3.55's, 3.73's Or 4.10's???

BowTie Eater 5 Liter · 03-17-2001, 04:20 AM

I Was Wondering What Gears I Should Get For My Rear End. I Will Have A 358w With 400hp & 450ft.-lbs That Wont See Much Over 5000rpm's (Peak Power At 5000RPM). I Will Also Race The Car On DOT Slicks. I Dont Care About Gas Milage, But It Will Be A Daily Driver.

Thanks.....

------------------
1988 Mustang GT, T-5
No Smog Pump (Shorty Belt), Dumps At The End Of Stock H-Pipe (Sounds Mean), K&N Air Filter (Stock Air Box, Removed air silendcer), 198.9 rwhp @4200 (235 Motor!!), 285 lbs-ft @2900 (336 Motor!!!).
My Stang

Skyman · 03-17-2001, 04:42 AM

To see that your back with the 351, what heads are u planning to peak HP out so low?

3.73 is my vote

Sky

------------------
-1989 Saleen Mustang #406- TFS Heads, E-303, edelbrock intake,70MM TB, 73mm MAF, off road H, 2 1/4" exhaust, and 4.10's.
332RWHP@5500
351RWTQ@3750
Runs on 87 Octane!

03-17-2001, 04:48 AM

Anutter vote for 3.73's..

------------------
Paxton Blown 87GT

dinomite · 03-17-2001, 10:14 AM

I'd say 3.73 or 3.55. Many people will disagree, but I think that 4.10 is too much for the street.

Bob · 03-17-2001, 11:42 AM

Depends on the tire size. I have 3.73's with a 26" tire now which works fine, but now I'm thinking 4.10 gear with a 28" tire would work better. Little softer hit, and more traction.

------------------
1985 Mustang GT

'85 GT 13.20 @ 105.8 / '72 Mach1
Long list...check website!!
My Website

BowTie Eater 5 Liter · 03-17-2001, 01:43 PM

Sky, Im gonna be using the TFS "R" heads, & a crane cam that is the same as an e-303, TFS 351 intake.

Sky, did u check & see if you have 4.10s out back?? or are they 3.73s???

------------------
1988 Mustang GT, T-5
No Smog Pump (Shorty Belt), Dumps At The End Of Stock H-Pipe (Sounds Mean), K&N Air Filter (Stock Air Box, Removed air silendcer), 198.9 rwhp @4200 (235 Motor!!), 285 lbs-ft @2900 (336 Motor!!!).
My Stang

jimberg · 03-17-2001, 01:58 PM

With all that torque, go with 3.55s. 4.10s will have you losing too much traction on launch. 3.73s should be the highest you consider.

------------------
351W 89 Mustang GT Convertible

lx mike · 03-17-2001, 06:39 PM

with al that torque 3.55 would be good for your combo, but you will have some d.o.t slicks so i'd say 3.73 would realy make most out of your combo if you run drag slicks then the 4.10's would realy make that thing jump of the line.

------------------
93-LX: 5 Speed, Flow's with H-Pipe, 3.73's Sub's and K&N.

vande97 · 03-17-2001, 08:06 PM

go for the 4.10's i love them!1, you can get one hell of a launch if you can keep traction!

jonnyk · 03-17-2001, 08:34 PM

I disagree, I think 4.10's will be the way to go. Launching with more gear is easier (I think anyways) since the RPM's match up faster with the tire speed, so on a bog it'll come out of the low revs faster, and you can easily backpedal if you spin too much (or adjust launch RPM accordingly). With that kind of torque though you could get away with less gear (3.73 is as tall as I would go) if you wanted to retain a bit more gas mileage. Just my 2 cents.

------------------
1991 LX Hatch 5.0L

03-17-2001, 09:56 PM

What tranny are you going to run? If you plan on a c4 I'd get 4.10s.

03-18-2001, 12:17 AM

It depends on what tranny you're gonna use. If C-4, then definatley 3.73's or 4.10's. If you are gonna go 5 speed, i would say 3.55's for one simple reason. Everyone likes 3.73's however, with 400 hp or better, your traction is gonna suffer greatly with higher (numericaly) gears, even with slicks. With that much hp, and a big tourquey 351, 3.55's would give you the best of both worlds, better launch, decent traction.

------------------
'93 Gt, Stock as a rock, but plan an AOD to T-5 swap, steeda tri-ax shifter, 3.55's, cobra intake, gt-40 irons, e303 cam, mac headers, off road h-pipe, flowmasters cat back, msd ignition, blaster coil, mac cold air box (fenderwell), eibach springs, silver cobra r's, and an obnoxiously large mustang in the back window =0)

jimberg · 03-18-2001, 11:21 AM

I thought you might like some further reasoning as to why 4.10s are too much.

Let's say that your RPMs will be good to 5000 as you suspect, the last gear ratio of a C4 is 1.00, and you have 28" slicks.

Since the tranny is turning as fast as the engine, just divide your engine RPMs by differential ratio. 5000/4.10 approximately = 1219.51. Now take your tire height and multiply it by PI. 28 * 3.14 = 87.92. Multiply this result by the previous result and you get the number of inches per minute you will be going at 5000 RPMs. 1219.51 * 87.92 = 107219.3192. Multiply that by 60 and then divide by 63360 for MPH. ( 107219.3192 * 60 ) / 63360 approximately = 102 MPH.

That's it. You'll be losing steam at 102 MPH. High gear ratios are either for weak engines that need a boost in torque or for strong engines that can put out high RPMs. Even with 3.55s you'll be losing steam at 118 MPH.

Come to think of it, you either want to do something so you have power through 6000-7000 rpms, go with maybe 3.27s or 3.08s, or use really tall tires.

------------------
351W 89 Mustang GT Convertible

MustangLX90 · 03-18-2001, 02:48 PM

3.73's all the way.

------------------
1990 LX Hatch: FRPP 3.73's, 9mm wires, Dynomax Super Turbos, Off road h-pipe, Superchip, K&N, and more to come!!!

DirtKing · 03-18-2001, 04:53 PM

373s were too much with the blower and my 327 first gear(tremec)..355s were a better fit. on the strip with 28 inch slicks 373s or 410s will work well, but I just launch 500rpm higher to compensate. On the street i like the 355s alot better. like jimberg said, 410s usually are a bandaid for the motor unless you're running an automatic or purpose built for the strip.

------------------
88LX notch, Speedpro EFI Procharged!

dinomite · 03-18-2001, 05:01 PM

I'm with jimberg. 3.08 is a little low, I would say. My vote is 3.55 or 3.27. You'll get good gas mileage, still have some speed. Depends on whether its street or stip. If it a street car, 3.27.

Skyman · 03-18-2001, 05:24 PM

I cant find my jack stands, and I'm too weary to go under the car to check with just a floor jack.

If your using those heads and cam, think more like 6000rpm for your peak HP. So I still say 373 your gonna hook fine.

Sky

------------------
-1989 Saleen Mustang #406- TFS Heads, E-303, edelbrock intake,70MM TB, 73mm MAF, off road H, 2 1/4" exhaust, and 4.10's.
332RWHP@5500
351RWTQ@3750
Runs on 87 Octane!

slider · 03-18-2001, 05:29 PM

skyman
you need to get off your lazzy a$$ and check for those gears !

03-18-2001, 11:48 PM

Quote:

Originally posted by jimberg:

Since the tranny is turning as fast as the engine, just divide your engine RPMs by differential ratio. 5000/4.10 approximately = 1219.51. Now take your tire height and multiply it by PI. 28 * 3.14 = 87.92. Multiply this result by the previous result and you get the number of inches per minute you will be going at 5000 RPMs. 1219.51 * 87.92 = 107219.3192. Multiply that by 60 and then divide by 63360 for MPH. ( 107219.3192 * 60 ) / 63360 approximately = 102 MPH.

Ok, now I have a headache.

I really can't imagine not going over 5000rpms.

BowTie Eater 5 Liter · 03-19-2001, 12:52 AM

Sky, Go & check those gears, even with a floor jack, it doesnt havce to be high off the ground, just mark the axel with chalk, takes 2 min.
Also, I have an article of the motor, so it COULD rev higher, but it makes max power at 5000, i probably wont rev much higher in fear that the stock bottom end might give

I will have a 5-speed tranny, dont know if termec or t-5z, but it will be daily driven

thanks for all the help!!

------------------
1988 Mustang GT, T-5
No Smog Pump (Shorty Belt), Dumps At The End Of Stock H-Pipe, K&N Air Filter (Stock Air Box), Removed air silendcer), 198.9 rwhp @4200 (235 Motor!!), 285 lbs-ft @2900 (336 Motor!!!).
My Stang
My Site

03-17-2001, 04:20 AM	#1
BowTie Eater 5 Liter Registered Member Join Date: Nov 2000 Location: Maple Ridge B.C. Canada, The Best Place In The World Posts: 871	3.55's, 3.73's Or 4.10's??? I Was Wondering What Gears I Should Get For My Rear End. I Will Have A 358w With 400hp & 450ft.-lbs That Wont See Much Over 5000rpm's (Peak Power At 5000RPM). I Will Also Race The Car On DOT Slicks. I Dont Care About Gas Milage, But It Will Be A Daily Driver. Thanks..... ------------------ 1988 Mustang GT, T-5 No Smog Pump (Shorty Belt), Dumps At The End Of Stock H-Pipe (Sounds Mean), K&N Air Filter (Stock Air Box, Removed air silendcer), 198.9 rwhp @4200 (235 Motor!!), 285 lbs-ft @2900 (336 Motor!!!). My Stang

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03-17-2001, 04:42 AM	#2
Skyman I need 110mph Trap Speed! Join Date: Feb 1999 Location: So, CA Posts: 4,315	To see that your back with the 351, what heads are u planning to peak HP out so low? 3.73 is my vote Sky ------------------ -1989 Saleen Mustang #406- TFS Heads, E-303, edelbrock intake,70MM TB, 73mm MAF, off road H, 2 1/4" exhaust, and 4.10's. 332RWHP@5500 351RWTQ@3750 Runs on 87 Octane!

03-17-2001, 04:48 AM	#3
Mustanguy Guest Posts: n/a	Anutter vote for 3.73's.. ------------------ Paxton Blown 87GT

03-17-2001, 10:14 AM	#4
dinomite The Dude Join Date: Feb 2001 Location: Arlington, VA Posts: 1,262	I'd say 3.73 or 3.55. Many people will disagree, but I think that 4.10 is too much for the street.

03-17-2001, 11:42 AM	#5
Bob "Old School Gearhead" Join Date: Oct 1998 Location: Peru, Illinois Posts: 617	Depends on the tire size. I have 3.73's with a 26" tire now which works fine, but now I'm thinking 4.10 gear with a 28" tire would work better. Little softer hit, and more traction. ------------------ 1985 Mustang GT '85 GT 13.20 @ 105.8 / '72 Mach1 Long list...check website!! My Website

03-17-2001, 01:43 PM	#6
BowTie Eater 5 Liter Registered Member Join Date: Nov 2000 Location: Maple Ridge B.C. Canada, The Best Place In The World Posts: 871	Sky, Im gonna be using the TFS "R" heads, & a crane cam that is the same as an e-303, TFS 351 intake. Sky, did u check & see if you have 4.10s out back?? or are they 3.73s??? ------------------ 1988 Mustang GT, T-5 No Smog Pump (Shorty Belt), Dumps At The End Of Stock H-Pipe (Sounds Mean), K&N Air Filter (Stock Air Box, Removed air silendcer), 198.9 rwhp @4200 (235 Motor!!), 285 lbs-ft @2900 (336 Motor!!!). My Stang

03-17-2001, 01:58 PM	#7
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	With all that torque, go with 3.55s. 4.10s will have you losing too much traction on launch. 3.73s should be the highest you consider. ------------------ 351W 89 Mustang GT Convertible

03-17-2001, 06:39 PM	#8
lx mike Undescribable Join Date: Sep 1998 Location: Ft Myers Fla Posts: 1,539	with al that torque 3.55 would be good for your combo, but you will have some d.o.t slicks so i'd say 3.73 would realy make most out of your combo if you run drag slicks then the 4.10's would realy make that thing jump of the line. ------------------ 93-LX: 5 Speed, Flow's with H-Pipe, 3.73's Sub's and K&N.

03-17-2001, 08:06 PM	#9
vande97 Registered Member Join Date: Jan 2001 Location: okemos Posts: 205	go for the 4.10's i love them!1, you can get one hell of a launch if you can keep traction!

03-17-2001, 08:34 PM	#10
jonnyk Being stroked is great Join Date: Oct 1998 Location: Alberta, Canada Posts: 772	I disagree, I think 4.10's will be the way to go. Launching with more gear is easier (I think anyways) since the RPM's match up faster with the tire speed, so on a bog it'll come out of the low revs faster, and you can easily backpedal if you spin too much (or adjust launch RPM accordingly). With that kind of torque though you could get away with less gear (3.73 is as tall as I would go) if you wanted to retain a bit more gas mileage. Just my 2 cents. ------------------ 1991 LX Hatch 5.0L

03-17-2001, 09:56 PM	#11
rbatson Guest Posts: n/a	What tranny are you going to run? If you plan on a c4 I'd get 4.10s.

03-18-2001, 12:17 AM	#12
Bangin Gears Guest Posts: n/a	It depends on what tranny you're gonna use. If C-4, then definatley 3.73's or 4.10's. If you are gonna go 5 speed, i would say 3.55's for one simple reason. Everyone likes 3.73's however, with 400 hp or better, your traction is gonna suffer greatly with higher (numericaly) gears, even with slicks. With that much hp, and a big tourquey 351, 3.55's would give you the best of both worlds, better launch, decent traction. ------------------ '93 Gt, Stock as a rock, but plan an AOD to T-5 swap, steeda tri-ax shifter, 3.55's, cobra intake, gt-40 irons, e303 cam, mac headers, off road h-pipe, flowmasters cat back, msd ignition, blaster coil, mac cold air box (fenderwell), eibach springs, silver cobra r's, and an obnoxiously large mustang in the back window =0)

03-18-2001, 11:21 AM	#13
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	I thought you might like some further reasoning as to why 4.10s are too much. Let's say that your RPMs will be good to 5000 as you suspect, the last gear ratio of a C4 is 1.00, and you have 28" slicks. Since the tranny is turning as fast as the engine, just divide your engine RPMs by differential ratio. 5000/4.10 approximately = 1219.51. Now take your tire height and multiply it by PI. 28 * 3.14 = 87.92. Multiply this result by the previous result and you get the number of inches per minute you will be going at 5000 RPMs. 1219.51 * 87.92 = 107219.3192. Multiply that by 60 and then divide by 63360 for MPH. ( 107219.3192 * 60 ) / 63360 approximately = 102 MPH. That's it. You'll be losing steam at 102 MPH. High gear ratios are either for weak engines that need a boost in torque or for strong engines that can put out high RPMs. Even with 3.55s you'll be losing steam at 118 MPH. Come to think of it, you either want to do something so you have power through 6000-7000 rpms, go with maybe 3.27s or 3.08s, or use really tall tires. ------------------ 351W 89 Mustang GT Convertible

03-18-2001, 02:48 PM	#14
MustangLX90 Registered Member Join Date: Dec 2000 Location: Windsor, Ontario, Canada Posts: 21	3.73's all the way. ------------------ 1990 LX Hatch: FRPP 3.73's, 9mm wires, Dynomax Super Turbos, Off road h-pipe, Superchip, K&N, and more to come!!!

03-18-2001, 04:53 PM	#15
DirtKing Registered Member Join Date: Feb 1999 Location: brooklyn center,mn,USA Posts: 169	373s were too much with the blower and my 327 first gear(tremec)..355s were a better fit. on the strip with 28 inch slicks 373s or 410s will work well, but I just launch 500rpm higher to compensate. On the street i like the 355s alot better. like jimberg said, 410s usually are a bandaid for the motor unless you're running an automatic or purpose built for the strip. ------------------ 88LX notch, Speedpro EFI Procharged!

03-18-2001, 05:01 PM	#16
dinomite The Dude Join Date: Feb 2001 Location: Arlington, VA Posts: 1,262	I'm with jimberg. 3.08 is a little low, I would say. My vote is 3.55 or 3.27. You'll get good gas mileage, still have some speed. Depends on whether its street or stip. If it a street car, 3.27.

03-18-2001, 05:24 PM	#17
Skyman I need 110mph Trap Speed! Join Date: Feb 1999 Location: So, CA Posts: 4,315	I cant find my jack stands, and I'm too weary to go under the car to check with just a floor jack. If your using those heads and cam, think more like 6000rpm for your peak HP. So I still say 373 your gonna hook fine. Sky ------------------ -1989 Saleen Mustang #406- TFS Heads, E-303, edelbrock intake,70MM TB, 73mm MAF, off road H, 2 1/4" exhaust, and 4.10's. 332RWHP@5500 351RWTQ@3750 Runs on 87 Octane!

03-18-2001, 05:29 PM	#18
slider Registered Member Join Date: Mar 2001 Location: San Diego, CA, USA Posts: 86	skyman you need to get off your lazzy a$$ and check for those gears !

03-19-2001, 12:52 AM	#20
BowTie Eater 5 Liter Registered Member Join Date: Nov 2000 Location: Maple Ridge B.C. Canada, The Best Place In The World Posts: 871	Sky, Go & check those gears, even with a floor jack, it doesnt havce to be high off the ground, just mark the axel with chalk, takes 2 min. Also, I have an article of the motor, so it COULD rev higher, but it makes max power at 5000, i probably wont rev much higher in fear that the stock bottom end might give I will have a 5-speed tranny, dont know if termec or t-5z, but it will be daily driven thanks for all the help!! ------------------ 1988 Mustang GT, T-5 No Smog Pump (Shorty Belt), Dumps At The End Of Stock H-Pipe, K&N Air Filter (Stock Air Box), Removed air silendcer), 198.9 rwhp @4200 (235 Motor!!), 285 lbs-ft @2900 (336 Motor!!!). My Stang My Site