help! brake trouble related to my differential???

[83 chif]

okay, so my rear dif started making some ugly clanking and chirping noises. I changed the fluid and found some metal shavings. I can also grab and wobble the pinion...that's no good, eh? Just before my dif went south on me, I replaced both my rear wheels cylinders and brake shoes. I hadn't bled them correctly, and the pedal went to the floor on the first bump, then the second was normal. I tried to bleed them again, and now they go to the floor the first two pumps. And when I drive, not far or long, I can feel the brake pedal push back on my foot in unison with the inconsistent clanking noise from the rear. what's going on here? any clue??
thanks for any help you can give me...

 

[pappy]

The diff has nothing to do with the brakes. You have two different issues unrelated to each other.

Diff: my guess is you have a toasted pinion bearing. If you need to re-gear now would be the time to consider getting both diffs done.

Brakes: Sounds like you might still have air in the line, or the new wheel cylinders are no good. Were they OEM or aftermarket?

 

[the truck doctor]

Fill the brake res. w/fluid, open both bleed valves and let them gravity bleed a few. Then close them drive around the block cautiously, do it again if need be.

 

[missouriman]

pinion, see if the stamp in the nut holding it on is still in the correct place. or try to tighten it.. use an electric hammer or air hammer.

brake bleeding. go to local vet and get a 60cc syringe, with a luer lock, threaded end. use a piece of vacume hose. over fill the rez. put some grease around the bleeder screw. connect the vacume hose to syringe and (have your 10mm wrench on the bleeder valve) and the hose to the bleeder valve.

look for the order of bleeding.. I think that it is proportioning valve. right side, left side.. anyways you can pull out 60cc at a time.

that is how I do it and works great.
course I work at a hospital so I can get the stuff easy.. but at the vets it is less then 2 bucks.
I have rock hard brakes the first time.. people that have seen this just shake thier heads and say why didn't I think of that, it is cheating.

that is after he spent 3 hours doing the pump.. hold bleed,, pump hold bleed stuff... lol..
I have also used a needle on the rubber of the rez to push air pressure in and the crawl under quickly.. and bleed.

heck I have even used a needle mounted on a garden sprayer to supply the little bit of bleeding pressure.

 

[raydouble]

pinion, see if the stamp in the nut holding it on is still in the correct place. or try to tighten it.. use an electric hammer or air hammer.

I can't stress enough that this shouldn't be done.
The torque put on the companion flange nut compresses the crush sleeve, which in turn, puts preload on the pinion bearing. (Too much preload will do this to a bearing.

http://www.ncttora.com/fsm/1993/suspensionandaxle/35differen.pdf
Page 17 has the torquing procedure for the rear companion flange.

I'm sure you have air in your brake system and I don't think your problems could be related.

http://www.ncttora.com/fsm/1993/brakesystem/3checksan.pdf
This page has checks + bleeding procedure.

Longest to shortest ie: RR,LR,RF,LF then load sensing proportioning valve.

BTW it sounds like your pinion bearing may already look like the one above, you might try retorquing it, but I would look to get a replacement asap.

 

[83 chif]

alrighty

yea, by the sound of my rear, the bearings look worse than that.

and so we've got our money on air in the brake lines, right? i'll try a new method of bleeding them, not sure which yet. but i still think it's really strange how the pedal pushes back on my foot as i hear the clanking noise, but when there is no clankin noise, the pedal feels like regular poorly bled brakes....i'll keep you updated. thanks for the tips!