1969 Manual transmission swap?

Joined
Apr 23, 2022
Thunderbird Year
1969
I've got a 1969 tbird, in pretty much stock condition. It currently has the 429 thunderjet and C6 transmission. I'm interested in hossing it up a bit and swapping to some flavor of tremec.

I think I have the clutch figured out. What I'm not sure of is the tunnel. Is the tunnel large enough to fit a tremec? I was leaning towards a TKX, but could be easily swayed if one of their other ones would be a better fit. And does the tremec place the shifter reasonably far enough back? I was hoping to have the shifter end up right about where the factory ash tray is.

It would be really handy if there was a crossmember I could buy that would just work, if anybody knows of one. Otherwise, I've got a welder, a drill, and some bar stock.


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jon774

Active Member
Joined
Sep 23, 2018
Thunderbird Year
1968
This is not an answer to your question, just a comment.
I installed a shift kit in my c6 and had the gear selector come up through the ash tray. It's great. I can shift through the three gears without the clutch and the shifts are hard and on point. The only issue I have is the throw is a bit long and I have to modify the armrest cover. Currently I open the armrest door to get the full use of the shifter.
The car is at the paint shop right now. I can send a pic when it's done.
I originally wanted to go to route but ended up going a simpler way.
 
Joined
Apr 23, 2022
Thunderbird Year
1969
This is not an answer to your question, just a comment.
I installed a shift kit in my c6 and had the gear selector come up through the ash tray. It's great. I can shift through the three gears without the clutch and the shifts are hard and on point. The only issue I have is the throw is a bit long and I have to modify the armrest cover. Currently I open the armrest door to get the full use of the shifter.
The car is at the paint shop right now. I can send a pic when it's done.
I originally wanted to go to route but ended up going a simpler way.
Yes, definitely send pictures.
When you say "without the clutch", does that mean you haven't installed a clutch pedal yet, or you just dont need to use it?
 

jon774

Active Member
Joined
Sep 23, 2018
Thunderbird Year
1968
There is no clutch. It's essentially the same c-6 transmission. When I rebuild it I beefed it up to handle the additional hp of the engine. I used a Broader Performace shift kit. You can upshift and downshift through the gears on the fly. You can also just put it in drive and treat it like a traditional automatic.
 
Joined
Apr 23, 2022
Thunderbird Year
1969
There is no clutch. It's essentially the same c-6 transmission. When I rebuild it I beefed it up to handle the additional hp of the engine. I used a Broader Performace shift kit. You can upshift and downshift through the gears on the fly. You can also just put it in drive and treat it like a traditional automatic.
Oh. I'm going for a real manual transmission with an overdrive. I'd still like to see your pictures, though. The tremec transmissions are used to replace the C6 in plenty of cars and the shifters at least line up in the correct place.
 

74 Harley

Active Member
Joined
Jul 8, 2020
Thunderbird Year
1962
The tunnel should be fine for size. There's a bit of room all the way around the transmission. You should be able to use the transmission crossmember with little if any modifications. Your biggest challenge is going to be the console. However you might be able to swap in one from a 4 speed Mustang or combine some parts.
 
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