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-   -   MTX75 Final Drive Upgrades (http://www.focusfanatics.com/forum/showthread.php?t=312489)

RedComet 03-23-2013 03:56 AM

MTX75 Final Drive Upgrades
 
I've seen that with the prior Focus, people had considered or done the final drive swap for something better than the 3.82:1 final drive for >/= 4.06:1 ('European' MTX75 spec). The SVT/ST170 and RS had an even more aggressive final drive; would any of these be good candidates to swap into a Mk.III to achieve better acceleration?

JeremiahD 03-25-2013 06:03 PM

I would also be very interested in this.
The gearing on the 5-spd is pretty tall.

in my last car (1990 BMW 535i) I swapped to a shorter read diff and it was WAY more fun. You do loose some mpg's but this car has them to spare... would also be nice if it was some sort of LSD....

suss6052 03-25-2013 06:49 PM

I found the gearing on the MTX-75 to be too short personally, but I can't see why if its the same gearbox that the final drive from another MTX-75 equipped Focus would work if it wouldn't interfere with the axles that is.

FocusBoy58 03-26-2013 11:30 AM

Should work but to be honest I find that the gearing is already to short. 3000+ rpm on the highway kills gas mileage as a 4.06 and youll go up another 800-1000.

A LSD would also be nice but without supporting power mods I dont see the point in it yet.

The 4.06 would make it slightly quicker at the cost of a decent amount of highway mpg.

RedComet 03-27-2013 06:43 AM

Quote:

Originally Posted by suss6052 (Post 4653435)
I found the gearing on the MTX-75 to be too short personally, but I can't see why if its the same gearbox that the final drive from another MTX-75 equipped Focus would work if it wouldn't interfere with the axles that is.

Yeah, that's really what I'm wondering. Replacing stuff like pinion gears etc is okay, but a complete axle refit is pricey. Considering I've got the idea in my head that down the line, I want to put in an Exedy clutch in this car, and maybe a 1.5-way LSD, if I'm going to crack it open to do that, a final drive swap might not be a bad idea...

Quote:

Originally Posted by FocusBoy58 (Post 4654395)
Should work but to be honest I find that the gearing is already to short. 3000+ rpm on the highway kills gas mileage as a 4.06 and youll go up another 800-1000.

A LSD would also be nice but without supporting power mods I dont see the point in it yet.

The 4.06 would make it slightly quicker at the cost of a decent amount of highway mpg.

I'm not terribly worried about highway MPGs. The car as it stands is outperforming its EPA targets even with an intake and exhaust on the car. Dunno if that'll stick when a 4-1 header goes on, and when, eventually, tuning and more parts become available. As for the LSD, I think that it'd at least be better than relying solely on that brake-eating e-diff... [poke]

Yeah, I'm aware that if this were done, I'd have a real crackpot III on my hands.

sleepyboy 03-27-2013 07:15 AM

The change from a 3.82 to the 4.06 would only gain 200-300 rpm more not 800-1000.

I_go_for_Gs 04-20-2013 10:00 PM

That sounds right. My last car had a 4.29 final drive and it is exactly 500rpm more at 65mph in 5th gear. This is the main reason why I traded it in for a 2013 5 Speed Hatch. 3 years of 3500rpm on the highway got real tiring and the mileage, I know of V6 Impalas that did better than my old ride at 75mph.


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