Gear pattern check

Whatcha think?? .010 on the inner pinion with the oil shim, about 15 in lbs on preload on new bearings. .08 backlash, no sideplay on the carrier, all #'s within spec of Yukons instructions.






This was my first gear install. Used 4.88 yukons with a master install kit. Axle=HP30

Everything was fine after the install, pulled the rear shaft, ran in 4hi. No gear whine except the noise from the transfer. Ran approx 15 miles and let cool. Ran another 30 miles, during this 30 miles a noise has developed that is scaring the crap out of me. It seems to be getting worse, at speed back off the gas, then reapply. As soon as you get back on the gas there is a grumbling noise for a split second. Once you back off the gas the noise comes in again as you unload the driveline. If you get very slowly on the gas you can get it to continue to do it. I've got new front u joints, and the drive shaft joints are good.

The noise has only started since the regear, I've never heard it before.

Also I changed the diff oil, slightly grayish, and FILLED with shiny bits. How much is normal after a re gear??

I changed the transfer oil tonight so I'll take it for another ride tomorrow and try to get the noise nailed down a little.


Also these pics are not of the install, aftyer the 30 miles I changed the oil and checked the pattern (pics) Theres about a 1/16 of an inch between the face and the root of the gear on the pattern.

Looks like pinion depth needs set

Yeah that pattern dosent look close enough it will probbaly be fine thought just make a little noise. You can try and go back and get it closer but now that you have allredy driven it like that it may be difficult to get the noise to go away. The black oxide on the gears makes the fluid look strange when you change it for the first time so your prob ok there

They don't seem to whine or howl, just that on/off driveline noise. Any idea where that could be?? Bearings??

Pony,
As far as the sound goes, at what speed does it happen? What size tires are you running? I ask because I just did my 4.56's (32" tires) and when at 65 - 70 if I let off the gas I get an odd, rattle type noise as well. Same symptoms, at speed, let go of gas get this rattle, apply gas it goes away. I can get it to continue to do it by feathering the gas pedal and keeping just below the amount of pressure to actually accelerate again. Sound like what yours is doing?

i thought maybe it was backlash related but I am 100% positive my backlash (even runout) is within spec. I am now leaing towards an exhaust rattle because my RPM's are up near 2900 at 70mph.

I really can't pinpoint it though, our sounds seem similiar.
Mitch

.08 backlash, or is it .008???

ABSdad, sounds EXACTLY like what mines doing. I'm going to mess with it some more tonight to see if I can pinpoint it a little better. Almost a rattle/grumble noise that is not in time with the tire or engine rotation.

Mine happens at pretty much anything over 40, running 37" mtr's at the moment.