3.73's effect on top end?

10-01-2001, 09:24 AM

I live in Germany (army) and frequently drive my '93 AOD(mostly stock) around the 110 mph range. I want to increase my 60' times, but I don't want to lose any high end speed and stability (not to mention gas mileage-$2/gal.) How much effect would 3.73's have on top end speed to rpm ratio.

slo95 · 10-01-2001, 11:02 AM

For gas, you will notice a diff going from your 2.73's or 3.27's? (whichever) to 3.73's. I noticed about a 2 to 3 mpg drop, about 30/40 miles less per tank (15 gal tank x 2.5 mpg).
for speed,
I cut this post from MYTKWIK on another site...
qoute "
3.73s at 6000rpm with 26in tire = ~124 mph
4.10s at 6000rpm with 26in tire = ~113 mph

Here is the formula if you want to do you own calcs.
(rpm * tire diameter)/(axle ratio * trans ratio * 336)

AODE Gear Ratios:
1st: 2.40
2nd: 1.47
3rd: 1.00
4th (OD): 0.67
Reverse: 2.00
end quote"

Mr 5 0 · 10-01-2001, 11:35 AM

If you 'frequently' cruise at 110 mph you do not want a 3.73 ratio rear.

You're going to noticably raise the the RPM's at that speed and shorten engine life.

You have to decide if you prefer top-end speed or low-end acceleration or else give up some of both. That's why most Mercedes-Benz and BMW's sold in Europe have very high top-end speeds but so-so quarter-mile times, despite sophisticated, high horsepower engines.

I suggest a shift kit for your AOD to help it on the low end. Stick with the stock gears.

10-01-2001, 01:23 PM

I wouldn't suggest going over a 3.55 rear if you're cruisin' on the autobahn!

------------------
'90 LX 5.0;12K original miles;FMS 3.55 gears; March pulleys;Edelbrock Performer Heads;BBK 1 5/8" equal length shorties;MSD 6AL ignition w/ blaster 2 coil;FMS E303 cam;Pro-M 75mm MAF;BBK 70mm TB; Eibach drag-launch spring kit;Southside weld-on subs;9" K&N cone filter charger;Hurst shifter;Cervini 3" turbo hood;A/C delete;gutted cats;2 chamber Flomasters;Corbeau racing seats;FMS 30# injectors;JMS custom chip;Holley 190lb fp;TFS track heat intake (12.299 @ 113mph w/ a 1.78 60')
....soon to be b

srv1 · 10-01-2001, 03:47 PM

Mustank, i have a set of 3.08's if you are interested. top speed in my stock Mustang was 143. maybe you want to go that route. PM me if you are interested.

------------------
90 LX Black on Black
Flowbabies, h-pipe, Mac unequal shorties, K&N, Hurst, subframes, Motorsport springs, MSD coil, 3.55's

10-02-2001, 06:17 AM

Thanks everyone. I'm not going to be driving on the autobahns forever, so I guess I'll keep the stock gears for now and switch them out when I come home.

10-01-2001, 09:24 AM	#1
Mustank the Destroyer Guest Posts: n/a	3.73's effect on top end? I live in Germany (army) and frequently drive my '93 AOD(mostly stock) around the 110 mph range. I want to increase my 60' times, but I don't want to lose any high end speed and stability (not to mention gas mileage-$2/gal.) How much effect would 3.73's have on top end speed to rpm ratio.

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10-01-2001, 11:02 AM	#2
slo95 Registered Member Join Date: Dec 2000 Posts: 168	For gas, you will notice a diff going from your 2.73's or 3.27's? (whichever) to 3.73's. I noticed about a 2 to 3 mpg drop, about 30/40 miles less per tank (15 gal tank x 2.5 mpg). for speed, I cut this post from MYTKWIK on another site... qoute " 3.73s at 6000rpm with 26in tire = ~124 mph 4.10s at 6000rpm with 26in tire = ~113 mph Here is the formula if you want to do you own calcs. (rpm * tire diameter)/(axle ratio * trans ratio * 336) AODE Gear Ratios: 1st: 2.40 2nd: 1.47 3rd: 1.00 4th (OD): 0.67 Reverse: 2.00 end quote"

10-01-2001, 11:35 AM	#3
Mr 5 0 Conservative Individualist Join Date: May 1997 Location: Wherever I need to be Posts: 7,487	If you 'frequently' cruise at 110 mph you do not want a 3.73 ratio rear. You're going to noticably raise the the RPM's at that speed and shorten engine life. You have to decide if you prefer top-end speed or low-end acceleration or else give up some of both. That's why most Mercedes-Benz and BMW's sold in Europe have very high top-end speeds but so-so quarter-mile times, despite sophisticated, high horsepower engines. I suggest a shift kit for your AOD to help it on the low end. Stick with the stock gears.

10-01-2001, 01:23 PM	#4
bada$$lx Guest Posts: n/a	I wouldn't suggest going over a 3.55 rear if you're cruisin' on the autobahn! ------------------ '90 LX 5.0;12K original miles;FMS 3.55 gears; March pulleys;Edelbrock Performer Heads;BBK 1 5/8" equal length shorties;MSD 6AL ignition w/ blaster 2 coil;FMS E303 cam;Pro-M 75mm MAF;BBK 70mm TB; Eibach drag-launch spring kit;Southside weld-on subs;9" K&N cone filter charger;Hurst shifter;Cervini 3" turbo hood;A/C delete;gutted cats;2 chamber Flomasters;Corbeau racing seats;FMS 30# injectors;JMS custom chip;Holley 190lb fp;TFS track heat intake (12.299 @ 113mph w/ a 1.78 60') ....soon to be b

10-01-2001, 03:47 PM	#5
srv1 Get down..... Join Date: Apr 2001 Location: Room 103 Posts: 2,095	Mustank, i have a set of 3.08's if you are interested. top speed in my stock Mustang was 143. maybe you want to go that route. PM me if you are interested. ------------------ 90 LX Black on Black Flowbabies, h-pipe, Mac unequal shorties, K&N, Hurst, subframes, Motorsport springs, MSD coil, 3.55's

10-02-2001, 06:17 AM	#6
Mustank the Destroyer Guest Posts: n/a	Thanks everyone. I'm not going to be driving on the autobahns forever, so I guess I'll keep the stock gears for now and switch them out when I come home.