Ok, so I knew that ther was a slight difference in final gear ratio from teh 5AT to the 6MT, but I had no idea that it was this big. In my 5AT it used to rev about 2500RPM (at 130Kph) while my 6MT revs about 2800 at the same speed.

Here are some specs that I pulled:
6-speed manual transmission
1st - 3.933
2nd - 2.478
3rd - 1.700
4th - 1.250
5th - 0.976
6th - 0.771
Reverse - 4.008
Final Drive - 3.286

5-speed automatic transmission
1st - 2.563
2nd - 1.551
3rd - 1.021
4th - 0.653
5th - 0.470
Reverse - 1.846
Final Drive - 4.428

So... here is my problem... according to the specs... the 5AT has a higher ratio and should therefore rev higher at the same speed as the 6MT.

 

Final drive ratio is the differential gear ratio. You still have to account for the transmission gear ratio.

The effective ratio is the final drive X gear ratio.

6sp=2.534
5mt=2.08

So the higher ratio is the 6sp which, as you said, does rev higher.

Now when is sombody going to make some lower gears and a LSD for the AT?

 

Yeah the important figure is the effective gear ratio, as roo said. As you can see the 6spd is alot more tightly spaced vs. the 5at.

 

yeah but in a top speed test with the limiter removed and the car set up right the 5AT trans would leave the 6MT in the dust, i think i figured out the top speed to be something like 180 vs 220 or something, i did it a while back.

 

Thanks... that makes sense!

 

Theoretically... you may be correct in the math, but remember that final speed is not just a function of gear ratios, but also power (and therefore ability to get there) and with the stock 5AT laying down 20hp less than the 6MT, it is unlikely that it would be left in the dust

 

Theoretical top speed:

6spd = 207mph
5at= 251mph

Thats redline in top gear. Yeah, so thats pretty much worthless since both cars would need alot more hp than they are capable of to reach redline in top gear.

 

ok i though it was something higher, i just didn't remember i should have said all thing being equal with a car built up right in a top speed test the auto would take it.

 

This is a quick chart I made some time ago; 2002 timeframe.

 

You'd need un-Godly amounts of horsepower to even come close to 200 MPH

 

Actually supra guys do it all the time around 600+hp... So its possible but I dunno about a CL doing it. I think aerodynamics would be the biggest setback...

 

So why is it that auto's get a better launch than 6 speeds? Given the lower ratio with the auto, one would think that they would be at a disadvantage. Is it related to best ratio / HP combination for traction?

Steve... you must have a hell of time launching with all that HP. I have a hard time with a normally aspirated 6MT.

 

I beleive you are confusing numerically higher ratio number with the actually ratio. The higher the numerical value the shorter the gearing.

As per the numbers I provided, the numerically high overall ratio of the 6MT, 12.924, is actually a shorter gearing ratio than 5AT, 11.349.

So the 6MT has a shorter 1st gear. Combine that with a solid connection, a torque converter in an automatic is somewhat forgiving when launching as it is a fluid connection, to the drive wheels makes launching more difficult. Your only option at launch is the work the clutch to smooth the power delivery, a torque converter takes care of that in an automatic.

 

When I had my CL-S6 SC/IC (369 WHP and 310 WTQ) I was finding that launching in 2nd was giving me quicker results. I just couldn't control 1st well enough to do anything other than just spin at anything more than 1/2 throttle.

 

It's all about tire selection and throttle control. Stock tires suck. Stock size tires suck. With a 235/45 Falken tire I can actually start out soft, go WOT by 2500rpm and get traction all the way up to around 6000rpm where it will break loose again.

 

Awesome

 

Thanks Scalbert... I can understand having to launch in 2nd to avoid just sitting there and spinning... although that does tend to scare the hell out of the competition. The autos having a lower ratio (higher gearing) for first are sort of doing this.

I also agree with your earlier point re the fluid connection in the auto rather than the solid connection on the 6MT. Makes it a lot easier to launch an auto. Too bad that Acura doesn't make an auto that holds up.

 

Speaking of traction, I did some runs not too long ago in the S4 to test my GTech Comp RR which the girls got me for Father's Day. I was happy with the results considering it was 85 degrees out and at 1300'. I should be able to drop 0.5 seconds off this, maybe more, with cold weather, down pipes and exhaust. This was with just the GIAC X Chip.

As you can see, it is nice having traction for low speed acceleration. The highway pull pales in comparison to what my CL-S6 SC/IC would do.

Speed Chart

Gs Chart

Oh yea, I tested the //M Roadster and got 5.4 seconds to 60 MPH in three seperate test runs. I got 8.9 in the Sienna with the girls and Jennifer in the car with the AC on. So it seems to be pretty close to actual.

 

Agreed, the stock Michelins are total crap. I had the ES100's on my 01 CLS and they were great. I currently have the Toyo TPTs (inherited from previous owner) on my 6MT and I don't like them at all. Which model of Falkens are you running? I tried some on my 01 and they were a really hard tire and I found edge to edge cornerning unpredictable (non linear). I would be going through S curves and the transition point was not smooth and kind of "flipped" from one side to another.

 

what about Bridgestone Potenza SO-3's? 225/40/18 I have them equipped.....are they as good as falken tires???

 

Those are supposed to be very good tires. My dad has a set of RE090s, which is a lower version of them on his 87 325is, and with just the tires (we went down one size) and a suspension, we can take off-ramps at 80 mphs and the tires won't even squeal. Granted its a lighter car and RWD, but its still impressive.

The only thing I would look to see is if they meet the load rating required by the CL, as it is fairly high (93 I believe) compared to many other cars.

 

The pole posistions are extremely soft and will not last very long at all (think 15,000 miles). However they are supposed to be amazing in the corners.

I'm running the Falken Ziex 512 in 235/45 on stock rims. Happy for now.

 

how much does the Falken tires go for $$? and were can I get those tires? I see that tirerack doesn't sell them....I've been hearing a lot from people that they are the best...including Import magazine's and D-1 drifting applications

 

I have always thought that 5th gear on the 6MT was kind of useless... I often shift from 4th to 6th. Graphing the ratios explains why...

It also explains why the 5AT is such a dog in 4th...

 

I also often skip 5th, figure less shifts = less clutch wear.

 

The wind resistance after 150 mph becomes exponential and your HP's must increase almost exponential to get anywhere near a speed like that. Just watched a video on the Bugatti Veyron. 1001 HP. The guy narrating said it only used 250 of the available HP to get it to 150 MPH, however, it took the other 750 ponies to get to 240 mph. wind resistance is the main reason most street cars won't go over 150.

 

i see someones cl came with a brand new shovel.

 

Who's?