I am new to the forum and have owned modern mustangs and have a 76 Bronco in the garage. Have always wanted to own a pre-70 mustang and stumbled into what seems like a good deal on a '66 "restomod" with a 351w and a rebuilt C4. My concern is that it is running 4.10s and I will use it almost exclusively as a street car. At hwy speeds I would be spinning 3500+ rpms in the current set up. I am handy but do not have the facilities to do major component changes on my own. Would some of you mustang veterans mind providing your thoughts on re-gearing vs swapping in a t-5. Pros/cons, costs, etc. It's already far from original so no value destruction by swapping out driveline components. Thanks for any input. Eric
Re-gear Vs Overdrive
- Thread starter ELSchlotty
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it really depends on what you want from the car. for instance if you are going to do a lot of highway driving, it might be better to regear the car to something like a 3.25. if you are going to use a T5 or similar manual transmission, it would be wise to do both, regear and go with the overdrive, why? because most overdrive 5 speeds have a low first gear, and running more than a 3.50 rear gear for the street usually means first gear is basically unusable. if you are going to go with a automatic overdrive, then leave the rear gear alone as the AOD needs the low rear gear, and teh overdrive puts your final drive at around 2.80.
I replaced a 2 speed auto with a three speed auto in a different classic. I really regret not installing an overdrive transmission instead. If you can do it with a third pedal too, there is where I would go.
if you are going to do a trans swap in the future anyway, then i say it would be better to do that now, and live with the short first gear until such time as you decide what rear gear you want. you may find that you like the combination after you put it together, and can live with the short first gear. especially if you are not going to drive this car that often.
in the end its best to go with the mod that gets you closer to what you want from the car, rather than sneak up on it by spending lots more money doing several mods.
jetmech807
10 Year Member
I would try to find something close ratio. 1st with my cars original TR3650 was useless even the the stock 3.27 rear gear. Running a TKO600 (Yeah, they're a little pricey) with a 3.55 rear gear now. Much much better.
woodsnake
15 Year Member
I have a 3.50 gear in my 68, with a T-5 trans. I also have the Edelbrock performer RPM cam in that engine. (.496/.520 lift)
I would base the rear gear at least as much around the cam, as the desire for highway mileage. My engine pulls very well, but I would be happier with the performance with a taller gear. As it is, at 70 mph, I have to downshift from 5th to pass somebody! If the engine were still stock, I might be happier with the speed/rpm, however, with a better than stock cam, I feel like at least a 3.89 would be a much better option.
Also, I am running a 16 inch wheel and tire, so that should be included in your planning. Do you know anything about the cam in the car?
I would base the rear gear at least as much around the cam, as the desire for highway mileage. My engine pulls very well, but I would be happier with the performance with a taller gear. As it is, at 70 mph, I have to downshift from 5th to pass somebody! If the engine were still stock, I might be happier with the speed/rpm, however, with a better than stock cam, I feel like at least a 3.89 would be a much better option.
Also, I am running a 16 inch wheel and tire, so that should be included in your planning. Do you know anything about the cam in the car?
bartl
Active Member
Changing the "chunk" (center section) on a 9-inch is about the same mechanical complexity as changing a light bulb. Just about anybody could do it, in their driveway on jackstands, on a Saturday afternoon. Find a deal on a nice Traction-Loc setup in 3.50's and you should be much happier.
PS: Unless you're concerned about the mileage, 3,500 rpms isn't all that horrible. Back in the fifties and sixties when you'd be on the highway, thruway, turnpike, parkway, etc., at 65-70 most cars were turning 3,000-3,500 rpms anyway.
PS: Unless you're concerned about the mileage, 3,500 rpms isn't all that horrible. Back in the fifties and sixties when you'd be on the highway, thruway, turnpike, parkway, etc., at 65-70 most cars were turning 3,000-3,500 rpms anyway.
