5th gear swap talk

[LN323]

Okay....here we go again! Years ago with the help of other M323P car kooks (as my wife calls us) my car got the 626 5th gear swap. Recently, even though I've been checking mileage at 30+ MPG on highway road trips (33 MPG with tail wind) I have been thinking about how to squeeze more mileage out of my GT. I recently came across a 1994 Mazda 626 V-6 5-speed. Now, my first thought was that if I were Mazda I would have geared it differently from the 2.0L 5-speed because it was a bigger engine and it wouldn't need to run as high of RPMs. So, I started wondering..... Is it geared differently? If so, is it geared differently just in fifth gear or did Mazda perhaps do something that impacted the gear ratio all across the board including the final drive ratio? If they only changed the fifth gear somehow, is it compatible with my tranny? In other words, is it possible to lower my RPMs even more than I'm running now? That would be sooooo cool.

I've got an acquaintance of mine at the local Mazda dealer trying to do some research in their old manuals to try to figure out the differences/similarities. I haven't heard back from him yet.

I am starting a thread to see if any of you might know anything about this? Currently at around 70mph I'm running about 3100 RPMs. I'd love to drop that even more (maybe 300 RPMs more). I have the HP in this range for it to run fine, I'm sure and it would more than likely help my MPG even more.

Start talking! :D

[LN323]

Oops.... I guess I should have started this thread in a different category. Sorry. If any admins could move it for me I would appreciate it! :D

[monoxidechild]

The KL 626/mx6 5th gear is actually worse then your stock set up. They usually swap to the FS/F2 5th gears.

[azgtx]

Correct...Larry I don't think we can do better than what you have in the .717 gears. I have sold close to 200 gear sets over the years and if there was another that was better I would hope that I would have found it. If you aren't happy with 30mpg in the GT then you need to buy a Prius
Clay

[LN323]

If you aren't happy with 30mpg in the GT then you need to buy a Prius
Clay

LOL..... I'm happy.... I'm just always hoping for more.

I guess I'll just have to focus on something else on my car to try to improve (like the 25 year old paint).

[crazycanadian]

Hey Larry... If you do a search on some of my transmission related posts, I did a big comparison on a B6T transmission and KL powered transmission...

In short a B6T transmission has a 3.86 final drive, where as all the other BP, KL transmissions have either 4:10's or 4:38's... So your transmission all ready has the best final drive available to get best fuel milage... Top that off with the .717 5th gear we put in it way back when, you are as set as you'll ever be...

For anyone running KIA transmissions, or KL transmissions, search some of my posts.. the B6T final drive wont interchange..

[azgtx]

It will fit in the G series they put in the Sephias. I think that tranny was dubbed the K24.

[LN323]

Thanks guys. Your responses have been very helpful. I was just wishful thinking! LOL.

I guess I'll just have to live with the gearing that I have.... NOT that I'm unhappy. It's nice to know that I have the best gear ratio possible for mileage. I just wanted to be sure.