Gear ratio
 

If there is one place I may toy around on mine it's the gearing. I'm assuming it will have 3:06 or so based on Viper and Charger configurations. If a a 6speed, some much steeper gears can be had and still be highway friendly. I'm thinking 3:73 on the low side and 4:10's possibly.

Be interesting to see what limited slip unit they use as well??

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To get the same final drive ratio the A580 transmission has with in the SRT-8 cars. They could easily use a 4.10 rear-axle with the top .5 overdrive that the T-56 Tremec has and still be ahead.

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Lets hope that the rear end ratio option will be available. I'd like a 410 or 411 please.

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Agreed. It is interesting that the Shelby GT 500, w/ 6 speed is a 3:31 final ratio. I suspect the main culprit is EPA. Can't meet the mileage and emissions output limitations turing the gears we're thinking...just a guess.

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Do you think that is why the factory usually doesn't have the rear end ratio as an opton anymore is because of the EPA? To get the millage. You'd think that the factory would have the one gear as standard for all the cars and then have an optional gear or 2 for people who wanted it. You can still order the gearing in trucks. Probably for different pulling/hauling situations.

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I've wondered about that one quite a bit. Probably the EPA won't let them have a lower-speed axle due to the increased fuel consumption. I wish we could get rid of the EPA. They have screwed cars up.

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While I would like a higher rear end ratio....I would really like to see a 6th gear that will put the rpm's at around 2K for highway cruising. Not only for gas consumption (what a laught)
but to minimize wear on the engine. I plan to keep it a long time.....maybe pass it on to the kids.

Jeremiah 29:11

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The 6spd gearing even w/ 4:10 should place your Chally at comfortable cruising speeds...especially for a HEMI to withstand;)

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If I can get 2K RPM at highway cruising speeds then 4:10 gear ratio has my vote.

What is real cool are some of the cars do not need shifting into 2nd gear until 60-70 MPH. Mostly because they have a lot of torque and the gear ratio is not too high.

As a result, they beat other cars at the start and win because there a fewer gear changes since they win in 2nd gear.

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If I understand correctly about how transmissions work, then a 4.10 rear-axle shouldn't be a problem with the transmission they are planning on using. The T-56 Tremec has a .50 gear ratio for 6th gear resulting in a 2.05 final ratio which is much better than the SRT-8 models have with their 3.06 with the .83 overdrive offers about a 2.54 final drive which means it would probably run at a lower rpm with the manual because of the top overdrive ratio is much taller, to where it will off-set the lower speed axle-ratio of a 4.10.

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Well hear are some 1st Gear numbers if you can read the image.

[IMG]local://upfiles/17/8A893A18158347DFA6B200CDE5540F14.jpg[/IMG]

RE: Gear ratio
 

Here are some 6th Gear numbers. I guess I get my 2K RPM range at 70 MPH in 6th Gear with a 4:10 gear ratio.

[IMG]local://upfiles/17/8498831353E04635931E1FEF4D221E3D.jpg[/IMG]

RE: Gear ratio
 

I wouldn't be surprised if it can because the gearing on the T-56 is very tall in comparison to many manuals used in trucks and some European performance cars, or the A580 transmission for that matter.

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For drag strip and automatic is the way to go, but I plan to do more with road handling hence I prefer a manual tranny.

"Dave Smith of Factory Five Racing said there are numerous reasons to install a standard transmission in your kit car: "A Cobra replica with a manual transmission has a better resale value because that is how the original car was configured. Therefore, typically, buyers looking for a Cobra replica will look for a stick shift, but if you are going to do hard-core drag racing, you cannot beat an automatic transmission. For road racing and autocrossing, I believe you need to have a manual transmission. For driving on the street, it is personal preference. I prefer the manual trans because it is more period-correct. An automatic in your daily driver may be more convenient, but banging a four-speed is a lot more fun for me." "

For road handling I believe manual is the way to go. Kit car builders who understand that you put 15 to 20 percent more power to the ground in a manual than in an automatic, as there is very little parasitic loss in a manual trans system. Heat is parasitic loss, plus you link power to the ground instantly in mechanical coupling (manual) as opposed to hydraulic coupling (automatic). Another key point is that manual transmissions can be 99 pounds lighter than an automatic, and some automatic systems weigh as much as 200 pounds more.

Every 100lbs can be .1 seconds off of ET times

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Very true! I don't think it matters what you do, manuals I believe are always going to be superior. I don't think you can match them. They are less convenient but a better design.

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while i agree that the manual is more efficient, your numbers are bit off...a manual trans is not 15 to 20 percent more efficient based on whp...unless im unclear on what numbers youre using...ive seen an MTX car dyno 5-8 percent better based on bhp..but not 20%


and in the event of some cars, the auto is better for the track, especially older cars. old MTXs were crude and inefficient...ive seen someone take a high 12 second cuda, and swap in a 4 speed, and slow the car down quite a bit. while its more efficient than the 727, it isnt as fluid, and time is lost in shifting...hell, even the fastest LS1 based GM cars have automatics...i know a guy who has a built 02 camaro, and when he went from the mtx to a built atx, he went from 12.1s to 11.80s...

RE: Gear ratio
 

The fastest LS1 based GM cars have automatics? What? The numbers I have always seen show the manual transmission as being faster consistently every time. Sometime it depends on the person using the manual. Even people who are supposed to be experts aren't quite as good as others.

RE: Gear ratio
 

The 15 to 20 percent #'s are from Factory Five and they know their stuff because they decide those things all the time in building cars.

Your 12 second Cuda is obviously for the 1/4 mile drag strip and I am talking about talking the road. Automatics are very consistent for the drag strip but if you want to feel the road
you need a manual tranny.

RE: Gear ratio
 

I think Dodge will set it up so you will only shift once to get to 60mph. One set up for the automatic and one set up for the 6-speed. They will do this for the 0-60 times that most car mags will test. Just my opinion and we all know what that means.

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What was cool was the older Ford GT40 could hit 93 MPH in 1st gear alone.

No wonder they would win in the quarter mile when they were not racing in Le Mans.

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You learn something new everyday. I never knew that, of course back then 1st gears were much taller than they are today so that isn't too surprising. Back then they were about as tall as second or third gear in most 6-speeds, weren't they?

RE: Gear ratio
 

The old versions had several different ratios on the Mach I,II,III, IV versions. My favorite was the Mach II.

What was amazing was these cars weighed around 2500 lbs, would generate 475 HP and many time much more at 5K RPM.

On one of the older version the ratios were:

TRANSMISSION
Type ZF 5 DS-25 Transaxle

Ratios Final Drive 4.22 : 1

(Optional) 3.33 : 1

Gearbox First 2.42 : 1

Second 1.47 : 1

Third 1.09 : 1

Fourth 0.96 : 1

Fifth 0.85 : 1

Reverse 3.75 : 1

On the Recent version it was:

Type 6-speed manual
Gear Ratios 1 - 2.61
2 - 1.71
3 - 1.23
4 - 0.94
5 - 0.77
6 - 0.63
Reverse - 3.135

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Wow! Which final drive did the one that went 93 mph have?

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Here are the specs for the old 1966 GT40 in the 1st column and a GT40 Superformance replica in the 2nd column:

SPEED IN GEARS

mph @ rpm
1st 89 @ 6200 53 @ 6400
2nd 140 @ 6200 85 @ 6400
3rd 170 @ 6200 120 @ 6400
4th 205 @ 6200 161 @ 6400
5th N/A 207 @ 6230

ACCELERATION

Time to speed
0-40 mph, sec 2.8 2.1
0-60 mph, sec 4.2 3.7
0-80 mph, sec 5.6 4.8
0-100 mph, sec 8.2 6.9
0-120 mph, sec 10.8 9.2
0-140 mph, sec 14.0 11.8
0-160 mph, sec 19.1 15.3
0-180 mph, sec 27.0 21.7

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That was one impressive car especially for its time. I wish Ford could have put in the same level of effort into the GT.

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Man, pretty impressive findings since I first posted this thread. Never would have TRULY expected 3:92 gears w/ the 6 spd as rumored. I know, that's w/ 20" wheels, but still, some serious gears behind a stick! Just wish it was a solid axle...personal preference. And man, can you imagine if they offered a Dana as an option??? Sweeet.

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I'm also surprised by this and in some ways disappointed. As much as I would like the advantage of this kind of axle ratio, it is going to lack the potential of getting good enough fuel economy to get past the gas guzzler tax.

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Yep, but as we know, even w/ 3:06 and automatic they slapped the Guzzler tax. It is inevitable, especially the way the CAFE standards are headed. Ugh

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Well the issue with the pair up with the 3.06 axle with the W5A580 is because of the gear ratios. This is one of my biggest grips about that MB sourced transmission. 5th gear has a ratio of .83. Most other 4-speed automatics have an automatic of around .69, and this 5-speed was built for performance while not really adding speed to the LX cars when comparing it on the V6 models where they keep switching back and forth between the 42RLE 4-speed and it. If the gear ratios were more wisely chosen, the mid 20s would not be unrealistic If they were to give it ratios like GM gave to the Firebird/Camaro or Corvette, we would probably get the best of both worlds.

I'm cringing about that one as well; however, that does not take effect until 2020 so we have 12 years to enjoy cars.

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Is it possible Dana would offer it directly as an aftermarket item?

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ive seen people run mopar 8 3/4" rears with 9 second cars...no need for a dana, just a properly built mopar rearend...and they dont come built that way...:D

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Damnsk,

I would not be surprised if DTS or other outfits that deal in Dana's might offer a swap out version. I also agree the 8 3/4 is plenty strong for the new Challenger too, just the Dana always came w/ hemi equipped, manual trans cars. Either one would be stronger than the Independent rear...as the Mustang guys can attest to.

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Here's one from Road and Track 4.6 on an auto vette' and 4.8 on a manual 0-60 so what you assume is very wrong both are LS1 cars.
These rumors everyone talks about with manuals is bogus a lot of cars now are becoming a lot more effienct with auto transmistions.
While I agree manual cars handle a little better many auto cars are hands down faster. It show's true with the LS2 GTO also with the auto takeing a manual hands down by about the same margin.
My Hemi in my truck had a final gear option of 3.73 i think and 3.92 I being understanding of gear ratio's at the time went with the 3.92 which was no more than a few hundred dollar option.
Im very suprised that there isn't a 3.92 option in the challenger and am almost dissapointed in the 3.06 honestly. I think there should be a choice most definatly. The CAFE standards are across the board we need to get some cars running on AIR:D so we can get the ratio's we should be paying for;)
Yeah Hemi's hold the gears for a long time two, second to third is fun as heck but you can hold third to forth FOREVER. Just some thoughts Peace...

RE: Gear ratio
 

They are saying the manual SRT's will have 3:92's so there is some hope. I believe automatics will stay at 3:06

RE: Gear ratio
 

Remember the transmissions they use may have a real short first and second gear. So the rear gear at 3.08 may be sufficiant. You might be getting into granny gearing if you go too short on the rear. That is one use of a manual 6-speed. Spread the gears out and use short gears 1-3 and taller gears 4-6. I'm not so sure this is what is being done but it is the reason for the addition of 2 more gears for the 4 speed. This way you have the convenience of a short gear on take off with the gears spread out to taller gears on top.

RE: Gear ratio
 

MrKrisSullivan, one example is not sufficient to completely prove anything beyond a reasonable doubt. First of all, did they test both of these cars back to back or were these tests done in different articles which you are comparing. Secondly, you have to take into account of human error, even if its a press outlet with "professionals" not everyone is as talented as the next driver. The reviews I read showed the GTO being faster with the manual over the automatic. There is still the scientific math that shows that they are less efficient, you can't just ignore that either.

Another point, the transmission in your Ram and the one that will be offered in the Challenger are not the same. You have a Chrysler 545RFE, the Challenger will have the Mercedes built W5A580. Your gearing is like this

1st..............3.00
2nd(up).......1.67
2nd(down)...1.50
3rd..............1.00
4th..............0.75
5th..............0.67

The one in the Challenger has the following:

1st..............3.59
2nd.............2.19
3rd..............1.41
4th..............1.00
5th..............0.83

The W5A580 is geared more for shorter gearing which means that if they want to maintain their current fuel mileage with the 6.1L, they will have to keep the gearing they have. The manual's numbers haven't been released yet, so we don't know which set of gears they will be using, but whatever it is. It certainly provides a much taller overall final drive ratio combined with the 3.73 axle ratio than the 2.82 and .83 combo found in the R/T, since the R/T will have the same HWY mileage despite not having MDS with the manual while the auto still has it. I would tend to think that the SRT-8s rumored 3.92 axle-ratio with the manual will probably translate into something like 20-21mpg on the HWY under the new standards.

lear4406: You are right. They have to be careful not to overdo it. I expect they will have close gearing on the manual and will hopefully be able to go to at least 60 while still in 1st gear.

RE: Gear ratio
 

Sounds like they are calibrating it pretty carefully because the other variable is tire size. I noticed the freshly released specs for R/T's and SRT's w/ Manual trans reference 3:73 w/ 18" wheels and 3:92 w/ 20" rims. In addition, they do point out that '09 automatics will have a "more aggressive low gear" for better launches. All this coupled w/ a truly "off button" for the EPS" just warms my heart!!