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6 speed in a '90

1K views 24 replies 17 participants last post by  Hypertek99 
#1 ·
Has anyone heard of this being done before? If so, tell me how.
 
#5 ·
Ive been lookin in to this myself. I wanted to do it for extra durability, planning on 300+hp.
I may be wrong about this...but as I used to be in the 240SX/Silvia scene...it was known that the 6-speeds are actually WEAKER, due to skinnier gears to fit in the same space as a 5-speed. So, for those that are looking for higher horsepower/drifting applications, it is preferrable to use a 5-speed instead.

Like I said, I may be wrong...so don't flame me if I am! ^-^
 
#7 ·
Depending on what gear ratio you have now, changing your rear end ratio may be relevant as well.
 
#9 ·
IIRC you'll also need a 6 speed driveshaft. If you like to row the box then the 6 speed is the way to go. I admit driving my friends 10ae is a bit more entertaining in that area. I've heard its stronger too but don't quote me on that.

This should help with gearing: http://www.idsfa.net/miata/gearing.html
 
#10 ·
I had looked in to this myself previously. The 6spd trans will fit, but you need a plate to mount the starter. BUT that's not all. You also need the rear end gearing to go with it. AND, if I am not mistaken, you also need the drive shaft. Any gains with the extra gearing is not worth the work/mods IMO.
The 5spd (and 6spd?) are borrowed from the RX7. The trans is pretty much indestructable from what I have heard from several mechanics....
 
#16 ·
Did a little research, all you need is trans, plate, and rewire reverse switch. Starter can be reused with only 2 bolts. Rear is not required but have to pay attention to gearing. You can swap speedo gear for more accurate speedo. But any driveshaft, clutch and flywheel will work, but clutch and flywheel will have to match each other.
 
#17 ·
Did a little research, all you need is trans, plate, and rewire reverse switch. Starter can be reused with only 2 bolts. Rear is not required but have to pay attention to gearing. You can swap speedo gear for more accurate speedo. But any driveshaft, clutch and flywheel will work, but clutch and flywheel will have to match each other.
You're right!!! =D>
I did that swap and it's that simple.
You might want to put a 3.9 gear ratio in the diff. but it is not necessary.
You could also use the 1.6 flywheel and clutch but you should go for a 1.8.
Serge
 
#19 ·
Yeah, but 6 on the floor is not as cool as 4 on the floor. What are you people thinking?
 
#20 ·
I'd like a 6spd tranny once I get a 1.8 diff and whatnot....but thats pretty far down the line...and its mainly for the pimp factor...lol
Plus I already have a 5spd tranny with 30k miles on it, sitting in my room with an 1.6 Exedy clutch and 1.6 Fidanza flywheel. However, that won't be going in until I find a 1.8 to play with, and then swap in.

My question on the gearing is this:
If you swap to a 6spd, and you get a 3.9 or even a 3.6 rear end, how much will it change your top gear RPMs for freeway driving? I drive about 130 miles a week on the freeway on a stock 4.3, and I hate it. If I could drop the top gear rpms with a lower geared diff, I'd be quite happy. However, I'll only do that if I can maintain the close ratios of a 5spd tranny, with a 6spd tranny.
 
#23 ·
Yeah, same here.
turbored, thanks. If I can verify that its slightly lower in rpm in 6th, I'll probably do it.

Plus, I can't think of many people that want 3.6 rear ends in the Miata community...lol
 
#24 ·
I'll be doing the 6 speed swap next saturaday. Check out my car in the garage i just updated with lots of pics. You will need the 6 speed tranny, and the backing plate for the swap. I also picked up the driveshaft, axles, and the 1.8L rearend with the 3.90 gears so i'll be doing the whole swap at once. All the parts i got came out of a 10th anniversary.
 
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