Rb20det To Rb25det Manual Gearbox Ratio Differences

[fubar]

Heya peeps

I've got a r32 with a neo motor and a stock rb20 manual box behind it. Only pushing 300rwhp but that is the limit of the rb20 box so i have smashed a few of them:)

I know i have to put a rb25 geabox in but the rb20 ratios are perfect for the way i drive it on the track and apparently it is 20kgs lighter and 1/5 the price!

Can anyone tell me the ratio differences between them? My current box at 100km/h sits at 3000rpm in 5th. I know the diff also has a say in this and from memory its a 4.11 2way.

looking at buying a 1993 r33 series 1 gearbox.

Any help would be appreciated

Cheers

[Bl4cK32]

dunno if this might help:

http://justskylines.com/knowledgebase/widg...calculator.aspx

[The Dan]

300rwhp is not the limit of the RB20 box. It's the limit of an old one that get's changed in silly ways.

I have 2 RB20 boxes I built in cars making over 400hp at the wheels......2 years and still together on one, 18 months on the other.

And you'd be looking at approx 2750-2800rpm in 5th at 100 with the 25 box in place

[fubar]

Cheers for the reply

Lol yeah it does sometime get drivin in silly ways but i try not to. i mainly use it on the track time trials and drifting so it gets a bit hot.

When you say built one, do you mean new gears or just bearings and sycros?

thanks for the web site black32 but i put my settings in and at 100km/h was saying 4000rpm lol i tried all different setting and didn't get close. good website tho

[Bl4cK32]

fwiw when i slapped in my rb25 box it made sfa difference. You most likely wont notice.

Sticking large wheels on or a new diff ratio has more effect on changing the speed from memory

[Rekin]

300rwhp is not the limit of the RB20 box. It's the limit of an old one that get's changed in silly ways.

I have 2 RB20 boxes I built in cars making over 400hp at the wheels......2 years and still together on one, 18 months on the other.

And you'd be looking at approx 2750-2800rpm in 5th at 100 with the 25 box in place

so would you recommend a rb20 gearbox rebuild as a reasonable alternative to a 2nd hand rb25 gearbox?

Can get a rebuilt rb20 gearbox for $1000~ from http://www.japanesegearbox.com.au/rebuilds.html

[Curmi]

^^^good question also want to know this.

[fubar]

Yeah you didn't notice much difference, lol and slapped it in how much fun was it? what did u do for the speedo

[bubba]

Yeah you didn't notice much difference, lol and slapped it in how much fun was it? what did u do for the speedo

I used an unmodified Navara sender for the speedo but I'm running 3.9:1 diff gears, the 17T Navara cog matched up pretty nicely.

I also didn't notice much difference in 5th at 100km/h going from the RB20 to the RB25t box.

Edited June 29, 2010 by bubba