Am I going to be the first....??

[cook2456]

My 3.90 gears, Pro-50 shifter, K&N, and 255/45 17 inch G-force KDW's are going to be put on as soon as I get 500 miles and an oil change or two done. I havent heard of anyone putting gears in their Mach 1 yet. I want to know the difference its going to make. I think my tires are going to make a big difference in traction compared to my Gatorbacks on the back if I kept the 3.55's but with the 3.90's I bet even with the better tires, she'll still spin in third gear. What do you all think?? She left the factory Jan. 3rd and is somewhere between there and me right now, so Im expecting it anyday. Does anyone have lower gears right now, or am I going to be the first one to write in and comment about them??

Cook

[#1 Mach]

I think that you are waisting your time with the 3.90 gear and should go AT LEAST a 4.10. Trust me if you get a 4.10 you wont be sorry and thats a promice.

[69mach03]

He's upgrading from 3.55 to 3.90 and you're putting him down because you're a fan of 4.10 gears? Give the man a break. He's installing 3.90 gears because that is what he wants.

[#1 Mach]

Negative sir, Im trying to help my friend out by guiding him in the right direction.

[FL Mach 1]

What #1 Mach said is the same thing that I have heard from many others who have the 4.6 DOHC, granted they aren't Mach 1s. Everything that I have heard is that the motor loves 4.10s and responds very well with them.

But on the other hand if he wants the 3.90s then by all means go for them but I would at least look at the 4.10s

[69mach03]

It's personal opinion. PERIOD. 3.90 - 4.10? There's not much difference between the two, and that's the truth.

[Darkhorse]

The 3.90's would be a great choice, ratio-wise in my opinion. I would watch out though. You can't get 3.90's from FRPP(Ford). Richmond is the only one making 3.90's and there has been a huge number of people complaining of gear noise with the Richmond's. You'll find a few without any but very few. I would steer clear and get Ford gears only. They're much better quality-wise and the only time you hear of noise with them is from improper installation. 4.10's would be great, but forget traction in first on the stock tires. First will become a very short gear with 4.10's. They are the ideal gear for pre-03 Cobra but most who have went to 4.10's on the 99/01 cobras have experienced high speed vibrations and have had to try things like indexing their driveshafts. I believe it was related to the IRS though, which wouldn't apply to you but since I'm not 100% on that issue you should go here (http://www.blueovalnews.com) and go the Cobra board and post a question on the gears, your brand choice, and any potential vibe issues. There are a lot of guys on the Cobra board that really know their stuff.

[Tomcat427]

I have my 4.10's (Ford) and they will be installed tuesday morning. I also picked up the alluminum racing drive shaft. It goes in tomorrow night.

[Verk]

Originally posted by cook2456
My 3.90 gears, Pro-50 shifter, K&N, and 255/45 17 inch G-force KDW's are going to be put on as soon as I get 500 miles and an oil change or two done. I havent heard of anyone putting gears in their Mach 1 yet. I want to know the difference its going to make. I think my tires are going to make a big difference in traction compared to my Gatorbacks on the back if I kept the 3.55's but with the 3.90's I bet even with the better tires, she'll still spin in third gear. What do you all think?? She left the factory Jan. 3rd and is somewhere between there and me right now, so Im expecting it anyday. Does anyone have lower gears right now, or am I going to be the first one to write in and comment about them??

Cook

Just a reminder, you could run into some warranty problems if you put gears in. When I had my 97 Cobra, and was thinking about installing 3:73s, the Ford dealer said that no matter who did the install, it would void my warranty for anything that could be related to the gear swap. Just something to think about.

If this is not an issue for you then by all means....press on and let us know how they work out. :THUMBSUP:

[cook2456]

Gee, #1 Mach, I appreciate the concern....

I got the 3.90's from Pro50.com, they were 189.99. I also got my shifter and knob from there also. I didnt just want 3.73's and 4.10s were going to be the next choice but then I seen the 3.90's and thought they would be a good compromise for the 4 valve characteristics all the while keeping highway revs down about 200 revs compared with the 4.10's. I have those 255/45 BF Goodrich KDW's too Im going to throw on there once I do the gear change. They should help out compared to them dadgum Gatorbacks. As for the warranty issue with Ford and those gears. Yes, they did mention it, and they said basically if something goes wrong with my Tremac 3650 then Im SOL, but the gears wouldnt void any other component of the vehicle. I told them, "Good to go, thats all I needed to know" and left it at that. Im like an expecting father here, this is my first new vehicle and also the one Ive always wanted...

Cook

[Verk]

Originally posted by cook2456
Gee, #1 Mach, I appreciate the concern....

I got the 3.90's from Pro50.com, they were 189.99. I also got my shifter and knob from there also. I didnt just want 3.73's and 4.10s were going to be the next choice but then I seen the 3.90's and thought they would be a good compromise for the 4 valve characteristics all the while keeping highway revs down about 200 revs compared with the 4.10's. I have those 255/45 BF Goodrich KDW's too Im going to throw on there once I do the gear change. They should help out compared to them dadgum Gatorbacks. As for the warranty issue with Ford and those gears. Yes, they did mention it, and they said basically if something goes wrong with my Tremac 3650 then Im SOL, but the gears wouldnt void any other component of the vehicle. I told them, "Good to go, thats all I needed to know" and left it at that. Im like an expecting father here, this is my first new vehicle and also the one Ive always wanted...

Cook

Sounds like a plan to me then! :THUMBSUP:
Would love to know how this setup does at the track so let us know how it works out. Good luck.

[headhunter]

fact....the 4.10 will perform noticebly better in the 4.6 engine than the 3.90 will ....i have seen it many times....

[#1 Mach]

Headhunter is correct. Anyone who tells you that the 3.90's are the same as the 4.10's on a 4V motor is telling you a lie to your face as well as being disrespectful.

[Kevin]

is there 4.30? or is that too high?

[Darkhorse]

Originally posted by #1 Mach
Headhunter is correct. Anyone who tells you that the 3.90's are the same as the 4.10's on a 4V motor is telling you a lie to your face as well as being disrespectful.

No one on here told him that 3.90's were going to be equal to 4.10's. There's no disrespect going on here. In my opinion 3.90's would be ideal in this car, especially for a car that sees mixed duty or mainly street driving. Hell, 3.73's would be great in this car but you've already got 3.55's so the small increase in performance wouldn't justify the expense. So it's 3.90's or 4.10's in my opinion. The problem with the 3.90's is that they are made by Richmond only, not FRPP. They have had an insane amount of people complaining about gear noise. Their quality is not up to FRPP's standards. You only here about noise on the FRPP gears when they aren't installed properly.

Actually the Mach 1 has more low end than the previous 4v motors so it isn't easy to compare the effects of 4.10's on those motors and just say 4.10's are the only way to go on the Mach 1. These cars are stronger in the low rpm's than the 99/01 Cobras so gear choices on this car don't have to mirror the Cobra completely. Some people do not like the very short first gear and the lack of first gear traction that 4.10's bring. Some also don't like the decreased gas mileage, increased sound from the engine and exhaust, or higher rpm on the highway that you get with 4.10's versus the stock ratio. Others love 4.10's and don't mind any of the drawbacks or actually don't see drawbacks from their perspective.. It comes down to an educated personal choice and what the intended use of the car is going to be. If I was drag racing the car regularly, I would put 4.10's in the car in a heartbeat. If 90% or more of my driving was street driving I would consider it very carefully before making my decision. It still might come out to 4.10's or maybe not. In terms of track times you will only see a .10-.20 difference at the track with the 4.10's versus the 3.90's. I believe about .12. And that's assuming you get traction.

Someone mentioned 4.30's. They are way too steep for an everyday driver, in my opinion. Those are for hardcore racers, not people who would drive these cars everyday and only see the track a couple times per year if that.

[#1 Mach]

My apologies for over reacting.

[starscream]

I'm not endorsing anything, but in regards to the 4.30s, I've read from plenty of Cobra owners who went from 4.10s to 4.30s and said they wished they never wasted time with the 4.10s. I don't remember any of them saying they wanted to go back to 4.10s. And some are daily drivers.

[Kevin]

what is the RPM jump going to be between 3.55's and 4.30's at 70 mph in 5th? anyone know?

[starscream]

Originally posted by Kevin
what is the RPM jump going to be between 3.55's and 4.30's at 70 mph in 5th? anyone know?

My calculations on a stock tire, 5th gear, 70MPH:

2017 RPMs for 3.55
2444 RPMs for 4.30

[Darkhorse]

Originally posted by Kevin
is that liveable??? I think that seems liveable......will my top speed be hurt alot?

You'll lose some but you'll still be able to go faster than you'll probably ever need. If I were you, I'd take your car out on the interstate as the car stands now and leave it in fourth and get yourself near the 2500rpm range and see how you like it. If you don't mind the increased noise then you could do it. If you're not going to race the car at the track I really wouldn't bother going over 4.10's at the most. You're definitely going to lose top speed as you go to lower ratios. You'll need to figure how much and if it matters to you. A lot of people base their gear choices on 1/4 mile alone. You need to consider what the bulk of your use will be. If this is going to be a stoplight racer and see the track a lot and only get driven on the weekends then consider the lower gear ratios.

[starscream]

By the way, if anyone wants to know the formula I used, here it is:


MPH = [Z * RPM]

Z = [Y/Rear End Gear Ratio] (3.55, 4.30, etc.)

Y = [(X * 60)/Transmission Gear Ratio] (5th gear according to Ford's specs on the Mach is .62)

X = [W/5280]

W = [(V *pi)/12] (pi = 3.14159)

V = Diameter of wheel in inches

To find the diameter of the wheel, take the [(width * profile percentage * 2)/25.4] + Rim height

On stock Mach 1 the tires are 245/45 on 17" rims so that's:
[(245*.45*2)/25.4 + 17]

Basically if you start at the wheel diameter and work your way up, plugging in all the numbers you know, you'll end up with these values:

V = 25.68 in
W = 6.723
X = .00127
Y = .12322
Z for 3.55 = .03470
Z for 4.30 = .02865

3.55:
.03470 * RPM = 70MPH
RPM = 70/.03470 = 2017

4.30:
.02865 * RPM = 70MPH
RPM = 70/.02865 = 2444

[Kevin]

Can someone explain why a numerically higher gear helps your et....What benefit is a 4.1 over a 3.55 and why?

[starscream]

Originally posted by Kevin
Can someone explain why a numerically higher gear helps your et....What benefit is a 4.1 over a 3.55 and why?

Sure. Just think of the gears on the back wheel of a 10 speed bike. The bigger the gear, the easier it is to get your feet moving from a stop. The smaller the gear, the harder it is to get moving from a dead stop. The result is two things. First, the higher gear basically acts as a torque multiplier, it gets your engine moving faster, which in turn puts you up in the powerband quicker. Secondly, the higher gear means less of a dropoff in RPMs when you shift gears, so you'll stay higher up in the powerband where more Torque and HP are available after you shift. That pretty much sums it up.

[the stallion]

Once I get my Mach 1, it is gonna be purely a pleasure cruiser and red light racer. I may occasionally take it to the track, but most of my tire smoking is gonna be done on public roads. Given these circumstances, is 4.10 too steep for me? Will 3.90's throw off the speedometer like I've heard higher gears will?

-Any feedback would be greatly appreciated
-Dan

[cook2456]

Its about time. She's all mine. Cant wait to add the parts I mentioned above too. You can never go too fast. Gotta break her in more first though...

You will have to get your chip reflashed once you add gears or bigger/smaller diameter tires. Here is a cool site:

http://www.geocities.com/monterosportrock/calcs.html

This site has all the calculators you ever need to figure out what you want to know about gears and pretty much anything else important. Its pretty handy. It takes the time out of doing the math yourself. Make sure you get the tire diameter of your tire before you start playing with RPM's and MPH in gears. The 245/45/17 is 25.681 inches tall.

I defininetly think the 3.90's are going to be my best all around choice. Ill let you know how they are going to be next Tuesday night. Take care of your Machine...

Cook

[jrscobra]

the engine in the mach is alot like my cobra. i installed 3:73 gears in the cobra and regret it everyday. 4:10 is the way to go. if i keep the cobra, they will be changed. the 4v motor loves to rev. I say 4:10
jr