finding rear end gear ratio

[pistolpete837]

i jacked up one wheel and turned it one turn and the drive shaft only turned exactly 3.5 turns what does that mean? and i do not have any after market lockers

thanks peter h

 

[Broncobowsher]

Well something is weird. If you just jacked up 1 wheel and only turned it one revolution and you got 3.5 turns of the driveshaft, then you have 7.00 gears and an open diff or some traction device and a broken axle.

Did you turn the tire over twice maybe?
Did both tires turn together?
Something isn’t adding up right with your numbers.

 

[DebosDave'72]

That should mean that you have a 3.50 ratio in there. I don't think you have a locker, since I don't think you could turn only one wheel, uless the locker is off (maybe a selectable locker)? You can tell if you have limited slip by jacking both wheels up and if they turn the same way when you turn one wheel, then there is limited slip in there. If they turn opposite directions it is an open differential. There are others more knowledgable on lockers that will help you there....

DD

 

[DebosDave'72]

Well something is weird. If you just jacked up 1 wheel and only turned it one revolution and you got 3.5 turns of the driveshaft, then you have 7.00 gears and an open diff or some traction device and a broken axle.

Did you turn the tire over twice maybe?
Did both tires turn together?
Something isn’t adding up right with your numbers.

Jumped in late with my answer and it was wrong! LOL forgot about the ratio problem with only one wheel up.

DD

 

[SaddleUp]

That would give you a gear ratio of 7:1 which is impossible. Try again.

 

[pistolpete837]

i only turned the tire onces and the other tire did not turn but it was off the ground

 

[SaddleUp]

How is it that we were all typing a reply to this at the same time? ;D

 

[DebosDave'72]

if you have both wheel off the ground, what happens when you turn the driveshaft?

 

[DebosDave'72]

How is it that we were all typing a reply to this at the same time? ;D

Got one that caught all of our attention

DD

 

[pistolpete837]

i did not do that but i will check that right now be back in a little bit

 

[SaddleUp]

i only turned the tire onces and the other tire did not turn but it was off the ground

If it's an open carrier then even if the tire is off the ground the numbers are not right. The tire will either stay still and you multiply by 2 or it will turn in the opposite direction and the number will be even smaller. The only way possible to get the number you have given is for it to be a spool or locker with a busted axle if only one tire is turning.

 

[pistolpete837]

ok i tired to jack up the truck just now to see what happens when i turn the driveshaft like dave said but the truck slid off the jack two time. i have a high lift bumper jack and smittybilt 3' in tube bumpers i dont know why it did that but i think im going to what until tomorrow to lift it up with the tractor

 

[DebosDave'72]

yeah, that is no good.... perhaps the other guys know of a way to tell if the axle is broken without jacking in up??? I was thinking if you turn the wheel that wasn't turning, and nothing goes on, then that axle is probably broken. I don't know enough about traction devices to tell you how to determine if there is one in there.... or how to tell what ratio you have with the given circumstances...

DD

 

[pistolpete837]

this might be a stupid question but the truck drives fine so can the axle be broken and the truck still drives?

 

[Jeepster]

ok i tired to jack up the truck just now to see what happens when i turn the driveshaft like dave said but the truck slid off the jack two time. i have a high lift bumper jack and smittybilt 3' in tube bumpers i dont know why it did that but i think im going to what until tomorrow to lift it up with the tractor

What ever the outcome on the axles....you need to buy yourself a good floor jack and jackstands. And for Gods sake dont crall under the rig to turn the drive shaft with out the jackstands.

SAFETY FIRST!!!

 

[pistolpete837]

thats true jeepster im a 16 year old guy i dont think things throw every well LOL but im not going under there with only that bumperjack

 

[SaddleUp]

this might be a stupid question but the truck drives fine so can the axle be broken and the truck still drives?

Not if it's an open carrier. With an open carrier it will not move using the rear axle if an axle is broken. You also wouldn't get 3 1/2 turns on the driveline because the broken side would just turn in the housing. Try jacking up one side only and recheck to see how many turns you get on the driveline again. It really sounds like you turned the tire 2 revolutions without realizing it. In which case it would have 3.50 gears (which is common) and that it is an open carrier that is working correctly.

 

[pistolpete837]

im positive that i am only turning the tire once because there was a little rock stuck in the treed and i used that as my start/stop point

 

[Jeepster]

thats true jeepster im a 16 year old guy i dont think things throw every well LOL but im not going under there with only that bumperjack

Is cool, Just be safe. The damn thing weights a ton. (or 2)

 

[Madgyver]

All you need is some string and some tape......

http://classicbroncos.com/gearratio.shtml