Searched and found some stuff on this but nothing like my case.
I had a slight whine/howel upon acceleration at around 50mph coming from what seemed like the trans but probably was the rearend and it wouldn't happen all the the time just sometimes. Not a big deal as i was going to do gears anyway.
Well now i had the rearend rebuil by local 4x4 shop with the new gears and all new bearings etc.
And now it howels Everytime time under light/hard acceleration around 50mph and i think it is louder now too.. The shop owner drove it and said it was the transmission. But i know the diff is closer than most people realize.
1.Unitrax gears...like 500 mile break in i think
2.I have driven it 20 miles so far.
3. I bought the unitrax rebuild kit dosent that come with a new pinion bearing?
1) Did they start howling immediately?
1a) Are you following the correct break-in procedure? Two very mild 20 minute drives followed by a COMPLETE COOL DOWN each time then mild driving for the rest of the 500 miles?
2) 20 miles should comprise the first heat up and cool down stage of the break-in procedure. Assuming you are following it.
3) Did you watch them install it?
Question 1) is the most important here. Unless you nailed it the first time you got in the car. At which point the break-in process is the issue.
I've seen shops do this and never put a drop of oil back in it. I've seen the same bearings be re-used, I've seen them bolt the cover to the housing with an impact gun, I've seen them put the cover on without even putting a gasket or any kind of RTV on it, I've seen them not clean anything while they went through it.....all of which is a problem. nevermind the clearances required. if it's howling, a bearing is already fucked somewhere at a minimum.
When my front hubs went out they just squeaked. I suppose the rears could be quite different tho.
I've done dozens of them on various vehicles, one of my personal cars that I had to find was my 99 cobra. both front wheel bearings went about the same time. the exhaust kinda covered the sound at first, and no squeaks at all, but about 40mph it would start and become deafening at 60. I was in germany when it happened. it was so bad that when I got to the craft shop to check it out I went to turn my tires by hand and it felt like little indentations (think like the scroll wheel on a mouse kind of indentations) it was terrible. luckily those are REALLY easy replacements, unbolt, bolt new on (with new studs already on it) pricey though, like 200 a pop if memory serves me correct.
best way to describe the roar, it was similar in a jeep we had at the shop with 44inch aggressive mudders going down the highway.
Something else worth mentioning i guess is i bought some new slotted and dimpled rotors from the viperstore (viperstore brand). Put them on and took a 400mile trip. it was on that trip that i first started to notice the howel upon light acceleration at cruising speed and an annoying vibration in the gas pedal an d steering wheel at 80 mph.
All of this was prior to the rearend being rebuilt.
I talked to John Donato and im probably going to send the trans to him but first im going to take it in tomorrow and have the diff fluid changed. It has 70miles on the new rearend gears now. So i imagine if it is the pinion bearing the fluid should be full of metal by now.
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