I did a search on this but only found a few stalled threads with tidbits of info.

Really it's seems straight forward since I bought a donor axle from a 2003 Durango and am pulling it apart. I'll be using the dust shield, caliper bracket, caliper, hardware...ect, ect.

In the process of removing this hardware it seems I will have to remove the rear end cover, remove clips from the axle shafts, and remove them from the axle tubes.

I guess not a a big deal but not what I was expecting to have to do. I replaced an axle shaft on a Jeep Grand Cherokee and the axle shaft was held in place by the bolted on bearing assembly. I guess I assumed that's how it was designed.

At any rate, my questions are:

What type of fluid is best when re-filling the rear end?

How much fluid is recommended for the rear end? Just fill till it pukes?

Should I clean it out somehow before closing it up and re-filling it?

Thanks in advance and I'll report back as the project progresses today and maybe tomorrow.

 

a couple of things here, it will be MUCH easier on you if you just swap the axles out, the 2003 axle should bolt up to the 98 D pretty easily, dont waste your time tearing the axle shafts out and what not, just swap the whole damn thing.

and the 9.25 rear end holds just over 1.5 quarts of fluid iirc, so buy two, and you fill it till its just below the fill plug, if you have a limited slip dont forget to put the additive into it.

 

Changing the rear end was my original plan. However upon inspection the caps showed signs of significant wear and I didn't want to have to rebuild the rear end.

So, that bring me back to changing over the brakes. I haven't tore into my Durango's rear yet, but it doesn't seem to be that difficult. I've already disassembled the 2003 rear end.

I'll get some fluid, and while I don't believe it's a limited slip diff I will double check and if it is I pour in some additive first.

Thanks.

 

HERE is a link to my write up on the complete axle swap. real easy to do.

Though I see you have a plan already due to the cap shwoing wear. Maybe just change them out?

I swapped mine when I was having 4.56 gears installed. We found that my '98 axle had spun racers.

Good luck and you will love rear disk brakes.

 

After checking my stock ratio I also realized that swapping the rear end wouldn't have worked simply because of different ratios.

Also, in the time that I have been compiling parts for this swap, I seem to have lost the bolts that hold the rear caliper cradle to the caliper bracket. Anyone have that bolt size and length handy?

I'm close to done with the swap, with the exception of the caliper bolts. Something I didn't anticipate was the length difference in the axle tube end studs that hold the caliper bracket in place. The drum studs are shorter than the caliper bracket studs...so I had to drive them out of the donor axle and press them into my axle.

Everything else has, and is, going to plan.

 

Okay, it's done. All four wheels have discs.

Here's the problem after my test drive: The two rear calipers held tight...too tight, every since bleeding it and never released. After the short test drive the two rear sets of pads were smoking and noticeably hot.

Why would the rear two calipers not release? I saw mention somewhere of needing to replace the distribution block. I noted that all the lines fit up well so I wasn't sure if or why I would need to change the distribution block.

Would it somehow keep pressure at the rear two brakes, being that it was a drum brake setup, would that distribution block keep the fluid pressure from backing up the lines to the master?

I need to figure this out soon. I might assume bad caliper, but on both rear wheels?

 

I don't think so, it sounds like there is something stuck in the main rubber line that hangs down from the frame to the axle. Replace, ensure a good bleed all the way out as you play with it and re-test.


***EDIT***

I was wrong, there is a difference. https://dodgeforum.com/forum/1st-gen...-and-disc.html

 

holy cow, I cant believe nobody else has said this yet. on drum brakes you have to have a residual pressure valve to keep the brake cylinders from fully retracting so it dosn't take as much pedal travel to make the brakes work. when you switched to drums I bet you didn't know you have to remove the residual pressure valve. on some vehicles its possible to open it up and render the residual pressure valve useless so without having to replace it, im not sure if you can do this on a durango. it may be part of a larger unit that you have to change the entire unit.

the reason you dont need this with discs is the seal for the caliper piston is designed in a way to let the piston come back ever so slightly before it holds the piston from retracting further because the suction in the master brake cylinder when you let off the pedal is not enough to pull the piston against the seal. this is what makes discs self adjusting. drums have strong springs holding the brake shoes in place so it would not work on drums hence the residual pressure valve.

 

Thank you sir for the enlightenment. However I did a quick search for either an explanation or even a part number and can't find anything on a residual pressure valve. Does it have a more technical name?

So much as I can see, there is a small 1 to 1 distribution block on the axle housing that splits the single rear line two ways to each wheel. Then further up there is the distribution block itself.

Is it possible the distribution block IS the residual pressure valve, and is there a way to confirm that?

 

i'll try to look under my '00 Durango tonight to get a better idea where it might be as I really dont know where it would be on a Durango. the block on the axle probally takes one line and splits it into 2 lines to feed both sides? that shouldn't be it, that should just be a splitter. there is probally a block near the front that the front and rear brake lines go into then come back out of, it might be in that.

I will try to look tonight thought and see if I can find it.