3 speed to 4 speed manual transmission swap?

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waterlife

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Jan 12, 2015
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Location
MARLBORO NJ
My Car
1972 Mustang Convertible
What is need to switch  a 3 speed manual to a 4 speed manual transmission?

I was looking at a yellow 1973 on ebay.  :huh:

Thanks 

Al

 
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It depends what the tranny comes with.

Aside from the actual gear box, I believe the basics are a shifter, a new driveshaft yolk, backup lamp wiring and speedo cable gear.  Some of those may be interchangeable too.  But if you do not have the 4-Speed already, I suggest you look at the 5 speed Tremec conversion, but keep the original 3-speed around in case you sell it.

kcmash

 
If that many parts need to be exchanged, i guess just installing an auto trans would be tbe way to go, plus easier to get all the parts

 
So you are looking at a car that is currently a 3 speed manual, correct? So why would you want to go through even more work to switch to an auto? I'm just thinking aloud here, but you would also need to remove the clutch pedal and (maybe) install an auto brake pedal, let alone add the kick-down mechanism, maybe a different drive shaft and who knows what else. Not being an owner of an automatic car, I can't say for sure, but I'm sure others with this knowledge will chime in.

If it was born with a manual gear box, I'd keep it that way by either dropping in the 4 speed if you can find one, or go the whole hog and install the Tremec 5 speed. That's what I'd do. Just saying!

Geoff.

 
Swapping the 3 speed to a 4 speed is very simple. You'll need the 4 speed with a shifter assy, and the appropriate speedo gear and cable for the 4 speed, as the cable goes into the trans on the passenger side, vs the driver side for all other Ford transmissions. The back up lamp wiring will probably work.

Driveshaft and yoke will be the same as long as you are using a small block 4 speed.

Mount and crossmember are the same, even the hardware can be reused IIRC.

An auto swap is a lot more work and just less fun to drive IMO.

 
As Hemikiller said, as long it is a 3.03 being replaced. Even the speedo cable will reach if rerouted . Just need to change the driven gear for the other side.

 
What is need to switch  a 3 speed manual to a 4 speed manual transmission?

I was looking at a yellow 1973 on ebay.  :huh:

Thanks 

Al
 Al, what engine is in that without me going to look on ebay. If it's a 6 or 302, why not look for a complete 351C with trans,  4 speed manual preferably and drop that in. However, there may be other more important issues that need to be addressed before thinking about upgrading the trans. A bit more info might help.

Geoff.

 
Just a basic 302, he wants $4500, its too much for the car, plus a tow to NJ is $750, new top, paint and the trans swap

 
Just a basic 302, he wants $4500, its too much for the car, plus a tow to NJ is $750, new top, paint and the trans swap
 The 302 is a good motor to start with and the 3 speed might not be too bad for now until you can afford the upgrade. I would want to see the car in person before buying, period. I flew to LA to see mine before I forked over the cash, but in my case, I could of just had him ship it. I got very lucky!

It depends on your budget I guess and what seems like a fair purchase price considering the restoration costs that add up quickly.

Good luck with it and let us know what you decide.

Geoff.

 
In 73 you could not get 4 speed with 302 and no 3 speed with 351. I have a 72 3 speed vert with H code 351 and they only made 82 of those and I am parting it out. Very rare but not worth fixing.

A 302 will probably never hurt the toploader but make sure you get a 28 spline output and not an early 25 spline.

David

 

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