SWapping Auto Trans for Manual
12-07-04 | 08:37 PM
#1
Thread Starter
Junior Member
Joined: Oct 2004
Posts: 43
Likes: 2
From: CR, Iowa
SWapping Auto Trans for Manual
I am looking at a low milage '83 GS w/ auto, and would like to swasap the auto trans for the manual in my '83 GSL. Any major problems doing this? Thanks, Bill
12-07-04 | 09:43 PM
#3
Senior Member
Joined: Nov 2004
Posts: 311
Likes: 0
From: Birmingham AL
I was looking at doing this a couple years ago. My 85 (manual) was just totalled and I had just put an Atkins rebuild in it six months earlier. Now I was looking for a body to put the engine in. There was an 84 auto I was thinking about getting for the swap. I wanted to keep the manual so I called around about how to go about it. If I remeber correctly just a couple issues right off the bat was the rear end is geared differently, cpu and wiring is different plus having to install the clutch and tranny was enough to change my mind. It took me almost a year later to get a non running 7, but it was worth just getting another manual for the swap. Now I have an extra tranny along with everything else stripped off the first car.
12-08-04 | 01:33 AM
#4
Lean Mean Speed Thingie
Joined: Mar 2002
Posts: 1,102
Likes: 0
From: Moscow, ID
totally worth the swap, id say the hardest part was swapping out the pedal assembly! That was a pain in the ***, no room to work...second to that (or first, its not easy either), you'll have to fab your own tranny mounts
this thread helped a bunch with the fabbing of the mounts https://www.rx7club.com/1st-generation-specific-1979-1985-18/auto-5-speed-swap-i-need-talk-someone-who-has-done-223583/
good swap, you'll never regret it
this thread helped a bunch with the fabbing of the mounts https://www.rx7club.com/1st-generation-specific-1979-1985-18/auto-5-speed-swap-i-need-talk-someone-who-has-done-223583/
good swap, you'll never regret it
12-08-04 | 01:55 AM
#6
Fabrineer
Joined: Oct 2002
Posts: 976
Likes: 1
From: Charlotte, NC
I think the pre 84-85's (the 79-83) are completely swappable. I know my friend did it on an 84-85 and had to have a custom tranny mount lengthener made because the place where it mounts on the chassis is about 5 inches farther back than the manuals. I think the 79-83's use the same mounting location, though.
As for the wiring, there is no real issue, except that you unplug the wires you don't need. The CPU works just the same. Remember, our cars are carbureted, so the CPU really doesnt do anything except for emissions. There really are no CPU/wiring issues.
There is no difference between rear end ratios on an automatic and manual. The only differences on rear end ratios are on the GSL-SE and non GSL-SE's.
As for the wiring, there is no real issue, except that you unplug the wires you don't need. The CPU works just the same. Remember, our cars are carbureted, so the CPU really doesnt do anything except for emissions. There really are no CPU/wiring issues.
There is no difference between rear end ratios on an automatic and manual. The only differences on rear end ratios are on the GSL-SE and non GSL-SE's.
12-08-04 | 09:42 AM
#7
Thread Starter
Junior Member
Joined: Oct 2004
Posts: 43
Likes: 2
From: CR, Iowa
Gang
Thanks for the help.
AS it turns out the car w/ the Auto Trans is an '85 w/ 4 speed auto. So far researching it , there doesn't appear to be major problems w/ '83 to '83 3 speed auto, but looks like more of a challenge taking an '83 manual and installing it into an '85 auto.
Any additional help is greatly appreciated. God I love these 1st generation RX-7's. No question in my mind they are the most eye appealing car ever designed, and the most fun to drive for the $$$.
Bill
Thanks for the help.
AS it turns out the car w/ the Auto Trans is an '85 w/ 4 speed auto. So far researching it , there doesn't appear to be major problems w/ '83 to '83 3 speed auto, but looks like more of a challenge taking an '83 manual and installing it into an '85 auto.
Any additional help is greatly appreciated. God I love these 1st generation RX-7's. No question in my mind they are the most eye appealing car ever designed, and the most fun to drive for the $$$.
Bill
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12-08-04 | 02:34 PM
#9
Speak of the devil. 
If you are putting a 5 spd. into an 84-85 4 spd. Automatic then you are going to have a little bit of fabrication to do. Nothing major. Any gearhead should be able to handle the swap without much problem. Here are the basics of putting a 5 spd. manual into your 4spd auto body. These are also assuming that you are using an automatic engine. If you are using a 5 spd. engine then you can disregard most of this....
1) Get a pedal assembly from an 84-85 manual tranny car. The brackets and everything are the same as your auto, you just need the clutch pedal. If you can't find an 84-85 pedal set, then you can use pedals from earlier rx7s, BUT YOU CAN"T USE THE EARLIER BRACKETS! If you use an 83 or earlier pedal assembly, you'll have to take the clutch and brake pedals off. Then take the big automatic pedal off of your assembly, and put on the smaller brake and clutch pedals. The pedal assemblies from pre '83 look the same as 84-85 BUT THEY AREN'T. I found out the hard way. Just swap the pedals over and use your existing bracket to put them on.
2) You're going to need the clutch hydraulics (master and slave) and the hardline that connects the two.
3) You're going to need a flywheel from an 84-85 manual car, or you can leave your counterweight on the back and use a racing beat light flywheel. I would recommend buying a RB flywheel and using it. Nice performance gains, and is easier to put on too. (If you're using a manual engine then forget all this.)
4) You're going to need a clutch disc and pressure plate. I just got a whole clutch kit from the local NAPA. You'll also need a throwout bearing, shift fork, and all the usual 5 spd stuff. (Forget this too if you're using a different engine)
5) You're going to need a pilot bearing and pilot bearing seal to install into the end of the eccentric shaft. If you're using an automatic engine there won't be a pilot bearing in there, so just tap one in, and then follow it up with a bearing seal.
6) You're going to need the driveshaft from a 5 spd. car. The 4 spd. automatic trannies are much longer (which is what causes all the mounting problems to begin with) and as a result the driveshaft will be shorter. Since the new 5 spd. is going to be shorter than the automatic, you will need a longer driveshaft to compensate. This is also why you have to make new tranny mounts, to compensate for the differences in length.
7) Use the automatic crossmember and put it on the 5 spd. tranny. You'll have to make some custom mounts to compensate for the differences in lengths again. I'll post some pictures that Bouis provided for me. In this case a picture is worth a thousand words.
8) You're going to have to remove the automatic shifter. I firmly believe it is impossible to remove in one piece. I had to cut mine apart with an angle grinder to get it out. Unless you wanna take out the whole dash. No thanks for me.
9) Finally, I think you're probably going to need a speedo cable.
If you have any questions let me know. I think this pretty much covers the basics. Of course there are going to be little bumps along the road. I still haven't finished mine, but I'm hoping to get it up and running before Christmas. I'd have it done already, but it is merely part of my massive restoration project. Good luck!
Jamie
If you are putting a 5 spd. into an 84-85 4 spd. Automatic then you are going to have a little bit of fabrication to do. Nothing major. Any gearhead should be able to handle the swap without much problem. Here are the basics of putting a 5 spd. manual into your 4spd auto body. These are also assuming that you are using an automatic engine. If you are using a 5 spd. engine then you can disregard most of this....
1) Get a pedal assembly from an 84-85 manual tranny car. The brackets and everything are the same as your auto, you just need the clutch pedal. If you can't find an 84-85 pedal set, then you can use pedals from earlier rx7s, BUT YOU CAN"T USE THE EARLIER BRACKETS! If you use an 83 or earlier pedal assembly, you'll have to take the clutch and brake pedals off. Then take the big automatic pedal off of your assembly, and put on the smaller brake and clutch pedals. The pedal assemblies from pre '83 look the same as 84-85 BUT THEY AREN'T. I found out the hard way. Just swap the pedals over and use your existing bracket to put them on.
2) You're going to need the clutch hydraulics (master and slave) and the hardline that connects the two.
3) You're going to need a flywheel from an 84-85 manual car, or you can leave your counterweight on the back and use a racing beat light flywheel. I would recommend buying a RB flywheel and using it. Nice performance gains, and is easier to put on too. (If you're using a manual engine then forget all this.
)4) You're going to need a clutch disc and pressure plate. I just got a whole clutch kit from the local NAPA. You'll also need a throwout bearing, shift fork, and all the usual 5 spd stuff. (Forget this too if you're using a different engine)
5) You're going to need a pilot bearing and pilot bearing seal to install into the end of the eccentric shaft. If you're using an automatic engine there won't be a pilot bearing in there, so just tap one in, and then follow it up with a bearing seal.
6) You're going to need the driveshaft from a 5 spd. car. The 4 spd. automatic trannies are much longer (which is what causes all the mounting problems to begin with) and as a result the driveshaft will be shorter. Since the new 5 spd. is going to be shorter than the automatic, you will need a longer driveshaft to compensate. This is also why you have to make new tranny mounts, to compensate for the differences in length.
7) Use the automatic crossmember and put it on the 5 spd. tranny. You'll have to make some custom mounts to compensate for the differences in lengths again. I'll post some pictures that Bouis provided for me. In this case a picture is worth a thousand words.
8) You're going to have to remove the automatic shifter. I firmly believe it is impossible to remove in one piece. I had to cut mine apart with an angle grinder to get it out. Unless you wanna take out the whole dash. No thanks for me.
9) Finally, I think you're probably going to need a speedo cable.
If you have any questions let me know. I think this pretty much covers the basics. Of course there are going to be little bumps along the road. I still haven't finished mine, but I'm hoping to get it up and running before Christmas. I'd have it done already, but it is merely part of my massive restoration project. Good luck!
Jamie
12-08-04 | 02:40 PM
#10
Here are the pictures. I can't take credit for these. Bouis uploaded these to help me when I was having problems. He can also help you if you have any questions. Hope the pics clear things up....
The big washers under the tranny mount are used to make up for the thickness of the 1/4" pieces of steel. If you don't space the tranny back up with the washers then your driveshaft is going to be off, and it will make it try to bind up. It's really hard on it, and over time the torsional stress combined with the bending stresses will cause the driveshaft to fatigue and snap. So in short, make sure you put washers in the appropriate places so you don't screw up your driveshaft.
The big washers under the tranny mount are used to make up for the thickness of the 1/4" pieces of steel. If you don't space the tranny back up with the washers then your driveshaft is going to be off, and it will make it try to bind up. It's really hard on it, and over time the torsional stress combined with the bending stresses will cause the driveshaft to fatigue and snap. So in short, make sure you put washers in the appropriate places so you don't screw up your driveshaft.
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