66 manual 3 spd to manusl 4 spd - Ford Mustang Forum
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post #1 of 10 (permalink) Old 4 Weeks Ago Thread Starter
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66 manual 3 spd to manual 4 spd

I would like to investigate how to turn my 66 200ci manual 3 speed to a manual 4 speed. I believe a 4 speed man was available but haven't yet stumbled upon it's name or number and if it may bolt up.

Reason I would like to move to 4spd is I shift into 3rd at about 30mph and it has no choice but to wind up from there. And the 3spd in mine leaks out the rear seal. Is that easy to fix?


Thank you

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1966 Coupe
200 ci 6 cyl
3 speed man
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post #2 of 10 (permalink) Old 4 Weeks Ago
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Yes it is an easy fix..... very common part...slide out the driveshaft from trans, pull out the seal (with a seal puller) and tap a new one in...apply a little oil/grease to the rubber portion and slide the driveshaft back in...also for balance potential issues, mark the driveshaft at the tranny & at the rear diff so it is connected at the same position...not 180 degrees out of phase....although this should not affect the balance, I have seen to mnay times where for some unknown reason it has.


With regards to the 3 speed, the 6 is designed for that...it is a very "torq-ee" engine...honestly, I doubt if you would have any gain from a 4 speed.....that's why most came with the 3 speed.

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Don't forget the both the 3 speed and 4 speed have a 1.1 final drive ratio.
If it was me, let it hang in 2nd and feel the torque.
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15/5/1964 260 Manual Coupe.
23/3/1965 289 Manual Fastback.
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post #4 of 10 (permalink) Old 4 Weeks Ago Thread Starter
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Thanks Beechkid. I will follow the words of experience and knowledge. Makes life much simpler.
Does this 3spd standard have a trade name or such like the T5 or the T10 or the C4 does.
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1966 Coupe
200 ci 6 cyl
3 speed man
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Thanks Tony. I did not know they both had the same final ratio. Would have been alot of work for a synchronized first gear.


I suppose the T5 from the folks in Idaho would give me the result I was looking for? But not at the price I was looking for.

1966 Coupe
200 ci 6 cyl
3 speed man
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Quote:
Originally Posted by opakahum View Post
Thanks Beechkid. I will follow the words of experience and knowledge. Makes life much simpler.
Does this 3spd standard have a trade name or such like the T5 or the T10 or the C4 does.


That one I don't know...ÖÖ...

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In your shop manual you will find descriptions of 4 different manual transmissions used for a '66 Mustang. The 6s used the 2.77 3-speed while the V8s used the 3.03 3-speed. I think those numbers are the distance, in inches, between the main and lay shaft inside the transmission. For the V8s the 4-speed was officially called the 'Ford' 4-speed but is now usually called a Top Loader since the plate that opens up the gearbox is on top. V8s could also have had a T-10 Borg-Warner designed 4-speed since Ford couldn't make their own fast enough. The T-10, usually with different gears and minor other differences, was used in many other cars of the day including the Corvette. You won't find the T-10 in the '66 Mustang shop manual but its in the '65 Mustang shop manual (the '66 design was somewhat different but the exterior was the same). The 4-speed used for a 6 was the Dagenham which is the name of the eastern London, England, suburb where those transmissions were made by Ford of England.

As mentioned, every one of them had the exact same gear ratio in high gear: 1.00. Once in high gear your engine will act exactly the same no matter which of those transmissions you use. If there is a problem with how your engine behaves in 3rd gear its an engine problem and nothing to do with your 3-speed transmission.
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The now somewhat rare ( and hard to get parts for) Dagenham that Ivy66GT mentioned is a direct fit for your '66. To use a Borg Warner T-10 or toploader , you would have to switch to a '67 up belhousing which has the proper bolt pattern for those transmissions. The driveshaft yoke might have to be changed unless you find an early <acronym title="transmission">trans</acronym> with the 25 spline output shaft.
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post #9 of 10 (permalink) Old 3 Weeks Ago
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Quote:
Originally Posted by opakahum View Post
Thanks Tony. I did not know they both had the same final ratio. Would have been alot of work for a synchronized first gear.


I suppose the T5 from the folks in Idaho would give me the result I was looking for? But not at the price I was looking for.
By saying you have no syncro in first it would have more likely came out with a Ford 2.77 3 speed or toploader as they are more commonly known with 4 bolts holding down the top plate. These are a weaker gearbox for a V8 but perfectly suited for 6 cylinder.
The 3.03 3 speed top loaders have 9 bolts holding the inspection plate to the top of the gearbox, 4 speeds had 10 bolts.

As said above, the Ford shop manual identifies both the 3 speed gearboxes, all 3 four 4 speed gearboxes and the overdrive gearbox.
If you don't have a manual I suggest you get one, the best investment you will make.

15/5/1964 260 Manual Coupe.
23/3/1965 289 Manual Fastback.
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post #10 of 10 (permalink) Old 2 Weeks Ago
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I went from the 3 speed to a "World Class" Borg-Warner T-5 5 speed. The one I have came out of a 1990 Mustang 5.0. I bought all of the adapter components thru Modern Driveline. The rear yoke is the same as a C4 Automatic. The setup works great, the car isn't screaming it's head off at highway speed, and I get about 27 MPG. If you shop around, you can get some of the components used, which will save quite a bit of money. FWIW I did some investigating on the Daegenham 4 speed, and the reason you can't find them, is that they were a very light duty trans, and prone to failure.
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