Hey fellas, I just had the Zetec final drive gear installed in my mtx-75. I was wondering exactly what change this will do on my shift points. in other words how fast can I go in each gear before shifting?
As I am doing the samething, Terry told me it's just going to make the gears longer and able to put the power to better use with a 3L Hybrid or an FI 2.5/3L. My car isn't mobile as of just yet, but I will know first hand in no time.
IIRC, Kinger has a Zetec FD in his trans..........
The tach will not "magically" change because you changed the gear.
You still shift at the stock redline. Hopefully higher (if it's raised of course)
The only thing the Zetec gears accomplish is making launching a little easier. The bad trade-off is that you will be slower in every gear due to less torque multiplication factor!
Well "technically" another thing the gears change is top speed. Provided you have a hundred or 2 extra HP to use it.
Remember stock gearing, tires, and redline is good to 166mph already & even 200FWHP will only get you around 150mph.
My advice is to stick with the 4.06 gears!
Just a very rough guess you would gain about 5mph in each lower gear before you would have to shift. Without added horsepower your top speed in 5th gear would be lower.
This should be enough to get you through 0 to 60 at the top of second gear instead of starting into 3rd gear.
Without additional horsepower this would not be a befificial modification. With a 3.0L conversion this would make the car much more drivable.
Whoops, kinda misread the original question.
I'll be able to put enough power through my MTX75 with the zetec FD thanks to my 3L Hybrid backed with the VCN-2000 that I should be getting in the next few days
what does it do for ur top speed.....lower it???
It should raise it.....check out what demon posted higher up in the thread.....
Thats odd that you would say it only makes sense on Low hp applications. Mabey I'm tired and I didn't see the sarcasim. if so, sorry. But, Terry told me that he wouldn't have did it if he didn't think I had enough power. Demon can you please expand on why you would have kept the 4.06 gear?
I meant the 4.06 is good for low HP applications. Once you get over 250 to the wheels the zetec gear is the money.
cool, well i'm on the money then!!!!
Your missing the point...with an extra 150 hp on tap you have more then enough power to make MORE TQ in ANY gear then you currently can with your SVT and the 4.06 ratio. I haven't tried yet but I feel I can make the 1/4 through 3rd gear at 7200. I might have to shift but don't know for sure and don't have the time to work the math to see what my top speed in 3rd is.
Don't compare a street car to a race car. You know better
There are reasons for everything and they are for the most part opposite in street trim vs race trim.
just get a wider tire, it'll raise your ratio (or lower, whatever) effectively. . .what I'm trying to say is even though everybody thinks the 3.84 ratio is the way to go when you go hybrid or FI, just widening your running track (from 205 to 225) will be more effective than changing your gear ratios. . .I didn't change it for that reason, since I knew I'm setting up for some serious FI, I just got wider tires, and believe you me, I'm bogging down in stock csvt form, can't wait to sf her. . .i'm with demonsvt on this one. . .
I'm not sure that I really want to jump in here or not but let me make a few observations about gearing from real world experience.
Time frame mid 60's.
Subject vehicle. 1963 Chevy Impala Convertible. Highly modified 327 engine. Modifications changed frequently. 4 speed manual trans. No power steering.
Engine had 11:1 Corvette pistons. Several different cams, including several Duntov mechanical lifter cams as well as the 350 HP high performance hydraulic cam. I even had an Isky and a Sig Erson cam in at at times. Several different carbs, ran best with a Carter AFB off from a 409. Corvette heads with 2.02 valves and liberally ported. Depending on cam, engine would rev to 7,000 RPM on the low side and 9,000 RPM on the high side.
At different times I had 5.18, 4.56, 4.11, 3.70, and 3.36 gears in it.
The 5.18's were awsome for the hole shot. I was into third gear before clearing the intersection though. With a top engine speed of 7000 RPM the top speed with this gear was just a little over a 100 MPH. I did not experiment with this gear any further but at 9000 RPM top speed would have been about 130 MPH.
The car was highly modified before I bought it and came with 4.56 gears. Freeway driving was very tiring because of the high revs just cruising.
I wasn't much happier with the 4.11s.
Since it was my daily driver, I ended up with 3.70s. I still didn't loose many street races. The cam that I liked best with those gears was the Duntov 30/30. It ran OK with the 350 HP hydraulic cam with those gears but not as well matched as with the 30/30.
With the 30/30 cam and 3.70 gears I would pull off the line and match the acceleration of my oponent (who usually had to shift at about 5,000 RPM), and when he would shift, I would open the throttle the rest of the way and pull away decisively. Almost always end of contest.
What has all this have to do with your current discussion on gearing?
I've been there and done that. I know from real world experience what gearing can do.
The general rules.
The hotter the cams the less torque pulling away so lower gears are indicated.
The more the low end power, the more beneficial taller gears are. Taller gears are especially indicated with addition engine displacement or artifically asperated applications.
Usually a blown engine benefits from slightly taller gears compared to a turbo engine due to the power charteristics of the engines.
Taller gears do not mean more top speed. Additional horsepower is usually needed to get the engine to the rev limit.
If the gears are too low, you don't really do much more than just generate a lot of noise.
If the gears are too high, you will never be able to keep the engine in it's working range.
Drag racing usually uses lower gears than road racing or oval track racing.
Back to my original post on this thread. A 3.0 conversion would benefit from slightly higher gearing for most street and high performance street applications unless it has much hotter cams.
Anyway, that is my $.02. I welcome further input, but I will not join the argument.
Point of interest. Bondurant SVT's had Rousche prepped transmissions with the zetec final drive. No big engine mods, just auto crossing. Discuss.
Check most any tire chart and you will find the a 205/55R16 and a 225/50R16 are the same diameter.
? ?
I'm always into 4th through the 1/4. But then I shift about 6500-6800 usually since it's turbo'd.
More like $2..... 
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or your tire diameter is NOT stock. If so then the gears made no difference in being able to run it in 3rd except to make your acceleration slower through them. If you can make the 1/4 mile in 3rd then your extra tire diameter on top of the taller gear would make your acceleration potential significantly slower.