1967 Mustang Coupe 5-speed swap

Trent K.

Member
Oct 21, 2019
20
2
13
Hermann, MO
So I have a 1967 mustang coupe, and my grandpa had a 5-speed trans out of a 4 cylinder thunderbird from the '80s. I know get your laughing out of the way now lol. I just want to know if this trans will be able to hold if I have a 300 hp 302 behind it doing launches on prepped surfaces. Has anyone swapped one of these transmissions in before? I'm only 17 so I cannot afford to just go grab another trans, this is what I have. I really don't want to have to go back to the c4 that was in the car. I'd love to have a manual instead of the boring auto that was in it.
 
  • Sponsors(?)


rbohm

SN Certified Technician
Apr 12, 2002
6,550
518
204
61
tucson,az
it will last a short period of time. it wasnt designed to handle a lot of torque, not to mention the very low first gear will hamper the issue.

you should be able to find a V8 T5 from a 93 or earlier stang and use that instead. it is stronger than what you have now, and they are fairly cheap. i have one that i paid about $100 for sitting around doing nothing. it will need a rebuild though.

and by the way, automatics are not as boring as you think they are.
 

Trent K.

Member
Oct 21, 2019
20
2
13
Hermann, MO
it will last a short period of time. it wasnt designed to handle a lot of torque, not to mention the very low first gear will hamper the issue.

you should be able to find a V8 T5 from a 93 or earlier stang and use that instead. it is stronger than what you have now, and they are fairly cheap. i have one that i paid about $100 for sitting around doing nothing. it will need a rebuild though.

and by the way, automatics are not as boring as you think they are.
I figured it wouldn't last long, oh well. At least it will allow me to get the swap mocked up and ready for an actual trans lol. I don't know how much torque I'll be making considering I'll be getting 300+ hp out of a 1977 302. I'd assume somewhere around 360 or so, but I'm not sure.
 

Olivethefet

Slap me as well as point and laugh
May 17, 2018
970
564
103
39
Enterprise AL
I saw your other thread where you are asking for guess as to the horsepower of your 77 302. A quick google search brought up a table listing the 72-80 302 at 135hp. It also list the 81-93 302 at 185 which I think is a bit low, at least for the later years. Your base motor might be closer to 150. With everything stock on your motor except a cam, carb, intake, and headers where are you getting your 360hp estimate? From everything I ever heard about most stock heads manufactured in the 70's they were not that great. Emissions laws made it hard at the time to get good power from the factory. I'm not throwing stones. I'm not an engine builder by any means. The 360 just seems a bit ambitious based on what I do know. I'm honestly curious and just looking to learn a little myself.

If I had to take a stab at what that engine would make i would put it closer to 220 maybe 240.
 

Trent K.

Member
Oct 21, 2019
20
2
13
Hermann, MO
I saw your other thread where you are asking for guess as to the horsepower of your 77 302. A quick google search brought up a table listing the 72-80 302 at 135hp. It also list the 81-93 302 at 185 which I think is a bit low, at least for the later years. Your base motor might be closer to 150. With everything stock on your motor except a cam, carb, intake, and headers where are you getting your 360hp estimate? From everything I ever heard about most stock heads manufactured in the 70's they were not that great. Emissions laws made it hard at the time to get good power from the factory. I'm not throwing stones. I'm not an engine builder by any means. The 360 just seems a bit ambitious based on what I do know. I'm honestly curious and just looking to learn a little myself.

If I had to take a stab at what that engine would make i would put it closer to 220 maybe 240.
Considering I was talking about torque when I said 360 it doesn't seem that ambitious to me. I'm hoping for 300hp but I'm having doubts that I'll be able to achieve that, just looking for estimates on what other people think I will be making.
 
  • Like
Reactions: Olivethefet

zookeeper

Founding Member
Aug 25, 2001
3,328
44
109
57
Rogue River, Oregon
...and by the way, automatics are not as boring as you think they are.
Ohhhh yes they are. :) Seriously, when I first got my fastback all together, I was out of money and just put the auto back in until my bank account grew back. It was horrible. I know you can build auto's for performance in a straight line, but they're only fun if you have enough horsepower to make them necessary. Street auto vs street manual is no comparison in my book. Three pedals and a big smile. As for using the 4 banger T5, go for it. If it breaks before you have money for a WC T5, then get another 4 banger trans for a couple hundred bucks or less and see how long it'll last. Expect to pay at least $500 for a good WC T5 and for a 17 year old that's serious money. I applaud your willingness to perform this swap and encourage you're budget-minded build. Now how about some pics?
 

Trent K.

Member
Oct 21, 2019
20
2
13
Hermann, MO
Ohhhh yes they are. :) Seriously, when I first got my fastback all together, I was out of money and just put the auto back in until my bank account grew back. It was horrible. I know you can build auto's for performance in a straight line, but they're only fun if you have enough horsepower to make them necessary. Street auto vs street manual is no comparison in my book. Three pedals and a big smile. As for using the 4 banger T5, go for it. If it breaks before you have money for a WC T5, then get another 4 banger trans for a couple hundred bucks or less and see how long it'll last. Expect to pay at least $500 for a good WC T5 and for a 17 year old that's serious money. I applaud your willingness to perform this swap and encourage you're budget-minded build. Now how about some pics?
I'll try and get some pics pretty soon, I need to take some more. Thanks for the encouragement though, it's hard money wise but it's well worth it in my book.
 

zookeeper

Founding Member
Aug 25, 2001
3,328
44
109
57
Rogue River, Oregon
You're a smart guy. Here's a bit of advice, and that is to take free advice for what it's worth. If I believed everything I read online, I'd think that 8" rear ends are made of glass, early Mustangs can't be made to handle without $5,000 worth of Mustang II front end stuff and having a pro shop cut your car in half to install it and cars with carbs aren't any fun. You'll be fine with what you've got as long as you at least try not to side step the clutch at redline. I love seeing younger guys build with what they have. My 19 year old son is into Toyota off-road stuff as are all of his buddies. I love seeing them tearing rear ends apart in my driveway, learning the do's and don'ts of repairs, swapping trans and transfer cases and in general having fun on a budget. Live a little and make do with what you have, provided you don't risk your life doing it.
 
  • Like
Reactions: Olivethefet

Trent K.

Member
Oct 21, 2019
20
2
13
Hermann, MO
You're a smart guy. Here's a bit of advice, and that is to take free advice for what it's worth. If I believed everything I read online, I'd think that 8" rear ends are made of glass, early Mustangs can't be made to handle without $5,000 worth of Mustang II front end stuff and having a pro shop cut your car in half to install it and cars with carbs aren't any fun. You'll be fine with what you've got as long as you at least try not to side step the clutch at redline. I love seeing younger guys build with what they have. My 19 year old son is into Toyota off-road stuff as are all of his buddies. I love seeing them tearing rear ends apart in my driveway, learning the do's and don'ts of repairs, swapping trans and transfer cases and in general having fun on a budget. Live a little and make do with what you have, provided you don't risk your life doing it.
That's pretty inspirational, thanks for it though. It makes me feel good about what I'm doing. I love working on these cars I just hate that I'm only 17 and don't have any money to buy stuff for them.
 

02 281 GT

Agreed...My wife has great Boobs
10 Year Member
Feb 3, 2009
1,790
1,042
164
Wichita Falls, TX
I swapped a 4-cylinder T-5 into my 1986 GT when the original transmission gave out. I was in a similar boat as you. The guy from whom I purchased the transmission said it was out of an '88 GT, however, I found out when I tried to install a steel bearing retainer that it was a 4-cylinder transmission.

It lasted a while, but it had a lot of issues. A lot of the synchros were garbage after a little while and the transmission would also get stuck in third gear from time to time. That transmission lasted until I sold the car.

Be advised that you will need a non standard pilot bearing for that transmission. The inside diameter of the required bearing is much smaller on the 4-cylinder transmission. Also be aware that the gearing on the 4-cylinder transmissions is much steeper to account for the lack of low end torque on the 4-cylinder engines. I had installed 3.55 gears in my '86 before I did the transmission swap and ended up with the car running nearly 3k RPM at 65 mph.

I can be done, but it's not ideal. I would say that it would be a great learning experience for a 17-year-old, though. I learned so much on that '86. It was kind of a junky car.
 

Trent K.

Member
Oct 21, 2019
20
2
13
Hermann, MO
I swapped a 4-cylinder T-5 into my 1986 GT when the original transmission gave out. I was in a similar boat as you. The guy from whom I purchased the transmission said it was out of an '88 GT, however, I found out when I tried to install a steel bearing retainer that it was a 4-cylinder transmission.

It lasted a while, but it had a lot of issues. A lot of the synchros were garbage after a little while and the transmission would also get stuck in third gear from time to time. That transmission lasted until I sold the car.

Be advised that you will need a non standard pilot bearing for that transmission. The inside diameter of the required bearing is much smaller on the 4-cylinder transmission. Also be aware that the gearing on the 4-cylinder transmissions is much steeper to account for the lack of low end torque on the 4-cylinder engines. I had installed 3.55 gears in my '86 before I did the transmission swap and ended up with the car running nearly 3k RPM at 65 mph.

I can be done, but it's not ideal. I would say that it would be a great learning experience for a 17-year-old, though. I learned so much on that '86. It was kind of a junky car.
Sounds like the guy didn't really know what he was talking about. Did it ever make you wonder if he actually took care of the transmission or not before you got it?
 

02 281 GT

Agreed...My wife has great Boobs
10 Year Member
Feb 3, 2009
1,790
1,042
164
Wichita Falls, TX
Sounds like the guy didn't really know what he was talking about. Did it ever make you wonder if he actually took care of the transmission or not before you got it?
I honestly think the guy just lied about what he had to get rid of it. It actually was a fine transmission when I installed it. All the issues I mentioned developed later.

The old transmission went out because someone had put gear oil in it instead of ATF.
 

Trent K.

Member
Oct 21, 2019
20
2
13
Hermann, MO
I honestly think the guy just lied about what he had to get rid of it. It actually was a fine transmission when I installed it. All the issues I mentioned developed later.

The old transmission went out because someone had put gear oil in it instead of ATF.
That sucks, could've been easily avoided but some people just don't know I guess.