Ford 9" -center the pumpkin or center the pinion

You brought back an old thread, but with a popular subject that comes up often.
First, you'll find that Granada 9" measures much less than 80"!
Second, the 9" pinion is offset 15/16" from the housing center. Vehicles with offset pinions usually have the engine/trans offset a similar amount.
Third, there are two types of U-joint operating angles: single plane, where the engine/trans are parallel and inline with the pinion, and compound, where the engine/trans and pinion are parallel but not inline when viewed from the top and side. Compound angles have to be calculated to arrive at their true operating angle, which should be 3 degrees or less.
Open the pdf below, spend some time scrolling through the info and learn from the people that design and build U-joints how to properly set up your driveline.

http://65.170.161.218/~spicerpa/sites/default/files/pdf/driveshaft_installation.pdf

 

Having issue with my 54' Chevy with 4 link welded in to a 2nd gen Camaro rear . After getting thrust alignment done & adjusted the whole rear is shifted 1" to the passenger side with right rear tire rubbing fender . Walton fabrication engine/ trans mounts have engine / trans centered but drive shaft crooked to the right , has vibration & noise when driving , NOW going to somehow have to be corrected . Found this about offset pinion :. https://www.dragzine.com/tech-stories/pinion-offset-guide-and-how-to-with-chassis-engineering/ ha

 

^^^ offset pinion has nothing to do with the housing being 1" over in the car. That has to do with someone who doesn't know how to read a tape!

The pinion has no bearing on the position of the actual housing under the car, so if one side of the housing is hitting the vehicle then a couple things have happened, 1- the 4 link brackets are not centered on the housing 2- the 4 link frame brackets are not centered on the frame.

So basically someone set a housing under the car with no tires on it, centered the pinion and went to welding brackets on it with no concern of the actual position of the housing itself or measuring backing plate to frame measurements....

 

I think its, especially regarding the 8 or 9 inch ford axle....
ahem
f100, bronco, econoline
f100 - truck, no back seat or floor pan to rear,
bronco - high up jeep
econoline - van no rear seat, flat floor in back

any car
lower floor pan
raised rear drive shaft tunnel
rear seat,
= keep the drive shafts straihjht through the centre or the hump in the floor is going to be quite largeabout the rear passenger

which leads to....
yes the pinion should be offset and not in the middle
as, the roller needle bearings fret ? in the joints IF the drive shaft only moves up and down
the articulation of a univeral joint about all axes can only occur if its in two planes
something like that

so , if you have a little hot rod, where you have no rear tunnel in the floor
what do you do?

 

This sounds a lot like a panhard bar that has been incorrectly installed. If they aren't right, they'll excessively push or pull the rearend to the side during suspension travel.

 

I don't think Henry had anything to do with the position of a 9' in a car as he had been dead 10 years when 9' came out. On all the cars that were built when de was alive the pinipn was on center.

 

Why follow either herd?
Center the pinion and fabricate a crescent to tack on and visually fake the pumpkin back to center. Use your imagination. Add fins or bolt heads...... maybe a U-clamp to hold it on the axle.

 

I'm not an engineer so I don't understand this burnell thing. As the suspension lets the car move up and down the cross is rotating in the cup so what's the difference?

 

None, as long as pinion offset does not exceed U-joint operating angles, it'll be fine. Just picture a driveshaft 6 inches long and it being 3 inches off center, now keep the 3 inches off center and have it a 100 feet away. The severe angle on the 6 inch shaft will be a problem, 100 foot shaft, no issue.

I'm sure you knew that anyways

 

I have been saying that for years, if there is suspension there is movement. Offsetting center lines is more for factory "packaging I think, allows other things to happen.

 

Im with this guy! Cut the pumpkin from another rear end and weld it next to the functional one! Double pumpkins !

 

Running the pumpkin centered and the pinion offset gives you your driveshaft "pinion angles" without having to do it the old-fashioned way. I would bet that this is probably why manufacturers do it. Once set, hard to go wrong.
The universal joints and tailshaft are blissfully unaware if pinion angles are acheived horizontally or vertically, or a combination of both.

 

So, by straight, do we mean it hasto be straight, forward, perpendicular to the rear end..?
OR
say we have 1/2” pinion offset, can a person shift the front of the engine or rear of trans over (depending on factors and room of course) to bring that all straight even though not perpendicular to the rear...

That wouldnt work would it, as the front and rear U joints would then have non matching angles from above aye..

 

I guess this andwers my and alot of the questions here..

 

Nothing has to be "straight" in any plane - vertical, horizontal, or any angle inbetween. All you need is for the compound offset to be within the limits. Once again, the uni's and driveshaft have no awareness of the direction of offset.

Go back to post #31 by @V8 Bob . He covers it all..................

 

Watch 54chevkiwi's demonstration thread, explains it perfectly. Remember in the 70's when Mopars had had the with torsion front suspension

 

Make sure you view 54chevkiwi's u joint demonstration. Illustrates it perfectly. Remember back in the 70's when Mopar offset their v8 engines to the right 2 or 3 ". ( I am guessing they did this for steering sector clearance.) Did they also offset the pinion the same amount? If not I bet the engine and pinion were parallel to each other when looking down from the top and also looking from a side view. Hope you Mopar lovers will chime in on this. Greg

 

Yes, these need to be parallel for correct phasing, as shown in the video posted by @54chevkiwi .
When offsetting the pinion sideways or up and down, the transmission output shaft and the differential pinion still need to be running parallel to each other.

 

That's what I was told by a Chassis shop : that on factory cars the engine /trans are mounted NOT in the middle of the car but offset to be in line with the rear pinion . When people do customs or builds they put everything in center & don't know about the fact that the pinion will not be in a straight line . But I would think as long as it's close , should be ok , mine kicked to the right when Thrust angle was set at alignment shop , now I am 1/2"-1" to the right .

 

I offset the engine in my tub 1.5 inches. It aligns with the pinion CL in my un-narrowed rear axle. In my snug home made body this gives the driver 3" more foot room than the passenger side has, allowing more room for the three pedals needed. Can you tell the engine is offset from the pic?

 

This is my 41 PU, 9" with pinion centered. One axle is shorter but only noticeable in this pic due to the pipes and the sway bar gaps. When I had the rear built I opted for a straight drive line and there is no room to scoot the hemi over.

 

On a purely visual aspect, a lot of the debate has to do with visibility and whether it is important to the owner of the car but on fenderless cars the actual shape of the housing and getting it centered is where this debate mostly started.
In my view this big Kardashian butt needs all the help it can get!

 

^^^That is a bedonkadonk!

 

My personal preference is centered pinion. But they run fine with the punkin centered instead. On a short driveshaft it puts a little more strain on the U joints and you get a little more parasitic loss but most cars and their drivers will never notice.

 

Drain pan

 

numbers off the top of my head
centred pinion half shaft difference = 105mm
centred case difference 60mm

pinion is offset 45mm on a centred case
or onr ube will be 45mm longer than the other
or 5mm less than two inches

 

Yeah , I just don't want my passenger rear wheel rubbing my 54' skirt clips or fender , so this will need to be figured out one way or the other , maybe cutting this custom 4 link out & starting fresh with Universal Ridetech 4 link ( installed by reputable shop) will be easier but not cheaper .