5th Gear Change Out
I've searched. Maybe someone has asked but I can't find it.
I'm in the middle of rebuilding my tranny and was wondering if I can change the 5th gear to a higher gear? 86 N\A Base |
Yes, a .756 was available for an NA beginning in 89, or you can swap over to a TII driveline with a .719 (89-on) or .762 (87-88). There are also certain Miata and 626 transmission parts that will work with RX-7 transmissions, but I am not sure about the specifics. You may have better luck asking in the Race Car Tech forum.
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Originally Posted by Evil Aviator
Yes, a .756 was available for an NA beginning in 89, or you can swap over to a TII driveline with a .719 (89-on) or .762 (87-88).
The 86 and 87 used a .711 5th gear. In 88 the coupes got a .697 while the vert got a .711 5th gear for 89+ non turbos (including the GTUs) all got a .697 5th gear. Perhaps your gears mentioned are non stock gearing??? |
Originally Posted by Icemark
Perhaps your gears mentioned are non stock gearing???
I agree with your listed values, Mark, although the technical data sheets list a 0.756:1 overdrive when a viscous LSD was installed. |
Originally Posted by scathcart
I agree with your listed values, Mark, although the technical data sheets list a 0.756:1 overdrive when a viscous LSD was installed.
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Originally Posted by Icemark
Yeah I think that is a misprint of the Turbo's .765 5th gear.
Its lost on me. |
Originally Posted by Icemark
Perhaps your gears mentioned are non stock gearing???
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Originally Posted by scathcart
But the turbo was 0.719:1 for S5's, not 0.762:1. That's what I don't get.
Its lost on me. |
Originally Posted by Evil Aviator
No, that's stock gearing. Let me clarify: The .756 came stock in the GTUs, which uses the same transmission case as every other NA FC of the same year.
http://www.mazdamark.com/GTUs.jpg |
My owners manual and the FSM both list .756 with the LSD installed. Also there was a formula for calculating speed in any given gear in an old RB catalog and using the.756 in it comes out to what I am doing in 5th at the RPM I plug into the formula.SO I think the GTUs did in fact have the .756 5th gear.
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Originally Posted by Evil Aviator
The 87-88 TII had the .762 gearing. ;)
I also don't think the GTUs got a special overdrive... I've never found any literature to prove it, but I have found literature to state its the same as all other N/A transmissions. |
so what all is interchangable ?
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Using my formula I get 77mph@3500rpm in 5th gear using the .756 ratio. I get 84mph@3500rpm using the .697 ratio.Whe I am at 3500rpm my speedometer is between 70 and 80mph thus I believe I have the .756 5th gear ratio. Here is the formula.I've found it useful.
(T.C)x(RPM) _____________ (1056)x(A.R)x(T.R.) T.C.= Tire circumference A.R.=Rear Axle ratio T.R.=Transmission gear ratio RPM=Engine RPM |
Thanks for all the replies, that formula is nice to know.
I saw it somewhere else in here. I guess the main question is will the s5 gear fit into an s4 unmodified? Say it works how do you get a .756 gear without tearing apart a used transmission? When using old parts who knows what you'll get. I'd like to buy it new. Who sells this gear other than the dealer? |
Holy shit, archive please!
--Gary |
1 Attachment(s)
Originally Posted by Bob_The_Normal
Holy shit, archive please!
--Gary |
Well as long as I have the attention of the Gurus,
In the 89 engine parts list it says that the over the top gear is P/N: M512-17-611 (Non-Turbo)>(nor.susp) and P/N: M514-17-611A (Non-Turbo)>(hard.susp) Which one is the .756 gear? |
Originally Posted by Pyrocloud
Well as long as I have the attention of the Gurus,
In the 89 engine parts list it says that the over the top gear is P/N: M512-17-611 (Non-Turbo)>(nor.susp) and P/N: M514-17-611A (Non-Turbo)>(hard.susp) Which one is the .756 gear? Could it be that all S5 GXL's came with a different 5th gear than the GX's? Hmm... time to do some testing. |
Update
If any one cares.
I called the dealer and found out that the part number for the .756 gear has changed. It's now M517-17-611. Price: $205 USD For all the fanatics. |
Originally Posted by Pyrocloud
If any one cares.
I called the dealer and found out that the part number for the .756 gear has changed. It's now M517-17-611. Price: $205 USD For all the fanatics. |
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