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Discussion Starter #1
Hi Guys,

I'm dirt racing a 2001 ZX3 Zetec with an MTX75. The problem is that I need gear '2.5'... 2nd gear bounces off the limiter 2/3 of the way down the straight and 3rd gear doesn't have the RPM I need coming off the corners. Shifting between the two takes a lot of talent when you've got someone bumping you from behind while someone else is rubbing your door and you can't keep your wheels pointed where you want without two hands on the wheel...

I've been fooling with tire size and it's helping, but there are only two sizes of Hoosier dirt tires we can run and neither of them are good with the MTX75... I'm running winter tires for the right size but they aren't as fast as the Hoosiers.

Does anyone know the ratios in the MTX 75 and the 6spd out of the SVT for comparison?... I'm thinking of a swap...

Thanks!
 

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Old Phart
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Here's part of your info., the SVT details: http://www.focusfanatics.com/forum/svt-performance-2002-2004/546562-svt-getrag-mt285-tranmission-information-thread.html

MTX-75 also had different final gear ratios avail., it'll take some searching to find them.

Don't know if the SVT third would hit the magic spot for you or not, offhand I wouldn't guess it for a "2.5" vs. the MTX you have - prob. a bit higher than that. SVT IS a "close ratio" type vs. the MTX, splitting it 6 ways in the same space 1-6 rather than 1-4 plus overdrive.

DO need axles, shifter & cables as well as the trans. to make a switch. With SVT parts getting hard to find & the trans not rebuildable it could be a tough one for a race car. There's a plastic bush in the SVT trans. shift tower (external) that people have to make or find someone who's made some for example & axles aren't as easy to acquire.

Maybe research the final drive ratios & see if you can find/make a replacement MTX that works better for you.
 

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FF's Night Security
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You can try the ring gear from a duratec trans mission which I think come in a 3.42 and the stock zetec ratio is 3.82. That should help as well. 2nd gear in my zetec 5 speed goes up to 58 mph my SVT can do 65mph in 2nd gear. My 5 speed is much more punchier in 2nd coming out of a turn, the SVT not so much but once your going you got lots mid to top end power. Now this is also from the different power bands delivered between the motors. I'll let you know how the SVT type motor feels on a 5 speed hopfully before the year is out.
 

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Discussion Starter #4
Thanks guys! From what I can tell now the six speed 2nd and 3rd gear both fall between the MTX 2nd and 3rd, so it would give me options for 3/10 mile courses and 4/10 mile courses. But yeah, if parts are getting hard to find that's a big deal... That's why I didn't build an Escort GT. They're almost extinct...

That ring gear might be just the ticket though!
 

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Does anyone know if I can just slap the duratec 3.42 ring gear in my trans? I assume I need to do the pinion too?...
You will need the pinon shaft as well, and all MTX75s are not the same, but maybe all Focus MTX75s are interchangeable? I'm not sure. Maybe someone else will chime in.

It is the 2003-2004 Duratec that had a 3.42. Later Duratecs had a 3.82.

Might just be easier to swap the whole transmission...
 

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Old Phart
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Bell housing portion of the trans. is what changes between applications (duratec to zetec).

Not just a simple swap of bolt on clutch housing as on many RWD transmissions though, as it's the whole side of the case.
 

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The mtx 75 installed in the 05-07 focus st had the 3.82 rear. The swap from zetec to Duratec will as said before will not bolt up. You can swap all the guts but you need to know trans very well to do that and be able to set the pre loads of the bearings. It can be done.
 

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Discussion Starter #10
I found a ring gear and pinion shaft. Dropped the tranny, started to go at it, and realized the output shaft from my 2001 is completely different. My output shaft has a press on pinion and the gears look to be part of the shaft. The '04 duratec shaft has press on gears and the pinion is part of the shaft... ?

Has anyone ever changed their MTX 75 to a 3.41 ratio?... Is changing the entire guts straight forward as long as I properly preload the bearings?...
 

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I found a ring gear and pinion shaft. Dropped the tranny, started to go at it, and realized the output shaft from my 2001 is completely different. My output shaft has a press on pinion and the gears look to be part of the shaft. The '04 duratec shaft has press on gears and the pinion is part of the shaft... ?

Has anyone ever changed their MTX 75 to a 3.41 ratio?... Is changing the entire guts straight forward as long as I properly preload the bearings?...
Have you ended up figuring this out? I'm in the same boat debating buying a duratec trans from the yard and moving the guts over.
 

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Discussion Starter #12
I did figure it out. It works awesome! 74mph or so in second at 7000rpm with my tire size.

I got an 04 Duratec with the 3.41 final drive. Split both cases and just swapped all the guts from the duratec into the Zetec, then put the ring gear on my diff (could have swapped the diff too but I had a welded diff I wanted to use from the Zetec).

I went to the trouble of going through the process of popping the bearing races out of the case and going through the pre-load sequence, but there were no changes to shims. It should be fine just to toss the guts in and go.

It's easier than it seems. The shafts come out together. Just pay attention to which way the shift forks go back together.
 
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