Rear end
 

Sorry if this question has come up before (I searched and could not find an answer...)

I put my car on jackstands and wanted to run the car to see if the wheels are bent. I was told the passenger side might have a wobble and I am installing new tires so I want to change rims now.

The driver side runs fine with the engine idling in gear. The passenger side doesn't. It moves about an inch and stops, then moves about an inch and stops..... over and over. I guess if that is a differential thing, I get it but is it normal to perform that way?

Thanks,

Jack

Re: Rear end
 

Block the drivers side.

Re: Rear end
 

Great! that worked. Thank you.

Jack

Re: Rear end
 

The differential is designed to let one wheel move more than the other when going around a curve. If one brake is dragging more than the other, that brake will prevent the wheel from turning while the other one spins. If you put the car in gear with the engine stopped and turn one wheel forward the other will turn in reverse. If one wheel is stuck in a muddy patch while the other wheel is on dry asphalt, the one in the muddy patch will spin and the car will not go anywhere. Anti slip differentials were invented to eliminate this problem. British light cars that are used to navigate muddy roads for rallies will have independent rear brakes operated by hand levers so that spinning wheel can be stopped so that the wheel with traction will move the car forward.

Re: Rear end
 

Some VW dune buggies that were set up for sand also had “fiddle brakes”. They pulled the emergency brake cables individually for left and right. Not just for braking, you can slow the slipping wheel and gas it to push the one with traction.

Re: Rear end
 

For the young and the hip

"The traction control system (TCS) detects if a loss of traction occurs among the car's wheels. Upon identifying a wheel that is losing its grip on the road, the system automatically applies the brakes to that individual one or cut down the car's engine power to the slipping wheel."

Re: Rear end
 

More fascinating information: Logging trucks in the early days, that were used to haul logs out of the forest, not for transportation to the mill, were WW II surplus trucks. The trucks were 10 wheelers with power to all 10 wheels. The differentials were welded up solid so that there was no slipping wheels. The logging trails were usually muddy or just loose dirt so going around corners was not a problem as the tires just slipped a bit.

Re: Rear end
 

A little off topic but to check for a bent wheel you can make a redneck dial indicator with a block of wood and a nail. Just hammer a nail in the wood block only to hold it, then push the nail head against the wheel and spin the wheel by hand and see how it tracks.