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Gearbox - worth doing?

Posted: Mon Jul 16, 2007 9:07 pm
by AlpineRaven
Please tell me if I am wasting my time!

My plan is to work on gearbox to make it better to match my requirements.

I have EJ22 Dual Range box with 3.7:1 diff.
All internals will remain same except:
--> Dual Range - upgrade from 1.19:1 to 1.59:1 (by getting gearset from L series)
--> 5th gear upgrade from 0.871 down to 0.780 from RS Liberty or gen 3 2.0 turbo gearbox. Why? My aim is to drop the revs on highway as 80% of the time for work-home commuting is on highway.

Currently my revs at 5th gear with 15" mags 195/65 tyres is approx 2950rpm @ 100kmh. With 0.780 5th gear my revs could be around approx 2500-2600 rpm.

Cheers & thanks for your inputs.
AP

Posted: Mon Jul 16, 2007 10:31 pm
by Gannon
Sounds like a good idea


Ive been thinking along similar lines, but by putting lib gears in a l series box and mixing ratios

Posted: Mon Jul 16, 2007 10:50 pm
by Suby Wan Kenobi
You may be wasting your time with the top gear increase in overdrive as you will spend more time changing down at the first sight of a hill. If you get the engine out of the sweet spot they become very doughy

Posted: Wed Jul 18, 2007 2:01 pm
by El_Freddo
Suparoo wrote:Ive been thinking along similar lines, but by putting lib gears in a l series box and mixing ratios
Hehehe... reminds me of my changing diff ratio ideas to run bigger tyres and retain the same speed reading/engine performance...

I didn't know you could just swap out second or third etc for another second or third etc ratio from another gearbox without taking all the gears from the other box...

Does that make any sense?

Cheers

Posted: Thu Jul 19, 2007 7:03 am
by brumbyrunner
If you could borrow some larger tyres you could feel the effects without pulling your gearbox.

195/65R15 tyres are 24.9" tall.
195/70R15 are 25.75" for a 3.4% height increase.
This will drop your revs to 2850@100kph.
195/75R15 are 26.5" for a 6.4% increase so will give 2770rpm@100kph.

...and so on...