Topic: rear 3rd member blues

[89toy]

I have a V6 3rd member in the back originally built by Marlin.  I have 5.29 gears and an ARB, but it is having a few problems  .  The original gears only lasted about 5,000 miles (I think that guy that had the truck before me didn't change the fluid after initial break in).  I figured that new gears (since the old ones were fried) would solve the problem, but this little problem is happening again  .  At about 70 on the highway, everything sounds and runs fine, but when I get off the gas (not all the way, but in more of the neutral position), the rear starts to vibrate and has an extremely loud "hum" to it that sounds like metal on metal.  When a buddy of mine and I rebuilt it, everything was to spec, the only thing I didn't replace were the bearing because they seemed fine.  I don't know if the gears have anything to do with it or not.  What do ya think?

[AaronB]

is your drivline balanced?

[89toy [OP]]

yeah, I just finished a crawl south of me and bent the driveshaft.  I sent it back to Tom Woods and I just got it back, so everything in the balance "area" should be good.

[79coyotefrg]

how many miles on the new gears??  what brand  are the new gears??


it sounds  like you have  bad  pinion depth 

[89toy [OP]]

I have about 1000 on the new gears.  I ordered them from marlin (Yukon)

[79coyotefrg]

and  when you changed  the oil at 500  did you have  much shavings ??

[89toy [OP]]

very, very, little.  nothing more than i would consider normal on break in.

[Gittinit]

Its the bearings for shure.     Did you use a crush sleave or a solid spacer? When your driveshaft got bent on the rocks it is possible that you could have crushed the crush sleve a bit and caused the pinion to have extra room to move around.
 Something definately aint right ...Quit driving on it and tear it apart, then tell us what you find. Its hard to guess what your problems are through the housing and even harder through the internet, and the housing.

[79coyotefrg]

i agree,  crushed  crush 

[89toy [OP]]

I have the solid spacer in it right now...also, it has made the noise before and after I messed up the shaft.  I'll take it apart and let ya'll know.

[Rocksurfer]

how many miles on the new gears??  what brand  are the new gears??


it sounds  like you have  bad  pinion depth 

  or the crush sleeve is loose and is allowing the pinion to drop under deceleration and contact the carrier.

[Gittinit]

I have the solid spacer in it right now...also, it has made the noise before and after I messed up the shaft.  I'll take it apart and let ya'll know.

If you have the solid spacer in there I put my money on the bearings.
































Did I mention I don't have any money..... yea I'm broke!

[79coyotefrg]

the kids pick your pockets??


i have actually  seen a  diff once  that  pulled the pinion  so hard it stripped the threads  off the  pinion nut