8 3/4 Noise

[Greenmachine225]

Just got everything squared away on my duster for the v8 swap and I go to drive the thing and there’s a huge howling noise coming from the 8 3/4. It happens when I give it over 1/4 throttle and the car doesn’t accelerate hardly at all. Noise goes away when I let off the gas but I’m not able to get the car above about 30mph. The third member was rebuilt with a sure grip and 2.94 gears, it’s all I could afford but it was fully rebuilt. I don’t know anything about adjusting the parts in the diff but I’d appreciate any input on what the problem might be.
Thanks, Carson

 

[Steven190]

I do not know a whole lot about the third member, but it sounds like the gears are not set to the proper back lash.

 

[512Stroker]

Just got everything squared away on my duster for the v8 swap and I go to drive the thing and there’s a huge howling noise coming from the 8 3/4. It happens when I give it over 1/4 throttle and the car doesn’t accelerate hardly at all. Noise goes away when I let off the gas but I’m not able to get the car above about 30mph. The third member was rebuilt with a sure grip and 2.94 gears, it’s all I could afford but it was fully rebuilt. I don’t know anything about adjusting the parts in the diff but I’d appreciate any input on what the problem might be.
Thanks, Carson

No one on here can tell you what's wrong without alot more info and pic's.
You will need to remove the carrier from the axle for inspection, check for metal in the gear grease.
Who "rebuilt" the carrier assembly? Were all new parts used?

 

[abodyjoe]

nothing wrong with a 2.94 gear. car should be plenty peppy with them...

is there gear lube in there? the howl sounds like the gears are set up wrong... as far as not getting over 30mph goes who knows. you think its the rear holding you back or are there two different issues?

 

[512Stroker]

nothing wrong with a 2.94 gear. car should be plenty peppy with them...

is there gear lube in there? the howl sounds like the gears are set up wrong... as far as not getting over 30mph goes who knows. you think its the rear holding you back or are there two different issues?

That was my thought too, maybe the transmission? Automatic?

 

[Murray]

First- how are the tires, front and back? Cupped tires can mimic a bad rear end. If tires are questionable, then change them or rotate them front to back and see if the noise changes. No outside adjustments are going to fix that rearend if the problem is in the carrier.

 

[Steven190]

Years ago I built a 30 street rod with a 340/727/posi 8 3/4 all have been rebuilt. Had it on the jack stand for the first fire up as a complete drive train. The was a noise coming from it and thought it was coming from the trans. So I took the trans apart and did not find anything wrong. Put it back together and fired it up again. Still making a squealing noise, sounded like the trans.
Now I am confused. So I looked at the rear axle, I had the correct gear oil in it, but not the additive. Got the additive in it and the noise went away. The car is still going.