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6 speed gearbox
Posted: Fri Oct 19, 2012 12:19 am
by Connor_1994
so i want/need another gear,
how would i go putting a 6 speed 6a13 gearbox on my gpx?
or is there a way to rebulid my gearbox and add another gear?
Sent from my GT-I9100 using Tapatalk 2
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 12:44 am
by adzski
with money, you can do anything your heart desires!
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 3:17 am
by spetz
Don't think the 6A13 came with a 6 speed.
Also what do you feel you need a 6th gear for? To drop the revs on the highway?
This is pointless. You should want a 6th so that you can get the rest of the gears closer together
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 8:33 am
by fraz91
Agree with spetz. The only use for a 6th gear is to get the rest of the gears closer together, which is only really useful on the track so you can stay in the power-band of the engine. Dropping revs on the freeway will only be done by installing a new overdrive gear that's taller gear, or installing new diff gears.
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 3:18 pm
by Kustom
fraz91 wrote:Agree with spetz. The only use for a 6th gear is to get the rest of the gears closer together, which is only really useful on the track so you can stay in the power-band of the engine. Dropping revs on the freeway will only be done by installing a new overdrive gear that's taller gear, or installing new diff gears.
^this.
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 3:29 pm
by Astron_Boy
2nd gen GTO/3000GT had 6 spd, but strapped to the 6g72/4.
Bell housing difference means no dice.
That... And what has been said above.
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 3:34 pm
by Connor_1994
damn,
the reasons i want an extra gear is to
1. gain speed quicker
2. reduce reving on highway driving
3. once i chip it and bypass the ECU limiter be able to reach a higher speed,
i dunno honesrly just throwing ideas and seeing whats out there, haha
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Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 4:16 pm
by Taz
Just get a different final gear, higher speed, less highway revs - you wont get any quicker through the gears, but you wont gain too much through them anyway with another box. If your hell bent on it, just get a different final gear.
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 4:46 pm
by Sahin
Taz wrote:Just get a different final gear, higher speed, less highway revs - you wont get any quicker through the gears, but you wont gain too much through them anyway with another box. If your hell bent on it, just get a different final gear.
Yeah coz that's so easy lol
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 4:52 pm
by Taz
easier than trying to mate another box with the 6a12 correctly.
Im sure there is a straight fit final drive from another box out there.
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 6:22 pm
by fraz91
Taz wrote:easier than trying to mate another box with the 6a12 correctly.
Im sure there is a straight fit final drive from another box out there.
Evo springs to mind, although may be a little difficult given the gearbox setup (AWD).
And isn't bennoz running an LSD for an Eclipse in his red rocket?
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 6:51 pm
by Taz
wasnt astron boy or Aj or something running a different final gear as well? i know someone here was, werent they? or am i just making up stories in my head again

Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 7:05 pm
by Astron_Boy
No, we just have a 5spd tip, which is a different final to even the manuals.
HKS runs a standard 4spd.
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 7:10 pm
by Taz
hmm i remember there being a thread or brief discussion on someones fto final revving 1k below normal at 100 - was probably yours yes?
Well im sure with the many many boxes out there that there is one that will fit, maybe even bolt up. surely
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 7:31 pm
by Astron_Boy
Taz wrote:hmm i remember there being a thread or brief discussion on someones fto final revving 1k below normal at 100 - was probably yours yes?
Yeah, that was us.
Can't remember if it was 1K however... will try and find the thread.
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 7:33 pm
by Rob Furniss
Doesn't the GR box have a longer final gear?
Re: 6 speed gearbox
Posted: Fri Oct 19, 2012 7:47 pm
by Astron_Boy
Re: 6 speed gearbox
Posted: Sun Oct 21, 2012 8:49 pm
by spetz
I have a 1.6 MIVEC gearbox which has a 4.625FD.
It also has a longer 1st and 5th gear, so the rpm drop between 1st->2nd isn't as much, and highway rpm is the same as the FTO gearbox.
You could use a gearbox like this + the FTO 4.312FD so you will drop highway rpm but like mentioned there is no point.
If you're worried about fuel savings, consider that you will not even get back the money you spend on changing gearboxes around.
The FTO gears are too long in my opinion. 4th goes well beyond 200km/h which is completely unnecessary in a car like an FTO, no less with the 180km limit.
The "viable" option of going 6 speed is using a Evo 9 gearbox while deleting the transfer case. From my research bolting it onto the 6A12 should not be too difficult, but again the cost of all this is quickly rising (these gearboxes are not cheap + labor + customizing + lets assume to make the most out of it you want a different final drive).
Re: 6 speed gearbox
Posted: Sun Oct 21, 2012 9:10 pm
by fraz91
As spetz has said, it's not worthwhile if you're looking at long-term savings. Lowering the rpm's at 100km/h my give you -0.1L/100km MAX, which is f-all. If you're concerned about fuel usage, leave earlier and cruise at 90. You'll find there's about a 1-1.5L/100km difference between 90 and 100km/h as the difference in wind-resistance is phenomenal.
I've done the diff gears in my truck and, while they're a lot easier to get at than a FWD diff, I wouldn't do it again. The amount of time and hassle that was spent sourcing the gears, finding all the parts necessary to make it work, and then taking my car off the road for 3 days to get it done.
Sure, my speedo is now reading back to factory spec with my larger tyres, and the low-range crawl ability has improved, but overall it hasn't improved the vehicle driveability all that much. Still takes off at the same speed, still cruises at very similar rpm (3.917 ratio = 105km/h @2200rpm, 4.1 ratio = 100km/h @2200rpm) and still tows lawso's cars without breaking a sweat.
Re: 6 speed gearbox
Posted: Sun Oct 21, 2012 9:17 pm
by Taz
Just chuck a bugatti box in there and youll be right. Cruising in 7th gear on the highway at 1500rpm
