S5 NA transmission issue.
Thread Starter
Joined: Apr 2003
Posts: 1,707
Likes: 177
From: South Eastern USA
S5 NA transmission issue.
My first real problem since putting this car together has finally happened! Back story : Car is a 1990 6 port running a Stage 3 BNR turbo and Haltech 1500 on e85. Car puts down right at 300Rwhp at 14psi on factory NA drive train with an S4 NA LSD and has been fine for several years of driving. (I never dump the clutch and never overly harsh on the transmission.
Last week I had shifter issues, and took everything apart and replaced the upper, lower (with springs) as well as a new groove bushing (which was disintegrated) I put everything back together, test drove the car fine and drove it to work today just fine.
On the way home and nearly to my neighborhood I did a WOT first gear pull to 7000 rpms at 14 psi. Clutch in to shift to second.... Won't come out of 1st.. STUCK in first. clutch still in i was able to FORCE the shifter back into neutral. 2nd gear would not enter.. 3rd, 4th and 5th gear seemed fine so I was able to limp home the last couple miles.
I took apart the shifter assembly again and everything looks to be still in place, I don't see anything obvious.. Looking for others with this issue in the past. Am I looking at a Bent 1-2 shift fork?? Good news I guess is NA transmissions are fairly in-expensive.
Thanks,
M
Last week I had shifter issues, and took everything apart and replaced the upper, lower (with springs) as well as a new groove bushing (which was disintegrated) I put everything back together, test drove the car fine and drove it to work today just fine.
On the way home and nearly to my neighborhood I did a WOT first gear pull to 7000 rpms at 14 psi. Clutch in to shift to second.... Won't come out of 1st.. STUCK in first. clutch still in i was able to FORCE the shifter back into neutral. 2nd gear would not enter.. 3rd, 4th and 5th gear seemed fine so I was able to limp home the last couple miles.
I took apart the shifter assembly again and everything looks to be still in place, I don't see anything obvious.. Looking for others with this issue in the past. Am I looking at a Bent 1-2 shift fork?? Good news I guess is NA transmissions are fairly in-expensive.
Thanks,
M
Rotary Freak
Joined: Nov 2001
Posts: 1,514
Likes: 229
From: Alexandria, VA
You wrote:
>> "Good news I guess is NA transmissions are fairly in-expensive."
They used to be a dime a dozen, but that's not the case anymore. Parts for these cars are becoming more and more scarce.
Shift lever assembly looks ok? Sometimes if the shift lever spring breaks (https://www.atkinsrotary.com/81-92-r...-17-465b-.html), the broken piece could wedge itself in there and limit the shifter lever's movement. This happened to me last spring. The spring broke and I wasn't able to shift into 2nd, but after a couple tries it apparently dislodged itself. So, I now have no centering spring, but am able to drive the car. If that's not it, than you might have a more serious problem.
Clutch hubs and shift forks are paired as 1-2, 3-4 and 5-R. Since you're only having this trouble with 1-2 gears, I'd would say the most likely culprit would likely be either 1st or 2nd gear synchro, 1-2 shift fork or clutch hub.
>> "Good news I guess is NA transmissions are fairly in-expensive."
They used to be a dime a dozen, but that's not the case anymore. Parts for these cars are becoming more and more scarce.
Shift lever assembly looks ok? Sometimes if the shift lever spring breaks (https://www.atkinsrotary.com/81-92-r...-17-465b-.html), the broken piece could wedge itself in there and limit the shifter lever's movement. This happened to me last spring. The spring broke and I wasn't able to shift into 2nd, but after a couple tries it apparently dislodged itself. So, I now have no centering spring, but am able to drive the car. If that's not it, than you might have a more serious problem.
Clutch hubs and shift forks are paired as 1-2, 3-4 and 5-R. Since you're only having this trouble with 1-2 gears, I'd would say the most likely culprit would likely be either 1st or 2nd gear synchro, 1-2 shift fork or clutch hub.
Thread Starter
Joined: Apr 2003
Posts: 1,707
Likes: 177
From: South Eastern USA
Thread Starter
Joined: Apr 2003
Posts: 1,707
Likes: 177
From: South Eastern USA
You wrote:
>> "Good news I guess is NA transmissions are fairly in-expensive."
They used to be a dime a dozen, but that's not the case anymore. Parts for these cars are becoming more and more scarce.
Shift lever assembly looks ok? Sometimes if the shift lever spring breaks (https://www.atkinsrotary.com/81-92-r...-17-465b-.html), the broken piece could wedge itself in there and limit the shifter lever's movement. This happened to me last spring. The spring broke and I wasn't able to shift into 2nd, but after a couple tries it apparently dislodged itself. So, I now have no centering spring, but am able to drive the car. If that's not it, than you might have a more serious problem.
Clutch hubs and shift forks are paired as 1-2, 3-4 and 5-R. Since you're only having this trouble with 1-2 gears, I'd would say the most likely culprit would likely be either 1st or 2nd gear synchro, 1-2 shift fork or clutch hub.
>> "Good news I guess is NA transmissions are fairly in-expensive."
They used to be a dime a dozen, but that's not the case anymore. Parts for these cars are becoming more and more scarce.
Shift lever assembly looks ok? Sometimes if the shift lever spring breaks (https://www.atkinsrotary.com/81-92-r...-17-465b-.html), the broken piece could wedge itself in there and limit the shifter lever's movement. This happened to me last spring. The spring broke and I wasn't able to shift into 2nd, but after a couple tries it apparently dislodged itself. So, I now have no centering spring, but am able to drive the car. If that's not it, than you might have a more serious problem.
Clutch hubs and shift forks are paired as 1-2, 3-4 and 5-R. Since you're only having this trouble with 1-2 gears, I'd would say the most likely culprit would likely be either 1st or 2nd gear synchro, 1-2 shift fork or clutch hub.
I did find an outfit called JO motorsports. Jason rebuilds Miata and NA Rx-7 transmissions and offers a race version for an additional 300 or so. Total cost would be around 1650 for EVERYTHING new and he does not need my core. I am very tempted.. if in fact I have something internal damaged.
-M
Thread Starter
Joined: Apr 2003
Posts: 1,707
Likes: 177
From: South Eastern USA
Considering the power output of the car and the age of the current transmission I am biting the bullet and getting a JO motorsports rebuilt transmission with REM gear treatment. There is also some strengthening of the C/S from what I understand to keep it from twisting under heavy load. This of course will not be as strong as the sought after Turbo transmissions, BUT, it's still cheaper than doing a full Turbo drivetrain swap which requires Flywheel, clutch, starter and either a full rear end or a custom drive shaft to mate to my existing NA LSD. The price is reasonable, i'll share some photos once it arrives and will update my build thread with photo's of the transmission swap.
-M
-M
Last edited by Relisys190; Oct 18, 2025 at 08:20 PM.
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Thread Starter
Joined: Apr 2003
Posts: 1,707
Likes: 177
From: South Eastern USA
The transmission has been excellent, very smooth, not a single issue. I have around 800 miles on it so far and need to replace the fluid closer to 1000 miles break-in. I am looking forward to many years of service from it. I'm not terribly harsh on the car so it should hold up to the turbo power level fairly well. I opted not to go with a Turbo II swap trans as A: I dont have one, B: the auxilary parts needed are added costs and C: .. More work to get the car going again and I was trying to minimize downtime to enjoy the car.
I recommend JO motorsports 100%
-M
Thread Starter
Joined: Apr 2003
Posts: 1,707
Likes: 177
From: South Eastern USA
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