fastboyslim

iTrader: (2)

Hey guys just a quick question. Making a JDM more highway friendly with a longer ratio, could i just replace some gearbox internals or is a UK gearbox the only way to go?

L.J.F

iTrader: (31)

i dont there is much difference between the 2 tbh. What is wrong with your current box on motorway journeys?

fastboyslim

iTrader: (2)

Oh really, No problem yet but with the JDM running a close ratio box you get stuck on the highway in 6th gear doing 70mph at 3500rpm. I am hoping a UK gearbox has longer ratios and therefor a lower rpm at the same speed.

Am i far off the mark here?

TurboAndy

iTrader: (1)

A UK box has a different ratio to a JDM, so yes they are different.
I also have a JDM bug sti and wanted to do the same.
To be honest your better off getting a UK box and rear dif other wise the Ratio will be different.

Hope this helps.

fastboyslim

iTrader: (2)

That helps loads mate. Will have to keep an eye open for one, might be a costly thing.

TonyBurns

iTrader: (3)

Only 5th and 6th are different to a UK box, you can get different cogs and the JDM boxes are better than a UK one (use different parts ) so it may be cheaper just changing 5th and 6th, though unless your having serious problems (and as ive said before, its ratio'd about 170mph) I wouldnt change it at all.

Tony

TimH

iTrader: (11)

If the spreadsheet I did a few months ago is correct, then swapping 5th and 6th in a JDM box (with 3.9/1.0 JDM final drive) with those from a UK car will mean:

3000rpm
JDM 5th=54 6th=69
UK_ 5th=60 6th=77

3500rpm
JDM 5th=64 6th=80
UK_ 5th=70 6th=89

Top speed (8000 rpm!) is 205 rather than 184.

All based on 235/45x17" tyres, E&OE

fastboyslim

iTrader: (2)

Wow! Thanks for the help, cleared up loads you guys.