O'well, Broken 7.25 rear

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AdamR

AdamR

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And I havent even driven the car yet. I was laying under the car putting in the drive shaft and decided to spin the axles.Car is in Park, Driveshaft bolted up, Spin the driver side axle It spind free. Thats weird. Spind the passenger side, spins free, Driver side axles turns backward. Put the car in neutral, Turn the axle , driveshaft doesnt move. Turb=n the other axle, same thing.

Strange I think and Im a little and confused.

Turn the driveshaft and the Passenger side kinda turns. Turn the drive shaft and hold the axle and the driveshaft turns fine like its not hooked up.

Still confused I put it in gear and turn the driveshaft, same thing, I can turn it and hold the axle from moving like nothing is hooke up.

Whats the deal ? Theres no way Im putting money in to the 7.25, I didnt even want to buy gear oil and a U joint but did because I thought it would be nice to be able to drive the car in and out of the garage.

Nothing looked out of place or broken when I pulled the cover off.
 
Adam, let me get this right, when the car is in Park and you spin the drivers side axle it only spins (passenger axles stays still) but if you spin the passenger side axle the drivers side also spins? Wierd.

Chuck
 
In park if I spin either the other doesnt really mover. In P, R or N, I can spin the drivershaft easy while holding the axle completely still.
 
Probably did not read this close enough. First thought that popped into my head is that of the standard dog leg rear. One will spin as the other is held. Like when you do a bit of a burn out and only one side spins.

What happens when you put it in gear with both tyres on the ground holding both axles still and try to turn the drive shaft?
 
Pull The Cover Off And Have A Buddy Spin The Driveshaft. Then Try Not To Laugh As Your Discover That The 7 1/4 Broke By Magic....no Seriously I'd Pull The Cover And See Whats Going On...
 
It sound to me like one of the axles is broken. Do you still have the cover off? if you do, rotate one of the axles again while in Park that way you can tell which one is broken. If you spin the good axle the spiders will turn. If you spin the bad one the spiders will stay still. If you take off the drums the broken one will have a lot less drag than the good one.




Chuck
 
Im to lazy to pull the cover. I'll wait till the carb comes back from Demon sizzler and put the car back on the ground and drop it in reverse. If it dont go, its broke. Just another 7.25 for the scrap pile.
 
On Second Thought, Are You Sure That The Tranny Is In Park? The Driveshaft Should Turn If It In Park Because Of The Tranny Not The Rear End
 
In an open rear end with the drive shaft is locked (i.e., the tranny in park) so it can't turn and you rotate one axle the other one has to rotate the same speed in the opposite direction. If it doesn't then something is broken.

With the drive shaft free to spin and you turn the the axles the drive shaft may or may not turn it depends on how much friction there is in the differnent components. But if it's not turning then the opposite axle should be turning the opposite direction.
 
That rear probably heard about that hot 340 you're going to run in there and decided to let you know it doesn't want any part of it!
 
dgc333 said:
In an open rear end with the drive shaft is locked (i.e., the tranny in park) so it can't turn and you rotate one axle the other one has to rotate the same speed in the opposite direction. If it doesn't then something is broken.

With the drive shaft free to spin and you turn the the axles the drive shaft may or may not turn it depends on how much friction there is in the differnent components. But if it's not turning then the opposite axle should be turning the opposite direction.
Click to expand...


So your saying even in park they can spin ? I think Im having a brain fart today. To hot.

So the axles spinning in different directions is what keeps the car from rolling? Makes sense, never gave it much thought.
 
Even in park if you have both wheels off the ground both wheels can turn but they have to go in opposite directions.

Each axle is splined to a side gear and the two side gears are connected by spider gears that ride on a shaft that is supported by the carrier. If the carrier is prevented from turning (tranny in park) and you turn one wheel the side gears spin the spiders which turn the other side gear in the opposite direction.

Yes with the tranny in park and both wheels on the ground the car will not roll because the only motion avaialbel is for one to turn one way and the other the opposite way.
 
This is also why you need to block your wheels if you jack up one side to change a tire. Being you picked up one side the other side on the ground is able to roll.

Also when you do a open diff one tire burn out and your speedo is indicating 60mph, your wheel speed it 120mph. The differential gears were never meant to spin that fast this is why alot of them find there way out.


Chuck
 
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