Diff/gear Ratios And Rb30det .

[discopotato03]

Many people seem to have issues with diff and gearbox ratios with RB30DET's in light R32 GTST's .

My personal hate with Nissan production gearbox ratios is the big 1-2 gap , they must have figured the RB20/25 DET's had little torque off idle and used a short 1st to get the ball rolling . I have never been in a VLT so I'm curious to know what they felt like given a little stick off the line but nothing too harsh . When I crunched the numbers the ratio difference (VLT) is shorter 1-2 but a little wider 3-4-5 than the typical RB20 and RB25 turbo boxes . Most manual production boxes cop the worst hiding when snaching 2nd as the speed is low , flywheel affect retards engine deceleration and if the wheels were spinning they virtually stop when you leap on the clutch . All these things gang up on the 2nd coupling sleeve and baulk ring and they wont stand up to it for long .

I'm wondering what people think of emulating the VLT's ratios ie its box with a similar maybe slightly shorter ratio diff to make up for the larger diametre wheels on a typical Skyline ie 16s . The reason why I asked about VLT's is that the overall ratios soon get reasonably tall you when get to the 3-4-5 end of the box .

Most say that RB30's are pretty torquey but would they pull these ratios easily in a road driven R32 at 1250-1300 Kg . I have zero interest in race / drag / drift or spinning the wheels to impress the schoolies so there wont be any gorilla gearchanges at the redline for me . The last thing I want is a torquey engine and short ratios so what do you all think ?

Only mechanical problems I can think of is speedo drive gears in the 3.5 to 3.6 range and what ratios exist ie whats the next step down from the S15's short nose 3.59 R200 ?

Cheers A .

Edit : Actually the OD looks pretty tall , whats a VLT like on the expressway in 5th ?

By my calcs 3.7-3.8 diff ratio looks like reasonable compromise , any lower and 1st looks too short . Smaller Nissan boxes had variations in OD gear pairs and also the input and front lay gear pair . Is the situation the same with these larger 25T/VLT boxes ?

Cheers A .

Edited January 22, 2006 by discopotato03

[Bl4cK32]

From memory Sky30 ran a vl box with his rb30 in the r32 with the 4.3 std diff. It wasn't too much different from the std rb20det box ratios. Unsure if the vlt and the vl are similar though, but they run the 3.4 diff....

I'll be running the 3.9 centre with the r33 box in mine. It would be good if you could swap out just 1st gear for a taller one. Im pulling my gb out in the future, so it may be something to look at while its out....

[Guilt-Toy]

I posted something similar to this the other day...

We decided that changing the dif to 37 or 39's are the go. I have a RB30DET with a 4:39:1 diff ratio.. Sure its great for smashing commodores on the street but it doesnt do my economy any favours