Gear Calculator Numbers

[vex]

For those who have stand alone ECU's and the appropriate dashes and tables these numbers may come in handy:

Stock wheel size and NA transmission

1st Gear: 05 mph/1000 RPM
2nd Gear: 09 mph/1000 RPM
3rd Gear: 13 mph/1000 RPM
4th Gear: 18 mph/1000 RPM
5th Gear: 26 mph/1000 RPM
6th Gear: 00 mph/1000 RPM **I think; need to get someone to double check**

Other transmissions will follow eventually

[infernosg]

Check out my post in the transmission FAQ thread:

http://rotarycarclub.com/rotary_foru...2&postcount=27

The information came from all over the place and I get numbers similar to what you have.

[vex]

Wish I knew about that before. Would have made my life easier. I ended up re-inventing the wheel and doing my own spreadsheet. I'm planning on doing a set of new equations to calculate pulses/mile from an electric speed sender. But I'm still a little iffy on the details.

I'm thinking that if you have some # of pulses/rev from the sender the # of pulses/mile can be calculated by finding revolution/mile then multiplying that number from pulses/rev.

Does that make sense or have I gone crazy?

[tweiss3]

sounds correct to me vex. pulse/rev*rev/mile=pulse/mile, units cancel out

[My5ABaby]

Originally Posted by vex

For those who have stand alone ECU's and the appropriate dashes and tables these numbers may come in handy:

Stock wheel size and NA transmission

1st Gear: 05 mph/1000 RPM
2nd Gear: 09 mph/1000 RPM
3rd Gear: 13 mph/1000 RPM
4th Gear: 18 mph/1000 RPM
5th Gear: 26 mph/1000 RPM
6th Gear: 00 mph/1000 RPM **I think; need to get someone to double check**

Other transmissions will follow eventually

Which N/A transmission? Which stock wheel size? Which stock rim size?

[vex]

Originally Posted by My5ABaby

Which N/A transmission? Which stock wheel size? Which stock rim size?

S4, GXL, such that wheel dimensions are: 205/60-15, thus wheel diameter is 24.685 in.

[My5ABaby]

Originally Posted by vex

S4, GXL, such that wheel dimensions are: 205/60-15, thus wheel diameter is 24.685 in.

86 or 87-88?

[vex]

Well... Looks like I hit a snag. From what I can see, the mechanical speedo has a gear in it (prior to the speedo cable) that has an unknown ratio to the output shaft. I have done my best to figure out what that ratio is, but it's all hear-say until someone can actually find out what it is.

I calculated the Output Shaft as 3349.777962 Rev/Mile. This means that in order to get the pulses/mile close enough to given pulses/mile (which was emailed to me by the manufacturer) the speedo gear ratio must be in the neighborhood of 3.35:1.

With that information (which may or may not be right), the resultant PPM is found to be 15998.94 such that one could be fine with 15999 or even 16000 without much issue.

[vex]

Originally Posted by My5ABaby

86 or 87-88?

I'm not aware of any differences in the respect of transmissions or diff gear ratios, but I calculated all values using the 88 FSM numbers.


Edit: Just double checked to see if there were any differences. There is only 1; the 5th gear ratio.

Thus 5th Gear Calculation for the 88 is 26 MPH (25.7 to be precise), while the 5th Gear Calculation for the 86 is 25MPH (25.2 to be precise).

[My5ABaby]

Originally Posted by vex

I'm not aware of any differences in the respect of transmissions or diff gear ratios, but I calculated all values using the 88 FSM numbers.


Edit: Just double checked to see if there were any differences. There is only 1; the 5th gear ratio.

Thus 5th Gear Calculation for the 88 is 26 MPH (25.7 to be precise), while the 5th Gear Calculation for the 86 is 25MPH (25.2 to be precise).

Cool thread thus far.

[vex]

So I automated all the calculations now so I can easily write out the following given certain conditions:

Wheel diameter is kept constant at 24.685 inches.
All numbers correspond to MPH/1000 RPM, and significant figures kept to 3.

6th Gear still needs to be verified as proper input:

1987-1988 Turbo

1. 5.18
2. 8.89
3. 12.88
4. 17.91
5. 23.5
6. 0

1988 Convertible

1. 5.40
2. 9.38
3. 13.75
4. 18.78
5. 26.9
6. 0

1989 Convertible

1. 5.15
2. 8.95
3. 13.11
4. 17.91
5. 25.7
6. 0

1988 Automatic

1. 6.61
2. 12.19
3. 18.78
4. 26.09
5. 0
6. 0

5th and 6th are not used in the automatic, so those values will need to be inspected.