hey all,
i’m planning hopefully soon to do a DIY car conversion.
I worked on a chain drive plug-in go-kart in school and now i’m considering doing a biggger car version.
I’m not a mechanic so I was wondering about installing a custom simple 2 gear tranny or is it possible to modify the stock tranny to reduce some weight?
or who makes the tesla roadster tranny?
is moding the tranny worth exploring?
thanks!
sounds like your better off making your own and making it a 2 stage tranny… one low gear and one high gear. lots of math involved… or even better for ease would be a CVT transmission 
Although I have not done this I have done a little research into the same thing. There are a few options. A lot of low buck racers use a 2 speed tranny so you can look into those. They may be overkill and may not have desirable gear ratios but it is an area to look into. Also most 5 speed trannies can be modified. If you are itching to reduce the weight by a few pounds then you can probably remove some of the unneeded gears and effectively make it a two speed transmission. You would be wise to install some sort of stop on the shift fork so that you don’t accidentally shift into a gear that no longer exists.
[QUOTE=ZPD;2026]There are a few options. A lot of low buck racers use a 2 speed tranny so you can look into those. [/QUOTE]
i tried looking for custom trannies online but i couldn’t find anything… any links? yeah if these 2 speed tranny are a cheap option then i think it’s worth exploring… i think selling the original car tranny for something cheaper and lighter is worth it?
[QUOTE=ZPD;2026]
5 speed trannies can be modified…you can probably remove some of the unneeded gears and effectively make it a two speed transmission. [/quote]
well i don’t know how difficult removing/changing some gears around but that’s what i was thinking of doing if it’s possible… would this be a better option in terms of cost and weight? I’m just trying to explore all opportunities…
[quote=FEUS;2022]
or even better for ease would be a CVT transmission[/quote]
sounds expensive! 
my goal is a low budget, used car and designed for longer range in city driving…
[QUOTE=immortalc;2027]sounds expensive!
my goal is a low budget, used car and designed for longer range in city driving…[/QUOTE]
its actually not if you know how to make one, its not bad at all… way cheaper than a gear setup. research it a bit
just google 2 speed transmission and it will give you a few links. One of them was to a 1914 transmission from a model T- obviously not ideal for your application but I thought it was pretty cool.
Didn’t GM have a performance 2 speed transmission in the sixties? There may be a ton of aftermarket support out there, and newly manufactured versions available.
[QUOTE=Jack the R;2083]Didn’t GM have a performance 2 speed transmission in the sixties? There may be a ton of aftermarket support out there, and newly manufactured versions available.[/QUOTE]
the “powerglide” is the 2 speed GM transmission, however, it’s an automatic, and from what little I’ve looked into EV’s, it seems like manual transmissions are prefered.
To me if you want a RWD setup, I think the VW bug transaxle is the way to go. Easy to find, compact, Lightweight (about 100 lbs+ axles and hubs vs. trans, driveshaft and live axle), reduced rotational mass, and with the aftermarket industry lots and lots of options for gear ratios, plus all the guys that are experienced with building them. I bet they could tell you if a couple of gears could be sacraficed. Plus there are a number of adapters already on the market.
The GM Powerglide is used by drag racers for it’s simplicity, but drag racers use automatics in general more so for their consistancy in shift timing.
Another reason that drag racers use automatics is because you get torque multiplication with the torque converter (replaces the clutch mechanism when compared to a manual trans).
Even lock up type torque converters used in more modern automatics eat up RPM more than a clutch, making them less efficient for milage, but they shift more consistantly than a manual (which is something of total unimportance unless you are racing). The GM powerglide isn’t a very lightweight transmission, and because of the torque converter constantly slipping in any automatic transmission and relying on constant RPM to run the oil pump and pressurize the system by design, wouldn’t be my first choice for an electric motor.
Lenco designed a very small, stackable 2 gear transmission in 1970 that serious drag racers use. It’s a manually shifted planetary transmission that shifts mechanically, either with a lever or with an air operated solenoid. There is no need for a clutch. They can be stacked in sequence in as many as you can fit into your vehicle. They have updated their desins and have an ultra small unit that utilizes a magnesium casing and even utilize optional titanium gears. They even make a reverse end unit (which wouldn’t be necessary for any electric motor that the polarity could be reversed on)…
The only down side is that I think they are very expensive. They are a straight cut gear, which can handle rediculous amounts of torque and horsepower (thousands), but because of that, they don’t do too well on the street.
There was a guy that used one in a street rod, but as to my understanding, he was changing the hypoid gear oil in the unit every day that he drove it. He said that if he didn’t, he would likely fry the planetary gears inside the sun ring gear. I don’t know if Lenco makes a street friendly unit or not. The multiple stacked units (4 and 5 speed w/ reverse) go anywhere from $3G to $15G, but I would think that if they made one that had beveled gears (less friction) for street use, only needing one unit probably wouldn’t be unafordable.
If I can get a voltage controller or find a switch with enough voltage and amp capacity, I’m going to use the electric motor on reverse polarity for reverse and just adapt the switch to an automatic shifter. If I can do that, I’ll just use a separate voltage regulator on the reverse switch, to control the speed of the motor in reverse (as not to get full power in reverse).
I am going to use an electronically shifted overdrive unit with a tall ratio for a transmission, if I can manage reverse out of the motor.
Gear Vendors makes an array of electronically shifted under/overdrive units that they have made adapter housings to retrofit on to older transmissions for the muscle car and resto crowd as well as commercial and fleet vehicles. They can be had in any range from 15% all the way up to 40% overdrive.
They also make remote mount units for tight fit areas, although I don’t see why you couldn’t just adapt it straight on to the back of an electric AC or DC motor.
I have been told that they use the same internal planetary gear setup as an older Volvo, but I have yet to see them side by side.
Any factory overdrive unit that is not hydraulically engaged could be used as a transmission. Although, if you felt up to the task, I’m sure you could retrofit some sort of hydraulic shifter into a hydraulically engaged overdrive from an automatic transmission. Something similar to a hydraulic clutch, only instead of using a momentary lever, like a clutch pedal with a return, you could use a simple hydraulic lever.
It would take some engineering and finding out how much pressure and fluid was needed to operate a hydraulically engaged overdrive tailhousing unit from a conventional automatic transmission, like a GM 700R4 or Chrysler/Mopar A-518 or A-500, because those are very cheap and can be found easily if you could get one to work. I know that they take an immense amount of pressure to overpower the throwout/ return spring, but it’s nothing that a hydraulic cylinder can’t handle. And the nice thing about hydraulics is that they can be remotely controlled relatively easy (think about a hydraulic clutch system).
The best way would be to go with a mechanical or electrically engaged/ disengaged unit and you would have to flip through some car manufacturers to find one. I’d start with Volvo and go from there. Ford made a mechanical overdrive unit for some of their older cars too, if I’m not mistaken.
But if you did your research and just found a simple overdrive unit capable of withstanding the mechanical horsepower and torque ratings of whatever AC or DC motor you decide to use, any overdrive unit would work if you could use reverse polarity on the motor instead of a reverse gear.
Two things I’ve been thinking of, and I admit I don’t know enough about either…
Automatic - use a 12v hydralic pump to “pressurize” the transmission at the optimal pressure and eliminate the torque converter. Then, the elect motor can be off and pressure still exists in the automatic, simulating a torque converter.
2 speed rear axle used as a differential instead of a transmission.
theory would be to get one from a 47 or so Mercury and modify it to attach to your half shafts (FWD). But that’s a lot of work for little gain.
In my project car I’m probably just going to swap out the auto for a manual unless I can talk to some transmission shop guys I know and come up with a conversion for the automatic less torque converter, wouldnt that be sweet.
I’m starting the process of converting my 1960 corvair with and automatic 2speed power glide transmission. The oil pump is driven off a separate shaft that runs inside the input shaft. My plan is to remove the torque converter and build an adapter to join the two shafts together. I’m going to allow the oil pressure to drop when the motor is off. I’ve been told that pressure is produced very quickly so it should take just a second to reengage the transmission on acceleration. I’m hoping the time needed to build pressure will let the clutches engage slow enough to create a gentle start. The transmission can be shifted manually so keeping it in the lower gear for longer than the ICE would have liked is easy.
Lots of hopes and shoulds, but what the heck, if it doesn’t work the way I hope I’ll just look for a manual tranny or go direct.
I was thinking of using a volvo electric OD unit. They are small and bullet proof and bolted on the back of the manual trans in the old 240 volvos . Most performance car people will recognize the name “Gear Venders”. Same thing. The volvo’s had a little square switch on the shifter that engaged it. Then the motor could be mounted where the OE trans was on a RWD application. I think the rear axle gear ratio would have to be changed to something real low and no reverse humm…
Check it out and tell me i’m crazy.
By the way old hot rodders used to do something called a “clutchable automatic”. They machined off the bellhousing and somehow adapted it to a manual bell housing. I’m not sure exactly how they did it. but it might be interesting to look into. Believe it or not a guy I knew had one in a prostreet Bronco the 80’s
Hello all, I’m new here. An industrial electrician, Navy trained. I’ve worked with AC and DC industrial drives and servo’s for that matter for over 20 years. That’s not an attempt to say I know it all as I don’t by a long shot but to give you an idea of where I’m coming from.
DC motors used to be preferred over AC motors due to their significant torque advantage but since the 80’s, AC Drives are much improved and some claim even better than DC now.
Regardless, I’ve seen DC motors do some things that would rip a rear end apart! Also remember that a DC motor isn’t anything like an ICE, in that it can produce serious torque at extreme low rpm as well as high rpm. That said, and after reading that it isn’t uncommon to couple the motor straight to the differential via drive shaft, omitting the tranny, why does one need a tranny? Some have said to lock the tranny in the middle gear.
That is a lot of extra parts to break and weight to haul around. You don’t need reverse gearing as these motors, both AC and DC are bidirectional and don’t care which direction you operate them.
I personally want a vehicle that will reach maybe 65 or so MPH if needed for a brief interstate trip. If the rear diff is geared properly, you can reach speeds that fast without overspeeding your 1750RPM motor. I had a 69 Camaro with 3.73 gear rear that at 2500 rpm was travelling at 55.
If you lower the diff gear to say 2.50 or so, you would lose torque but your speed would increase by 49% I believe. That would mean at 1750 rpm you would be travelling at about 58 mph if my math is correct. Of course that depends on the tire size (circumference) also. My factory size I believe was a G78-15 (215/75R15) which is nearly 28" tall, a little large for a sub-compact.
I know there’s a tradeoff so there will be a serious loss of torque as would be if you tried to start an ICE off in 5th gear vs. 1st. However if you aren’t making a drag car do you need to bother with a tranny?
I know next to nothing about EV building thus my reason for joining this very educational forum. I just want to contribute my .02 where I can and learn as well from those of you who have “Been there, done that”!
Hello,
I’m brand new to this site. I thinking about building a EV. But am doing a lot of looking around first. I own a street rod shop in Marysville, Wa. In that bizz in seems everything is small block chevs. I want to build a light street rod type EV. Anyways I thought I would toss in my 2 cents here.
What about a Gearvender unit in place of a trans? there small,elec. operated and very strong.
I’ve been kicking around the idea of a direct drive using a transwarp 11. As near as I can tell I’d need to come up with a 9" ford rear end to accommodate 5.26 gears. These new motors spin at up to 5000 RPM.
The other thought I had on this is the possibility of using a 4x4 transfer case and using the low and high gear from this. As near as I can tell they are around a 2:1 ratio in low. Even with 4.56 gears that would fit in most 8.25" differentials that would give a decent low end range. Top speed would be somewhat hair raising.
[QUOTE=GimmeRed;3237]I’ve been kicking around the idea of a direct drive using a transwarp 11. As near as I can tell I’d need to come up with a 9" ford rear end to accommodate 5.26 gears. These new motors spin at up to 5000 RPM.
The other thought I had on this is the possibility of using a 4x4 transfer case and using the low and high gear from this. As near as I can tell they are around a 2:1 ratio in low. Even with 4.56 gears that would fit in most 8.25" differentials that would give a decent low end range. Top speed would be somewhat hair raising.[/QUOTE]
the 9" ford takes more HP to drive than other rear-ends
[QUOTE=COMP;3247]the 9" ford takes more HP to drive than other rear-ends[/QUOTE]
I’m not sure why a 9" running 5.26 ratio would need a lot more HP then a 8.25 running 4.56 on a direct drive. It would be interesting to see the HP draw comparison with a manual running in second and third gear on stock 3.20 gears to a direct drive with lower gears.
Point me to the link if you can find one I’m just in this to learn.
I still like the Idea of using a transfer case on a direct drive from the motor. If one could be found with a 1.75:1 low range it would be better.
[QUOTE=GimmeRed;3256]I’m not sure why a 9" running 5.26 ratio would need a lot more HP then a 8.25 running 4.56 on a direct drive. It would be interesting to see the HP draw comparison with a manual running in second and third gear on stock 3.20 gears to a direct drive with lower gears.
Point me to the link if you can find one I’m just in this to learn.
I still like the Idea of using a transfer case on a direct drive from the motor. If one could be found with a 1.75:1 low range it would be better.[/QUOTE]
its wear the pinion meshs with the ring , also the pitch of the teeth make a differerence
It is possible to direct drive without a transmission, but the current draw at low speeds will be extremely high. You will kill the batteries and your operating range will be dismal. This is typically done only for electric drag cars where the duty cycle is measured in seconds.
-enganear