Gearbox/tranny change from 5 to 6 gears?

Kimu · Feb 25, 2012

Hi,

I have S60 from 2007, 2.5T, 210HP, 5 speed manual, and I travel with it a lot on highways and long distance runs. The thing is it only has 5 gears and it uses much more gas then I think it could with 6 gears and more of an overdrive.

This is the torque curve (quite a bit more then the factory 320Nm, I dunno why, haven't done anything with it except lpg installation but that is not the reason):

http://imageupload.org/en/file/188136/img-0544.jpg.html

For example if I'm driving 140km/h the rpm is about 3000 or so, and for that rpm the engine produces 350Nm of torque which is way more then enough to support easy cruise speed. So in theory if I could get a 6 speed gearbox the speed would reduce to 2500 rpm (or I wish even less, 2000....), and at that rpm there is even more torque and again enough power for steady cruising at that speed. Also less of a fuel consumption which is my goal. Of course acceleration would be terrible but that is what I have 3rd and 4th gear for. I have been using it for 5 years now and the car just "loves" low rpm, with normal mainstream driving I don't even need anything above 2000-2300rpm and without choking the engine.

The final question is, is that possible, could it work and how much would that sport cost?

tobythesandwich · Feb 25, 2012

2007? If it's a manual it should already be a six-speed. So I'm going to assume it's an automatic.

And to put a 6-speed auto in a 5-speed equipped car is ungodly expensive.

Kimu · Feb 25, 2012

No, it's manual, forgot to mention. T5-s and R versions were offered with 6 gears, but this one not.

tobythesandwich · Feb 25, 2012

That's easier. I can't speak for sure on the difference. I know the transmissions can run a good bit. But i don't know for sure.

NJGreenBudd · Feb 25, 2012

6Spd swap as a cost saving measure? that's new to me. It can be done, physically everything will bolt together but you're gonna spend a lot of cash on something that ultimately won't net you much of an improvement. The difference between 5 and 6spd is about 4mph/1000rpm in the middle, the top gear is almost the same anyways, just shorter, tighter gears till you get there.

If you want to improve mileage you can address it through more conventional means like maintenance and driving habits.

Good thread on S60 5 to 6spd swaps, this particular discussion involves diesel models but the principals remain the same: http://www.volvoforums.org.uk/showthread.php?t=122963

Kimu · Feb 25, 2012

Thx, I read the link.

Besides the fuel saving thing, the gears are way too long for a car that has low end torque, if pushed to the limit its approx: 1st 60km/h, second 120, third 170, fourth 225... And it does effect performance in short burst overtaking, I rarely or never run out of rpm range.

But that's just the perk besides, not the main thing. And for the 6th gear, if it's the same ratio or almost the same as my 5th gear then it's pointless. And that's what I'm wondering and asking if someone knows.

Kimu · Feb 25, 2012

As I can tell both the T and R versions of s60 with 6 gears have the final gear ratio of 0.7, the exactly same as mine, even the final drive ratio is the same with R so putting M66 is pretty much pointless. My car tops out at 5000rpm and the more powerful T and R versions can push it to 5500-6000rpm...and from my understanding that's pretty much it.

D5 has 0,54 as final ration but final drive is higher so that would be too much for the engine.

Gearbox/tranny change from 5 to 6 gears?

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