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Discussion Starter · #1 ·
Maybe b/c our cars are AWD - this is an impossible mod...I don't know.

I have read several threads on 350Z forums, S2000 forums, Vette forums, where these guys swap out their final drive gear and go to a higher gear ration - and get really nice gains in acceleration.

can we do this on our cars?
 

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Re: Final Drive Gears - Change??? (23109VC)

It's not impossible, but it might as well be. You'd need to change out both front and rear differentials, and probably rejigger a bunch of electronics settings.

The easiest way to change your effective final drive ratio is to alter the wheel/tire diameter. I considered that in my V50 but concluded there is not enough vertical clearance from the spring seat on the strut to the top of the front tires to make a significant difference.

My V50 has a 4.00:1 ratio and I toyed with the idea of achieving 3.77:1 as on the R. Interestingly, a 235/50-18 tire would exactly reproduce the existing sidewall of my stock 205/55-16's, and bring the final drive to exactly 3.77:1. Oh, well, in addition to hitting the strut they'd probably rub, too.

Tom.
 

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Re: Final Drive Gears - Change??? (JimLill)

Maybe - I doubt the front diff is interchangeable though, being embedded in the trans and all. The rear is probably a straight swap.

In the 04 and 05, the GT final drive is 2.65:1, in the 06 it's 3.33:1. MT final drive is always 3.77:1. That's quite a jump!

Tom.
 

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Re: (23109VC)

Quote, originally posted by 23109VC »
why couldn't we change the rear ratio in a MT car to 4.00:1 or 4.11:1 or some other higher ratio to get even more acceleration???

if you could find those gears............
 

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Discussion Starter · #7 ·
Re: (JimLill)

so IF someone made gears in that size - we could put them into the rear differential of the R??

Jim - are you saying that no one makes them? if someone did make them, would they work?
 

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Re: (23109VC)

You want a shorter ratio? Hey I'll swap you the 4.00 gears from my V50! (same trans
)

Smaller tires would be the way for you to go, I think. You'd need to drop about 6% total circumference, which might be possible on 17's with some radical 35's or 40's...

Don't jump to the conclusion you'll get more acceleration though. You might be rewarded with wheelspin.

Tom.
 

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Re: (23109VC)

The only gears that are likely to have a chance of working are stuff from Volvo. That selection is pretty limited and even then I have no way of knowing if it would work.
 

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Discussion Starter · #10 ·
Re: (JimLill)

excuse my ignorance...

if the stock R gears are 3.77:1.....

which way do I go to make the car accelerate faster.

do I go toward 3.50:1 or go toward 4.00:1 ???

whichever way i would want to do - did Volvo ever make diff's with those reatios...that would fit an R?
 

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Re: (JimLill)

Or don't want!
Personally I think the R will light up its tires with that much mechanical advantage on the wheels. OTOH, my V50 doesn't do it... has less torque than R though.

I poked around a little and I'm wondering if the rear differential might not need changing. It all depends on whether the angle gear gets final drive output, or gear output (i.e. takeoff ahead of or after front differential).

If it's after the final drive, then only the front differential gearset needs changing. Not that it's a huge help, because the AWD final drive physical configuration is different internally from FWD. But, I can say that most manual AWD Volvo's are 4.00:1, and most FWD are 3.77:1. In other words, the R is "special" in that it has the taller 3.77:1 ratio, with AWD. I think this is because of the extra power.

All this might lend options to parts swapping, since there exist both AWD and FWD cars with otherwise similar drivetrains. But, even if it can be done, there's the matter of programming the rest of the car to match. The speedo/odo would change of course, but the brake (traction) and chassis modules need to know the ratio as well. It won't be easy.

Tom.
 

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Re: (Johann)

Quote, originally posted by Johann »
T5's have been 4.00:1

Various cars have... even the 2006 V70 2.4. The question would be will the front fit a M66 equipped car and is there a matching rear set from an AWD model.
 

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Re: (JimLill)

Never looked in to it.. And also a lot of work.
I'm pretty happy with the gears as they are except for 3rd, should have been a tad longer.
With my S70 I can reach 112 in 3rd which can be convenient from time to time.
 

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Re: (JimLill)

Quote, originally posted by JimLill »
the prop shaft runs at the trasnmission output speed... so you need 2 gearsets

That's what I thought until I noticed the (rear) final drive is the same part # between MT and GT. Not conclusive, of course.

Johann - my V50 AWD has the M66 and a 4.00:1 gearset, verified with wheel speeds. So it exists.

Tom.
 

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Discussion Starter · #19 ·
if someone WERE to put 4.00:1 gears into the S60R would there be a noticeable improvement in acceleration or not?

what would it cost to get these gears and put them in?

or would there be all kinds of problems with the ECU or AWD system seeing different data than it is expecting cuaseing a ton of problems?

i read a review where a guy put gears into his 350Z and he spent about $1500. he said the improvement in acceleration was BETTER than any other mod he did - and the general consensus was on the Z cars, aside from forced induction - the gears were one of the best bang for the buck mods.

seems like worth looking into if it could be done on our cars at a reasonable cost.
 
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