Differential Action

[leversole]

My front differntial is a CRDP92...which should be an inter axle power divider...the absence of a "1" at the end should indicate that I have normal four pinion differentials.

I am wondering why I was able to jack wheels off the ground individually and run them in gear? Should'nt the power divider have put some torque on the rear that was on the ground? Each wheel was able to turn at high speed with the other differential stationary.

Leslie

[Rob]

The power divider works on the pricipal of equal torque to all wheels on the ground. When you remove one of the points, (such as elevating a wheel, or placing it on ice) the torque bias is sent to the unladen axle, and the unladen axle differential then sends all available torque to the unladen wheel. This is why it will spin independently of the others.

I'm with the other suggestion thinking there is wear in the cam and peanuts of the power divider. I've seen these things cause an uneven balance condition during operation causing a shake or vibration much the same as you are experiencing. I think one of my R models is suffering the same fate. I have "Centramatics" on the steer axle, and am going to put "Equal" balance powder in the drives for good measure next week. I do suspect I'll be rebuilding the power divider however as the rear wheels don't hold together quite like a couple other trucks I have.

Try to butt your truck up against something so it won't move. Place the trans in low gear and let it "dig" to ensure both drive axles are pulling together. If not, something could be amis in the power divider as this is a good indication I've used in the past.

Rob

[daveigou]

I scanned a piece here that explains how an "inter axle" power divider (from one axle to another) not to be confused with "inter-wheel" (side to side on same axle) works. At no time is there ever a positive "lock" with this arrangement, and it works better if the vehicle is still moving. Think of as more a "limited slip" arrangement than a differential, or in this case a power divider lock.

Towards the end of this piece it describes exactly the situation you're describing.

Hopethis answers your question.

Dave

[RowdyRebel]

....and here I always thought it was "magic"!

[theakerstwo]

It is a limit slip. And if the drive tires is not kelp the same size all around then it is to be exspected to find the peanuts and both cams worn out to were you can pick up one wheel and not feel the drag.This is a spring loaded efect antislip.

[other dog]

The power divider works on the pricipal of equal torque to all wheels on the ground. When you remove one of the points, (such as elevating a wheel, or placing it on ice) the torque bias is sent to the unladen axle, and the unladen axle differential then sends all available torque to the unladen wheel. This is why it will spin independently of the others.

I'm with the other suggestion thinking there is wear in the cam and peanuts of the power divider. I've seen these things cause an uneven balance condition during operation causing a shake or vibration much the same as you are experiencing. I think one of my R models is suffering the same fate. I have "Centramatics" on the steer axle, and am going to put "Equal" balance powder in the drives for good measure next week. I do suspect I'll be rebuilding the power divider however as the rear wheels don't hold together quite like a couple other trucks I have.

Try to butt your truck up against something so it won't move. Place the trans in low gear and let it "dig" to ensure both drive axles are pulling together. If not, something could be amis in the power divider as this is a good indication I've used in the past.

Rob

Is that that tire balancing powder you're talking about, or some magic powder? They used to put balancing powder in the tires at H.H.'s and I hated it because every time you checked the tire pressure it would get in the valve core and hold it open a little and cause a slow leak. They stopped using it for that reason.

[Rob]

Is that that tire balancing powder you're talking about, or some magic powder? They used to put balancing powder in the tires at H.H.'s and I hated it because every time you checked the tire pressure it would get in the valve core and hold it open a little and cause a slow leak. They stopped using it for that reason.

There is a special "core" you have to use with the powder!! A lot of tire dealers don't realize you need to install this core. In fact to check tire pressure you need to have the core at the top, (best) and hit it with a short blast of air to clean the incorporated screen on the inside. I ran it in all the trucks that had spokes. I firmly believe in the "Centrimatics" for the "Budd" style wheels as my tire life was great in the medium duty service.

Rob

[slpwlker]

Is that that tire balancing powder you're talking about, or some magic powder? They used to put balancing powder in the tires at H.H.'s and I hated it because every time you checked the tire pressure it would get in the valve core and hold it open a little and cause a slow leak. They stopped using it for that reason.

I never had luck with them. I got centramatics on the drives and lift axle. Gonna order the ones for the front floats. then do all the trailer axles. Try to get as much tire life as I can

[other dog]

There is a special "core" you have to use with the powder!! A lot of tire dealers don't realize you need to install this core. In fact to check tire pressure you need to have the core at the top, (best) and hit it with a short blast of air to clean the incorporated screen on the inside. I ran it in all the trucks that had spokes. I firmly believe in the "Centrimatics" for the "Budd" style wheels as my tire life was great in the medium duty service.

Rob

oh.