1989 Jeep Comanche 4.0 Disc Brake Conversion Dana 35

[ComancheLee]

hey y'all want to swap my rear drums for disc brakes don't want to swap out axles want to stay with the dana 35. what parts can i use or are there any kits that would work????

[xjrev10]

Yep. You can remove everything off a ZJ 93-97 Grand Cherokee and it will bolt right up.

[ComancheLee]

all i needed to know thank you

[xjrev10]

E brake cables work also with little modification.

[ComancheLee]

What about master cylinders and brake boosters

[Eagle]

The master cylinder and booster will work. If your rear, height-sensing proportioning valve is working you may need to play with the adjustment after the conversion because the discs will provide better stopping.

[big66440]

The master cylinder and booster will work. If your rear, height-sensing proportioning valve is working you may need to play with the adjustment after the conversion because the discs will provide better stopping.

Amen to that, this should be on the " must do" list of every Comanche owner.

[big66440]

What year is your truck O.P? if you have a "bolt in" rear axle Dana 35 you will need these as well ( Mopar 5083678AA ) to keep your rear wheel seals in place.

[ComancheLee]

Is 89 and I think the axles go all the way through the diff.

[ComancheLee]

That proportioning valve would you guys recommend

[ComancheLee]

What do you mean by bolt in axles?? How do I tell if they are or now ??

[DirtyComanche]

What do you mean by bolt in axles?? How do I tell if they are or now ??

 

He means non-C Clip style, aka conventional semi-floating, where the axle is retained by a retainer plate against the wheel bearing/seal at the end of the axle tube.  I believe a 1989 D35 will use that style of axle shaft retention.

 

I don't know if there's any obvious way to distinguish one from another, save pulling the cover off and looking for the lack of C Clips on the axleshafts, or actually taking the retaining plates off.

[xjrev10]

I used my stock prop valve. WJ master/booster. Elimated the load sending valve and plugged on port (think the front) on the prop valve. Run ZJ rear discs and WJ front brakes. Works like a charm. Stops like a new one ton.

[Eagle]

That proportioning valve would you guys recommend

 

Unless you have removed it or disabled it, your proportioning valve is the height-sensing valve mechanism mounted above and to the left of the rear differemtial housing, and connected to the diff cover with a rod.

[ComancheLee]

Will a 98 zj grand Cherokee master cylinder fit a Comanche?

[ComancheLee]

I seen that but isn't it set up for drums would you want something that would apply more break fluid/ pressure to the new rear disc brakes?

[DTA]

Step by step

[Eagle]

I seen that but isn't it set up for drums would you want something that would apply more break fluid/ pressure to the new rear disc brakes?

 

 

That's why I wrote that you will need to adjust it after the conversion.

[Jeepman]

Yep. You can remove everything off a ZJ 93-97 Grand Cherokee and it will bolt right up.

I thought that only works for 1990 and newer interesting...

[big66440]

Will a 98 zj grand Cherokee master cylinder fit a Comanche?

Don't know for sure but for MJ's the 95-96 XJ Cherokee or WJ Grand Cherokee booster/master cylinder combinations are the most popular. There's lots of info on the net that covers swapping them in. XJ's, ZJ's and WJ's all have a 1" bore master cylinder so doing the guess work on piston ratios is unnecessary. I'm personally using a 96 XJ booster/MC, WJ front brakes and ZJ rear disc's and my truck will do a front flip if I slam on the brakes fast enough :yes:

[gogmorgo]

So, uh...  :hijack:

Looks like I'm moving to Jasper in a couple weeks (not 100% unexpected but the suddenness was) and that's gonna mean dragging the Niva with the MJ. On a dolly most likely, ballpark 1000 miles. And that means the MJ probably should have working brakes, which means the easiest way to do this is fixing the drums. But (bringing this thread back on topic) I've got a disc brake 8.25 out of a KJ in storage. Can I (easily) rob the disc setup off that axle to work on the MJ's D35? Ideally without having to irreparably modify any of the components on it? The plan was to swap the 4.10 8.25 into the MJ which would be great for towing but holy hell do I not have time for that and I don't have a matching front axle yet so that's out of the question for now. I haven't been able to find anyone who's put KJ brakes on a d35 yet, seems like all the KJ brake write-ups are for 8.25 XJ's, and everyone swapping d35 drums out is just using a d35 ZJ setup. And my MJ is my only street-legal vehicle right now so if I blow the rear axle apart I can't exactly run to a parts store if I forget something.

Umm... TL/DR: can you put KJ brakes on a D35 without significant modification? 

[1989 Eliminator]

If you haven't already... click on the link in my signature for the dual diaphragm brake booster upgrade.

[1989 comanche mj]

I don't like the rear discs, because the parking brake is lousy.  That little drum just is no good, and the new shoes you can get are crap.  They fail quickly.  Now if you have an auto trans and don't live on hills its no big deal.  Drums are just fine IMO.  Now if you swap to an 8.8 you gotta use discs unless you want to go with a weaker older rear.

 

Also 8.8 and zj rear discs are identical except for the caliper.  Use whatever pads are for the caliper you use.  Jeep calipers will fit on the ford rear and vice versa.

[Loki]

I just purchased an 87' comanche, I am looking into doing this brake conversion for mine. Would I be able to use the same parts for it??  

[CoastChief]

On 3/21/2017 at 7:20 PM, Loki said:

I just purchased an 87' comanche, I am looking into doing this brake conversion for mine. Would I be able to use the same parts for it??  

I'm reading this with a year newer trying to make sure I don't mess this up haha