I’m planning on changing the stock gearing on my 1997 GTS….my 2019 392 Challenger with a manual transmission (6 speed tremic) and 3:90 gears was an absolute animal, it ripped. My Vioer is fast, but the stock 3:07 gears leave a lot on the table. Could you guys please give me some advice. It’s solely a street car with no track duty in its future. I just want it to be able to hold its own on a street drag race. Thanks guys.
Which gearing is the best all around…3:55 or 3:73 (1997 GTS)
- Thread starter yzf1999
- Start date
GTS Dean
Enthusiast
3:55 is a very popular gear. Some have done 3.73, but you'll be rowing through the box constantly.
redtanrt10
Enthusiast
3.55’s are the most common gear swap or upgrade. If you do some searching you’ll find many threads in this subject
I have the 355/30/19's on my rear also with stock gearing and both performance wise and visually it kind of bothers me, so rather than jumping straight to gears I'd like to go to 345/30/19's first. Bummed there is no 335/30/19. My question would be if anyone sells a straight diff swap, or if it's better to just rebuild the old with new gears.
There's really no one size fits all with gearing. It's always going to be dependent on what your priorities are, how much rpm you can tolerate on the highway and what speed you normally cruise at, what kind of driving you mostly do and also aspects of the car like tire diameter and engine mods (stock cam, big cam, turbo, blower etc...)
With that said, with the .50 final OD ratio of the Viper T56, I wouldn't worry too much about RPM on the highway unless you like to cruise at 100 lol. Even with a 3.73, you'd only be turning about 2k at 80mph with a 26" (stock 335/35/17) diameter tire.
As far as holding its own in a street or drag race, there's a few things you must consider.
For a 1/4 mile you'll want to be crossing the traps in 1:1(4th gear) and ideally you'll want to be crossing the line just at or a little above peak HP. Not knowing your mods, assuming the car is stock and traps around 118-120 for a gen 2, a 3.73 puts you across the traps at around 5700 RPM. With peak HP on a stock motor coming at around 5200, that's a good stretch past redline and means you'll either be winding it out well after power drops off or you'll be shifting into 5th, either one being detrimental to your 1/4 mile time. So while the 3.73 should allow the car to accelerate to that point quicker, you'll likely lose any benefit in ET due to running out of power band.
A 3.55 should put you across the traps at around 5400 which is just a little over peak power, and should be more ideal.
For a street race, it really depends, since there's no set stopping point. Typically, if racing on the highway, you'll want a taller gear since it'll allow you to complete the race in a lower trans gear without having to upshift into a higher gear, losing leverage and falling out of your power band. Example, if you're racing say 60-130, you may even be better off with a stock gear as either a 3.73 or 3.55 will be forcing you to shift into 5th before hitting 130, and your rate of acceleration will plummet as you drop out of the power band into the bottom of a very tall overdrive gear. and you'll watch the corvette pass you just as you're needing gear optimization the most.
Last factor to consider is on the street, how much traction can you get? 3.73 is a pretty big jump from a 3.09 and with the torque of a viper, it'll likely make hooking in first gear from a dig difficult on any sort of steetable tire on an un-prepped surface. It'll be a blast to drive if you like blowing the tires off with ease, but you'll probably end up losing most races from a dig due to lack of traction. Starting line ratio would be about 9.7ish which normally I'd say is ideal, but not on a car as light as a viper with a motor generating freakish off idle torque unless you roll around on some real sticky rubber.
Personally, for those reasons, I would think 3.55 would probably be better for what you're trying to do, but again, everything I just mentioned changes slightly depending on tire height (significantly taller tire may warrant a steeper gear) or if you're making significantly more power than stock (which may warrant a taller gear).
With that said, with the .50 final OD ratio of the Viper T56, I wouldn't worry too much about RPM on the highway unless you like to cruise at 100 lol. Even with a 3.73, you'd only be turning about 2k at 80mph with a 26" (stock 335/35/17) diameter tire.
As far as holding its own in a street or drag race, there's a few things you must consider.
For a 1/4 mile you'll want to be crossing the traps in 1:1(4th gear) and ideally you'll want to be crossing the line just at or a little above peak HP. Not knowing your mods, assuming the car is stock and traps around 118-120 for a gen 2, a 3.73 puts you across the traps at around 5700 RPM. With peak HP on a stock motor coming at around 5200, that's a good stretch past redline and means you'll either be winding it out well after power drops off or you'll be shifting into 5th, either one being detrimental to your 1/4 mile time. So while the 3.73 should allow the car to accelerate to that point quicker, you'll likely lose any benefit in ET due to running out of power band.
A 3.55 should put you across the traps at around 5400 which is just a little over peak power, and should be more ideal.
For a street race, it really depends, since there's no set stopping point. Typically, if racing on the highway, you'll want a taller gear since it'll allow you to complete the race in a lower trans gear without having to upshift into a higher gear, losing leverage and falling out of your power band. Example, if you're racing say 60-130, you may even be better off with a stock gear as either a 3.73 or 3.55 will be forcing you to shift into 5th before hitting 130, and your rate of acceleration will plummet as you drop out of the power band into the bottom of a very tall overdrive gear. and you'll watch the corvette pass you just as you're needing gear optimization the most.
Last factor to consider is on the street, how much traction can you get? 3.73 is a pretty big jump from a 3.09 and with the torque of a viper, it'll likely make hooking in first gear from a dig difficult on any sort of steetable tire on an un-prepped surface. It'll be a blast to drive if you like blowing the tires off with ease, but you'll probably end up losing most races from a dig due to lack of traction. Starting line ratio would be about 9.7ish which normally I'd say is ideal, but not on a car as light as a viper with a motor generating freakish off idle torque unless you roll around on some real sticky rubber.
Personally, for those reasons, I would think 3.55 would probably be better for what you're trying to do, but again, everything I just mentioned changes slightly depending on tire height (significantly taller tire may warrant a steeper gear) or if you're making significantly more power than stock (which may warrant a taller gear).
Last edited:
Gibz
Enthusiast
All running 3.55, myself included, seem happy with the balance. You might want to plan a speedometer calibration as part of the gearing change so your speed and mileage accumulation are accurate. I did a yellowbox but I believe you can have your ECU reprogrammed.
It’s not the wheel size that is directly affecting the gear ratio, it’s the overall tire diameter.. Factory 335/30r17’s are about 26” and the 355/30r19’s are 27.5”.. Some simple math and you end up with final ratio..
For 3.73 gears
26/27.5 =0.945
.945x3.73=3.525 final ratio
Gibz
Enthusiast
I bought the "Yellow Box YBX with Splice Harness" directly from them at the site below. $140 to my door. They answered some questions I had well, sent clear directions, good experience from me.
You do have to splice into your wiring harness which I did not want to do but it went fine.
It is a PWM signal modifier that you calibrate yourself so whatever gear ratio/tires size you have you will be able to get the speed right. I ran with my phone GPS and changed the calibration switches (manual switches on the outside of the programmer) until I was dead on.
website: www.YellR.com
email: [email protected]
You do have to splice into your wiring harness which I did not want to do but it went fine.
It is a PWM signal modifier that you calibrate yourself so whatever gear ratio/tires size you have you will be able to get the speed right. I ran with my phone GPS and changed the calibration switches (manual switches on the outside of the programmer) until I was dead on.
website: www.YellR.com
email: [email protected]
I've found when changing gears its sometimes good to change to a gear drive (Tru-Trac) limited slip unit in the Gen 1-2's. More so if you drag race and run slicks.
The factory clutch LSD tends to break the spider gears and the clutches needs tuning. The second weak point is the half shafts. Once you upgrade those
you can run a smaller wheel with a wrinkle wall drag tire or a drag radial without issue. You will be amazed how many cars you can beat in the 1/8th mile.
With the stock clutch you got to let it out all at once or you will burn it up. Best choice is the heavy stock flywheel and the Mcleod double disc.
For road racing this all applies, the gear driven LSD is better out of the corners, but a lighter flywheel works better and the are many other lighter single, double and triple
disc setups that work great. The engagement can be a learning curve.
Hope this helps.
The factory clutch LSD tends to break the spider gears and the clutches needs tuning. The second weak point is the half shafts. Once you upgrade those
you can run a smaller wheel with a wrinkle wall drag tire or a drag radial without issue. You will be amazed how many cars you can beat in the 1/8th mile.
With the stock clutch you got to let it out all at once or you will burn it up. Best choice is the heavy stock flywheel and the Mcleod double disc.
For road racing this all applies, the gear driven LSD is better out of the corners, but a lighter flywheel works better and the are many other lighter single, double and triple
disc setups that work great. The engagement can be a learning curve.
Hope this helps.
Viper Swag
Enthusiast
Thank you so much Dan cragan for all your wisdom knowledge and for sharing this. You're one of the best. You are the goat. Thank you so much sir
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