Sawbladz;1537507 said:
I'm fairly certain you also need a diff with a much lower ratio to make the 6 speed work properly. Something like a 3.27.
Absalutely the #1 reason why I laugh at all these "ZOMG V160 in mah MkIII yoz!" posts.
If you do some research about the gear ratios in the V160/V161, you'll see that they are only suitable for a really low ratio diff, in the land of 3.2X, as Sawbladz mentioned. Any higher... like say, 3.73, like what is the lowest ratio, commonly available MkIII diff, and you'll swim gears more than you drive. Ontop of that, your top speed will be significantly lower and your highway milage will suffer. Furthermore, you may as well skip 3rd in the V160 because the ratios between 2nd, 3rd, and 4th are so close anyway... effectively making it a 5 speed.
Jawsgear made a 3.50 (I think) diff for the MkIII ages ago but as far as I know they aren't available anymore... unless you've REALLY got money.
If you want a 6 speed, a T56 is a MUCH better idea. It's geared very similair to an R154, but with an extra gear after 5th, making the T56 "double overdrive". It's ideal for a 7M which can lug around at 1200rpm without issues. The T56 wieghs about 130lbs and has a few weak spots... if you wanted to do it, get a trans out of a Viper or get a rebuilt unit from one of the many trans shops that rebuilds them.
I don't know what you'd do for a clutch and flywheel on a T56, but you'd be just as SOL with a V16X trans anyway, but atleast you'll have more money to spend making custom stuff because the trans isn't 5 grand. A rebuilt T56 is ~2500-3500 depending on the specs, and a used one is probably a grand. Also, there's adaptor plates kicking around for 7M to GM bellhousings, I'm sure success could be found adapting the two. For a 1JZ series motor with a T56, a 4.10 gear set would probably be a neccessity. The T56 also has a funky clutch arrangement, so you'd have to do some research and figure out how to adapt an existing clutch and flywheel onto a 7M, I'd imagine... probably cheaper than making a 7M flywheel and clutch work on a T56.
Just my 2 cents.
Edit: To actually put a T56 in a MkIII would be easy: custom driveshaft, BFH [Big F*cking Hammer] to pound the sh** out of the trans tunnel, a custom bent shifter, custom transmount, and all the adaptors and stuff mentioned previously. Piece of cake really...
The only reason I'd do it is to go over 200MPH and still get good gas milage. But those two concepts next to each other is rediculous anyway.