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Thanks for this great explanation! I have a question though -- are there any special issues with an AC system going clutchless? Would it affect regen?
Clutch Vs Clutchless
Whether you choose to leave the clutch in place on an EV is purely a personal choice. There are pro's and cons to each method such as; "with a clutch I can change gear faster if I have an emergency but it was complicated to set up correctly." or "without a clutch I save 25 pounds from my EV which allows me to put more batteries in and stay under my cars max weight, but it takes me twice as long to change gear".
You have to consider your preferences and decide whether you go clutchless or not.
Going clutchless on an EV means, simply that. Hooking the motor "directly" to the gearbox without a clutch. In this situation an adapter is normally made from an old clutch plate that hooks the motor shaft solidly to the gearbox input shaft with no way to dis-engage it. You remove the WHOLE clutch assembly. None of it is used. Not the flywheel , the peddle, nothing!!
You can do this because In a modern manual transmission there are things called syncro’s in between each gear. Their job is to mesh together (there's probably a better term) before the gears do. As they come together, they match speeds and in doing so bring the gears to the correct speed for "crunch" free meshing before the gears come into contact.
When you want to change gear it is made possible by the fact that an electric motor has virtually no mass(compared to an ICE motor). This allows the syncro's in the gearbox to match the internal gear speeds reasonably quickly, which allows the gear to be selected. To change gear you just take your foot off the gas and slip the leaver into neutral. You then GENTLY & SLOWLY introduce the gear leaver to the gear you want to select. The syncro's will match the gear speeds and you will "FEEL" the gears mesh and the leaver will sort of "fall" into place. Then you put your foot back on the gas.
This may sound complicated but it can be done easily with practice and it only takes only a second or two longer than changing with a clutch. The important thing is to remember NOT TO RUSH IT!!
You can actually do it with SOME normal ICE cars, but it takes a lot more concentration because you have to use the gas peddle to balance the motor speed to the gearbox speed. It's harder because the ICE motor has far too much mass for the syncro's to overcome and they can't match the speeds. The clutch helps out here by removing the motor mass from the equation so the syncro's can do their job with only the mass of the clutch plate to deal with.
An electric motor has somewhat more mass than a clutch plate, that is why you can't shift as fast when you go clutchless in an EV.
Here is a description of how to make a clutchless motor coupler: http://www.electric-lemon.com/?q=node/213
It's simple and effective.
You have to consider your preferences and decide whether you go clutchless or not.
Going clutchless on an EV means, simply that. Hooking the motor "directly" to the gearbox without a clutch. In this situation an adapter is normally made from an old clutch plate that hooks the motor shaft solidly to the gearbox input shaft with no way to dis-engage it. You remove the WHOLE clutch assembly. None of it is used. Not the flywheel , the peddle, nothing!!
You can do this because In a modern manual transmission there are things called syncro’s in between each gear. Their job is to mesh together (there's probably a better term) before the gears do. As they come together, they match speeds and in doing so bring the gears to the correct speed for "crunch" free meshing before the gears come into contact.
When you want to change gear it is made possible by the fact that an electric motor has virtually no mass(compared to an ICE motor). This allows the syncro's in the gearbox to match the internal gear speeds reasonably quickly, which allows the gear to be selected. To change gear you just take your foot off the gas and slip the leaver into neutral. You then GENTLY & SLOWLY introduce the gear leaver to the gear you want to select. The syncro's will match the gear speeds and you will "FEEL" the gears mesh and the leaver will sort of "fall" into place. Then you put your foot back on the gas.
This may sound complicated but it can be done easily with practice and it only takes only a second or two longer than changing with a clutch. The important thing is to remember NOT TO RUSH IT!!
You can actually do it with SOME normal ICE cars, but it takes a lot more concentration because you have to use the gas peddle to balance the motor speed to the gearbox speed. It's harder because the ICE motor has far too much mass for the syncro's to overcome and they can't match the speeds. The clutch helps out here by removing the motor mass from the equation so the syncro's can do their job with only the mass of the clutch plate to deal with.
An electric motor has somewhat more mass than a clutch plate, that is why you can't shift as fast when you go clutchless in an EV.
Here is a description of how to make a clutchless motor coupler: http://www.electric-lemon.com/?q=node/213
It's simple and effective.
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If you have off-throttle regen (often included to simulate engine braking) it needs to be turned off when you want to shift. If even mild regen is happening the syncros will not be able to do their job and it should be difficult (and damaging) to pull the transmission out of gear.
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4,334 Posts
The other consideration that is rarely mentioned is that retaining the clutch allows small amounts of misalignment without damage.
A completely solid coupler, the slightest misalignment will cause tiny flex with each revolution and eventually break something... especially if you have welded something together and not hardened it afterward.
If you go clutchless, SOME couplers have spirals, or plates, or rubber bumpers designed to handle some mis-alignment. The rubber ones are generally bad news at high torque. The metal plates work well, but add back almost as much weight as you take out with the clutch.
A completely solid coupler, the slightest misalignment will cause tiny flex with each revolution and eventually break something... especially if you have welded something together and not hardened it afterward.
If you go clutchless, SOME couplers have spirals, or plates, or rubber bumpers designed to handle some mis-alignment. The rubber ones are generally bad news at high torque. The metal plates work well, but add back almost as much weight as you take out with the clutch.
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2,217 Posts
Some clutchless couplers are built from the sprung center of a clutch disc. These will allow slight motion, essentially like the stock clutch assembly.
On most transmissions and transaxles the pilot bearing part of the input shaft should still be supported. A pilot bushing is not required because it will not rotate relative to the motor shaft, but often the transmission depends on that support for alignment. The spline fit is not tight enough to provide the proper support.
On most transmissions and transaxles the pilot bearing part of the input shaft should still be supported. A pilot bushing is not required because it will not rotate relative to the motor shaft, but often the transmission depends on that support for alignment. The spline fit is not tight enough to provide the proper support.
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16 Posts
Great Info! This should be a sticky!
After many years of designing both clutch and clutchless adapters it has to be the choice of the builder. Some car tranny's work better than others as a clutcless. Having said that, I find that a clutchless design is better with a coupler as small as possible in diameter to avoid a out of balance as some shafts vary a little in diameter. About 2 3/4" is ideal without the clutch springs. Most splines have enough slop for a very very small alignment problem. Here is a few pictures of a coupler for the VW.
Attachments
I started my Electro-Willys as a clutchless car. The direct connector matched the motor output shaft directly with the splined input shaft for the transmission. That lasted about 6 months before it broke the output shaft for the motor. I'm not sure what the problem was, but it was an expensive repair. Then I went back to the clutch. Yes it added more weight to the vehicle. But the reduced stress on the transmission by allowing "normal" shifting was worth it. And by putting the clutch plate back in the mix, I reduced the chance of damage to either the transmission or the motor from something being out of balance or out of allignment. I've been running this arrangement for almost 2 years now and so far so good.
Mike,
The Willys, I got to see it man. Any kind of media anywhere on the forum? I have built a couple as wheelchair accessible vehicles so I would love to see what you have come up with. Hit me up if you have anywhere I can take a look.
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4,334 Posts
besides a little more wiggle room for possible mis-alignment, you have another method to disconnect the drive if you get stuck in a 'welded shut with full power on' situation.
Direct coupling of 80+ peak horsepower with lots of stops/starts is pretty tough on any solid coupling.
Direct coupling of 80+ peak horsepower with lots of stops/starts is pretty tough on any solid coupling.
I don't know about most older cars but I'm sure glad I kept the clutch in my '96 Ford Ranger. I've driven a lot of clutch vehicles without using the clutch. It usually isn't that hard. This thing is miserable trying to run it without the clutch. I realize the weight of the clutch changes how it would feel as opposed to going clutchless but I don't think it would help enough. And this body only has about 100,000 miles on it.
I'm guessing you could always keep the clutch pedal to act as a kill switch for the regen. Or convert an old domestic high beam low beam foot switch to do the same job. It might be a good idea to do this regardless since allowing the motor to spin during a shift might extend the life of the clutch somewhat. Wouldn't regen without a load just stop the motor completely?
Sorry, but is this saying that clutch-less is fine but not with the spring center plate of a clutch?
I wouldn't worry too much about the opinions of cruisin, there's a reason he got banned!
Assuming you've decided to go clutchless, there is nothing wrong with using the torque damper from a clutch pressure plate in your coupling design, it gives some damping effect and properly engineered adds little additional rotational mass. Other advantages are it can allow for very slight misalignment due to the "floating" nature of its centre component.
Assuming you've decided to go clutchless, there is nothing wrong with using the torque damper from a clutch pressure plate in your coupling design, it gives some damping effect and properly engineered adds little additional rotational mass. Other advantages are it can allow for very slight misalignment due to the "floating" nature of its centre component.
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370 Posts
This is my effort at a clutch coupler, there are four bolt holding it together although only two are shown in the photo.
The small spider that is the spline part has a bit of spring load slop built into it as standard and this takes care of a small bit of mis-alignment.
http://www.diyelectriccar.com/forums/showthread.php/converting-my-2001-volvo-v40-75026p4.html
The small spider that is the spline part has a bit of spring load slop built into it as standard and this takes care of a small bit of mis-alignment.
http://www.diyelectriccar.com/forums/showthread.php/converting-my-2001-volvo-v40-75026p4.html
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