Is there a way to add an overdrive feature without changing the transmission? Currently my '76 F-100 has a straight six and 3 speed column shift and only gets 15 mpg in town. I believe the axle ratio is 3.00, any suggestions would be appreciated.

 

you can add on an aux. trans. like a gear vendors, but they get pricy. I got one for my 72 F100 with a 5.0 mustang motor and can get 18-20 miles a gal.

 

An overdrive doesn't do squat "in town" just highway speeds of 50+ mph.

Josh

 

I thought about the gear vendors OD for my '79 460, but they do get pricey...
Gear Vendors Under/Overdrive Ford 2-Wheel Drive 3-Speed Automatic.

 

Indeed... well over $2000 new. That would buy a lot of gasoline.

Figure $2500 for GV and fab work and gas is almost down to $3 here. 833 gallons!!! Figure 15 mpg equals 12,495 miles.

Just something to think about it.

Josh

 

If your axle ratio is 3.00:1, I think it would work the motor too hard with overdrive. I could be wrong though.

 

x3 overdrive ain't the answer seems to me.
But what tire diameter you running and what's the -real- rear axle ratio?


The second tag is off my '75 F150 with Traction Lok.

Alvin in AZ

 

The axle ratio in my 72 is 3.25 (has a new motor) and has no problems in overdrive, it might not race up a hill in overdrive but it can hold speed, I think it has a 28% overdrive. But getting back to the OP 15mpg isn't bad for a truck intown. Most of my driving to and from work is highway 22 miles one way a short distance to the highway and the same when I get to work, so I loved it, it made my 72 the best gas milage vehicle I owned (but it is also feul inj.).

 

But basically if you want overdrive you can swap in a overdrive trans in a 2wd easy, and do it a hell of a lot cheaper than $2000+. I probably wouldn't buy the gear vendors unit now in my life, but the op was asking for info without replacing his trans, not quite the cheapest alternative.

 

You have an all-synchro 3 speed, right?

If so, the older OD units will not bolt to your trans. Those were BW transmissions. Those are getting hard to find.

As per prior posts, a GV unit new is $3k, and would require a divorced mounting, DS work etc.

An overdrive trans is the only practical way to do it.

4 speed OD from late '70s to mid '80s would approximate your 3 speed gearing with 4th being over. Floor shifter required. Possibly a direct bolt in.

Mazda or ZF from later models: floor shifter, hydraulic clutch, additional fiddling.

T5: adapter, floor shifter, additional fiddling.

 

Do you have to run a hydraulic clutch on a ZF? I don't see why you need to? If the spline count is the same then why could you take the throw out bearing clutch fork and clutch assembly from the 3 speed?

 

I don't really know but the ZF's 351w/300i6 aluminum bell housing ain't
set up for a lever so that isn't going to work out so good? :)

The ZFs for bigger blocked engines are setup with and external slave so
they have a lever (from what I've read) so a mechanical system could be
rigged up I'd guess?

Alvin in AZ
ps- where's the OP? :/

 

Oh I see could you take the 3 speed bellhousing put it on the ZF and just re drill the holes to mate the tranny to the bell housing?

 

The ZF has an integral bell housing. Same as the Mazda M5OD units.

Josh

 

x2

And it's thin like an automatics bellhousing too...

...that one fits 351w + 300i6.

Alvin in AZ