Taller Diff Ratio For Gtr

[Scooby]

Anyone know where I can get some taller diff ratios for a GTR

Cheers

[SteveL]

Anyone know where I can get some taller diff ratios for a GTR

S15 manual uses 3.7 CWP from memory and is same R200 (more-or-less), so should fit, but I haven't tried this one. But what do you do with the front diff ??....might be some aftermarket CWP's for the front diff, but probably not common and whether you could get the same ratio is another matter. Of course you could just always run in RWD, but the taller ratio will kill acceleration.

[ookami]

What model gtr?

[T04GTR]

use auto stagea.

4.08:1 or 34 gtr 3.5:1

[Scooby]

Thanks for the responses:

ookami; it's an R32 GTR.

SteveL; yes the front diff is a problem. using RB26/30 with a 7250 redline so would like to try using extra torque and taller ratios to give it longer legs. In 2wd I couldnt afford the tyres

TO4GTR; the 34 GTR ratios look good. It's got to be a signficant difference otherwise it's not worth the effort so the Stagea is probably out. Now to find some 34 GTR centres....

Cheers

[T04GTR]

Thanks for the responses:

ookami; it's an R32 GTR.

SteveL; yes the front diff is a problem. using RB26/30 with a 7250 redline so would like to try using extra torque and taller ratios to give it longer legs. In 2wd I couldnt afford the tyres

TO4GTR; the 34 GTR ratios look good. It's got to be a signficant difference otherwise it's not worth the effort so the Stagea is probably out. Now to find some 34 GTR centres....

Cheers

it will be tall as f**k

[sh@un]

from 4.11 down to 3.57 will give around 15% taller gearing.

[ookami]

change to R33 GTR gearing. Not sure why you would ever want taller than the r33 gtr ones as you can go close to (if not over 300km\h

[Scooby]

R33 GTR final drive is taller than R32?

[ookami]

i guess so, can do a lot higher speeds in each gear in my R33 than any R32 I've ever driven.

[Bl4cK32]

there are heaps of choices...3.5, 3.7, 3.9 4.08, 4.11, 4.3 etc..

as long as they are all r200 meh

3.9 is my vote for rb30det ( i know the pain of short gears with the 3lt )

[Gav]

there are heaps of choices...3.5, 3.7, 3.9 4.08, 4.11, 4.3 etc..

as long as they are all r200 meh

3.9 is my vote for rb30det ( i know the pain of short gears with the 3lt )

Yer - but there aren't heaps of choices for the F160 front diff

[Scooby]

The F160 is the problem...hence why the R34 GTR option looks good.

[Gav]

As a long shot, how about the Cima S-Four? This was a VH41 sedan equipped with ATTESSA.

You'll probably find a stack of these diff centres stocked at your nearest Hen's Teeth supplier, however lol

[kiwi32]

R32 gts25 use a 3.5 ratio this works really well with my rb30

I am doing 3000rpm at 100ks in 4th and 2600 at 100ks in 5th. This is in an r32 gtst and with a 7500rpm redline 300ks is almost possible, in theory anyway.

[Snowman]

I've gone the other way (put a 4.11 diff into my R34 GTR) and I can tell you it has made a massive difference. For my applications it's been awesome but I'd hate to imagine going back the other way. Still if thats what you are chasing it sure is an option.

[Scooby]

Hi Snowman, I thought that putting a 4.11 into an R34 would make it really short as from memory the box ratios are shorter in the R34, just more of them. If the intended application you're referring to is track work, that makes sense. Looked into an R34 box with standard diffs once and decided against it as there wasn't much gain in legs overall compared to the standard R32 set up.

[Scooby]

still wanting to run either 3.7 or 3.5 ratios, rarity of 3.7 looks like it will have to be 3.5 which means 34 GTR.

i think the 34 and 32 housings are the same but not sure if the internals are the same, and i'm under the impresson that that all 34s have active diffs.

does anyone know if the crown and pinion from a 34 will bolt into an R32 GTR and work, particularly if my assumption about the 34 diffs all being active is correct?

[Sydneykid]

still wanting to run either 3.7 or 3.5 ratios, rarity of 3.7 looks like it will have to be 3.5 which means 34 GTR.

i think the 34 and 32 housings are the same but not sure if the internals are the same, and i'm under the impresson that that all 34s have active diffs.

does anyone know if the crown and pinion from a 34 will bolt into an R32 GTR and work, particularly if my assumption about the 34 diffs all being active is correct?

I assume that you have actually done the numbers on this? Worked out the max speed in each gear and the top speed?

With 245/45/17 tyres and a 4.1 diff ratio you are currently looking at the following ~KPH in each gear at 7,500 rpm

1st = 66 kph

2nd = 115 kph

3rd = 168 kph

4th = 220 kph

5th = 289 kph

Do you really need a top speed more than 289 kph?

For cruising, 2,850 rpm = 110 kph (speed limit) in 5th gear. That's off boost for any turbo sized to allow max power at 7,000 rpm. So economy is good, but overtaking power is only a short squeeze on the throttle away, no down change required.

Keep in mind that R32GTST's have a 4.3 to 1 diff ratio and weigh 200 kgs less than your GTR. Similary comparing your GTR to a R33GTST with RB30 may lead to the wrong conclusion. So don't ignore the weight factor when you are working out optimal gearing or the extra transmission losses from the 4wd.

How often did you drive around 5th gear with the 2.6 litre? Not often (other than highway driving) I bet. With the 3 litre you just use a higher gear than you would with the 2.6 litre.

My suggestion, as it has been with 20 or so others that have had RB30DET's, drive it around first, then decide. So far not one of those guys has changed the diff ratio.

cheers

[Scooby]

Hi Gary:

it's not the top speed I'm wanting, it's the legs in lower gears. i know someone with a GTR and 26/30 and he suggests that it feels very short in the gears, from memory Cubes has remarked on the same thing.

i would like to take the drive it first then decide approach, i understood that getting the front diff out with the engine in place was almost impossible.