I decided to go with the Klune V.
This will give me a 1:1 and 2.71:1 gear ratio. The only downside is that it is not synchronous so initially I will have to come to a stop to shift gears. Using 1:1 if I know I am getting on the highway, and 2.71 if I am just staying on side streets. In reality 2.7:1 ratio allows me to hit highway speeds, just not at the most efficient RPMs. Eventually I will upgrade to a micro processor to enable on the fly shifting using a Linear motor.
Ultra Motion
Saturday, February 13, 2010
Friday, August 21, 2009
ElectricCamaro
I am converting a 1995 Chevrolet Camaro to electric. This conversion is more about learning about how to do this. I have received a lot of excellent advice that I am sure is correct but have decided I need to make my own mistakes.
I will not have a transmission. Making a single gear ratio from scratch has proven to be very difficult. Therefore after much searching I have found a few possible solutions.
The first solution is a transfer case that never went into 4 wheel drive mode. This is ideal because the ratio is 2.71:1 for most transfer cases. The main limiation is that I would need to buy a special part to enable 2 wheel drive low and the size does not fit in the transmission well. This would be the ideal solution if I can get someone to make a custom housing for it that removed the 4 wheel drive requirements and use the ATLAS internals since they support shift on the fly.
The second solution is the Rubicrawler. This is essentially a single pass through system that supports 2.7:1 and 1:1. This is perfect except it does not support switch on the fly.
The third possible solution is a Underdrive system which is perfect except it is not the right gear ratio.
The fourth option is an auxiliary transmission. There are two different auxiliary transmissions. The first would require a custom gear ratio but is the right size, is electric and supports shift on the fly (with letting off the accelerator slightly). The only down side is that it does not include neutral. The second is the correct gear ratio, but doesn't have synchronization for shift on the fly. This could be done electronically but would require additional DMOC control.
The controller I am using has a output for the speed based on the RPM from the motor. However the preference is definitely to have the speed sensor on the output shaft as this will be more accurate as the gear ratio changes.
Miles Per Hour
The differential has a ratio of 3.23:1. This will stay stock.
The sweet spot for the motor is about 2000 RPM.
This gives IDEAL Gear ratios of about 3:1 and 1.5:1. A compromise for a single fixed gear ratio would be about 2.5:1.
A ratio of 2.7:1 and 1:1 is not ideal since the 1:1 is a little low for highway miles and the 2.7:1 is a little low for side streets but based on the efficiency curves I think it is probably close enough to be a reasonable compromise. For Highway and side streets it puts the nominal driving speed between 2000 and 3000 RPM which seems to be a reasonable target.
The next table shows MPH for a number of possible gear ratios.
I will not have a transmission. Making a single gear ratio from scratch has proven to be very difficult. Therefore after much searching I have found a few possible solutions.
The first solution is a transfer case that never went into 4 wheel drive mode. This is ideal because the ratio is 2.71:1 for most transfer cases. The main limiation is that I would need to buy a special part to enable 2 wheel drive low and the size does not fit in the transmission well. This would be the ideal solution if I can get someone to make a custom housing for it that removed the 4 wheel drive requirements and use the ATLAS internals since they support shift on the fly.
The second solution is the Rubicrawler. This is essentially a single pass through system that supports 2.7:1 and 1:1. This is perfect except it does not support switch on the fly.
The third possible solution is a Underdrive system which is perfect except it is not the right gear ratio.
The fourth option is an auxiliary transmission. There are two different auxiliary transmissions. The first would require a custom gear ratio but is the right size, is electric and supports shift on the fly (with letting off the accelerator slightly). The only down side is that it does not include neutral. The second is the correct gear ratio, but doesn't have synchronization for shift on the fly. This could be done electronically but would require additional DMOC control.
| Transfer Case | Rubicrawler |
| 2.7:1, 1:1 | 2.7:1, 1:1 |
| Speed Sensor | Needs to be in DMOC |
| Bigger | Perfect size to fit |
| Neutral | No Neutral |
| $1000 to $2000 | $1500 (none used) |
| 2 manual shifters, one never used | Electronic |
| 4 wheel drive never used | Simpler System |
The controller I am using has a output for the speed based on the RPM from the motor. However the preference is definitely to have the speed sensor on the output shaft as this will be more accurate as the gear ratio changes.
Miles Per Hour
The differential has a ratio of 3.23:1. This will stay stock.
The sweet spot for the motor is about 2000 RPM.
This gives IDEAL Gear ratios of about 3:1 and 1.5:1. A compromise for a single fixed gear ratio would be about 2.5:1.
A ratio of 2.7:1 and 1:1 is not ideal since the 1:1 is a little low for highway miles and the 2.7:1 is a little low for side streets but based on the efficiency curves I think it is probably close enough to be a reasonable compromise. For Highway and side streets it puts the nominal driving speed between 2000 and 3000 RPM which seems to be a reasonable target.
The next table shows MPH for a number of possible gear ratios.
| Percent | RPM | 1 | 1.5 | 2.5 | 2.71 | 3 |
| 0.2 | 1600 | 37 | 25 | 15 | 14 | 13 |
| 2000 | 47 | 31 | 19 | 17 | 16 | |
| 0.4 | 3200 | 75 | 50 | 30 | 28 | 25 |
| 0.6 | 4800 | 113 | 75 | 45 | 41 | 38 |
| 0.8 | 6400 | 150 | 100 | 60 | 55 | 50 |
| 1 | 8000 | 188 | 125 | 75 | 69 | 63 |
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