Which tranny for 390?
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Joined: May 2003
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Which tranny for 390?
I have a '68 F100 that has a 4 speed in it right now. It's geared low (prob. a 4:10). I get around 12 MPG. I tow occasionally and I don't want to greatly diminish the towing capability it has.
However, someone told me a Mustang T-5 5 speed w/ overdrive transmission was a direct bolt on (well just need to cut down to drive shaft) and would greatly improve highway gas milage.
Is this true?
Thanks
However, someone told me a Mustang T-5 5 speed w/ overdrive transmission was a direct bolt on (well just need to cut down to drive shaft) and would greatly improve highway gas milage.
Is this true?
Thanks
Postmaster
Joined: Nov 2002
Posts: 3,447
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From: Littleton, CO
Which tranny for 390?
I believe the T-5 is a direct bolt on, when you have the appropriate bell housing for the FE. I'm no tranny expert, but if I remember reading some of the past postings regarding the T-5, it may not be up to the task of handling the torque the FE can put out. Check out a search for T-5 and see what you may come up with .
--Mike
--Mike
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Joined: Jul 2003
Posts: 193
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From: BC, Canada
Which tranny for 390?
I doubt you're going to get much more than 12MPG out of a '68, even with a 5-speed, but at least with the 4, you've got that low first gear which is great. The 5-spd was designed with a car in mind not a truck, so you may be disappointed with it.
I'd swap in lower rearend gears and keep the 4-speed just for that compound low. The lower final drive ratio will be the approximately the same as a 5-spd with 4:10's.
I'd swap in lower rearend gears and keep the 4-speed just for that compound low. The lower final drive ratio will be the approximately the same as a 5-spd with 4:10's.
Cargo Master
Joined: Aug 2000
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From: SW Michigan
Which tranny for 390?
Twkisner, I wouldn't use the T5 from a mustang or anyplace else. The T5 may well fit, thats true. But some of the mustang guys break 3rd gear in those trannys on a regular basis, and they have a whole lot less power ( from a 302 ) than your Fe does. You might do very well however with a Tremac TKO or a Clark 280 series. Or you could put a GV overdrive splitter behind the tranny you have now. How much are you looking to spend on this ? How about checking the ratio in your axle so you know for sure what ratio it is ? That would be helpfull in decieding your setup. DF
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Which tranny for 390?
Would not swap in a T-5. I know that a good torquey 390 would kill a T-5. If you want to stay with a manual tranny and are determined to get one the above suggestions are good. I would be checking my rear end ratio and think about a gear change if I were you.
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Which tranny for 390?
"Or you could put a GV overdrive splitter behind the tranny you have now. "
How much are these? What mods are required?
I know my truck would benifit from overdrive. At 60-70 MPH, I'm hitting 2500-3000 RPM. Overdrive might knock that in half....
I don't care for hitting the red line at 70 MPH....
How much are these? What mods are required?
I know my truck would benifit from overdrive. At 60-70 MPH, I'm hitting 2500-3000 RPM. Overdrive might knock that in half....
I don't care for hitting the red line at 70 MPH....
Senior User
Joined: Jul 2003
Posts: 193
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From: BC, Canada
Which tranny for 390?
I'm not sure about the pricing, but essentialy the overdrive/splitter is a seperate 2spd gearbox that mounts on the back of your exisiting tranny, giving you 8 forward and 2 reverse gears. You'll have to shorten your driveshaft, and probably fab up a mount for the unit itself, but it should be a fairly straight forward install.
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From: Tumwater, Wa
Which tranny for 390?
GV overdrive is about $1,000. I turn 3,000 rpm @ 70mph with 3.54 gears and 29" tall tires. How do you manage to only turn 3,000 at 70?
I don't hit my redline (5,000) untill about 130 mph.
I don't hit my redline (5,000) untill about 130 mph.
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