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Discussion Starter · #1 ·
I am using a ford 9 in my chevy truck. After centering the housing in the frame, and tack welding the 4 link brackets on, I discovered the center of the pumpkin is about 3 inches to the passenger side. Of course, the pinion on my center section comes out on the passenger side 3 inches or so from the center as well. I'm wondering since the housing is symmetrical, can it be mounted upside down? It is the round 9 inch housing, not the "hump" housing, and it has the big bearing ends on it. If this was mounted upside down, the pumpkin would be around three inches off center to the driver side, and the 3 inch offset of the pinion would make it pretty close to center. If anyone can help that would be terrific!
 

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:pimp: Bolt pattern on pumpkin dictates mounting, if you just flip whole unit, would you then have 1 speed forward and how many in reverse?? :spank: A new housing or one narrowed to meet your offset would be the best bet. You could get away with just shortening one side, so not too expensive. :thumbup:
 

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The drive rotation direction would still be the same, but nonetheless you won't go far , If you flip the whole unit, the pinion shaft will not get oiled.
The offset won't hurt anything mechanically, The driveshaft will function as long as the total angle of operation of the U-joints is kept under 3 or 4 degrees.

If you flip the housing only you probably have to move some or all the studs around. Take a gasket and see if it will flip over on the pumpkin. It doesn't look like the pattern will flip just looking at it.. ( I'm looking at a 9" pumpkin right now)
If you have a early style housing the ring gear will clear.

The axle lengths might not be right anymore either.

Later, mikey
 

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Flipping the unit won't work.

In almost all cases if a vehicle has a differential pinion offset to one side from the center of the output shaft on the transmission, the angles due to this offset will not cause problems or vibration. This is because the pinion shaft and the output shaft are still parallel with respect to these side to side angles. So having the pinion offset to one side won't make any significant difference. Ford used these units for years with an offset so there's no reason it won't work in your truck.
 

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I think he is talking about only flipping the housing and not flipping the 3rd. That would move his pinion to the center. I don't think it will work however but I have never tried it. I do not think the pattern is symmetrical.
 

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powerrodsmike said:
The drive rotation direction would still be the same,
A few guys have been down this road before:

If a standard rotation differential was flipped upside down, the results would be the wheels turning in reverse while in forward gears and in forward when the transmission is in reverse.

http://www.4x4now.com/gt0599.htm

The third member only goes in one way, you can't flip the housing over and keep the third member in a normal position.
 

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powerrodsmike said:
The drive rotation direction would still be the same, but nonetheless you won't go far
:pimp: Not so, had my butt beat by my dad after I put the rear end back in my '36 Ford and went forward looking to the rear and crashed his workbench. He didn't care about the grille, hood and fenders I dented. All pristine, but that was 1966 and they were cheap to replace but I did learn.
 

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Discussion Starter · #9 ·
upside down nine...

yeah, i guess i should have been more specific. i was wondering if the HOUSING only was upside down and the center section was in the correct way. I assumed the bolt pattern was symmetrical, but i guess i'll have to check it better.
 

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Ok I went and checked again for myself, you guys are right. :thumbup:
I didn't take the hypoid cut on the gear into account. The ring gear will rotate reverse from normal if you flip it.



I found a gasket and put it on the pumpkin then flipped it. The pattern on the studs is pretty close, but I would not count on it working.

I agree that the sideways offset won't matter as long as the operating angles of the U joint aren't exceeded. I said that in my first post. So at least I'm not 100% wrong.

Later, mikey
 

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And apparently, I'm not the only one who has made the same mistake when thinking about doing this. :thumbup:

Mikey
 

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I was in the exact same dilemna and wondered the same thing. I finally came to the conclusion I could live with the offset and I have a plan to make an oval cover and paint it flat black to make it less noticeable. Granted what I am building is not intended to win any trophies. I priced narrowing one side to cost between $185 - $250.
 
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