Change 3 speed stick to 4 speed stick

[lazer]

I put this in a different section I think it belongs here. I have a 66 comet gt with a 390 and a 3 speed on the floor. Can I change the 3 speed to a 4 speed and if so what would I need? Thanks

[SASSY]

You need to list what you have, do you want it stock or are rodder like me hack up anything and everything to achieve your goal?
Do you see how your question is a little too vague to answer?
Fred

[Joe Travers]

I put this in a different section I think it belongs here. I have a 66 comet gt with a 390 and a 3 speed on the floor. Can I change the 3 speed to a 4 speed and if so what would I need? Thanks

Is the 3-speed the original Toploader?

JT

[lazer]

Everything is stock.1966 Mercury Comet Cyclone GT 390 console on the floor, bucket seats and a 3 speed stick. I want to keep it stock looking. Do I need many parts or is it a fairly easy job. I have limited skills but my friend is very good. What model toploader would I be looking for? I saw some rebuilt trans but seem expensive. Would one from a scrap yard be safe to use because I read that they are a very strong trans. Thanks

[Joe Travers]

I'm pretty sure the 3-speed & 4-speed Toploader share the same casing dimensions, if my memory is correct.
I would think it would be a direct swap, if you can find the correct one.
There were two or three different lengths made.
Casting number for the correct one is C5AR-7006-D. The bellhousing should be C6OA-6394-B or D.
If it's all stock, I'd keep it that way. JMO.

JT

[comethead]

Would one from a scrap yard be safe to use because I read that they are a very strong trans. Thanks

Good luck finding a Toploader in a scrap yard.
If you do find a used one you should at least open it and take a look at the synchro’s. Yes the gears are strong but the brass synchros are subject to wear just like any other manual trans.

Joe

[vicegrip]

http://www.davidkeetoploaders.com/idchart1.htm

You would be extremely lucky to find the right trans in a junk yard.Everybody knows what they are and grab them as soon as they pop up,which is next to never.The swap is not going to be anything close to cheap but would really improve the value of your car.If you do find a trans and want an original shifter,call Bill Heeley, 301 774 6710. He doesn't do text or internet so you have to call.

[lazer]

Thanks for you guys posting back. I have been looking at rebuilt 4 speed trans and they aren't cheap, would I need much more than the trans and the shifter? The car is in really good shape and this is the only major project for it.

[poboyjo65]

there is a t-10 4 sp on here for sale. I have bought from him personally & he is good to deal with,a great guy.
https://cometcentral.com/forum/viewtopi ... 15&t=16362

[Joe Travers]

Thanks for you guys posting back. I have been looking at rebuilt 4 speed trans and they aren't cheap, would I need much more than the trans and the shifter? The car is in really good shape and this is the only major project for it.

The C5AR-7006-D should be a direct replacement but very hard to find and not cheap.
They also came in Fairlane 390 GTs.
A 289/390 Fairlane Toploader will fit as well. GT uses a slightly larger clutch but I believe the input shaft is the same.
That may be the way to go if they are, so you don't have to hack the shifter tunnel.

JT

[popscomet]

the input shaft is different between a SB and BIG BLOCK.....THE NOSE is longer (the part that slids into the pilot shaft bushing)on a Small block tranny.....shorter on a big block.....clutch makes no diff,,,,it's the same just cause it's a GT means nothing ......I've run big block trans behind Sb.....you have to trim just a hair off the SB input shaft for it to work on a big block......when installing the BB trans behind a SB,,,,,all it takes is a longer pilot shaft bushing to make up the difference in the length....discussion is over ,,,,be there and done it.....POP

[Joe Travers]

Thanks for the clarification on the input shaft, Pop!
The clutch size reference was for the 390 non-GT and 390 GT bellhousing.
It's a GT car, so it's not an issue. I didn't need to bring that one up.
Sorry for the squirrelly brain.

JT

[popscomet]

yrs ago I had a clutch,pressure plate rebuilt and beefed up for a 289,,,,ran it for awhile,,,pulled the 4spd out and installed a C4 ,,,,today that same clutch and PP is in my 66 f100 behind a 1963 390,,,,,you can take a cut off wheel and trim the SB input shaft to the correct length ,,,it seems to me ,,we have gotten away from the reason this post was posted so POP is signing off....thanks everybody......POP

[Joe Travers]

Don't know where you are located, but Dan Williams might be able to hook you up.
He's in North Carolina.
828-349-9125

JT

[lazer]

Thanks all!!