Gears - to answer the questions once and for all
 

this has all the gear ratios for every ford tranny (except for the 2004 mustang one... :rolleyes: not gonna comment on that)
http://www.vibratesoftware.com/html_...sions_Main.htm
site w/ correct ratios:
http://www.supercarsite.net/mustang_mach_1.htm



this is a speed/gear/rpm calculator:
http://www.allfordmustangs.com/Detailed/608.shtml


EDIT: Updated using .62 gear ratio, my bad :D
to save you all the trouble:
80mph at gear ratio:
3.55 = 2304
3.73 = 2421
4.10 = 2661
4.30 = 2791
4.56 = 2960

top speed w/ 3.55s, 5th gear @ 6798rpm (closest w/o going over 6800) = 236mph (obviously none of us will ever see anything close to this speed, so complaining about 'losing' top speed by going w/ a higher gear is pointless)

top speed w/ 3.73s, 5th gear @ 6780 = 224mph
top speed w/ 4.10s, 5th gear @ 6787 = 204mph
top speed w/ 4.30s, 5th gear @ 6769 = 194mph
top speed w/ 4.56s, 5th gear @ 6771 = 183mph


anyway, point is, doubt anyone is gonna 'lose' top speed... at least this was the main worry w/ 96-98 gt's :p (god it feels good now that I can rag on em :p)

EDIT: I guess I should update this thread with another calculation since this seems more appropriate now for my garage queen mach...

4th gear for manuals/3rd for autos (1:1), trap speeds at 6100rpm (stock engine peak) 6500 rpm (minor bolt-ons shift point), 6800 rpm (psr/cobra cams shift point)
I now prefer this calculator if anyone cares: http://www.4lo.com/calc/gearratio.php

Thanks for the numbers. I just installed 4.30s and love them. I did not cal my speedo yet so I was wondering about my rpm. I guessed right that 80mph is turning 3K rpm. I can live with that.

Jerome

Did you use a .62 for 5th for our cars? The first 3650's in Cobra's had a .67. The older 5 speed T45's had a .67. The earlier 5 speed 3550's had .68 (except for the .8 RR versions). Sorry to question this if you did.

I used a .67... where did you see the .62 ratio? more reason to go 4.30s or 4.56s :COOL: gonna re-run my #s soon I think... dammit, now you got me curious, i'm gonna do the test tomorrow morning w/ the digital tach and GPS going... :p

looked them up on yahoo... thanks! :)

Where's the love for 3.73's?!?!?!?

added :)

We have .62 5th. Yes you are correct. At cruising we turn fewer RPM's with 4.30's, than previous 5 speed cars with 4.10's. From .67 to .62 is a 7.5% difference. From 4.10 to 4.30 is only a 5% difference.

Wooohoooo. Makes me feel even better about chosing the 4.30s. Thanks for the added info Ralph.

P.S. Ralph, your sig is getting pretty long there ;)

Jerome

Thanks for the info Fosters , i have been wondering if i would be regretting the 4:10's i bought in case the wife and i would take a highway trip in the 100 mile range which we do sometimes. The car is a weekend driver. Feel good about e'm now.

Ralph when you going to add a set of gears to that list?

Ralph when you going to add a set of gears to that list? [/B][/QUOTE]

I'm not doing gears to this car. I changed rear gears 7 times on my 98 Cobra...and wound up with 4.10's. But it saw some track duty with over 500 RWHP on 15" BFG DR's. If doing again, that car would have stayed with 3.73's (which it had twice). Gears didn't really matter, car was traction limited.

I'm not drag racing this car, and think the stock 3.55's are almost perfect for all around use...with our 5 speeds (I might would prefer 3.73's for my use). If I had a 6 speed like was in the 2000R (2.97 first gear), (even if .62 6th same as our .62 5th) , I would like a little lower gear. Maybe a 3.90 or something for all around use.

Our Mach's make their power about 10% lower in the RPM range than previous 4V's, so 3.55's or 3.73's on our car feels about like 4.10's on previous 4V's, and you shifted them at higher RPM.

I'm not running race tires on this car, and no one has shown me gears make a car any faster for the way I drive this car, for my use. And even if they do make you a couple tenths faster on stock tires, that is not measureable for street use. And I like saving 5th for strictly highway cruising. I also like lazy 70-75 MPH cruising at a little over 2000. So stock 3.55's work for me.

If I were to get interested in drag racing this car with stock 5 speed, I would just jump to 4.30's, or maybe 4.56's, with a little taller than stock tire. Whatever tire/gear combo it takes to max out 4th at end of 1/4. But I will let you guys do all that stuff this time.

"Whatever tire/gear combo it takes to max out 4th at the end of 1/4."

What a wise and sage statement...

ralph, why do you think 3.73's would be better for all around use over 3.55's??, i know 4.10's or 4.30's would be the ticket for drag racing,but i haven't think about 3.73's as a replacement for the stock 3.55's until know. i know anything over 4.10s would improve acceleration in the 1/4 mile, but traction would be become an issue with street tires, specially with the ones that i was thinking to install (4.30s), i also know, dr's would cure the traction problem, but i drive 120miles every day, so i can't not afford to replace dr's every 2 months, plus i need to be able to drive in the rain.

I read somewhere that Mustangs are top speed limited, so top speed is really irrelevant. 139 or 149 mph, I can't remember which.

No love for 3.73s.:o

:LAUGH:

The Mach1 A/T is electronically speed limited in the 120+ mph range, the M/T @ 151 mph. (Doesn't mean they have to stay that way)

...and gears will help you attain them faster...

Wonder why the difference??

Well, IIRC the auto redline is @ 5800 rpm and the manual is @ 6800 rpm. I don't know what the gear ratios are for the A/T but I'm pretty sure that would come into play too.

There are a few people here who can answer this much better than I can since I don't know much about the auto's... I'd like a good explanation for this too. :CHEERS:

Good stuff!!

Would love to see those RPM's at 80 for the Mach's auto, as well as the top speed with each, but am uncertain how to figure that based on those links.

Got to think though that with the top speed being 120 with the 3.73's the 4.30's or 4.56's would have the car nearing or hitting it's top speed in the quarter.

find the gear ratios for the tranny, plug them in, plug your rear end ratio and play with the speed...

i have to go to work or i'd look the ratios up for you...i'll do it when i get back :)

Got bored :rolleyes: :D

Are the Mach1 4R70W ratios as follows???: :confused:
2.84
1.55
1.00
0.70 (OD)


Manual
.62 ratio, 80mph, at X.XX:1 rear gear ratio

3.55 = 2304 rpm
3.73 = 2421 rpm
4.10 = 2661 rpm
4.30 = 2791 rpm
4.56 = 2960 rpm

top speed w/ 3.55s, 5th gear @ 6798 rpm = 236 mph
top speed w/ 3.73s, 5th gear @ 6780 rpm = 224 mph
top speed w/ 4.10s, 5th gear @ 6787 rpm = 204 mph
top speed w/ 4.30s, 5th gear @ 6769 rpm = 194 mph
top speed w/ 4.56s, 5th gear @ 6771 rpm = 183 mph

Auto
.70 ratio, 80mph, at X.XX:1 rear gear ratio

3.55 = 2602 rpm
3.73 = 2733 rpm
4.10 = 3005 rpm
4.30 = 3151 rpm
4.56 = 3342 rpm

top speed w/ 3.55, @ 5789 rpm = 178 mph
top speed w/ 3.73, @ 5775 rpm = 169 mph
top speed w/ 4.10, @ 5784 rpm = 154 mph
top speed w/ 4.30, @ 5791 rpm = 147 mph
top speed w/ 4.56, @ 5765 rpm = 138 mph

Re: Gears - to answer the questions once and for all
 

The auto data would be more interesting in 3rd gear since we don't race (or even make full throttle runs) in OD.

Re: Gears - to answer the questions once and for all
 

I think that Ford set the speed limiter to 126 on the automatics to prevent a wide open throttle shift into overdrive. The shift with stock gears happens somewhere around 130MPH.

Why wouldn't you do a full throttle run in overdrive to get top speed? I bet it would be around 160+. I know you don't need overdrive on the drag strip.

I removed my speed limiter. I did have a chance to run to 135, but I let up on it around 125 and let it ease into overdrive. Once it shifted into overdrive I stomped it and it went from 125 to 135 so fast I couldn't believe it.

Re: Gears - to answer the questions once and for all
 

Awesome information! I have been looking for this because I am considering a gear change for my automatic. BUT I like top speed.

The rev-limiter is set to 6250 on automatics, so that's where we need to calculate top speed. Can you re-calculate for us?

Actually, 5800RPM is ok for 1'st, 2'nd, 3'rd, if you let the trans shift automatically, but 4'th will go all the way to 6250RPM.