Transmission swap
 

I have been looking at the possibility of putting in a manual transmission in my automatic 66 GTO convertiable. My car does not have the original engine, but does have the born with transmission. Would it hurt the value very much if I were to change out transmissions? I know that I can find a GTO 389 motor to replace the B body 66 389 engine that is in there now, and I believe it would bring it's value up some as oppose to leaving in the motor that is in there now. What would cutting a hole in the floor and changing transmissions do to the value of the car? I just don't want to hurt the value of the car anymore than it is just because I think it would be more fun to drive with a manual transmission. Any thoughts?

In all seriousness, I think it would enhance the value.

Are you building for resale or fun? There, you've got your answer.

If you're gonna do it go with a 5 speed overdrive.

Transmission swap
 

my 66 came with tri power auto 3.08 gear what a slug, put a muncie 4 speed in back in the 70,s what a differance I could now spin the tires, putting in a 5 speed is a little more work, you have to cut the tunnel and raise it a couple inches especially if your using a tremac, did mine will have the new motor done soon {421} can't wait. jd grim 66 gto

400 4spd. Why do you think it would increase the value?

arbys, would be building for fun, but if I could do it without having to cut the floor pan and it was just a bolt in that could easily be put back to original, it would be a different story. The car has all it's original sheet metal and in good original condition, it just had the motor replaced at sometime. I know that it will not be sold while I am alive and it will most likely be passed down to one of the children. Just looking at not devaluating it anymore than it already is. If the car had new quarters put on it, or had been built from pieces of donor cars I wouldn't even question it.

You guys know more than I do, which is the reason I am asking and value your opinions. All the other cars except the 76 SE T/A and the 78 T/A have the original engines. I might me putting more into this than I should, just don't want to cut the car and then 10 yrs from now find out that I should not have done it.
Thanks.

CB
I went through the same thing. I was afraid of cutting up my car. But after looking into it, it seemed to me that it really only matters for very rare cars, or cars that are super low mileage.
Still, you can do this: When you get the shifter porch aligned and trace out the hole you need to cut, just do it carefully (I used a jigsaw and it was super clean cutting) and make the new hole meet up nicely with the automatic shifter cable hole. Save that cutoff piece. It'll weld right back on and with care it'll almost be undetectable if you or subsequent owner want to put it back to automatic.
My 67 was an auto, and it has it's original drivetrain, (and floorpans) but I couldn't bear the thought of keeping it an auto, so I just made sure to keep my little cutout piece of floor pan. I also saved everything else; the trans, lines, line clamps, screws, driveshaft, etc. It all can be swapped back easy some day.
All other mods are pretty tame too....the weld on "Z-bar" tab, steering column clamp (with clutch rod hole and boot). Anyway, all those mods can be taken off if necessary.
Good luck!

I agree with 400 4spd. It will increase the value, mainly because most guys want a third pedal, and the original engine is already gone. The ST300 is of little value at this point.

Squid makes a great point too. Simply cut the floor, but save the original metal in the event you (or someone) ever wants to return it to original. But again, without the original engine, the ST300 is of little value I believe.

Another good point was also mentioned that the swap also requires welding on the tab on the frame for the z-bar and installing the clutch rod boot. Also, don't forget you will likely have to drill the hole for the return spring in the body mount bulkhead just above the body mount bolt.

All this to say... a manual swap is not a simple bolt on, unbolt type proposition. Nevertheless, it's largely about what you want in the car, and how you want to enjoy it. With nearly 13,000 convertibles built in '66, I don't believe you will devalue the car at all by installing a "hammer" now that the original engine is gone. Put in the third pedal, save the ST300 and sheet metal, then enjoy the heck out of it!

Hope that helps! :)

Charles, Legend gear supposedly sells a 5 speed that fits without cutting the hump (except for the shifter porch). Has anyone here tried this tranny yet? Let us know. Good luck which ever way you go. A GTO needs to be manually shifted IMO.

I'm with these guys....it would probably help the value. Owned a 2 speed GTO, no fun to drive. And slow compared to what it could have been. The 'porch' only fits in one place on the floor, so it's impossible to screw up the placement of the new hole. I would run a Muncie M20 if you have a rear gear of 3.08--3.36. I just love the way those old 4 speeds shift with the Hurst shifter.

I think the other responses have my reasons covered, but to sum it up here goes. The non original engine, the poor performance of the 2 speed auto, and the over all appeal of a the 4 speed/convertible combination are the reasons I think that.
Because the ST300 was nothing for bragging rights, I think the swap would have less of a positive effect on the later and better TH400 equipped cars.
Besides, you'll probably feel like you're behind a stronger engine just from the seat-of-the-pants difference.
That's my :2cents:.

No disagreement here at all with what you are saying. I looked at a beautiful 65 4 speed about 2 years before I bought this car. The car was originally an auto and the owner put in the 4 speed transmission. Can't remember, but I believe that the engine might have been replaced as well. It was a 389 though. I just loved the pick up the car had and was very impressed with the speed attained as we never got out of third gear before having to slow down for a stop sign or make a turn. We never got out on the hwy. My car with the automatic is quite slow. It would be nice to step on the gas and be pushed back in the seat like the 2006 goat does with the 66, as the rumble of the 389 engine winding up is quite different than the 6.0L.

For most of us a 4 speed is more desireable.... and fun. I've never owned an automatic GTO. 1st one and the one I have now are 4speed cars. The only GTO I've driven with an automatic was Old Goat 67s with the Turo 400. I have to admit tho it was fun to drive for an automatic. Faster than hell too. And I know why he put Hydroboost in it.... so you can freekin stop it. LOL

Just swapping in a TH350 for the 2 speed ST300 will be a night and day difference. The car will literally feel like it has 200 more HP. Mainly due to the lousy 1.76 ratio of 1st gear on the ST300. The TH350, being a 3 speed automatic, has about a 2.75 first gear. Regardless, an ST300, while super durable, and original, is a serious performance retarder. It's like running the 440 with your shoes tied together.

Put a 5 speed in it and don't look back

I didn't even flinch at putting a stick in mine. I originally had a auto/dual gate in mine. Mine is also a pretty rare, California HO,AC,PS,PB numbers matching car.....and its still way more fun with a 5 speed. :)

SO with everybody in general agreement to put in a 4spd manual as I want to do as well (I have a sluggo 2 speed with a 326 which needs some more pep), does anyone have any recommendations for sources of rebuilt 4spd manual trannys ?

DH, do you get up this way in the Spring and go to the Kowtown Swapmeet in NJ? It's not far from the Delaware Memorial Bridge, and you're not all that far away from there either. There's a guy that goes there with Muncie 4 speeds for sale. Rebuilt too and the prices seem reasonable... especially if you buy one and don't have to worry about shipping. I had one of his business cards but can't find it now. I can send you a PM when I hear what the date will be for this year.... usually it's around the end of March.

A 4 speed with your 326 would be a good choice. Maybe even a 5 speed if it's a 326 HO.

GT182, Thanks for the heads up. Sure I can come up there in March for the swap meet. It might cost a fortune in Tolls on I-95 but what the heck. Just kidding. I drive that stretch of highway often. I would appreciate it if you have more information about the timeframe and location.
Thanks, Daryl

Trans Swap
 

Nothing changes the character of a classic or muscle car as much as the addition of a clutch pedal.
My 67 Lemans convertible started life as a boring 326 2 speed automatic.
It's now an OHC 6 Sprint clone with an 89 T-5
Much more fun. ;)
I plan on changing out my 66 2+2 from an automatic into a 4 speed.
Like yours, it's original 421 was gone long before I bought it.
A 68 4 bolt main 428 will have to do for as long as I drive it.
It's a heavily optioned car, but like others have stated, it might actually increase it's value since it will never be a high dollar show car.
At least not as long as I own it.

You intend to keep it forever.
Build it like you want, not what's "correct"
Save everything you swap out.
You will definitely enjoy it more.

Ron

Will do Daryl. You can go around the tolls coming up and back on 95.... except for the DMB's 4.00 toll going south. RT 1 is has no tolls. I can give you directions too. ;)