Gearset

[M. Hendrix]

What is the procedure for finding out what gears are in a transaxle, without getting dirty? RPM/Gear vs Speed, right?

I need a chart, is there one?

Any help would be rewarded with a cap-locked thanks!


THANKS!


M

[red-beard]

Yep, and you need to get an exact measurement of your tires since they will affect the reading as well.

What makes you think you have anything in there except stock?

James

[John Rogers]

There are three measuremnets for the REAR tires: diameter by measuring, circumference by roll-out and revs per mile from the tire co. The roll-out is the most accurate I feel. Then you can download the GEARS.EXE program I wrote from the PP site here and enter the needed info. A slider will tell you RPM vs Speed in ALL gears. It is used by several shops on their race laptops, etc and works well. Good luck.

[M. Hendrix]

Rebuilder says they are stock, no reason not to believe him, doesn't feel like the other ones.

3rd gear in this car is a smooth ride to 4th, 3rd gear in other car (carbed) is more than a little attitude adjustment, and that car has 78k+ on the ticker. Maybe the gearing/power setup on that car just has converging sweet-spots.

Now that I consider it all in type, it doesn't really make any sense.

I had the rebuilt powered car (just over the break-in) 137mph.. could have gone a couple more.. I never knew that was possible, something is strange.

Euro-spec 2.0.. stock-stock... crazy.



M

[Dave at Pelican Parts]

Optimistic speedo. They are almost all wrong; just about all read higher than your actual speed...

That's my vote!

--DD

Well now wait a minute - the Tach measures engine RPM - the Speedometer measures Transaxel RPM, they are directly connected.

The tire size has nothing to do with the speedometer reading, although they do effect the actual speed if measured outside the car.

Right??

Ken

[red-beard]

You are quite correct.

In a specific gear, there is a direct relationship between the engine speed and the speedometer reading, assuming the clutch is fully engaged.

James

[John Rogers]

I've said it before and I'll say it again, the most accurate way to measure the speed of your car is with a GPS system. Either hand held or dash mount is fine but they are accurate to 0.1 MPH. No speedo is near that close as far as I can see? The loss/gain usually occurs inside the speedo due to the friction elements that take the rotation of the cable and turn it into a needle movement. This can easily be tested if you disconnect the cable from the tranny and turn it with a drill and see what the speed on the speedometer is reading. If you know the drill RPM you can work backwards through the tranny to see what RPM should be as all the gear combos are known.

[red-beard]

I use a GPS in my cars and now pretty much ignore the speedometer and use the GPS one. The only issue with the GPS is there is a time lag (slight) so it should be used for steady state driving.

I have "calibrated" myself so that I know that at this speed, the speedo is off by x amount. I was surprised that it was not exactly linear. The Speedo is magno electric and works against a fairly linear spring.

[M. Hendrix]

I sincerely doot that GPS will do anything aboot my question.

=oP

heh


M