Rear end advice

[handana]

I have a 1966 Bird with a 390 V8 A/C, and an economy rear end ratio. I'd like to get a little more performance from my engine transferred to the wheels and would appreciate any advice as to ratios, types, brands, etc...

[sseebart]

Originally Posted by handana

I have a 1966 Bird with a 390 V8 A/C, and an economy rear end ratio. I'd like to get a little more performance from my engine transferred to the wheels and would appreciate any advice as to ratios, types, brands, etc...

I'm not certain what you mean by an "economy" ratio. Do you mean you have the original rear end still in the car, or has someone swapped out the gears once already? (My 'Bird gets 8 mpg with the factory ratio!)

I've never heard of anyone doing this with a T-Bird, as most people consider these cars too heavy for serious speed mods.

My only advice would be to ensure that the springs and structure are sound before making the change: no rust in the shock mounts or torque boxes, no broken leaves in the springs and new bushings at the mounts.

Good luck.

~Steve

[Gary Tayman]

There were six axles offered by Ford for these cars.

There was the standard 3:1, and 2 other ratios. Then all 3 were available in limited slip form.

At least 95% of these cars had the 3:1 gears.

I had my "pumpkin" rebuilt a few years ago, and at the time was tempted to try another speed, but finally decided to go with what was stock. For what it's worth, both axles were slightly bent, and just recently I had new ones made by Moser, and new springs -- HUGE improvement in ride and handling!

If you have the slightest doubt about the axles themselves, I recommend investing in new ones -- and bearings, seals, etc. As for the pumpkin, it's simply a matter of choosing which gears you want and swapping them out. Get new ones -- chances are there's a place locally that specializes in such gears and you can pick them up. If you're taking the car to a shop, moist likely he knows where to go. The only OTHER consideration is the gear in the transmission -- you can get these at Mac's or elsewhere. You need this to keep your speedometer correct.

[Terry64HT]

I think handana's reference to "economy rear end ratio" meant he had the optional 2.80 gears, data plate code 6. Some years ago, I had to have my rear end replaced and the only thing I could find that was available at a reasonable cost was a 2.88. A little slower off the line, but better fuel economy at speed. Since I have headers, a Cobra Sidewinder manifold and large Edelbrock carb, I have no trouble from a standing start anyway and I have my fuel consumption up to almost 11.
Gary, your observations about the improvement in ride with the new rear end components is interesting since that vibration at 45 to 55 mph is fairly common. Everyone I've talked to about it considers it a front end problem, but maybe it's axles/springs.
Just some thoughts
Terry
64HT