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Discussion Starter #1
Hey I have a question that I'm sure a lot of you motorheads who are smarter than I can answer. I'm researching what it would take to get a taller 6th gear.

I have a 2006 Elise and I've read that it has a C64 transmission with a 6th gear ratio of 0.81. Monkey Wrench sells a gear, (it's probably from the C60 transmission), that has a 0.725 ratio. see: Toyota OEM 6th Gear Set - C6X - 0.715:1 - TOY-430611 van Toyota OEM - Monkeywrench Racing - Celica

So my question is, what sort of labor would be involved in swapping out the 6th gear? I'm looking for a rough estimate on the number of hours it would take in a decent shop.

Since I have a +90 hp vision function supercharger: my theory is that the gear would like to save wear on the engine, get better mileage on trips, keep the cabin quieter during commutes, and it might even let me get to a higher top speed since at 160mph it hits redline.

thanks!

--luke
 

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I'm glad someone posted this as I thought I was just the only one that felt it needed a taller gear (taller/shorter I always get confused). When doing city driving I always feel I'm in 5th and often looking for a 7th gear at highway/freeway speeds. I also go from 4th to 6th often. The car could still uses fourth/fifth for overtaking then have 6th as the cruising gear, dropping the revs right down. In countries where fuel is much more expensive this would be welcomed.

I don't know how this would effect the track guys, maybe they are rolling their eyes. But as a road car DD I would like 6th to be taller. The car could handle it easily (mines a SC standard)

It would be interesting to hear what is involved labour excetera and parts if doable.
 

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MWR gear set 3.9

I did the 3.9 set from MWR and love it! I have the tvs from VF! As far as work it required a complete tear down, luckily dad did all the work so not sure about cost.
Clearly lower rpm at highway speeds, I do not really pay much attention to gas mileage!
 

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It's nice to have so many gearing options available for the 6-speed.

For a naturally aspirated or lightly boosted car that works well on the street and track with the stock ratios the 0.715 ratio 6th gear swap is really nice. Most customers I talk to never hit 6th gear on the track so there is no performance drawback. RPM on the highway is reduced considerably which reduces fuel consumption as well as cylinder wall and valvetrain wear. Win-win. Installation is simply a matter of removinig the end cover of the transmission and swapping out 6th gear. I've even seen it done without pulling the transmission; remove transmission mounts and lower the transmission enough to gain clearance. You do need a good somewhat specialized gear puller so this probably isn't a job for an inexperienced mechanic working in his driveway.

For those with a bit more power the 4.3 and 3.9 final drives are a good option (stock is 4.5). I especially like them for a high boost engine that just spins the tires in lower gears anyway. You spend a little less time shifting since the gears are all longer. Changing out the final drive gear set is a full transmission teardown. No additional labor to swap in new synchros or an LSD during this job. Trans definitely removed from car.

The combination of Kaaz close ratio 1st-6th with the 3.9 final drive is a really popular setup for supercharged track cars since it really keeps the revs in the sweet spot on the track but is still pretty livable on the street.
 

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Do you have a more detailed write up on pulling the end cover to swap 6th gear? This is on my to do when I need to replace the clutch. Frankly, 6th on the highway at 4k rpm is maddening.
 

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Do you have a more detailed write up on pulling the end cover to swap 6th gear? This is on my to do when I need to replace the clutch. Frankly, 6th on the highway at 4k rpm is maddening.
I will get good pics and do a write up on the next one we do (volunteers?) We have not done it in the car before so I'll be interested to see just how easy it would be for an average mechanic. Having a very good gear puller with thin arms is critical.

Very easy job for a trans shop with the trans on the bench, would only take a few minutes.
 

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Thank you. Looking forward to seeing how big of a deal it is and whether it is doable in situ. I have also sorts of gear pullers and have done manual transmission work before.
 

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The fifth is hard to remove, but the sixth is not too bad. But it is probable that you will break edges of few teeth by removing it. A good puller is welcome. For the synchro side, you need another type of puller with a fork with 3 bolts and rod plus hammer weight.

But if you don't have mechanics experience, it will be not an easy job, the worst is to remove the transmission from the car.

In the past, I really liked the taller sixth with the stock box. In fact, I was also running a custom made shorter fifth... The set-up was nice. Now, my car is mostly used on track, and I am running a Kaaz box with a custom sixth (1to1 ratio) with a 4.3 diff. Not very nice on street since the engine is turning fast on highway, but for track, it is very cool.
 

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Discussion Starter #9
Wow thanks for all the great info guys!! :bow:

It's great to find out that the 6th gear can be swapped without completely removing the transmission. I don't have a specialized gear puller so I'm going to ask around and see if I can find a shop that can do it.
 

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Agree with Matt. I've done this on our street car and it is pretty quick. 2mpg better highway mileage also.
 

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Just did it myself in my garage, posted a write up in the transmission or elise forums here on the site. It was REALLY easy and I LOVE how low the RPMS rest while cruising at 60mph.

Also have a VF2 kit, and this gearing is GLORIOUS with the added power.
 

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So what are the new revs at 60 mph?
At 70 i am at about 2.5k, and at 60 almost at about 2k, if i recall correctly. I have not been able to drive the car in about a month. The gear i have is a 10% drop in rpms.
 

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Just did it myself in my garage, posted a write up in the transmission or elise forums here on the site. It was REALLY easy and I LOVE how low the RPMS rest while cruising at 60mph.

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I couldn't find your write-up. Could you post the link here?
 

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I couldn't find it either. I'm looking at throwing in that gearset as well. I've done it on a few cars and normally it's pretty easy without pulling the trans.
 

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Just did it myself in my garage, posted a write up in the transmission or elise forums here on the site. It was REALLY easy and I LOVE how low the RPMS rest while cruising at 60mph. ...
I found your write-up on changing the transmission at TOF, but you never wrote up the 6th gear change. If you have the time, many of us would appreciate a good write-up of the gear change.
 

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Gear set coming in. I asked the vendor for directions and they emailed back: "please refer to your service manual for gear installation." :mad:
I had to ship to my folks in Maine too cause UPS shipping was going to be $68 vs $20 to my folks and vendor refused to go with USPS. (Hardly ever run into this with mom & pop type places!)
My Mom will put it in a flat rate box for ~$12 and send my way, probably along with some cookies or something else delicious :coolnana:
 

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You guys really want this? The car doesn't have a lot of power and it seems like with a taller 6th gear by the time you reach 100 mph you'll have to have your foot on the floor just to maintain speed. I would do it if I had forced induction only.
 

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ill subscribe to this as well... more specifically the C6x 6th gear set from MWR

something i would certainly be interested in down the road
 
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