axle from my MJ and install a ZJ rear axle? The ZJ has a standard trapezoidal hole pattern on the retainer plate and it opens up a lot of disc brake upgrade options. I have seen nickintime's guide on 84-90 xj rear brake adaptions here:
http://www.youtube.com/watch?v=V5IDOZz3fo4&t=9m36s
and its a bit more how-you-doing than I'd like.  

Are there any other axle swaps I should look out for? Sure, I'd love to swap for a larger axle like a dana 44, but I don't know how lucky I will be at the junkyards. luckily a few local junk yards still have some Zj's and Xj's which is great.

Any input would be great!
Thanks!

 

[cruiser54]

94 to 98 ZJ rear discs should bolt right on AFAIK. 

[Salvagedcircuit]

4 hours ago, cruiser54 said:

94 to 98 ZJ rear discs should bolt right on AFAIK. 

Hi Cruiser! Thanks for the input. Unfortunately, I have found that the backing plate bolt pattern on the ZJ rear disc brakes do not match the backing plate bolt pattern on the non-c-clip rear axles on my comanche. The youtube video above shows it. The rear disc backing plate was from a Zj and needed to be drilled and modified to fit the non-c-clip rear axle. I checked several ways and I am nearly 100% sure that I have non-c-clip rear axles :/

 

I'm looking into the teraflex disc brake conversion kit, but it seems I would be locked into rotors and pads from teraflex for the life of the vehicle. They don't list any other alternative source of pads for when they wear out. seems kinda silly.

 

Thanks for any input!

 

[Salvagedcircuit]

Update: The video above showed a rear 89 cherokee rear axle. The rectangular bolt pattern on that axle is 2" x 3+9/16". I was under the impression that the XJ rear axle is identical to the MJ of similar generation. Something interesting on the Quadratec website for the teraflex kit mentions:

"The years between 1987 and 1991 are the dark years where anything is possible from Jeep, so check the bolt pattern with the drawing before ordering a kit. "

Is it possible for my bolt pattern to be different? Even though I definitely have a non-c-clip rear axle, is it possible that my bolt pattern is not rectangular?

Here's some photos to explain the differences. I went ahead and measured the rear of the drum brake and it turns out my original hunch was correct. I have the rectangular axle bolt pattern,  2" x 3.35." I wonder why quadratec labeled 87-91 as the dark years?

 

Update 2:

This right here is why I jointed this awesome place!
@WahooSteeler has already solved my problem, it just took me forever to find the answer. Teraflex actually sells the correct backing plates separately.

Thanks a ton guys!

 

[JIMMYRIG]

I tried to do this swap on my non c clip and even after drilling out backing plates ended up with about a quarter inch of play in each shaft. I'm assuming this is due to difference in backing plate and the flange that holds the shafts in place is clamping onto the backing plate before it can put tension on the bearings. Any suggestions on how to make it work or am I better off doing an axle swap?

[ghetdjc320]

7 hours ago, DLYMANCH said:

I tried to do this swap on my non c clip and even after drilling out backing plates ended up with about a quarter inch of play in each shaft. I'm assuming this is due to difference in backing plate and the flange that holds the shafts in place is clamping onto the backing plate before it can put tension on the bearings. Any suggestions on how to make it work or am I better off doing an axle swap?

There is a ring that fills in that gap (see pic). For reference, the non c clip D35 and D44 use the same brake backing plate.

 

 

[Salvagedcircuit]

I believe teraflex sells the spacer separately. Something like one of these:

https://www.amazon.com/TeraFlex-8636-Pre-Load-Spacer-Brake/dp/B00ZJB9XOE

https://teraflex.com/tj-rear-disc-brake-preload-spacer-each.html

 

If you call them and ask them nicely I they will let you buy it direct from them.

[Boilermaker]

Preload spacers can be ordered right from the teraflex website. I used part #86262 for a d44 out of an 87xj. If you search thier site for preload spacers there are a couple of other options based on the axle you are converting. Ordered a couple earlier this week, fedex shipping was free but had to set up an account on the teraflex site.

[JIMMYRIG]

You guys are the best, thanks for the quick response! I don't know if this option came on all comanches but i have the load sensing valve that sits on the underside of the bed. When I pulled off my sway bar I disconected the arm so that I wouldn't cut power to the rear brakes when I nose dive.  Am I best off removing that and replacing with the zj prop valve and throwing in a 97-01 xj brake booster?

[Boilermaker]

Can't speak to proportioning or load sensing valve modifications, but the dual diaphragm brake booster upgrade is worth the time.

[ghetdjc320]

On 8/31/2024 at 4:19 AM, DLYMANCH said:

You guys are the best, thanks for the quick response! I don't know if this option came on all comanches but i have the load sensing valve that sits on the underside of the bed. When I pulled off my sway bar I disconected the arm so that I wouldn't cut power to the rear brakes when I nose dive.  Am I best off removing that and replacing with the zj prop valve and throwing in a 97-01 xj brake booster?

For the load valve, if you’re running 4 wheel discs you can delete it and run either the ZJ/similar prop valve or retain the MJ distribution block with no prop valve. If you’re running drum disc combo, run something like an XJ prop valve or similar to lessen the pressure sent to the rear wheel cylinders.

[JIMMYRIG]

On 8/30/2024 at 8:19 AM, Boilermaker said:

Preload spacers can be ordered right from the teraflex website. I used part #86262 for a d44 out of an 87xj. If you search thier site for preload spacers there are a couple of other options based on the axle you are converting. Ordered a couple earlier this week, fedex shipping was free but had to set up an account on the teraflex site.

Is the spacer supposed to sit inside the bore of the axle or just inside the backing plate? I ordered this exact part from teraflex and am trying to install on my d35 non-c with junkyard zj backing plates. The OD of the spacer is larger than the ID of the backing plate and bore.