• Welcome to the Contour Enthusiasts Group, the best resource for the Ford Contour and Mercury Mystique.

    You can register to join the community.

Who has the larger 4.06 IIRC final drive gear???

H

Harrry

Addicted CEG'er
Joined
Jul 14, 2004
Messages
6,868
Location
Michigan
I was wondering what rpms are you...

@70mph rpms??
@75mph rpms??
@80mph rpms??

I found the final gear for 110 dollars. I will be pulling my trans out soon so i am wondering if it would be worth it to install this. I hate that my car runs at 3k rpms at 70mph. Plus better gas mileage might pay this thing off in just a year..... possibly. :)
 
And you might want a 3L or you'll hate it. Hopefully you have the correct level of output shaft to match as well.
 
Harrry said:
I was wondering what rpms are you...

@70mph rpms??
@75mph rpms??
@80mph rpms??

I found the final gear for 110 dollars. I will be pulling my trans out soon so i am wondering if it would be worth it to install this. I hate that my car runs at 3k rpms at 70mph. Plus better gas mileage might pay this thing off in just a year..... possibly. :)
Click to expand...

I was playing with this on the way home.
I have FSVT wheels 225/45/17s:
65 about 2800
70 about 3000
75 about 3200
80 about 3400

I think I see a trend :laugh:.
BTW, I think my speedo may be slightly faster than actual, anyone know?
I always look 5mph faster on the highway radar signs but the cop that gave me a warning for 84 in a 65 (thank you officer :cool:) was close--I thought I was doing 85.
-J
 
biminiLX said:
I was playing with this on the way home.
I have FSVT wheels 225/45/17s:
65 about 2800
70 about 3000
75 about 3200
80 about 3400

I think I see a trend :laugh:.
BTW, I think my speedo may be slightly faster than actual, anyone know?
I always look 5mph faster on the highway radar signs but the cop that gave me a warning for 84 in a 65 (thank you officer :cool:) was close--I thought I was doing 85.
-J
Click to expand...


Yea umm that's stock. Not Zetec final.
 
todras said:
Yea umm that's stock. Not Zetec final.
Click to expand...
Yep, his original question was asking about the stock ratio, I see he edited it. Either way, that's what I got on my tach.
I've thought of the change in final drive also if I do a 3L. It'd be nice if we could have longer 1st/5th ratios and keep the shorter final drive for acceleration, oh well.
-J
 
Easy to figure this out for exact #'s...

First, calculate your tire radius:
tire_radius = tire_width * ( tire_side / 100 ) * 0.03937 + ( rim_height / 2 )

So for me:
tire_width = 235
tire_side = 40
rim_height = 17

12.20078 = 235 * ( 40 / 100 ) * 0.03937 + ( 17 / 2 )
so my tire radius is 12.20078... which is smaller than stock.
(multiplying a number in inches with "0.03937" will convert to millimeters)


Next, figure the speed at what ever rpm in a certain gear:
The mtx75 gears: 3.42, 2.14, 1.45, 1.03, 0.77
v6 final: 4.06
4 final: 3.84

mph = ( rpm * tire_radius ) / ( final_gear * gear_ratio * 168 )

so, for me (with a 4.06 final)... at 3400 rpm in 5th gear (replicating what biminiLX already said)
78.984245 = ( 3400 * 12.20078 ) / (4.06 * 0.77 * 168 )

and to figure the same scenario, but with the 3.84 final gear, it results with 83.509384 mph.

And to reverse that to solve for rpm instead of mph:
rpm = (mph / tire_radius) * ( final_gear * gear_ratio * 168 )
which would show that I would be at 3257.119rpm at 80mph if I had the 3.84 final gear.


Last... just to show how different tire sizes affect things:
Using biminiLX's tires (225/45-17), and compared to mine at 3400rpm in 5th gear, with the 4.06 final...
me: 78.984245 mph
him: 80.832051 mph

and a little more extreme... same scenario but at 7200rpm .
me: 167.26075 mph
him: 171.17376 mph
 
biminiLX said:
Thanks man for doing the math.
I thought it might drop the rpm more but its not too much really.
BTW, any rubbing with the 235s?
-J
Click to expand...

Umm i maybe you were reading the tire cahnge in rpms/mph readings:shrug:

But the way i see it...
4.06 at 3400 rpm in 5th gear = 78.984245 mph
3.82 at 3400 rpm in 5th gear = 83.509384 mph
Subtract both and you get a difference of = 4.525139 mph

That is a difference i'm interested in :)

Thanks for the write up morbid. You are the man for doing this.!!
 
Harrry said:
Umm i maybe you were reading the tire cahnge in rpms/mph readings:shrug:

But the way i see it...
4.06 at 3400 rpm in 5th gear = 78.984245 mph
3.82 at 3400 rpm in 5th gear = 83.509384 mph
Subtract both and you get a difference of = 4.525139 mph

That is a difference i'm interested in :)

Thanks for the write up morbid. You are the man for doing this.!!
Click to expand...
hehe thanks!
Keep in mind, the numbers you quoted are based off my tires. OEM sized tires will be a little higher.

Really quick... to redo those using the E1 SVT OEM specs (215/50-16):
4.06 at 3400 rpm in 5th gear = 79.188135
3.84 at 3400 rpm in 5th gear = 83.724955
and the 3.82, which is rumourred to be in the BAT euro mtx-75:
3.82 at 3400 rpm in 5th gear = 84.163305

biminiLX said:
Thanks man for doing the math.
I thought it might drop the rpm more but its not too much really.
BTW, any rubbing with the 235s?
-J
Click to expand...
Slight rubbing on the fronts... the top of the fender arch, where the liner attaches to the fender. I actually wore off the head of the fastener before I realized it. For the rear, I pounded down the meat slicer before I had the wheels mounted. My next tire size should be interesting. :laugh:
 
My main concern is anywhere above 3100rpms. Because it's where i start to burn gas like crazy. So far, my recent test drives on teh e-way have told me that 70-71mph is the best mph for the best mpg. Which is great but at times i go 75-76 to get to places quicker and my MPG drops real fast.

Since i want to rebuild my trans before i put in a 3L i thought adding this would be the best choice.
 
Not

Not

Not to hi-jack this thread, but I just installed a MTX-75 out of a 2001 cougar into my SVT, and at 3350 rpms I'm doing 70mph (both speed and rpm confirmed as correct).

Yeah...what gives? Where did this high final drive gearing come from?
 
SVT Doood said:
Not to hi-jack this thread, but I just installed a MTX-75 out of a 2001 cougar into my SVT, and at 3350 rpms I'm doing 70mph (both speed and rpm confirmed as correct).

Yeah...what gives? Where did this high final drive gearing come from?
Click to expand...
whats your tire size?
 
S

S

Speed was "verified" by 3 different friend's cars driving next to me at various speeds then averaged. I also ran it several times thru a police "speed reader" they set-up. RPM was verified thru a friends OBD2 reader.

Believe me...I've owned 3 different Contours since 1998...1996 SE, a 1998 SVT, and now a 2nd 1998 SVT. Collectively, I've put over 300,00 miles on those cars. This trannie is totally blowing my mind. I researched which trans to purchase b4 I bought this one...and I have never heard of a higher gear ratio, except for the Bondoraunt Contours. I mean, the gear ratio makes the car peppy as hell in town, and by keeping the car to 70mph, I'm getting 28mpg...but I'm afraid the extended use higher rpms is gonna prematurely abuse my engine.
 
Did you do all your speed verifying in 5th gear? Did you check the other gears too? Best to get on a freeway with mile markers and use your trip odometer to verify your speed. I usually do 10 miles... long enough to be accurate, and easier to calculate.
 
You must log in or register to reply here.
Back
Top