A while back I bought a Strange 12 bolt rear with an Eaton posi and 4.30 gears. About the same time, I bought a Spohn extreme duty driveshaft with 1350 u-joints. When the rear showed up and I got all the parts together and operational, the gears in the rear end whined just a bit. Nothing terrible but it was there. I called Strange after a while and asked them about it and they said a little whine during break-in was common and should quiet down as the gears wore into each other, and also the rod ended suspension components that I put on the car transfer more noise than poly or stock rubber ended components.

Well, the whine never went away and after I took it to the track and launched it hard, of course the gears got substantially louder. I took it to a good friend of mine to check the backlash on the gears and make sure it was within specs, and it was. But, he found pieces of a shim that came out from behind a spider gear in the posi.

Not wanting to have to pull the axle out and send it back to Strange for repairs (which is what they wanted me to do) and be without a car for however long that took, I bought a spool and put the original 4.30s back in on the spool. The gears were now quieter than they had ever been, but the whine was still there. Is it possible the gears were cut just a bit out of spec, causing this whine? Or what could it be?

I'm probably going to get a rebuild kit for the posi that came out of the rear and put some 4.11 gears in because the situation with this combo is getting to the point where I dont want to drive it. I dont mind the spool, but the whine is really starting to get to me. I know, I've heard it all before. Too wish washy. Too impatient. I cant help it.

Also, the spohn ds I bought seemed to start vibrating noticeably around 60mph (per the speedo thats still calibrated for 3.42s) and got pretty scary as speeds increased. I tried swapping back to the stock piece, but the vibration was still there. The stock rear end/ds combo never vibrated, and I had it up to 150+mph. Could the pinion or the yoke be the culprit here too? Or something else?


EDIT: The pinion angle is set at -2 degrees, and I also tried swapping the ds 180 degrees, but no change.

 

Proper length DS?? broken trans mount, wheels out of balance, pulley backing of the crank....just a few things to check out, bent output shaft.

 

Everything was fine until I swapped rear ends and driveshafts... The shaft should be the right length, I ordered a stock length shaft from Spohn. The man I talked to from Stange said a stock length shaft would work just fine with the 12 bolt. Wheels are all balanced. It's a high frequency vibration tho, nothing like what an out of balance or separated tire feels like. Trans mount is good. I wondered about the output shaft being bent but my guy at the transmission shop said it was fine. I called Spohn and talked a little with a guy about the shaft being out of balance but he swore up and down they are balanced by computer to within a gram. I havent taken the shaft out to check the balance for myself tho, thats next on the list when I get the posi put back in.

 

weirdly enough an old timer told me to put a peeled banana in the rearend quiets it down instantly

 

Never heard that one b4????

 

A peeled banana! LOL My 9 inch has been screaming at me lately...

 

im serious an old timer told me once. he did it when he was tryin to sell a car that had a noisy rearend. needless to say he sold it!!!