The Stovebolt Site Forums The Shop Area Driveline stiff gearing? Worn U-joints maybe??

I have something that has me a little stumped...hope I can explain it right, and I hope this is the right forum to post this.

I have a 61 Chev half ton. I have been getting it freshened up over the last while, as it has sat for a long time. Upon driving it today, only after it had been driving a while and was thoroughly warmed up, the rear end (I think it was anyway) started acting unusual. When I drove slowly around tight corners, it almost felt like something was rubbing or grinding. The rear end felt "stiff" almost a gear feeling. I don't know what to think of it besides that...not sure if my gears in my rear axle are screwed, if it's my brake drums grabbing, or worn u-joints...Only thing I've done with the rear end is change the gear oil ( I used 80W90) and check the rear brakes, which were in great shape. It only does this after being driven for a while and everything's heated up.

Any suggestions?

Adam

look at the last thing you messed with - brakes - also check that all lug nuts are tight

Bill

All I did with the brakes was remove the drums to have a look. Also readjusted the ebrake cable so it would work. I'm sure the lugs are fine but I better check them anyway. It almost feels like it's on tracks instead of wheels when taking corners at low speed.

Does it have any sort of limited slip differential? If you don't use the limited slip additive on one with cone clutches, it will chatter and grab in a turn after it warms up. Try jacking up the middle of the rear end so both wheels are off the ground, and turn one of them with the transmission in neutral. If the other wheel turns the same way, you've got a positraction.
Jerry

Jerry, is a positraction the same thing as a limited slip diff? I don't know if it has that or not...will have to jack it up and check it once I get it back from the mechanic...having the out of province inspection done on it, finally.

Ok, found out from my mechanic that limited slip and posi are pretty much the same thing. He thinks the same...may be limited slip and I didnt put in the additive. But he doesn't think Chevy trucks actually came with them in 61. Does anyone know if they did? Was it an option or something? I'm pretty sure my rear end is original...

There are lots of options on posi units, OE and aftermarket. Some use multi-disc clutches, others have cone clutches, and one called a Detroit Locker actually mechanically locks the two axle gears together when one wheel starts to spin. That one ratchets over itself in a low-speed turn and makes all sorts of clicking noises- - - -no way to quiet it down. It's possible someone installed a limited slip carrier sometime in the truck's past. Positraction, Trac-Loc, No-Spin, and a bunch of other names have been given to traction-equalizing rear ends by various manufacturers. All of them allow the axle speeds to differentiate in a low speed power-off turn, but lock up if a wheel slips excessively.
Jerry

That makes sense. Yeah I don't have much history on it...all I know is what I pieced together from everything that was left in it...it was someones vacation vehicle...there was evidence of it having a camper on it, it has trailer wiring and brakes, and the rear bumper was completely covered in stickers of the places they took it...from Expo 86 in Vancouver ( I was there when i was six!) to the Grand Ole Opry. Maybe a positraction was beneficial for all the driving? Not sure why it would be...But I'm starting to believe that there isnt actually anything wrong with it.

Most dealer parts departments (Ford, Chevy, Mopar, etc.) sell a 6-ounce bottle of limited slip additive that seems to be generic regardless of whose name is on it. I don't think I've ever seen a similar product at the FLAPS stores. Add it to the lube in the rear end and if the cone clutches are the source of the drag or chatter, it usually cures the problem.
Jerry

Thanks Jerry I will try that

BG offers a limited slip product. Also Lucas has the limited slip additive. Your local flaps should keep some. The parts store where I worked did.

Hey Roy, we don't have Flaps in Canada! Ha ha! I just checked Canadian Tire..they had no idea what i was talking about...kinda typical for them. I will check with Napa tomorrow.

Canadian Tire sells 80W90 for "limited slip" applications. I think they sell some that doesn't say that too. Maybe you should check the bottle.