Ford 9" -center the pumpkin or center the pinion

When I narrowed the rear in my car I centered the pumpkin just because I think it looks better.This puts the pinion a couple of inches off center and looks funny with the driveshaft in it.Which do you guys prefer?

 

When you look at the finished car, can you see the rearend housing? can you see the driveshaft (in a way that you could tell it's off center)?

Looks like you have decided it's a matter of appearances....decide which looks best, and run with it.

 

Yeah thats what I thought too because you can see the rear end plainly from the rear.

 

I like the way you did it..I did it the same way on a 29 coupe I had years ago and it worked fine..Some factory cars were done the same way..........

 

I prefer the pinion centered. It prevents driveshaft angle problems. Ford did it this way as well. If you haven't noticed, the axles are two different lengths as well.

 

I've heard tale of some cars being that way from the factory. The theory behind it is to induce a slight drivetrain angle to prevent the premature wearing of u joints. (that was on cars where the drive shaft would otherwise be straight inline with both the output yoke on the transmission and the input on the differential.) The u-joints need to operate at a slight angle otherwise the needle bearings dont move and you end up wearing in just one spot. Now all that's just hear-say but it certainly sounds logical to me.

 

Henry had a good reason!!!----------CENTER THE PINION!!!

 

I own two cars that have 9" Ford rearends with the pumpkin centered. My reason was that I'm using triangulated four-bar setups in both cars. I can't see the driveshaft angle being a problem unless the driveshaft is really short.

 

Henry had the knowledge limited to the technology of the age, and no engineering degree.

It does not matter mechanically, centered pinion, or not, so long as the offset does not exceed the acceptable operating angles of the joints, throughout the full suspension cycle and articulation.

 

On a stock rear end, the axle tubes are the same length though. If you center a stock rear end, the pumpkin is centered - not the pinion.

 

I believe Henry centered the pumpkin to make installing brackets on coil spring cars easier,and also as a cost savings method as only one size axle was needed left or right. I center the pumpkin when I build a 9" rear end to bolt in to A & G body GM cars to make installing the brackets easier.

 

I'm no expert on this but my Model A Tudor was built with a 9" Ford rear with the pumpkin centered. The pinion is therefore a few inches off center and the driveshaft comes in at an angle of about 6 degrees. The car has a slight vibration which I was told is a result of this. I don't know if that's really the cause or not, but it's not bad and I can live with it. I hope that someone more knowledgeable than I can give their opinion on the significance of centering the pumpkin or not. Thanks.

 

When the pumkin can be seen from the rear I always center it and let the pinion be a couple of inches off center. As already stated, if the u-joint needle bearing don't roll in the cups they will "Burnell" into the ID and put flat spots on the needles. The whole idea of a u-joint is the allow offset alignment. Very few cars off the assembly line have the pinion centered. Take a look while the car is on the hoist, driveshaft is at a slight angle as it prodeeds back to the rearend.

Frank

 

Center the pumpkin, offset the pinion. It was designed that way for a reason.

 

Correct!!!!

 

Trucks and vans were ALL off centered pinion with centered housing thus having equal length axles, Most cars were centered pinion with off centered housing thus 2 different axle lengths. Now the reason, I really do not know. But it is OK to run offset as it WAS factory on many Fords. Same with some 8" rears also.

 

Seems like a no brainer to me, unless you plan on the additional expense of getting another rear axle...........Like everybody else that has had cut of a rear axle, you are either fifty percent right or fifty percent wrong depending on who you ask. Me? I wouldn't ask anybody.

 

Street rod/ hot rod Center housing

Race car/ drag car- center pinion

 

Both right. My model A has a stock '57 9" out of a fairlane. It's pinion center. The car is channeled so you'll never see it, but it sure is handy having the driveshaft fit in that tunnel..

 

I usually center the pumpkin, that's what they make u-joints for. (G) The only problem is that you need a little wider drive shaft loops and tunnel. Your vertical alignment is probably going to be off anyway.
Don't u-joint manufacturers say that if you had a perfectly aligned drive shaft it would brinnel (sp) the u-joint bearings?
Larry T

 

It's because the engine was offset too.

 

I center the housing on the 28/34 chassis and the pinion on the 35/48 chassis. No problem with the driveshaft running to the right.

 

I found that out the hard way. Had to go back in and add an inch of clearance in my tunnel at the end of my mockup.

 

motor and tranny height gets you your angle to the rearend if the pinion is centered

 

I have always been told to center the pinion... I have a gauge that bolts to the housing so that when I narrow it, I build everything off of the pinion. I agree with the above post in that the vertical angle of the engine/trans to rear (pinion angle) is plenty for the u-joint. I think engine offset in trucks & some cars (early chevy II's, for example) is the reason that some aren't centerd from factory. Also, I'm a big guy, and like the driveshaft tunnel (especially in a low or channeled car) to be as narrow as possible...

 

short drive shaft..i center the pinion

 

3oK miles on the Track T, punkin centered, 17" shaft, no problems with drive line.

 

As long as the u-joints aren't running "out of spec", it's not really gonna matter.
Larry T

 

Me too.....

 

My 41' Willys sits on an S-10 frame, with the stock 3:42 rear-end (Centered chuck, but offset at one wheel well)
I have a 76" Ford Granada 9" rear-end, yes I'm sure it's a 9" housing (Un-assembled & 80" wide) that I want to install. I'm not sure of the "Center-chuck" Flange off-set (Anyone know?), so that I can center "It" to the transmission yoke, And the "Housing" in the wheel wells... Then cut one side (Axle & housing) to make them even in the tunnel & wheel wells. If I don't off set it, then one of the tires will hit the wheel-well.
DON'T let anyone tell you to center the housing within the wheel wells and just forget about the "Chuck" Left to right offset, because on a "Short wheelbase" car... It will vibrate! I talked to 3 people that offset the Chuck and their cars vibrated (Which they later had to center the chuck and cut the housing to center in the wheel-wells...
Even though the Pinion angle was correct!