Thread: dumb rearend question from a newbie

Tweet

Hi guys,
First, you guys are great.

I know they say there is no such thing as a dumb question, but I think you will agree this one from a newbie is.

I bought a '68 torino rear end and new brakes to slip under my '36 International pickup. It is the correct width drum to drum and the correct bolt pattern. Now I notice the differential is offset several inches on the Torino rear end and my transmission is centered between the frame rails.

Did I screw up purchasing the Torino rear end?

Thanks for your help.
Jumpin Jack Flash

no the drive shaft will take up the off set as long as you end up with a drive shaft with some length helps with angle .engine and trans can be moved over to one side as well but most times not needed

No, you didn't make a mistake. Level the frame. Lay an angle finder on the machined end of the transmission output shaft to determine what angle the transmission is installed in the truck relative to the leveled frame rails. I would expect to see maybe zero to 2 degrees down bubble. Install the rear end with the pinion 1-2 degrees difference from the trans with the truck at rest. Under driving conditions, the pinion will climb the ring gear a little and the angles will zero each other out.

If the trans is at zero, install the pinion 1-2 degrees down bubble. If the trans is 1 degree down bubble, install the pinion somewhere between 1 degree down bubble and zero. If the trans is 2 degrees down bubble, install the pinion somewhere between zero and 1 degree up bubble. What we want to do is have the centerline of the trans output shaft and the pinion shaft to be PARALLEL with the truck under power running down the road as viewed from the side of the truck. Parallel like raiload tracks, not converging like a vee.

Now, as far as the pinion being offset, as viewed from the top (bird's eye view), the transmission and the pinion shaft will be parallel. Do not point the transmission shaft toward the pinion. The trans shaft must be parallel with the centerline of the truck and parallel with the pinion shaft. As viewed from above, the driveshaft will be angled as compared to the centerline of the truck and that's OK, as long as the trans output shaft and the pinion shaft are parallel with the centerline of the truck.

Some builders will alter the length of the diff housing on one side, using different length axles in order to get the pinion shaft in the center of the vehicle. This might make a difference on a car where the driveshaft tunnel is very tight and you really don't have room to angle the driveshaft, but on a truck, there is no such sheetmetal arrangement rear of the trans output shaft, so angling the driveshaft will not interfere with anything.

As Pat mentioned, the original equipment manufacturers have moved the entire engine/transmission package to the passenger side of the vehicle in the past to miss steering or braking components in the engine compartment. I remember in the 60's, Mopar moved the package as much as 3 inches to the pass side of the car. You can do this as long as you keep the crankshaft centerline/transmission centerline parallel with the pinion shaft (perpendicular to the centerline of the differential housing).

Thanks Pat and Techinspector 1. I am so glad it will work that way. I understand about the trans centerline and the pinion shaft parallel and the pinion 1-2 degress down bubble from the tailshaft of the trans.

Thanks again. I really appreciate it.

Jumpin Jack Flash

yep your ok .i put many of the 9 inch rear ends in cars and trucks if i narrow one i put the pinion on center but if not then i run them off set like ford built them

Are you talking about the pumpkin being offset or the pinion shaft being offset???

for the pinion to be centered, the pumpkin is offset to the left---

Some street rodders (as compared to racers) will center the pumpkin for looks which will offset the pinion to the right and the shorter the drive shaft the more severe the angles become

Pat guess we were typing at same time but you got done first---

How would the Wiz do it

Originally Posted by jerry clayton

Pat guess we were typing at same time but you got done first---

How would the Wiz do it

using the same wave length

Pat and Jerry,
The pinion shaft is centered in the pumpkin. So, both are offset approx. 1 1/2" to the driver's side.
JJF

yep well its not center to the axle side to side so the rear end has some off set to one side . when i shorten a ford i put the pinion on center

[ . when i shorten a ford i put the pinion on center[/QUOTE] every one I ever done I centered

Originally Posted by cffisher

[ . when i shorten a ford i put the pinion on center

every one I ever done I centered[/QUOTE] well here is a trick some time it works put the short axle on the long side of the housing when cutting one down then you only need one axle send out for re spline if your lucky and have some axles to pick thru it works out

....or with an aftermarket housing (fabed or modular) you can have both.
centered pumpkin & center pinion.

is that dryrot on them tires????????

Not in those pics.........they were taken pre-rot.