Differential swap

I am looking into swaping out the 8" rear differential in my 64 convert to a 9" unit. Currie makes an assembly that is for the 64-66 Must. Question is: has anyone seen this done. I understand the tube is 3" in diameter, where the 8" is 2 3/4", so would need new U bolts for spring mount. The yoke takes a larger U-join, so would have to have the rear of driveshaft changed to that size. Anyone know of anything else?

Thanks,
Dave

Hi there,,so what is wrong with the 8" ??
john h

I also would just stick with the 8". The 9" is overkill unless you doing some serious drag racing. I doubt that with a convertible.

Keep the 8" but change the center section to a nice Trac-Loc unit.

http://cgi.ebay.com/ebaymotors/FORD-...spagenameZWDVW

If you really want a 9", get a new set of U bolts. Currie will be able to seel them to you with the rear end.

Thanks for the sugestion. I do have a built 302 in it with 283 HP and 313 lbs of torque, so would like to change. The car had been hit on the left rear at one time in it's life. Can't seem to get grease to stop leaking on that side. I suspect something isn't quiet right. I do have a traction loc type 3rd member in it. Was thinking on going from a 3.25 to 3.50 if I change.

Quote:

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Originally Posted by davidvana

I do have a built 302 in it with 283 HP and 313 lbs of torque, so would like to change.

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I have 403 HP and 418 lbs of torque, from a 331 stroker, in front of an 8". The 8" is fine up to about 400 HP. If I had tires that could hook, I would be in trouble.

Dave...if you trade out your 3.25 let me know....I have what I believe to be a 3.55...can try and measure closer if you like. I don't believe it is a limited slip but...I would like gears that would reduce my rpm....perhaps save a little gas? My speedometer is off but I think I'm turning about 2200 RPM at around 55 MPH...so I was thinking somewhere between a 3.0 and a 3.25 might help.

Thanks
Hal

Hal, what size tire do you run? I have a 2.79 [ salt flat gears ] and 205-60-15's and I turn around 2600 at 60mph...
john h:shift:

I'm running smaller 15"...don't have the exact tire size....I could be off on the RPM's but....isn't 2600 at 65MPH pretty high with a 2.79? When I lived in Colville Nathan helped (actually he did it, I just got dirty to make it looked like I helped) change out a 3.55 to a 3.25 and I could tell the difference cruising at 65 MPG....I didn't have a tack but the difference was noticable.

I would love to find someone that wants lower gears and have a set of higher gears...we could just trade them out. For me the 2.79 might be a little too high...but would like to cruise down the highway at lower RPM's.

Hal