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Revs is painfully high at 100kmh

Posted: Tue Jun 20, 2006 11:28 am
by alpineraven
G'day all,
Recenly changed from Single Range to Dual Range box, changed final drive ratios, the Dual Range box is good, but I don't like the high revs for highway sits around 3100rpm at 100kmh (its just under 3500rpm at 110kmh).

Now, I was wondering if I could modify the gearbox to drop down the revs of 5th Gear (1st to 4th is fine, I am happy with that, but 5th is the problem.)

Is it possible I could take out an lower ratio gear set from another Subaru gearbox ie. from 3rd Gen Legacy 2.0 Turbo which has 5th gear ratio of 0.738:1 or RS Legacy has 0.780:1 5th gearing and put it in my gearbox?


What other options do I have to drop the revs? (I do want the Dual Range box)
Cheers
AP

NB - Engine is EJ22 NA, 5MT Dual Range Transmission 3.9 front & rear diffs.

Posted: Tue Jun 20, 2006 4:47 pm
by Brat4by4
Larger diameter tires. Your speedo will be off, though.

Posted: Wed Jun 21, 2006 12:01 am
by alpineraven
I am not going to add larger tyres as its 17" already. I want to modfy the gearbox if possible?
Cheers
AP

Posted: Wed Jun 21, 2006 2:47 am
by Manarius
My 4.11 runs 2100 @ 100km/h(60MPH). There's something wrong with your tranny if your final ratio is 3.9 and it's way higher than mine.

Posted: Fri Jun 30, 2006 1:43 am
by thefultonhow
Manarius, if I'm not mistaken the 4EAT fourth gear is overdriven more than the 5MT fifth gear. So your revs will be lower.

Posted: Fri Jun 30, 2006 2:47 am
by Manarius
thefultonhow wrote:Manarius, if I'm not mistaken the 4EAT fourth gear is overdriven more than the 5MT fifth gear. So your revs will be lower.
I don't think that matters because my final drive ratio is still higher than 3.9

Posted: Fri Jun 30, 2006 11:38 pm
by BAC5.2
3100RPM at 100kmh sounds about right for something with ratios close to the RA gear ratios.

The RA ratio'd cars spin 3800RPM at 75mph or something stupid like that. 5th gear is like .957 or something like that.

I know with pre-99 trannies and with post-99 trannies, you can swap gears around to some extent, but I'm not sure about between dual-range and non-dual-range.

Posted: Sat Jul 01, 2006 12:03 am
by Manarius
Phil, 100kmh is 60 MPH. So, you're saying that he can go another 15 mph in only 700 RPM?

Posted: Sat Jul 01, 2006 2:30 am
by BAC5.2
No, that's why I said "close" to the RA gear ratios.