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Old 12-10-2002, 03:00 PM
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Post Narrowed 9" w/Centered Pinion

I've searched until blue in the face..maybe one of you Nova guys can help.

Im putting a 9" in my '68 Nova and ready to narrow it. I want the pinion centered and have taken all the measurements now that I have the wheels and tires, to ensure it ends up that way. Well then it hit me...why did Ford offset this thing in the first place? Obviously the engine and trans is offset.

I have the front frame out of the Nova so don't have a decent reference point for measurements. I need to know if the engine (ultimately the trans tailshaft) is exactly centered in the chassis. If so I can use my numbers considering the current offset of the 9" pinion, which appears to be approximately 1.2 inch (am I close??) Shoot, I'm even having problems finding out the brake standout distance for 9" axles (using disc brakes) and the width of new housing ends, to determine how much to take off the axle tubes.

Appreciate the help, Larry

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Old 12-10-2002, 03:41 PM
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"obviously the engine and trans is offset"

Yup, in my mustang the engine and transmision isn't centered in the engine compartment at all. IT SITS TO THE RIGHT ABOUT 2 INCHES!!

Just kidding.

The engine and transmission is centered in the chassis like any other car on the road. The pinion on the 9 inch appears to be offset because the entire pumkin is offset. In order for the pinion to be directly in a line from the transmission ford had to offset the pumpkin making one side of the rearend longer than the other side. If you measure from each side of the pinion to the spring perches, both sides should be the same.
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Old 12-10-2002, 04:08 PM
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I measured one I have in the garage out of a 70 Mustang and I would have to agree with this theory.
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Old 12-10-2002, 06:51 PM
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If you dont find the brake measurement, I can measure mine this weekend.
As for the pinion thing it depends on the chassis it came in. Some fords(I know 68-72 trucks) had offset motor and trans so the pinion was centered with the trans as opposed to the rearend. I think most chevys run on center, but I dont have any proof to back that up.

Chris
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Old 12-10-2002, 08:08 PM
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Ok, forget about trying to find measurements of existing rear axles and doing math to figure out how much to take off using figures from a (possibly) unreliable source. Including me!

The problem with all this is we are assuming...and we all know what assuming will get you. <img src="graemlins/nono.gif" border="0" alt="[nono]" />

My suggestion to you is do not cut anything until you can verify exactly where your transmission output shaft is going to end up, shift linkages and other factors could fool you into thinking the engine/trans is centered in the trans hump when in fact it is offset slightly.

Get the front subframe in and test fit the motor/trans combination, then take your measurements and cut your axles/housing. Remember that dimensions vary from car to car, it's called a tolerance...and tolerances can stack up. Just because Joe Blows car measured so and so don't assume yours is the same. There are just to many variables in this equation to say with any certainty what you have in your garage.

The last thing you want to do is guess. You are trying to do too many things all at once and you didn't take any measurements (did you?) before it came apart so don't be foolish and assume anything. You can bet that if you took everything to a machine shop tomorrow they wouldn't cut anything until they knew exactly where everything is going to line up. Test fits can number in the teens to get everything right if your not careful at this point.

Do your project in stages with the axle/housing shortening as one of the last steps before you fire her up for the first time. The good news is even if you were an inch out the universals would probably accomodate the slight misalignment (thats their job!), but we want it perfect... RIGHT!.

Remember Rome was not built in a day and you can bet they didn't order the columns until they knew exactly how high the roof was going to be. Get your parts together and wait until you can test fit before you start cutting anything, if you don't know where the brakes are on the axle then wait until you have all the parts to check. Your doing the right thing by asking questions.

Get your subframe in and take your measurements from the installed engine/trans combination, be patient and make sure the front subframe is aligned correctly. Don't forget these things are rubber mounted!

Get the horse before the cart and it will all work out. Good luck.
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Old 12-11-2002, 02:57 AM
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Maybe this -diagram- will help you while ciphering.
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