5 speed vs 6 speed?

[bratboy]

hey folks, I just joined and this is a first time post. I had a question about manual transmissions. Over the years I've seen more gears pop up in transmissions. Assuming the final drive ratios are the same and the lower and upper gears are the same...is there much fuel savings between a 5 speed and 6 speed manual?

[JockoT]

Welcome bratboy. A six speed transmission normally has a higher top gear, with the other ratios (sometimes) edged down slightly to make the most of it. As a result, the transmission is much more flexible with a lot less revs required for highway speeds. This makes for more economical highway driving, with a quieter, more refined environment.
I have a Honda Jazz with a 5 speed transmission and recently had a loaner of a 6 speed equipped Jazz. Highway revs were reduced considerably, with no appreciable change in flexibility around town.
I would far rather have a 6 speed transmission than a 5 speed, though I did find the gear change pattern took a bit of getting used to.

[bratboy]

Originally Posted by JockoT

Welcome bratboy. A six speed transmission normally has a higher top gear, with the other ratios (sometimes) edged down slightly to make the most of it. As a result, the transmission is much more flexible with a lot less revs required for highway speeds. This makes for more economical highway driving, with a quieter, more refined environment.
I have a Honda Jazz with a 5 speed transmission and recently had a loaner of a 6 speed equipped Jazz. Highway revs were reduced considerably, with no appreciable change in flexibility around town.


I would far rather have a 6 speed transmission than a 5 speed, though I did find the gear change pattern took a bit of getting used to.

I was looking at the pontiac vibe. I'd have to swap the final drive gears to march between the 5 and 6 speed and first and 5/6 match. It's the middle gears that are a bit different. I wonder if it would be better around town and in general.

[MetroMPG]

JockoT - in North America, there is rarely a fuel economy advantage in the "new" top gear. The bottom and top ratios are often the same.

(FYI for JockoT: Pontiac Vibe here = Toyota Matrix. Not sure if you got that model. )

bratboy - welcome to the forum!

If the top/bottom ratios are the same, but the different intermediate ratios let you spend more time in the tallest possible gear for your road speed, there would be a slight fuel economy advantage.

Were you considering going with a numerically lower final drive to reduce RPM? I did that in my Pontiac Firefly (Chevy Metro). Reducing RPM by 25% translated to ~5% better cruising fuel economy in top gear.

http://www.metrompg.com/posts/tranny-swap.htm

here do you do the majority of your driving? City or highway?

[Daox]

The top gear ratio is the same on the 5 and 6 speed transmissions on the Vibe. It is .725:1. The final drive is taller on the 5 speed though. Therefore, cruising on the highway you would be better off with the 5 speed.

You could swap in a C59 from an 98-02 Corolla. It has .725 5th gear and 3.722 differential gearing.

[Xist]

Have you checked out Pontiac forums? Perhaps Matrix ones, too.

In general, I find members here to be friendlier and more helpful than people elsewhere on-line, but unless you drive the same car as several other people in the forum, specific advice is less consistent.

There are 88 1996 - 2000 Honda Civic HXes listed on here and I still often go to dedicated Honda forums for help.

Daox, that sounds like the manual versus automatic situation all over again. Should we make this more efficient? No! Why not? Because I'm evil!

[JockoT]

The Toyota Matrix was never available in Europe. 6th gear here tends to be an overdrive. Must hark back to the days when classier cars would be fitted with a separate Laycock de Normanville overdrive unit. My Triumphs had them, activated by a switch on top of the gear lever.

[bratboy]

If this was going to happen I would swap out the final drive gears in the 6 speed so they would be the same ratio as the 5 speed. The only gears that would be different are the middle gears although I just noticed there was a uk trans that has a very tall sixth gear...

[MetroMPG]

JockoT: essentially this car is a tall Corolla hatchback. Same drivetrain.

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bratboy: sadly for us, that's almost always the case (taller gearing options in the Euro market) compared to how our cars are equipped.

[cRiPpLe_rOoStEr]

I'd still rather get a transmission with fewer gears and a wider ratio. Anyway, another matter of concern is that 5-speeds still were better rated for flat-towing and EOC.