How do I identify a 1.6 vs 1.8 tranny? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 03-25-2007, 06:01 PM   #1
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Default How do I identify a 1.6 vs 1.8 tranny?

I believe the PO may have put a 1.8 tranny in my '91. Since I am shopping for a new tranny identification of what I actually need would be helpful <G>. So, can I look under the car and identify what I have?


FWIW, I've gone from thinking I had a worn out 220K mile 1.6 tranny to thinking I screwed up a perfectly good 60K mile 1.8 tranny.
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Old 03-25-2007, 06:05 PM   #2
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I was under the impression that they were the same
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Old 03-25-2007, 06:09 PM   #3
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Originally Posted by neogenesis2004 View Post
I was under the impression that they were the same
I believe they are interchangable (you have to use the correct clutch and flywheel) but not the same. If I have a 1.8 tranny in my '91 that means if I screw up and buy a 1.6 tranny I'll have to change my clutch and get rid of my lightened flywheel.
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Old 03-25-2007, 06:09 PM   #4
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The 1.8 tranny has a better synchro on 2nd, makes the 1-2 shift feel better. They are otherwise identical. They are exactly as strong/weak. Either clutch set up will work with either tranny.

I have a 1.8 flywheel and clutch between my original 1.6 engine and tranny.

The only 1.8 tranny that won't directly swap to your 1.6 stuff is the 6 speed. IIRC it will bolt up to the motor fine, but is a bit longer than the 5 speed so you'd need to swap driveshafts too. There may be some other misc minor issues as well, don't remember the details, but the swap isn't bad.
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Old 03-25-2007, 06:17 PM   #5
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the tranny makes no difference on your clutch choice man if you wanted you could run a 6 speed on a bone stock 89 with original clutch. the Flywheel etc have to match the clutch but the bell housing is exsactly the same. As is the slave etc i believe.
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Old 03-25-2007, 06:24 PM   #6
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Quote:
Originally Posted by magnamx-5 View Post
As is the slave etc i believe.
Word of caution: Early 1990 miatas have a different slave than mid 90 and later. Don't know if that has any relevance to transmissions, don't think it does, but it may.
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Old 03-25-2007, 06:30 PM   #7
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hey ben what does your License plate frame say? I can almost read the bottom something about a alarm clock?
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Old 03-25-2007, 06:37 PM   #8
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Quote:
Originally Posted by magnamx-5 View Post
the tranny makes no difference on your clutch choice man if you wanted you could run a 6 speed on a bone stock 89 with original clutch. the Flywheel etc have to match the clutch but the bell housing is exsactly the same. As is the slave etc i believe.
I thought the 6 was junk (to most people) since the gears were so short. Seemed like all you did was shift every 3 seconds. Is this not true? I think I have a 4.3 rear end in mine (was this the shortest?).
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Old 03-25-2007, 06:49 PM   #9
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Yeah you'd definitely be shifting more with the 6 speed. People get it for the pimp factor and the fact that it's stronger than the 5 speed. It would definitely be more work to drive, and not necessarily any quicker around the track due to extra shifting. I believe there are more ribs on the 6 speed case than on the 5 speed, makes the case stronger and less likely to flex.

The 6 speed with a 4.30 would surely suck *****, especially with a turbo.

The 6 is likely to survive with 250-300 rwhp. A 5 speed may have to be replaced from time to time. But you can find the 5 speeds for $200, and the 6 speed will run $600-800 for the tranny plus upfront costs for the swap.
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Old 03-25-2007, 06:53 PM   #10
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you could pick up a stock 5 speed in good condition for 200 or less. and if yiou want more top end swap in a rx7 5th gear solo miata has the info on that. 3rd misses on me sometimes in cornering laod etc. no way around it we just need to learn to adapt and hope it isnt our cases flexing.
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Old 03-25-2007, 07:04 PM   #11
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Quote:
Originally Posted by magnamx-5 View Post
you could pick up a stock 5 speed in good condition for 200 or less.
I'm seeing them for $350 with high mileage in the junk yards around here.
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