Changing final drive ratio in a transaxle box...

**mullett** · 12-03-2006, 02:35 PM

Given as I do that I have little knowledge of transaxles, how possible is it to change the final drive ratio. I bring this up because, as discussed in another thread, I'm looking at doing a big NA motor conversion to my AW11. The camry motor looks like a winner, but I'm going to have gearbox issues, mainly because the camry motor peaks at 6250rpm, and that will equate to about 190-200km/h top speed with the E153 box AFAIK. That's a problem in itself, but it's also going to make the thing a pain to drive with really close ratios and 3400rpm at 110 cruising. So...any ideas? I guess an aftermarket gearset would also do the trick...

RM.

**love ke70** · 12-03-2006, 04:18 PM

a larger rolling diameter on your tyres will give you a higher top speed. smaller rolling diameter = lower top speed. you will have to get your speedo recalibrated tho.
different gearbox or different gears will do this but is more fiddly/costly

**Bahnugget** · 12-03-2006, 06:42 PM

i'm sorry love ke70, but making your rolling diameter bigger to compensate for closer gear ratios is just completely stupid. Not only because its a cheap temporary way out, but because bigger sidewalls suck, and because they may not necessarily fit under the mr2's guards.

if im not mistaken, you can get aftermarket LSD centres in differnt ratio's for AW11s?? that may be one way, or as you say yeah, get a differnt gearset or regular final drive...

**love ke70** · 12-03-2006, 06:52 PM

twas merely an idea

and larger rims with a larger profile means the same sidewall size but a larger rolling diameter. i wasnt suggesting just wacking bigger tyres onto the same size rim.

anywho...

**wiso** · 12-03-2006, 07:21 PM

personally i don't think the current ratios will be too bad, sure hiway maybe a little high, but having it all closer will give much quicker acceleration. now that will be cool.

plus when do you plan on going to 200km/hr?

**Joshstix** · 12-03-2006, 10:37 PM

The ST165/185 has a 3.9:1 ratio rather than the 4.3:1 out of the MR2 turbo. This can be swapped between different E series boxes.

However I tend to agree with Wiso, the lower ratios are going to make an NA car more fun to drive.

**mullett** · 13-03-2006, 12:00 AM

The ratios are just too low...I don't mind them being close, but also remember that this is going to be a 3.0 or 3.5ltr torque monster pushing a light car, and I find the ratios too low as it is, especially 1st and 2nd, and that's with a motor that revs to 7500. As it is I can only get 50 out of first, so that'll go down to 40...Interesting about the LSD centres, are these available for the Mk2 turbo box (the one I'll have to use)? Also, is it just the drive gears on the LSD which are changed, along with the gear from the output shaft? I'm imagining the output shaft running parallel to the diff, with a gear on each. Is this way off? On the bright side, I have gear-cutting facilities...

RM.

**wiso** · 13-03-2006, 10:00 AM

if what Josh says about the final drive is true (and it would be) i would say this would be your best bet. i think they max out about 230/240km on the gt4. you can pick up gt4 gearboxes pretty cheap as people who buy half cuts and can't use them want to get rid on them, and not many people want them, i got one for $200

but that means you'd have to do what josh hates an pull apart the gearbox to swap them

but it seems you can't get around that fact, even with the lsd option

**Nim** · 13-03-2006, 10:17 AM

Modify the Camry engine to rev to 8000rpm. That'll fix you up for top speed anyway.

You're right though, cruising 3400rpm on a car like that would be a pain, and probably loud. The DC2 cruises at about 3200rpm and I find that uncomfortable. And that's not a big torquey monster sitting at 1/2 it's redline!

**Joshstix** · 13-03-2006, 12:23 PM

Originally Posted by KBlake from MR2OC

The ST165 also has the 3.93 setup, and requires 3 parts to be swapped. New cost on all 3 was ~$450.

The Toyota part numbers are:

3.933 Shaft, Output 33321-20120
3.933 Gear, Ring 41221-12240
3.933 Gear, Oil Pump 33407-12011

Note that price is US dollars and the labour to do the swap if you can't do it yourself will be substantial. You might as well have the box rebuilt with new synchro's etc while having the ratio changed.

**mullett** · 13-03-2006, 03:24 PM

yeah, I'm game to tackle the rebuild myself, the synchros won't be too expensive for the hassle it will save me later. I'd rather rebuild the box anyway, as a manual transmition is one of the nicest things about driving, and it's a pain when bad synchros ruin the experience. Does anyone know what the ratios are in the turbo box? Just working out roadspeed versus RPM. Also, food for thought, I can cut gears, so might be able to make my own ratios...

RM.