Question for a G series GURU

[stevesei]

I would like to use the 4cyl (FS2) MX-6 gears in my GS with KLDE engine. I would like to retain the 4.39 diff and gain the taller 5th gear and better gear spacing of the 4cyl box. Can you give me guidance as to:

1. Would it work to simply change the entire gearset and trans case, using the MX-3 bellhousing?

2. Would it be necessary to change all the gears, reusing the MX-3 primary and secondary shafts?

This is a long term project, and may include some form of LSD at the same time. The DE (which is in fact the 2/3 ZE that came in the early Millenias) has so much torque that it really needs taller gearing on the highway. I would use an MX-6 DE box, but want to retain the 4.39 for autocrossing.

Thanks
Steve

[Daninski]

There is a post here I believe Ryan posted it on engine and trans compatibility. Suggest you use the Search, should be easy to find.

[stevesei]

I have read the post, and yes, all 6 cylinder G transmissions interchange. The point here is whether I can do a mix 'n match, changing only the bellhousing, or do I have to disassemble the whole thing. My understanding is that some of these trannies have different length shafts, etc. This would make for a nightmare if not caught beforehand. Hence, the request for a guru to look this over and give me some thoughts. As an afterthought, how much shimming of backlash/endplay would be needed?

[RobMinhas]

Your best bet is probably Clubprotege.com, most folks on this forum like their KL-ZEs which have a habit of eventually eating up transmissions(or so I've heard), causing disinterest in trans modifications like swapping gears.

I know that the MX6 5th gear swap is quite uninvolved but I do not know for sure how any of the rest would go. I've heard that adding the MX6 fifth gear to the G series messes with the torque curve, which is why I'm passing on it.

[crazycanadian]

Are you trying to use the whole gear set?? Or just 5th gear??

F series transmissions are a totally different family then the G series.. I don't know about the non turbo 4 cylinder stuff, but the turbo 4 cylinder stuff wont interchange at all.. Even 5th gear...

Different gear widths are a product of the different generation of G series transmission... V6 and Kia boxes have a thicker ring gear... B6T G series have a thinner ring gear..

do a search I have posted lots of information with tons of pictures in different threads...

[stevesei]

I am only interested in the gearset that came with the FE 4cylinder MX-6. It SHOULD have the same gear widths since it is a high-torque engine. I am mostlly interested in whether the case will bolt up to the MX-3 GS bellhousing, and will all the spacers and shafts work out. I am NOT interested in any F series transmission or any transmission that came with a B6T. I may have to go to the MX-6 forum if no one at MX-3.com has knowledge of this.

Thanks,
Steve

[crazycanadian]

I am only interested in the gearset that came with the FE 4cylinder MX-6. It SHOULD have the same gear widths since it is a high-torque engine. I am mostlly interested in whether the case will bolt up to the MX-3 GS bellhousing, and will all the spacers and shafts work out. I am NOT interested in any F series transmission or any transmission that came with a B6T. I may have to go to the MX-6 forum if no one at MX-3.com has knowledge of this.

Thanks,
Steve

B6T is a G series transmission... B6 is an F series... F2T had an H series... I think the FE 4 cylinder transmission is a G series... The cases wont mix and match.. You will be swapping the entire gear set out and installing it into a complete mx3 gs case... The key is ring gear widths on the diffs, and counter shaft lengths... These have been the 2 biggest differences in g series transmissions I have seen...

[stevesei]

Thanks,

As I said, I'm only interested in the FE G series transmission. Are you saying the transmission cases are different enough that the FE transmission will not bolt to an MX-3 bellhousing. I am aware that the pinion gear will have to be swapped to fit the GS 4.388 ring gear. It seemed that shaft length issues could be avoided by swapping the entire case, and that a G series case should pretty much be a G series case, regardless of bellhousing. Of course this is Mazda we're talking about...

[crazycanadian]

Thanks,

As I said, I'm only interested in the FE G series transmission. Are you saying the transmission cases are different enough that the FE transmission will not bolt to an MX-3 bellhousing. I am aware that the pinion gear will have to be swapped to fit the GS 4.388 ring gear. It seemed that shaft length issues could be avoided by swapping the entire case, and that a G series case should pretty much be a G series case, regardless of bellhousing. Of course this is Mazda we're talking about...

I havent had an FE transmission apart... Since you seem set on doing this then pull one apart and compare...

I have rebuilt USDM GTX awd, B6T, K series, BP Kia, transmissions... I have also had an SOHC escort transmission apart.. In all cases it wouldn`t save, time or make anything simpler by trying to swap out just the bell housings...

[Nd4SpdSe]

The trans series is talking about the gearset inside, not the case or the bellhousing.

We talked about it a while back, but the gears 1-4 and the pinion is mounted in an interesting manner, and isn't easy to change

To swap the final drive, you need to change the pinion gear and the differential. The diff is easy, but I've been told that to take a gear of a shaft is a huge pain.

The gear is a shrink fit to the shaft. Where the gear is heated slipped onto the shaft then the final machining steps or completed. If you are going to change this gear you really should used the whole shaft otherwise the gear will probably become out of spec if it is heated and removed from the shaft and could micro fracture if removed cold creating all sorts of problems later. Also in certain cases I have seen were the gear and shaft were machined and one piece like in the trannys with the 4.588 final drive ratio

[stevesei]

Thanks, guys!

I was hoping to change the entire case and internals together to eliminate shaft length and case differences. From what I see in your replies, though, I should probably simply replace the 3rd, 4th, and 5th gearsets with the ones from the FE trans. Am I correct in assuming that the internals will interchange? This is a longer term project, based mostly on when I can find an FE trans. I'd love to find a reasonably priced LSD too.

Thanks,
Steve