Can gears hurt?

TwiLighTBluEGT · 07-28-2002, 03:53 PM

I just had my AOD rebuilt on my 91 GT. I have a set of 3.55's and a set of 3.73's. They mechanic at the shop said gears could actually hurt my car including my motor and tranny if not used properly. Is this true? One other thing... Which gear should I install first if I won't be running my car at the track, but driving it a lot of the highway?

sn95gt19 · 07-28-2002, 08:08 PM

If your going to do highway driving a lot, go with 3.55's. the only way that gears can hurt your motor or trans is the harder the hit off the line, and the higher the rpm that your car will run at on the highway. basically i think that your mechanic doesnt know what he is talking about.

cyberstang5.0 · 07-29-2002, 07:32 AM

I agree, your mechanic doesn't know what he's talking about.

Gears won't hurt your tranny or motor at all. The only think it's going to hurt if your gas budget

95mustanggt · 07-29-2002, 07:33 AM

The ONLY way gears are going to hurt your car is by reving it more therefore causing more wear. It will actually put less stress on the rear differential gear teeth. You are still putting out the same Horsepower with gears.

Go 3.55's if you spend all your time on the highway and this is your daily driver. Otherwise go 3.73's.

Mr 5 0 · 07-29-2002, 08:54 AM

Use the 3.73 gearset. It's only a slightly higher RPM difference from the 3.55's and with your AOD you need all the torque multiplication you can get.

The 3.73's will add around 400 RPM at highway speeds which is negligible and probably will make a 1 or 2 mpg difference in your gas use.

In my opinion, the words 'gas mileage' and 'Mustang' should not be used on the same line.

Better performance and good gas mileage are not compatible goals. If gas mileage is that important to you you've bought the wrong car. A Mustang V-8 gets somewhere in the low 20's for mpg on highway driving, maybe 18 or so overall, which isn't bad. You're feeding eight cylinders and pulling over 3,000 pounds. Be reasonable when it comes to gas mileage expectations and you won't be disappointed.

On other thing: Find a different mechanic.

magicmerll · 07-29-2002, 10:03 AM

This gentleman above knows best....

3.73 with AOD, period. Mileage can actually increase in around-town driving, and will only suffer slightly on the highway. Engine wear is really a non-issue, as the 5.0 plant is very tight.

Also, as I work at a dealership I can tell you....mechanics are not enthusiats. They think that removing any perfectly functioning part from a car is a bad thing! Take their advice for what it's worth...

TwiLighTBluEGT · 07-29-2002, 10:47 AM

I do want to put the 3.73's in more than the 3.55's, but you see, my car is my daily driver. I don't have another car. I drive it through the rain and snow. I live in New England and the winters tend to get pretty bad from time to time, but I have a seperate set of studded snow tires... And with those on, my car flies through the snow. I just want to know what will be better for a daily driver. If you guys think the 3.73's will be good for me, then great.

Chevyguy · 07-29-2002, 11:37 AM

The majority of those here will say

AOD 3.73 for street 4.10 for racing

T-5 3.55 for street 3.73 or 4.10 for racing

Going too steep in the rear gears can hurt your performance if the motor does not have a high enough RPM power peak, like a stock 5.0. The engine will run out of steam too soon, and you loose some of your top speed too!
If you install the gears wrong, that can hurt the car too!

I'm not certian here, but I suspect the AOD has a deeper OD gear.

Of course I have 2.73's and I'm in bummerville

95mustanggt · 07-29-2002, 12:06 PM

There is only a is only a small difference between the 3.55's and the 3.73's. I went with the 3.73's and definately have no regrets at all. I get better mileage around town and suffer only slightly on the highway.

I do notice the car running out of breath at the upper RPM's, but there is still plenty of time to keep shifting, even on the "stock" 5.0.

I though 3.73's would be too steep, but now I now why people like 4.10's. If I did it again I would even condsider 4.10's (but my car is not a daily driver anymore)

HORSEMEN RACING · 07-29-2002, 01:11 PM

I have had 3.73's in my 5speed 5.0 LX for 8 years,have driven cross country about 30 times since 1989,and have had no problems.

First up find another mechanic like everyone else has said,with an AOD get the 3.73's you will not be disappointed.

Gas mileage and Mustang V8 do not go hand in hand as Mr 5.0 said but a little sanity helps also when you are driving.On those cross country jaunts I went on,I averaged 22-24 mpg with the cruise control on,that is why it is there,use it and you will be surprised at how well your gas mileage really is.

Get the 3.73.

HiFlow5 0 · 07-29-2002, 05:39 PM

3.73's no doubt about it! Don't waste your time going with 3.55's in an auto! I'm running 3.73's and its just fine for a daily driver (which my car is). I almost wish I went with 4.10's, but oh well. Where abouts in MA do you live TwiLighTBluEGT? If you really want to see what 3.73's are like in an auto I'll take you for a ride, thats if your not too far away.

SCOTTLT79 · 07-29-2002, 05:52 PM

Hey HiFlow5 0,
I wish I heard that offer when I was out at amherst. I wouldn't have minded you taking me for a rip to see what the 3.73s feel like. Oh well.
I agree with these guys. Not to repeat others here but don't waste your money on the 3.55s, its pointless.

Scott

Mach 1 · 07-29-2002, 06:42 PM

3.73's as a minimun in an AOD. I had them and went up to 4.10's.

3.55s are a waste in AOD car.

TwiLighTBluEGT · 07-29-2002, 10:55 PM

HiFlo50, I live in East Longmeadow, MA. I sure would like to see what 3.73's are like in an AOD. If your not too far away, let me know.

Mopar1 · 07-30-2002, 01:19 AM

I got 4.10's with an AOD and its not really an issue as far as im concerned. I cruise at 90 mph=2200rpm on the clock thats NOT adjusted for the 4.10's. Tires are 65R 215 w/ 15" rims. I Figure the speedo is about 30% off with the 4.10 gears.

PKRWUD · 07-30-2002, 04:42 AM

Drop a pinion gear on your foot when your wearing your Vans, and then ask me if they can hurt.

Don't ask, I'm not in the mood.

The only decision you should be considering is whether or not you want to install a new torque convertor to go with your 3.73's.

Take care,
~Chris

Mach 1 · 07-30-2002, 05:38 AM

Exactly. Throw a Stallion converter in there while your at it, and you will really be happy with the combination, and you will be beating 5 speeds with lousy drivers.

93GTDIN · 07-30-2002, 11:13 AM

If 4.10's may cause a stock car to run out of steam in the top end, would I have that problem? My combo makes peak power from 4500 - 6000 rpms.

Also, what is the bottom line as far as ET improvements that gears offer? Will I actually pick up anything or will the car just feel faster?

Another question. WIth the 4.10's, I wont hit OD before I finish the quarter will I?

Chevyguy · 07-30-2002, 11:26 AM

93 GT, it looks like your motor combo should have plenty of higher RPM power. I would imagine only a real stock motor, meaning stock everything or just a catback and filter etc would actually slow down with 4.10's

Mach 1 · 07-30-2002, 12:45 PM

Quote:

Originally posted by 93GTDIN
If 4.10's may cause a stock car to run out of steam in the top end, would I have that problem? My combo makes peak power from 4500 - 6000 rpms.

Also, what is the bottom line as far as ET improvements that gears offer? Will I actually pick up anything or will the car just feel faster?

Another question. WIth the 4.10's, I wont hit OD before I finish the quarter will I?

Sounds like 4.10s are perfect for your car. You should see a couple tenths E/T improvement with gears. You wont hit OD because you will have your shifter in the D position, thus holding third gear. This will vary depending on tranny modifications.

If your trap RPM is to high that you run out of motor with the 4.10s by the end of the quarter in third gear, adjust the rear tire size to fine tune.

07-28-2002, 03:53 PM	#1
TwiLighTBluEGT Registered Member Join Date: Jun 2002 Location: Massachusetts Posts: 157	Can gears hurt? I just had my AOD rebuilt on my 91 GT. I have a set of 3.55's and a set of 3.73's. They mechanic at the shop said gears could actually hurt my car including my motor and tranny if not used properly. Is this true? One other thing... Which gear should I install first if I won't be running my car at the track, but driving it a lot of the highway?

07-28-2002, 08:08 PM	#2
sn95gt19 motors done......woohooo Join Date: Mar 2002 Posts: 799	If your going to do highway driving a lot, go with 3.55's. the only way that gears can hurt your motor or trans is the harder the hit off the line, and the higher the rpm that your car will run at on the highway. basically i think that your mechanic doesnt know what he is talking about. __________________ 95gt lazer red (98 cobra clone) Rice Haters Club Member #116

07-29-2002, 07:33 AM	#4
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	The ONLY way gears are going to hurt your car is by reving it more therefore causing more wear. It will actually put less stress on the rear differential gear teeth. You are still putting out the same Horsepower with gears. Go 3.55's if you spend all your time on the highway and this is your daily driver. Otherwise go 3.73's. __________________ 1995 Mustang GT 20016 F150 Lariat Super Crew

07-29-2002, 08:54 AM	#5
Mr 5 0 Conservative Individualist Join Date: May 1997 Location: Wherever I need to be Posts: 7,487	Gears and gas mileage Use the 3.73 gearset. It's only a slightly higher RPM difference from the 3.55's and with your AOD you need all the torque multiplication you can get. The 3.73's will add around 400 RPM at highway speeds which is negligible and probably will make a 1 or 2 mpg difference in your gas use. In my opinion, the words 'gas mileage' and 'Mustang' should not be used on the same line. Better performance and good gas mileage are not compatible goals. If gas mileage is that important to you you've bought the wrong car. A Mustang V-8 gets somewhere in the low 20's for mpg on highway driving, maybe 18 or so overall, which isn't bad. You're feeding eight cylinders and pulling over 3,000 pounds. Be reasonable when it comes to gas mileage expectations and you won't be disappointed. On other thing: Find a different mechanic.

07-29-2002, 10:03 AM	#6
magicmerll Registered Member Join Date: May 2002 Location: St. Louis, MO Posts: 19	This gentleman above knows best.... 3.73 with AOD, period. Mileage can actually increase in around-town driving, and will only suffer slightly on the highway. Engine wear is really a non-issue, as the 5.0 plant is very tight. Also, as I work at a dealership I can tell you....mechanics are not enthusiats. They think that removing any perfectly functioning part from a car is a bad thing! Take their advice for what it's worth... __________________ Ever notice the people that know the best way to raise kids are the people that don't have any?

07-29-2002, 07:32 AM	#3
cyberstang5.0 347ci of HORSE POWER!!! Join Date: Jul 2001 Location: Houston, TX Posts: 1,416	I agree, your mechanic doesn't know what he's talking about. Gears won't hurt your tranny or motor at all. The only think it's going to hurt if your gas budget

07-29-2002, 10:47 AM	#7
TwiLighTBluEGT Registered Member Join Date: Jun 2002 Location: Massachusetts Posts: 157	I do want to put the 3.73's in more than the 3.55's, but you see, my car is my daily driver. I don't have another car. I drive it through the rain and snow. I live in New England and the winters tend to get pretty bad from time to time, but I have a seperate set of studded snow tires... And with those on, my car flies through the snow. I just want to know what will be better for a daily driver. If you guys think the 3.73's will be good for me, then great.

07-29-2002, 11:37 AM	#8
Chevyguy Backyard Mechanic/Chemist Join Date: Feb 2001 Location: Acton MA USA Posts: 435	The majority of those here will say AOD 3.73 for street 4.10 for racing T-5 3.55 for street 3.73 or 4.10 for racing Going too steep in the rear gears can hurt your performance if the motor does not have a high enough RPM power peak, like a stock 5.0. The engine will run out of steam too soon, and you loose some of your top speed too! If you install the gears wrong, that can hurt the car too! I'm not certian here, but I suspect the AOD has a deeper OD gear. Of course I have 2.73's and I'm in bummerville __________________ 2001 Crown Vic Maurader Airbox/MAF, DR chip Edel IAS shocks Single exhaust :wtf: 93 P-71 Vic interceptor Backup car now 90 5.0 LX Notch SOLD 74 Chevy Laguna type S-3 454 under construction Currently apart undergoing bodywork.

07-29-2002, 12:06 PM	#9
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	There is only a is only a small difference between the 3.55's and the 3.73's. I went with the 3.73's and definately have no regrets at all. I get better mileage around town and suffer only slightly on the highway. I do notice the car running out of breath at the upper RPM's, but there is still plenty of time to keep shifting, even on the "stock" 5.0. I though 3.73's would be too steep, but now I now why people like 4.10's. If I did it again I would even condsider 4.10's (but my car is not a daily driver anymore) __________________ 1995 Mustang GT 20016 F150 Lariat Super Crew

07-29-2002, 01:11 PM	#10
HORSEMEN RACING Registered Member Join Date: Jun 2002 Location: Camp Pendleton,Cali Posts: 95	3.73 I have had 3.73's in my 5speed 5.0 LX for 8 years,have driven cross country about 30 times since 1989,and have had no problems. First up find another mechanic like everyone else has said,with an AOD get the 3.73's you will not be disappointed. Gas mileage and Mustang V8 do not go hand in hand as Mr 5.0 said but a little sanity helps also when you are driving.On those cross country jaunts I went on,I averaged 22-24 mpg with the cruise control on,that is why it is there,use it and you will be surprised at how well your gas mileage really is. Get the 3.73. __________________ OC "there are 5,000 Army troops sitting on their butts doing nothing,while 2 companies of Marines are securing this island" spoken by a Army General on the Isle of Grenada in 1983

07-29-2002, 05:39 PM	#11
HiFlow5 0 Registered Member Join Date: Mar 2000 Location: Springfield, Ma, usa Posts: 706	3.73's no doubt about it! Don't waste your time going with 3.55's in an auto! I'm running 3.73's and its just fine for a daily driver (which my car is). I almost wish I went with 4.10's, but oh well. Where abouts in MA do you live TwiLighTBluEGT? If you really want to see what 3.73's are like in an auto I'll take you for a ride, thats if your not too far away. __________________ NewEngland Auto www.baystategearheads.com -91 Mustang Coupe, ex 4cyl (sold) -99 F150, 3" lift, 35" Procomps, Magnaflow exhaust

07-29-2002, 05:52 PM	#12
SCOTTLT79 Registered Member Join Date: Aug 2000 Location: Raynham, Ma, USA Posts: 189	Hey HiFlow5 0, I wish I heard that offer when I was out at amherst. I wouldn't have minded you taking me for a rip to see what the 3.73s feel like. Oh well. I agree with these guys. Not to repeat others here but don't waste your money on the 3.55s, its pointless. Scott __________________ 95 Red Mustang GT Pro 5.0, MAC fenderwall cold air induction kit, BBK Off-Road H-pipe with Magnaflow cat-back system Mostly stock(looking to modify) Rice Haters Club Member #63

07-29-2002, 06:42 PM	#13
Mach 1 Registered Member Join Date: May 1999 Location: Georgia Posts: 3,866	3.73's as a minimun in an AOD. I had them and went up to 4.10's. 3.55s are a waste in AOD car. __________________ 2002 GT 1993 GT (SOLD) '93 Mustang GT RHC member #142

07-29-2002, 10:55 PM	#14
TwiLighTBluEGT Registered Member Join Date: Jun 2002 Location: Massachusetts Posts: 157	HiFlo50, I live in East Longmeadow, MA. I sure would like to see what 3.73's are like in an AOD. If your not too far away, let me know.

07-30-2002, 01:19 AM	#15
Mopar1 Registered Member Join Date: Mar 2002 Location: Lakewood, Wa Posts: 161	I got 4.10's with an AOD and its not really an issue as far as im concerned. I cruise at 90 mph=2200rpm on the clock thats NOT adjusted for the 4.10's. Tires are 65R 215 w/ 15" rims. I Figure the speedo is about 30% off with the 4.10 gears. __________________ '77 Aspen R/T: 318 w/273 heads, 4spd, Hurst Shifter, 600 holley, edelbrock intake, 8 3/4 axle, 3.23 sure-grip, dual 3" exhaust, MP cam 276 / 276 duration 490 / 490 mech solid lifter, Super Stock Springs (15.65@88 3900lbs) '91 Mustang LX: .030 Bored, Typhoon Intake, 4.10's, Lentech VB, BBK 70mm TB, FMS A/C elim bracket, 19lbs inject, off road H-pipe, 75mm pro-m MAF, FRP unequal shorty, stormin normin hood. 3420 Lbs w/ 220 (me) and 13 gal gas. '02 SS Camaro

07-30-2002, 04:42 AM	#16
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Drop a pinion gear on your foot when your wearing your Vans, and then ask me if they can hurt. Don't ask, I'm not in the mood. The only decision you should be considering is whether or not you want to install a new torque convertor to go with your 3.73's. Take care, ~Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

07-30-2002, 05:38 AM	#17
Mach 1 Registered Member Join Date: May 1999 Location: Georgia Posts: 3,866	Exactly. Throw a Stallion converter in there while your at it, and you will really be happy with the combination, and you will be beating 5 speeds with lousy drivers. __________________ 2002 GT 1993 GT (SOLD) '93 Mustang GT RHC member #142

07-30-2002, 11:13 AM	#18
93GTDIN Registered Member Join Date: Jan 2001 Location: Live music capital of the world, TX Posts: 324	If 4.10's may cause a stock car to run out of steam in the top end, would I have that problem? My combo makes peak power from 4500 - 6000 rpms. Also, what is the bottom line as far as ET improvements that gears offer? Will I actually pick up anything or will the car just feel faster? Another question. WIth the 4.10's, I wont hit OD before I finish the quarter will I? __________________ 96 Cobra - a bit too stock. 14.0 @ 101

07-30-2002, 11:26 AM	#19
Chevyguy Backyard Mechanic/Chemist Join Date: Feb 2001 Location: Acton MA USA Posts: 435	93 GT, it looks like your motor combo should have plenty of higher RPM power. I would imagine only a real stock motor, meaning stock everything or just a catback and filter etc would actually slow down with 4.10's __________________ 2001 Crown Vic Maurader Airbox/MAF, DR chip Edel IAS shocks Single exhaust :wtf: 93 P-71 Vic interceptor Backup car now 90 5.0 LX Notch SOLD 74 Chevy Laguna type S-3 454 under construction Currently apart undergoing bodywork.

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