Topic: Attn: Mechanics & BigMike

[blackdiamond]

I have a truck problem that needs some trouble shooting.  My rear differential is running much hotter than I would like or is normal.  There isn't any noises that are not normal for the Detroit locker (3+ yrs old), but the truck really drags backing up almost like the brakes are locking up.  It seems to roll normally going forward.  I would suspect that the brakes were the problem except that I have not noticed anything hot (smell) in the area, just the differential.  This is a slowly progressing problem that has gotten more noticeable very recently.  The differential has 4.88 Yukon gears and 33 inch tires.  Any ideas?  Can I damage the Detroit with heat?  I would expect that a rebuilt would involve new ring & pinion, but the Detroit gets expensive.  I smelled the carrier bearing on my Camaro when it failed, but nothing so far on the truck.

Any ideas?     

I'm not the type of guy to pull everything apart and just go looking, not my area of skill or ability.  Odds are I might not see anything wrong, but you never know.   

[synwars]

Hmmm. The only thing I could think that would make your third run hotter would be if the lash in the gears weren't set right, as in the gears are running too close together. I don't know a lot about them, but I know that if the ring and pinion are set too close together it'll run hotter. They are supposed to be half check or just over... Why is it you say the diff is running too hot?

My bet is that if you are still using the drum style e-brake that they are set too tight or seizing or something. I had a problem with my e-brakes seizing on or getting too tight from the self adjuster. It would roll forward fine, but it was a huge stress to roll it backwards, just like the brakes were engaged or something. Check the e-brakes cuz I never smelled anything burning either. Hammer the arms back in the drums and see if it loosens up. (They seize easy up here from all the salt they put on the road in the winter time. \ )

[Duffil]

are you low on gear lube?  that would let'er get hot..bad for bearings,too.

[blackdiamond [OP]]

I just had the rear brakes done by the stealer, so they should be ok.  I just change the differential fluid a while back and it ran cool for a while and then started getting warmer.  Differentials should be warm to the touch rather than hot.  My new Tundra is just warm to the touch.

[reklund5]

Just 'cause the dealer replaced the brakes doesn't mean the Tech that installed them did it right.  The tech could have adjusted the shoes a little too tight, which would especially be noticeable when backing up.  When going forward, the truck can easily overcome the braking force, but the added stress of the brakes dragging (even a little) could cause excess heat in the diff.  Are the drums hot/warm to the touch at all?

Ryan

[blackdiamond [OP]]

I will check them out the next time I take it for a ride.

[blackdiamond [OP]]

A dumb question:

Since the brake job was done in two steps since the wheel cylinders were not leaking the first time.  Is it possible that the new wheel cylinders tightened the adjustment of the rear brake shoes?  Maybe the stealer didn't readjust things.

[blackdiamond [OP]]

The brake drums were hot after a short trip thru town, that makes me think the brakes are the problem.

[SWAMPER]

O totally agree with the brea hypothesis because if like someone said that your gears were too close you would have noticed this sometime since you installed them...also once you get the breaks fixed up i recomend you change your diff fluid since its been running too hot....I would also recoment some gear lube addative by JB its good stuff

[79coyotefrg]

dude that stealer  didnt set your brakes right,    take your wheels off, then drums,  you may have to bleed off the brakes to get them off then loosen the adjustment

[toyman2]

if you breaks are getting hot like that , thats bad for drums,break fluid,shoes and spring hard ware
id take it back to where you had it all done and have them take care of i
if you wanted to tear it all down you woulda-shoulda did it the firt time

[79coyotefrg]

yep you got a good point   TAKE IT BACK

[blackdiamond [OP]]

To make it easy on myself I stopped by Sears and had them take a $15 look and everything looked OK with the brakes.  The mechanic said that the drums came off easily, hmm.

On the way home I came up with an idea.  This problem seemed to happen about the same time I installed my new rear springs that sit about 1-2 inches lower than the old ones.  My rear brake proportioner is adjusted for the higher lift height and may currently adjusted for a heavy load condition by default.  I would expect it to be more noticeable in reverse since front brakes are more important going forward and it would explain why there is some drag causing heat going down the road.  Also, the added pressure would be released when the truck is on a lift (i.e at Sears or Stealer).  I am planning to adjust and see how it works.  Sound reasonable?

[blackdiamond [OP]]

My bet is that if you are still using the drum style e-brake that they are set too tight or seizing or something. I had a problem with my e-brakes seizing on or getting too tight from the self adjuster. It would roll forward fine, but it was a huge stress to roll it backwards, just like the brakes were engaged or something. Check the e-brakes cuz I never smelled anything burning either. Hammer the arms back in the drums and see if it loosens up. (They seize easy up here from all the salt they put on the road in the winter time. \ )

I just put the truck on jack stands and hammered on the e-brake levers.  I think the problem is solved for now.  I still need to get the e-brake working again, but not today.

I noticed that I lost some pedal pressure after releasing the e-brake.  Would the e-brake being slightly engaged change the adjustment on the drum/shoe?  Obviously I am not a mechanic so I rely on this website and a few local friends to help me out.

[Rocksurfer]

hammering brake parts not good idea

[79coyotefrg]

Would the e-brake being slightly engaged change the adjustment on the drum/shoe?

    and absolutely