A question or two about AUTO tranny cars
02-26-15, 12:57 PM
#1
A question or two about AUTO tranny cars
I'm in the middle of putting a 13b 6port in my 85. For some reason I feel compelled to keep the car an automatic. The currant trans in the car shifts fine but does not go into overdrive. In fact the "O/D" light stays lit on the dashboard regardless of o/d switch position and even when unplugged.
I have not found much info on these transmissions. The 6 port that's going into the car is an s4 from 1988. It was also an automatic. I recently picked up a free transmission from an 84 and to my surprise they are practically identical. Internally I know the 88 has some differences as well as the splines on the output shaft but it looks like it will even bolt in place with no mods.
Now here is where I need some help. Where the 84-85 trans had this o/d on off switch feature, the 88 did not. As far as I know they had a "hold" feature which lets the car remain in a particular gear and not upshift until the button is released. I'm not interested in this feature. I just want a transmission with a functioning o/d. so it should work with o/d by default since there was never an option to turn it off on this model?
The 6 port will be carbed with a holley 600. I would like to run this later model trans since it only had 59k on it and it worked great in the fc I took it out of. Also how would kickdown be achieved with this set up? 89 and up were all computer controlled but I am less familiar with the carbed set ups. I know the trans needs a vacuum signal. But that's about it. Any help is appreciated.
I have not found much info on these transmissions. The 6 port that's going into the car is an s4 from 1988. It was also an automatic. I recently picked up a free transmission from an 84 and to my surprise they are practically identical. Internally I know the 88 has some differences as well as the splines on the output shaft but it looks like it will even bolt in place with no mods.
Now here is where I need some help. Where the 84-85 trans had this o/d on off switch feature, the 88 did not. As far as I know they had a "hold" feature which lets the car remain in a particular gear and not upshift until the button is released. I'm not interested in this feature. I just want a transmission with a functioning o/d. so it should work with o/d by default since there was never an option to turn it off on this model?
The 6 port will be carbed with a holley 600. I would like to run this later model trans since it only had 59k on it and it worked great in the fc I took it out of. Also how would kickdown be achieved with this set up? 89 and up were all computer controlled but I am less familiar with the carbed set ups. I know the trans needs a vacuum signal. But that's about it. Any help is appreciated.
02-28-15, 03:57 PM
#2
Coming to my senses...
I will take the forum's 190 views and silence to heart. You are all too polite 
to call me CRAZY for thinking about putting a silky smooth 59k 13b 6port even in the same room let alone car as a JATCO 4speed transmission.
This got me thinking...I'm a bit of a rotary hoarder and might have some bits to get started on the conversion to a 5 speed
The search ensued...and here are the results...
I found a pedal box, and a large clutch, as well as a flywheel that matches mazdatrix description of a 86-88 NA right down to the "326" stamping
I find this very weird because I'm sure that flywheel came off a 12a engine. I will weigh it and make sure its 24#
Also came across an 85 driveshaft and trans...
found a couple of starters and some hydraulic bits that I will prob just get from Rock Auto anyway. I got a manual cross member but I don't need it and will need to buy a mount. I had a brand new pilot and seal, as well as a t/o bearing. Wow! I even had a shifter and some console bits. Not a complete kit by any means, but off to a good enough start
to call me CRAZY for thinking about putting a silky smooth 59k 13b 6port even in the same room let alone car as a JATCO 4speed transmission. This got me thinking...I'm a bit of a rotary hoarder and might have some bits to get started on the conversion to a 5 speed
The search ensued...and here are the results...
I found a pedal box, and a large clutch, as well as a flywheel that matches mazdatrix description of a 86-88 NA right down to the "326" stamping
I find this very weird because I'm sure that flywheel came off a 12a engine. I will weigh it and make sure its 24#
Also came across an 85 driveshaft and trans...
found a couple of starters and some hydraulic bits that I will prob just get from Rock Auto anyway. I got a manual cross member but I don't need it and will need to buy a mount. I had a brand new pilot and seal, as well as a t/o bearing. Wow! I even had a shifter and some console bits. Not a complete kit by any means, but off to a good enough start
02-28-15, 05:01 PM
#3
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The 84-85 automatic is basically a 3 speed with an overdrive unit bolted in after the torque converter. You can lose the overdrive and the rest of tranny can keep on going. My aunt drove one like that for quite a while.
02-28-15, 09:50 PM
#4
Yeah I know I could drive the tranny for a while yet as a 3 speed, but I already daily an '82 626 with a JATCO 3speed. On the highway at 60mph the tach reads about 3400 rpm! If I was to go automatic I def wanted a functioning overdrive. But to be honest I think I wouldn't enjoy the car as much. So I guess I owe this decision to my 626...I love that car. 5 speed it is...stay tuned for the build thread. It's about time for this car
02-28-15, 11:33 PM
#5
84SE-EGI helpy-helperton
Interesting project and I was just looking through the 84/85 FSM (printed version) today looking at clutch/transmission stuff and read through the Auto Trans section out of curiosity.
On the 84/85 Auto transmission models, the 'kick-down' function is controlled by a switch located on the gas pedal cluster under the dash. When you go WOT, the switch registers this and sends 12v to the 'kick-down' solenoid located on the side of the transmission. This forces the next lower gear. It's entirely manual (mechanically switched) controlled, so no ECU function is over this.
Also, there's an O/D switch on the transmission which is used to illuminate the dash - if your switch is bad, or the actuator in the transmission is preventing O/D function, that may be indicated on the dashlight never going out. Also, the O/D switch on the shift mechanism may be at fault and is worth looking into. The 4th gear overdrive on these cars seems to be a highway cruising and fuel mileage feature and would be a valuable addition if you intend to leave it an auto trans car.
Most of us here follow the allure of the RX7 partly due to the sports-car nature of a stick shift, a light frame and enough horsepower to be fun and yet reliable. The auto trans from the mid-80's are nowhere near what auto trans are today - with many of today's top performance cars being FASTER with an auto compared to a stick, which is considered slow and cumbersome.
That said, it's your car and whatever floats your boat! Good luck,
On the 84/85 Auto transmission models, the 'kick-down' function is controlled by a switch located on the gas pedal cluster under the dash. When you go WOT, the switch registers this and sends 12v to the 'kick-down' solenoid located on the side of the transmission. This forces the next lower gear. It's entirely manual (mechanically switched) controlled, so no ECU function is over this.
Also, there's an O/D switch on the transmission which is used to illuminate the dash - if your switch is bad, or the actuator in the transmission is preventing O/D function, that may be indicated on the dashlight never going out. Also, the O/D switch on the shift mechanism may be at fault and is worth looking into. The 4th gear overdrive on these cars seems to be a highway cruising and fuel mileage feature and would be a valuable addition if you intend to leave it an auto trans car.
Most of us here follow the allure of the RX7 partly due to the sports-car nature of a stick shift, a light frame and enough horsepower to be fun and yet reliable. The auto trans from the mid-80's are nowhere near what auto trans are today - with many of today's top performance cars being FASTER with an auto compared to a stick, which is considered slow and cumbersome.
That said, it's your car and whatever floats your boat! Good luck,
03-01-15, 10:37 AM
#7
Interesting project and I was just looking through the 84/85 FSM (printed version) today looking at clutch/transmission stuff and read through the Auto Trans section out of curiosity.
On the 84/85 Auto transmission models, the 'kick-down' function is controlled by a switch located on the gas pedal cluster under the dash. When you go WOT, the switch registers this and sends 12v to the 'kick-down' solenoid located on the side of the transmission. This forces the next lower gear. It's entirely manual (mechanically switched) controlled, so no ECU function is over this.
Also, there's an O/D switch on the transmission which is used to illuminate the dash - if your switch is bad, or the actuator in the transmission is preventing O/D function, that may be indicated on the dashlight never going out. Also, the O/D switch on the shift mechanism may be at fault and is worth looking into. The 4th gear overdrive on these cars seems to be a highway cruising and fuel mileage feature and would be a valuable addition if you intend to leave it an auto trans car.
Most of us here follow the allure of the RX7 partly due to the sports-car nature of a stick shift, a light frame and enough horsepower to be fun and yet reliable. The auto trans from the mid-80's are nowhere near what auto trans are today - with many of today's top performance cars being FASTER with an auto compared to a stick, which is considered slow and cumbersome.
That said, it's your car and whatever floats your boat! Good luck,
On the 84/85 Auto transmission models, the 'kick-down' function is controlled by a switch located on the gas pedal cluster under the dash. When you go WOT, the switch registers this and sends 12v to the 'kick-down' solenoid located on the side of the transmission. This forces the next lower gear. It's entirely manual (mechanically switched) controlled, so no ECU function is over this.
Also, there's an O/D switch on the transmission which is used to illuminate the dash - if your switch is bad, or the actuator in the transmission is preventing O/D function, that may be indicated on the dashlight never going out. Also, the O/D switch on the shift mechanism may be at fault and is worth looking into. The 4th gear overdrive on these cars seems to be a highway cruising and fuel mileage feature and would be a valuable addition if you intend to leave it an auto trans car.
Most of us here follow the allure of the RX7 partly due to the sports-car nature of a stick shift, a light frame and enough horsepower to be fun and yet reliable. The auto trans from the mid-80's are nowhere near what auto trans are today - with many of today's top performance cars being FASTER with an auto compared to a stick, which is considered slow and cumbersome.
That said, it's your car and whatever floats your boat! Good luck,
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03-01-15, 10:53 AM
#8
Thanks Jeff...My GLC was an automatic before I did the rotary conversion. Not nearly as involved when swapping those old cars. A lot of my "parts for the swap will need some attention (cleaning and paint) but nice to know I have mostly everything.
03-01-15, 11:40 AM
#9
Let me know how hard it is to swap the pedal box. I didn't have to swap it on the Cosmo so I've never had to deal with as much under dash stuff as you will have to. All it needed was to get rid of the auto brake pedal and swap in the new manual brake and clutch pedals with the longer pivot bolt and the helper spring assembly etc.
Your pedal assembly looks like an 84-85 with the helper spring. It's a really lnice addition compared with the 83 and older pedals, but you have to swap the entire steel frame.
Your pedal assembly looks like an 84-85 with the helper spring. It's a really lnice addition compared with the 83 and older pedals, but you have to swap the entire steel frame.
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