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Rb20det To Rb25det Manual Gearbox Ratio Differences

fubar
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fubar Enthusiast

fubar

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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

The Dan Grand Master

The Dan

Posted
Posted

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 Enthusiast

fubar

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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

Rekin Grand Master

Rekin

Posted
Posted
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

bubba Grand Master

bubba

Posted
Posted (edited)
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 by bubba

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