3.73 gears

[viper1]

bit of a tech question, with 3.73 gears at what speed should i be at for every gear? 1=, 2=, 3=, and so on:confused:

[The_Greg]

I could tell you if you can tell me the Gen I/II gear ratios or if they are the same as Gen III/IV? I will do some googling also.

I built a calculator for Gen III/IV so could pop out these questions rapidly.

EDIT: Per first google source, they appear the same. (2.66, 1.78, 1.3, 1, .74, .5)

SO at 6k RPM, with 3.73 final drive, reported in MPH:
1st = 48.5
2nd = 72.6
3rd = 99.4
4th = 129.2
5th = 174.6
6th = 258.4

[JonB ~ PartsRack]

THE YEAR MATTERS

What speed should you be in? Gregs neat, theoretical calculator (minus mechanical and aero drag) predicts TOP speed.... for YOUR cruising speed consider this:

If you are used to an RPM range now with an OE 3:07 [Gen 1-2 ASSumed,] you would simply be revving 22% higher than you are now, at any given cruise speed.

So: 70 mph 1250 RPM in 5th would = 1525 RPM in 5th with 3:73; Or ~~1200 RPM in 6th with 3:73 at 70 mph.


Rule of thumb: With a 3:73, you will generally be driving in ONE GEAR HIGHER than you do now for a given situation.

A 3:73 "FEELS LIKE" you gained 22% more HP, by simply re-gearing the HP you have

[FrgMstr]

Here is a good gearing calculator. Of course you will need to put in your own values.

http://xse.com/leres/bin/gearratio?title=SS+%23670+with+MM6+manual+and+3.73 +gears&rpm=6500&mph=160&gear1=2.66&gear2=1.82&gear3=1.30&gear4=1.00&gear5=0.74&gear6=0.50&reverse=2.90&axle=3.33&tire=diameter&diameter=27.00&circumference=84.82&revs=747&section=&profile=&wheel=

[uvbnbit]

Stock tire diameter? I think i have a 373 gear around here somewhere if you need one

[The_Greg]

THE YEAR MATTERS

What speed should you be in? Gregs neat, theoretical calculator (minus mechanical and aero drag) predicts TOP speed.... for YOUR cruising speed consider this:

If you are used to an RPM range now with an OE 3:07 [Gen 1-2 ASSumed,] you would simply be revving 22% higher than you are now, at any given cruise speed.

So: 70 mph 1250 RPM in 5th would = 1525 RPM in 5th with 3:73; Or ~~1200 RPM in 6th with 3:73 at 70 mph.


Rule of thumb: With a 3:73, you will generally be driving in ONE GEAR HIGHER than you do now for a given situation.

A 3:73 "FEELS LIKE" you gained 22% more HP, by simply re-gearing the HP you have

Aero drag and mechanical loss only come into play in the real world time application of power. Drag will not change the relationship between engine rotations and tire rotations. But yes, its only theoretical, your results may vary :)

I am trying to develop the Excel sheet I have to help people better understand why different gears will be better, but I'm not done with it yet. It will also show you your theoretical acceleration. FWIW, 3.73 gears will put most gen Vipers over 1 g of theoretical acceleration in first gear. Stock, most don't go above 1 g. And most times a sticky tire can handle over 1 g too. This all comes into play when selecting gears!

[Sybil TF]

FWIW, 3.73 gears will put most gen Vipers over 1 g of theoretical acceleration in first gear.
I love mine! But my speedo is off and need to get that fixed.

[viper1]

gen II, asking this question because really dont want to damage anything when i'm downshifting, if im doing 120k on the highway in 6th and say i need to slow down to 80k where is it safe to shift down to 4th,5th 3rd?

[The_Greg]

gen II, asking this question because really dont want to damage anything when i'm downshifting, if im doing 120k on the highway in 6th and say i need to slow down to 80k where is it safe to shift down to 4th,5th 3rd?

You'll get the feel of the car when you drive it with the new gears - it will become instinct as to when to downshift. As far as what is appropriate, it kind of depends on your driving style.

120 kph = 75 mph
6th gear - 1700 rpm; 5th - 2400; 4th - 3400; 3rd - 4300; 2nd - ~6k; 1st - blown engine

80 kph = 50 mph
6th - 1100; 5 - 1600; 4 - 2200; 3 - 2900; 2 - 3900; 1 - ~6k

EDIT: D'oh, that's 3.55 gears, uhh... 3.73 would be...

120 kph
6th - 1800; 5 - ~2550; 4 - 3500

80 kph
6th - 1200; 5 - 1750; 4th - 2300

[viper1]

would shifting it to nutral and put in gear harm ?

[Ohiotj]

This is something I have been considering for my 93. It seems like each gear drags on forever. And I feel like the car doesn't rev up as fast as it should. However on the long stretch at mid ohio I am already in 4th gear before ever hitting the long straight. If I switched gears I think I would have to downshift to third in the key hole, then hit 4th and 5th on the straights. Don't know how accurate these thoughts are though. This is an upgrade I wish you could try it before you buy it. When I bought my 2013 challenger I went with an ugly wheel group to get 3.91 gears if I remember correctly. That made the fat pig seem a little more quicker to climb the rpm range.

[The_Greg]

would shifting it to nutral and put in gear harm ?

If you are asking if you push clutch in, move lever to neutral, then into gear, and the release the clutch.... then no. As long as you release the clutch slowly (do not 'drop' the clutch) you will be fine.

This was a strange question so I looked at your other posts... Says you haven't driven stick for about 10 years and the car currently has 3.73 gears and also came with a spare 3.07 rear end. I have to say, be careful! A wrecked G/W GTS will make us all cry, not to mention you could hurt yourself. Only drive how you are comfortable!

So with that in mind, I think the best for you would be to drive the car as is with the 3.73 gears. If you only downshift one gear at a time, and only when the RPMs drop to 1100 or 1200 (or what ever seems like it is bogging or the engine is struggling because its not revving fast enough) then you will be fine. Like I said before, you will get the hang of it. Then, after driving the car for some time and getting used to it, if you feel that the car is too high strung and you are shifting too often, or you want a lower cruising RPM in 6th gear, only then should you switch back to 3.07's. The 3.07's are really kind of a strange gear for the car, put in for emissions reasons IIRC. As long as you remain at relatively stock power levels, 3.73's will work.

[viper1]

ya I am babying it and what I meant was double clutching, clutch down put in neutral, release clutch, then clutch down and putting it into gear according to gear, speed, basically I just wanted to be sure as I'm slowing down on the highway how to downshift in the right gear so its safe and don't damage anything

[No hemi]

Greg do you have the numbers for 3.55's?, i just installed them on mine ( it's a whle different beast), and would like to see if it changes something for mine.

[gage]

ya I am babying it and what I meant was double clutching, clutch down put in neutral, release clutch, then clutch down and putting it into gear according to gear, speed, basically I just wanted to be sure as I'm slowing down on the highway how to downshift in the right gear so its safe and don't damage anything

Double clutching is the best way to downshift if your goal is limiting wear because you are pre matching the synchros and can let out the clutch more quickly, preventing the wear as the clutch engages the flywheel/pp

[JonB ~ PartsRack]

I love mine! But my speedo is off and need to get that fixed.



Splice-in digital Speedo converter box avail from VOA sponsors Unitrax [or PartsRack] for ~~ $139..... Thank You

PS in re USED gears: Once a gearset begins to rotate under load, even 100 miles or less, the teeth 'take a set' or "take a pattern" in the metal. The pattern depth depends on the accuracy of the lash-setup. A great setup is very quiet. Less-accurate setups can whine under Accel, Decel, or both, depending on the deviation.


But if you remove USED gears, it is IMPOSSIBLE to match the original lash-setup, and unless you have used gears (at least) polished, they will likely be NOISY. 3:73 more so than 3:55. So, save $ on used gears at your caution

[The_Greg]

Greg do you have the numbers for 3.55's?, i just installed them on mine ( it's a whle different beast), and would like to see if it changes something for mine.

3.55 numbers FYI:
120 kph = 75 mph
6th gear - 1700 rpm; 5th - 2400; 4th - 3400; 3rd - 4300; 2nd - ~6k; 1st - blown engine

80 kph = 50 mph
6th - 1100; 5 - 1600; 4 - 2200; 3 - 2900; 2 - 3900; 1 - ~6k

Top Speeds in each gear (6k rpm)
1 - 51.0
2 - 76.3
3 - 104.4
4 - 135.8
5 - 183.5
6 - 271.5

Sounds like I need to get with Jon and type up an 'ultimate gearing thread'... Haha!