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Discussion Starter · #1 · (Edited)
After owning a few dozen "sports" cars/trucks, I know the benefit of Gears and/or a Stall Converter. One basic example would be my 2000 Camaro SS. With a $400 3200rpm Stall, I gained .7 in the quarter mile, all while increasing the fun and driveability on the street. Same goes for my Turbocharged Denali (3400 Stall).

We've all owned or been in a Mustang with gears (I've had 4 of them) and know what a HUGE gain in performance these give without affecting fuel economy or driveability much if any.

Why aren't there any Stall Converters made for our cars yet? Even a simple "reflashed" stock converter? They usually cost $300-$800 plus install. Gears are usually in the $180-$400 range plus install. With the power characteristics of our cars, either one would make a huge difference.

Any thoughts?
 

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3200 stall = maybe 10 mpg in the city.


No thanks.


They'll be out soon, the LX platform is still new, and besides, the other cars that had our transmissions were Benz's. I don't think that's a great market for such components.
 

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Discussion Starter · #3 ·
vvv90 said:
3200 stall = maybe 10 mpg in the city.


No thanks.


They'll be out soon, the LX platform is still new, and besides, the other cars that had our transmissions were Benz's. I don't think that's a great market for such components.
My city MPG did not change 1mpg in the Camaro, or the Denali. Believe me, I check these things before/after very thoroughly. Remember, to get the same "quickness" off the line with a factory stall requires more "gas" then with a higher stall. It's a wash. There was always talk about loss of MPG with gears too. The worst change I saw was 1mpg, and that's close enough to be driving conditions.

I hear you on the newness. Whoever comes out with these parts first should make some money. I'm just wondering who that will be? :biggrin:
 

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Weedo said:
My city MPG did not change 1mpg in the Camaro, or the Denali. Believe me, I check these things before/after very thoroughly. Remember, to get the same "quickness" off the line with a factory stall requires more "gas" then with a higher stall. It's a wash. There was always talk about loss of MPG with gears too. The worst change I saw was 1mpg, and that's close enough to be driving conditions.

I hear you on the newness. Whoever comes out with these parts first should make some money. I'm just wondering who that will be? :biggrin:


Well then you've got me awefully confused and you're the first to ever say there was no change in MPG with a high stall convertos that I've ever heard of. Afterall, you're losing a lot of energy due to the fact that the convertor is constantly slipping under 3200 rpms. My friend has a really high one on his mustang. It's so high in city driving he's never running in full lock.

Maybe I'm missing something.

I agree with the gears however. Most people assume you will get worse MPG but with a 5 or 6 speed you will no notice anything unless you're cruising at 90MPH on the highway.
 

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vvv90 said:
3200 stall = maybe 10 mpg in the city.
I'm with Weedo on this one. I put higher stalls in two F-bodies I had and the milage didn't change. Both saw considerable gains on the track. We need to remember the modern PCM locks the converter at some point, so it really doesn't do anything at cruise speed.

I have probably mod'd our SRT-8 more than most owners ever will and I won't be doing a stall or much else on ours. Headers, what headers, would be the last thing I would consider ;)

Todd
 

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Someone just needs to take the rear-end gears from a base model 300 and put them in their SRT-8. That seems like a quick, easy first step.

Rear-end ratios:

300 Base: 3.90
300 Limited: 3.64
300C: 2.82
SRT-8: 3.06
 

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JMatt said:
Someone just needs to take the rear-end gears from a base model 300 and put them in their SRT-8. That seems like a quick, easy first step.

Rear-end ratios:

300 Base: 3.90
300 Limited: 3.64
300C: 2.82
SRT-8: 3.06
Is that really possible, though? I understand the SRT8 rear-end is different that the base and Hemi LX platform cars. Maybe it is just something simple, but it could be gears and housing. I would really like something around a 3.50:1 for ours.

Todd
 

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Update!!!!!

I just noticed that the upcoming Jeep Grand Cherokee SRT-8 uses the same transmission as the 300C SRT-8, but has a rear-end gear ratio of 3.73:1!!!!!

What are all the reasons we couldn't take the Jeep part, and put it under the 300C SRT-8? The Jeep weighs 600 pound more than us, has more driveline HP loss (4WD) has 15 less HP, yet goes 0-60mph in under 5 seconds? That rear-end should make a HUGE difference, and can obviously handle the torque, or it wouldn't be on the Jeep.

Thoughts anyone?
 

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JMatt said:
I just noticed that the upcoming Jeep Grand Cherokee SRT-8 uses the same transmission as the 300C SRT-8, but has a rear-end gear ratio of 3.73:1!!!!!

What are all the reasons we couldn't take the Jeep part, and put it under the 300C SRT-8? The Jeep weighs 600 pound more than us, has more driveline HP loss (4WD) has 15 less HP, yet goes 0-60mph in under 5 seconds? That rear-end should make a HUGE difference, and can obviously handle the torque, or it wouldn't be on the Jeep.

Thoughts anyone?
Solid axle vs IRS .... not so easy

Usually gear selection from the OE level is for fuel economy and strength. Numerically higher ratio gears mean less contact area for the ring and pinion.
 

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I'm pretty sure that the rear carrier in the Jeep is not the same size, and not as HD as the one in our LX SRT8s. It simply doesn't need to handle the same amount of torque, as a good chunk of the power is going to the front axle.
 

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WhiteDiamond said:
I'm with Weedo on this one. I put higher stalls in two F-bodies I had and the milage didn't change. Both saw considerable gains on the track. We need to remember the modern PCM locks the converter at some point, so it really doesn't do anything at cruise speed.

I have probably mod'd our SRT-8 more than most owners ever will and I won't be doing a stall or much else on ours. Headers, what headers, would be the last thing I would consider ;)

Todd

Ok, therein lies the difference probably. My examples of high stalls were on vehicles not PCM controlled. This is the first auto hotrod I've owned also, I've always been a manual guy....I'll do my research.

IF MPG and driveability aren't hurt, it might be a mod for the future afterall.
 

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3.73's sound like a great option for our cars .... I'd love to do'em .....

What rearend does the Charger SRT-8 have ? The same one as ours ? Or is it shorter ?
 

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JMatt said:
Someone just needs to take the rear-end gears from a base model 300 and put them in their SRT-8. That seems like a quick, easy first step.

Rear-end ratios:

300 Base: 3.90
300 Limited: 3.64
300C: 2.82
SRT-8: 3.06
More info on the LX rear gears.
In my LX service manual there are 3 rear axles listed.
198 MM RII
210 MM RII
215 MM RII

"The 198 axle is available only in all-wheel-drive (AWD) models, and in V-6 engine-equipped rear-wheel-drive (RWD) models, and is available in three gear ratios: 3.07 3.64 & 3.90:1."

" The 210 MM is available Only in V8 engine-equipped models with a 2.82:1 gear ratio."
The 215 MM does not give ratios or application information but I figure it is the SRT8 version. Because I’m assuming that the names are the ring gear diameter. 198 MM (7.79"), 210 MM (8.27"), and 215 MM (8.46").
All are listed as open differentials. I really don't think a 7.79" ring gear will hold up behind the either Hemi.

The gears are not interchangeable. But the whole rear ends can be swapped.
Good luck getting the computer calibrated.
It would probably be easier having a custom rear end made with the gear you want and a Posi unit.
 

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Here is another way to look at it.
Here are the shift points in mph for each rear-end gear ratio for both R/T and SRT.

R/T shift rpm 5400
-----------2.82------3.06-----3.42------3.73-------3.92

1st gear---45.8------42.2-----37.8------34.6-------32.9
2nd gear---74.4------68.6-----61.4------56.3-------53.5
3rd gear---115.6----106.5-----95.3------87.4-------83.2
4th gear---------------------134.0-----123.2------117.3

SRT-8 shift rpm 6000
-----------2.82------3.06-----3.42------3.73-------3.92

1st gear---50.9------46.9-----41.9------38.5-------36.6
2nd gear---82.7------76.2-----68.2------62.5-------59.5
3rd gear---128.4----118.4----105.9------97.1-------92.4
4th gear--------------------------------136.9------130.3
The bold is intended to highlight the last gear you would use in the 1/4.
 

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SRT8itchy said:
I'm pretty sure that the rear carrier in the Jeep is not the same size, and not as HD as the one in our LX SRT8s. It simply doesn't need to handle the same amount of torque, as a good chunk of the power is going to the front axle.
If they were the same MY assumption woudl be that the Jeep part would be as HD if not more than the LX ... The Jeep Cherokee SRT8 has the same motor and MORE GVW.
 

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maneval69 said:
SRT-8 shift rpm 6000
-----------2.82------3.06-----3.42------3.73-------3.92

1st gear---50.9------46.9-----41.9------38.5-------36.6
2nd gear---82.7------76.2-----68.2------62.5-------59.5
3rd gear---128.4----118.4----105.9------97.1-------92.4
4th gear--------------------------------136.9------130.3
I'll take the 3.42:1 gearing, then....Who do I need to see about machining a gear? Who wants to pay for that work :D

Todd
 

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WhiteDiamond said:
I'll take the 3.42:1 gearing, then....Who do I need to see about machining a gear? Who wants to pay for that work :D

Todd
I posted the responce that Richmond Gear provided when I asked them about cutting gears.
link to Richmond Gear thread.
 

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btlfed1500 said:
If they were the same MY assumption woudl be that the Jeep part would be as HD if not more than the LX ... The Jeep Cherokee SRT8 has the same motor and MORE GVW.
and the Cherokee SRT8 has a faster 0-60 than the SRT8 cars.
 

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I've been saying gears gears gears for awhile now...

In my 94 stang, after the gear swap, even though I installed the proper speedo gear, there is a VSS (veh speed sensor) in the computer - I was bouncing off the 6,250 factory rev limiter after the swap at 5,450 rpms on both the street and on the dyno. It would hit 5,450 rpms and just shut down. It took a custom chip to fix it.

With the complexity of the computer's in the 300C - I wouldn't even attempt the gear change unless you can reprogram the changes.
Gears would be my next mod if available, but not without proper reprogramming - too many issues if you don't.
 
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