bobatimez

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-Rz-UA5

According to my limited knowledge, the closer the gear ratio, the faster the accelaration is..... but less top speed...
Just like Impreza, their tranny is FAST because they got close G-ratio...

Anyone correct me if i m wrong..

RAdams

Gears effectively multiply the torque available at the wheels of the car. More torque = more acceleration. A numerically higher number represents a "short" gear and gives the most torque multiplication. A numerically lower number represents a "tall" gear and results in less torque multiplication. Anything numerically smaller than 1.00 is an overdrive gear and, if we remember math class, when you multiply by a number less than 1 you're actually dividing... so you can see what happens to torque multiplication in this sense.

The 2000+ TL's gear ratios are:

1st: 2.563:1
2nd 1.551:1
3rd 1.021:1
4th 0.653:1 (This is an overdrive gear)
5th 0.470:1 (Another overdrive... )
Final Drive 4.428:1

To calculate effective gear ratio, multiply the ratio of the actual gear by the final drive ratio. The effective torque multiplication in first gear is ~11.35 (2.563 X 4.428) whereas in, say, 4th gear it is ~2.9 (0.653 X 4.428). This gives you an idea of why your car accelerates faster in first gear than fourth gear.

With that being said, a "taller" gear allows for a greater speed in that gear, which is why despite the fact that first gear accelerates the car faster than fourth gear does, the car is obviously able to reach higher speeds in fourth gear than in first.

The trick is to design a transmission with ratios that are suited to the powerband of the engine (i.e. an engine with more torque can "pull" taller gears more effectively than an engine with less torque). The "spacing" of the ratios [read: The numerical difference between each successive gear] is also very important... well-spaced gears will not allow the engine to fall out of its powerband (or VTEC for that matter). In the TL transmission, they went for more economy than performance which is why you'll read a lot of complains about the car's acceleration dying off past ~100MPH. This is where the transmission shifts into 4th gear (an overdrive).

I think I touched on everything (too much?) but I'd rather be thorough than terse. Enjoy!

Nate

Very good explanation RAdams! What would it take to fix 4th gear?

jdl75

Excellent explanation. I couldn't have done better myself. For all you horsepower junkies, notice he never said a word about HP in acceleration

A very good question. Not as easy to do in an automatic, but when the 6-spd comes out, I suspect some interest in swapping ratios. Anyone interested?

eujinc

Good explanation. Can we put this in the FAQ?

RAdams

As jdl75 suggested, ratio swapping isn't all that easy (in an automatic anyway) but our big brother Mister MDX has a shorter 4th gear than we do (0.727:1). Assuming it fits, I'm not sure if the ratio difference is significant enough to justify the time and expense of swapping it since it, too, is an overdrive.. but it's a little shorter nonetheless.

Also... I'm glad you tech junkies enjoyed my explanation. I'd be honored if it was added to the FAQ

jdl75

With th eMDX being a 5-spd, I'm almost certian it would fit. Honda tries to keep as few different parts bins as possible. Anything would help the sudden lack of acceleration when shifting into 4th!