Toying with idea of taller Metro 5th gear (to go with the already taller final drive)

[Christ]

Hopefully, the performance will be high above the price spec. (Compared to COZX2's set, that is.)

[HydroJim]

Did anything ever happen with this?

[MetroMPG]

It got back-burnerized.

Bit off more than I could chew. TMFP! (Too many projects!)

[serialk11r]

Jesus, your stock rpms are lower than mine, and your engine has 55% the displacement of mine...definition of jealousy right here 230 dollars for an OEM 0.725 gearset is a bit steep for my sparse driving.

[MetroMPG]

Yes, and it still revs too high on the highway!

(Note: it's not the stock RPM though - I've already swapped in the taller final drive from a 1.3L version of this drivetrain.)

I'm pretty sure the Insight's stock gearing is even taller than the Firefly's - I should check that...

[serialk11r]

Originally Posted by MetroMPG

Yes, and it still revs too high on the highway!

(Note: it's not the stock RPM though - I've already swapped in the taller final drive from a 1.3L version of this drivetrain.)

I'm pretty sure the Insight's stock gearing is even taller than the Firefly's - I should check that...

Oh I know, I read the thread. Your stock rpms are lower than mine. 3000rpm over here is a tad under 55mph...the best mpg I can get drafting at 50-55 is a little over 40, and the best mpg in gear is about 50 rolling along at idle. Idle load is 18%, highway load is only 30%... If gas were more expensive, a 0.725 5th gear would already be in there, for 11% improvement. Next rear tire change I will try to go up 1 inch in radius to bring it down 4%.

Sort of sad for a car that's about the same size as the Metro. Still, I guess I should be grateful I'm not in an AP2 S2000, which spins it 2.2L engine at the same speeds :O Makes you really scratch your head when you consider that these 5th/6th gears are completely useless on the track, and equally useless on the street.

[Formula413]

What is your RPM at 60 mph with your current gearing? My HCH has very tall gearing, 3.6 final drive and I believe 5th is .76, which puts me at 2,000 RPM at 60

[arcosine]

Cool project, would like to do the same, that way I can get rid of these big oversize tires.

Might have been the press fit making the gears bigger that caused it to fail.

with 175/70R14 tires: geo still has smallest liter/min

car__________ final ratio__rpm@65mph__displacement-L/min
geo 3cyl_1L _____2.7176___2511.1_______2511.
saturn__1.9L____2.4502___2264.0_______4301.
Crx hf__1.5L____2.0500___1894.2_______2841.

[arcosine]

I was looking at these carborized and induction heated spur gears, looks like module 2.5 38-17 would be the right pitch diameters, that would give a .448 ratio.



QTC410 - Component Data Base

[arcosine]

It might be better to use the small gear as is and EDM cut the spline, that way there is no welding and will fit right on the shaft.. I am not sure what to do with the big gear.