# planning a classic car conversion



## toddshotrods (Feb 10, 2009)

DRAINSTURGEON said:


> ...I would like a direct drive system with 3.00 to 1 rear end or so...


Cringe  First, prepare for your thread to turn into the umpteenth debate about whether or not direct drive can or should be done.

For the record, I am building a direct-drive EV. I have no problem with a transmision, I just don't think it's always necessary.

You're probably going to need a numerically higher rear end ratio, more voltage, and a healthy controller to move the car. You guessed right on the motor weight because you're going to need at least an 11-inch or a couple 9's. Off the cuff, it sounds like you'd need some pretty good deals on used parts to do it for $6K.

Sweet idea!


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## DRAINSTURGEON (May 26, 2010)

Ok, well forget about the direct drive... It's not important to me at this point. A 4 speed transmission is cheap. Also, I should mention that I am not figuring the batteries into the 6k. That would be like adding the price of gas to an ICE build. I would depreciate my investment per mile used and hopefully end up cheaper than a 20 mpg ICE. I think it would be doable for 6k that but maybe not, even that is a starting point.


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## TigerNut (Dec 18, 2009)

Don't forget that the T-10 or toploader transmission that came with your Mustang would have had a 2.32 first gear, which is pretty steep for today's standards. If that were coupled with a 2.73 final drive then the total ratio even in first would only have been 6.33 to 1. 

If your 6 cylinder Mustang came with the 7 1/4" rear end then the shortest ratio you can get is 3.20:1 according to this: http://www.mustangandfords.com/tech...d_differential_builders_guide/five_basic.html

This smaller lighter diff has the benefit of not being as bulky as the heavier duty units, but it's not available in the really short ratios you'd want for direct drive. Scrounging a unit out of an import truck (Toyota 2wd or 4wd pickup) would give you about equal power handling capability but you can get up to 5.71:1 ratio, which would get you into direct-drive territory. Your motor would be spinning in the 4500-5000 RPM range at highway speeds, so you do need to consider that in your calculations.


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## DRAINSTURGEON (May 26, 2010)

TigerNut said:


> Don't forget that the T-10 or toploader transmission that came with your Mustang would have had a 2.32 first gear, which is pretty steep for today's standards. If that were coupled with a 2.73 final drive then the total ratio even in first would only have been 6.33 to 1.
> 
> If your 6 cylinder Mustang came with the 7 1/4" rear end then the shortest ratio you can get is 3.20:1 according to this: http://www.mustangandfords.com/tech...d_differential_builders_guide/five_basic.html
> 
> This smaller lighter diff has the benefit of not being as bulky as the heavier duty units, but it's not available in the really short ratios you'd want for direct drive. Scrounging a unit out of an import truck (Toyota 2wd or 4wd pickup) would give you about equal power handling capability but you can get up to 5.71:1 ratio, which would get you into direct-drive territory. Your motor would be spinning in the 4500-5000 RPM range at highway speeds, so you do need to consider that in your calculations.


Wow, This conversation went from Pre-K to grad. student. Very good info: 

I am in the process of a complete V8 conversion on this car (- the V8). I upgraded disc brakes in the front, Roller bearing suspension and V8 steering with "lighter" coil for my I6. I acquired an 8" rear with 3:00 gears, perfect for my sixer. 
This is an area where I really need to read up on for EV. I was under the assumption that an electric motor would do just fine with 3:00 gears keeping the rpms down at high speeds and because of the torque it would have no problem with acceleration. I guess that is not at all the case.
I could easily put 4:11 gears in and use any transmission I choose but I didn't think that was going to be needed. 
Time to go to school...
Thanks


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## DRAINSTURGEON (May 26, 2010)

At one time (on a previous computer) I had a pretty cool excel spreadsheet for EV conversions. I was using it for a motorcycle plan. I haven't looked to see if it is still out there, or maybe something better now?

BTW, I ended up buying a new motorcycle because the bank told me I could.


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## toddshotrods (Feb 10, 2009)

DRAINSTURGEON said:


> ...I was under the assumption that an electric motor would do just fine with 3:00 gears keeping the rpms down at high speeds and because of the torque it would have no problem with acceleration. I guess that is not at all the case.
> I could easily put 4:11 gears in and use any transmission I choose but I didn't think that was going to be needed.
> Time to go to school...
> Thanks


With EVs you have to reverse your thinking in a lot of ways. You don't necessarily want to run the motor at low rpm. It will probably be more efficient and happier running it closer to its rpm limit than to zero rpm. If you're going to run a 4spd, you can keep the 3.00:1 gears. The idea of a steeper ratio was just to help with acceleration from a standstill with direct drive. With the transmission you can select the gear ratio that gives the best acceleration, and shift up if necessary. From what I've read, many people that keep the transmission normally use one or two of the ratios. One for normal driving and maybe one for highway.

What type of driving are you planning to do? Most people who replace a six with a V8, like to lean on them once in a while. I asked because if you do want to play a little bit, and you have a big motor/controller combo, the transmission, driveshaft, and rear end have to be up to the task. Since you have full torque from 0 rpm, it's more like a nitrous hit, than a normal ICE ramp up of torque.

Edit - I forgot to add that if you have a big enough motor, or twins, it would have enough torque for acceleration. The smaller the ratio in the rear end though the more amps the motor is going to pull to accelerate. That means you end up with a bigger and/or more expensive battery pack to provide the necessary current. The idea of a numerically higher ratio was to find a sweet spot where it wouldn't push your motor and batteries so hard every time you accelerate from a standstill, and to still provide a reasonable top end. That's all for direct drive though. With the transmission, as TigerNut stated, you can accomplish this with first or second gear rather than a fixed rear end ratio.


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## DRAINSTURGEON (May 26, 2010)

As far as the driving goes I would vote cruise before "burn rubber". Another reason the EV seemed a good fit, I am not looking to weave in a out of traffic or light em up off the line. Smooth acceleration with reasonable top end and enough mileage to get to work and back. 

*28 mile round trip.*
70 MPH the first (or last) 3 miles little slope. Drive during rush hours so 60MPH is plenty
40 - 50 MPH for 11 flat miles with plenty of stop lights, traffic etc.
Now of course I would want the motor/controller to be able to handle more (or better) batteries as affordable to stretch out the range and maybe even get up to true highway speeds.

I have 60 MPH with standard tires and 3.00:1 rear @ just over 5K RPM's at the motor. So depending on the motor I got that may be my direct drive max speed no matter my battery packs huh? 

I have so much to learn, I will continue my education. I haven't even looked so if this has been COVERED please ignore. If the electric motor is more efficient at higher RPM's wouldn't an Auto trans losses kind of equal out? The difficulty of running an auto without an ICE aside.

BTW, the pic is why I upgraded my suspension


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## TigerNut (Dec 18, 2009)

DRAINSTURGEON said:


> I have 60 MPH with standard tires and 3.00:1 rear @ just over 5K RPM's at the motor. So depending on the motor I got that may be my direct drive max speed no matter my battery packs huh?


There's something wrong with your math. In my Tiger, when it had the toploader (direct drive in 4th) and 3.31:1 gears, it would do about 3000 RPM at 60 MPH. The tires are about 23" tall, so the circumference is about 6 feet (6.02 to be exact), giving 876 revs per mile. At 60 MPH, it's 1 mile per minute, so multiplying 876 x 3.31 gives 2902 RPM. Your tires (25" ?) and diff ratio (3.00) are each a little taller, reducing the engine or motor RPM.

This is why I suggested going for a diff in a higher range if you're going direct drive. If you want to max out the motor at 80 MPH, let's say, and you have a maximum RPM of X, do the following calculation:
Rear axle RPM = 80/60 * 5280/(tire circumference in feet) = 1173 (assuming a 6 foot circumference tire)
Rear axle ratio is X/1173.
So if your maximum safe RPM for the motor is 5000, you'd be best off with a 4.26:1 differential. This would give you maximum RPM at lower speeds, but your torque is limited by what the motor itself can provide and by the current loading that the batteries and controller can stand.

If you used a motor like the Warp11HV, with a 9000 RPM limit, then you could use a much higher (numerically) final drive ratio, and reduce the torque required from the motor.


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## toddshotrods (Feb 10, 2009)

DRAINSTURGEON said:


> ...I have 60 MPH with standard tires and 3.00:1 rear @ just over 5K RPM's at the motor. So depending on the motor I got that may be my direct drive max speed no matter my battery packs huh?...


What size rear tires? I get 119mph (theorectical) with a 24" diameter tire, 3.00:1 rear gear, and 5K rpm! That would also correspond with what the White Zombie runs through the 1/4 with direct drive.

What's the budget for the battery pack, and do you want new or used components? $6K + batteries should give room for a nice conversion, and since you're not looking for high performance, you should have a nice selection to choose from. A Warp 11 and a Soliton would be awesome in that stang and, with a transmission, should make a smooth little cruiser.


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## DRAINSTURGEON (May 26, 2010)

yup guys, I made a quick formula i a spreadsheet to get those figures. I found my mistake. Your figures are much closer.


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## DRAINSTURGEON (May 26, 2010)

toddshotrods said:


> What size rear tires? I get 119mph (theorectical) with a 24" diameter tire, 3.00:1 rear gear, and 5K rpm! That would also correspond with what the White Zombie runs through the 1/4 with direct drive.
> 
> What's the budget for the battery pack, and do you want new or used components? $6K + batteries should give room for a nice conversion, and since you're not looking for high performance, you should have a nice selection to choose from. A Warp 11 and a Soliton would be awesome in that stang and, with a transmission, should make a smooth little cruiser.


The TransWarp 11 HV is what I was looking at, just window shopping. I didn't know enough to make an intelligent decision but the Warps seem to be a popular choice. As far as the batteries go I hadn't put much thought into it. Figured the best lead acid and charging system I could afford to meet my goals. I would love to "invest" in better batteries. The only problem I see with that is there is always something new that is "better" than lead acid. The weight savings is instant but the overall "payback" seems to be a little more fuzzy. I am not familiar with the Soliton controler (I guess), but I am in the shopping stage so I will take a look. 
I plan to jump in with both feet, just not in the deep end.


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## DRAINSTURGEON (May 26, 2010)

Wow, so much info it take three replies. I am plugging your information in for direct drive. It seems like it still may be plausible with my requirements. Would a gear reduction system also work to dial in the ratio? We use them a lot for hydraulic systems. The systems we use are very expensive, was just wondering if they are commonly used for EV?


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## TigerNut (Dec 18, 2009)

I think a direct drive with a suitably large motor would be do-able, provided you use LiFePO4 batteries to keep the weight down. 
If you did go with the Warp11HV (the high-voltage, high RPM version) you can use a high ratio differential to get the torque multiplication you need at lower speeds. This would also require more cells in series, and therefore again you'd benefit from a lighter battery pack.

I don't think many people use non-automotive gear reductions, mostly because of the cost, and because the automotive environment is sometimes more harsh than what stationary rotating equipment is designed for. A gear reduction for a car would have to be able to deal with loading in either direction, for example (especially if you used regen), while some transmissions are really only designed to be driven from one end, in one direction.

From the Ford stable, a 4 speed toploader transmission (not the aluminum-case RUG types) would be fairly bulletproof against most any electric motor, I'd think. It's not even THAT heavy considering it's torque handling capability. If you wanted automatic shifting then probably something like a C-4 with solenoids actuating the brake bands and clutches would be the ticket. I'd be surprised if someone in the hot-rod or drag racing business didn't have an electronically shifted C4 conversion kit. If the torque converter could be eliminated then you'd save about 30 pounds.


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## DRAINSTURGEON (May 26, 2010)

I really appreciate you chasing down all these options for me! 
The picture that is forming here is:

Direct drive, while being doable, would require a larger motor/controller combination and more/lighter batteries. It would also require replacing one of the most expensive single components of my car, the rear end. So, if I ran a across a inexpensive used system, located at least a 4.11 geared bulletproof rear end I would still have to drop some serious coin on lightweight battery/charging system. The benefits of going direct drive seem to be performance/range (regen) oriented? If I wanted to match the output of a nicely modded V8 this would be my choice.

Since I am looking to replace a little 100hp gas sipper (by 1965 standards) and cruise it sounds like a nice warp11/lead acid/T-4 transmission is a viable option that fits my budget. 

With that in mind, I will concentrate on that drive combination. I was working off a lot of bad assumptions due to my lack of knowledge but I think this information will get my started down the correct path. I guess the main question that I have now is, with a lead acid battery system, is 144V the range I need to be thinking about? This also seems very doable with my platform and budget.

Thanks gain for your assistance, I shutter to think what would have happened to this project if I just blindly started ordering parts and tried to make it all work with my limited knowledge.


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## toddshotrods (Feb 10, 2009)

DRAINSTURGEON said:


> I really appreciate you chasing down all these options for me!
> The picture that is forming here is:
> 
> Direct drive, while being doable, would require a larger motor/controller combination and more/lighter batteries. It would also require replacing one of the most expensive single components of my car, the rear end. So, if I ran a across a inexpensive used system, located at least a 4.11 geared bulletproof rear end I would still have to drop some serious coin on lightweight battery/charging system. The benefits of going direct drive seem to be performance/range (regen) oriented? If I wanted to match the output of a nicely modded V8 this would be my choice.
> ...


I think you're hitting the nail on the head for your goals (warp11/lead acid/T-4 transmission). Direct drive, in my opinion, is pure EV. It capitalizes on the instantaneous torque of the e-motor and takes the whole powetrain into the 21st century - BUT - it is definitely costly to do right. I am building a race car. High costs come with the territory for my application, so it just makes sense to run direct drive. I would have to spend at least $3K for a transmission to survive the kind of abuse it would be subjected to, and it's not a critical element for my goals. I _have_ to spend around $4K for a race-built 9"-style rear end and nitrous-ready driveshaft, so... I _have_ to have an outrageously priced lithium battery pack to provide the needed current, without the huge weight penalty, so...

If I were building a cruiser, I would be looking at the combination you're thinking about. I would be tempted to go LiFePo4, or possibly upgrade to them later, with the batteries. The same performance for half the weight has its appeal, even for a cruiser. It seems as though the prices are reaching the points where they make sense now.

You might also want to consider an AC system too. Maybe JRP3 will chime in here and tell you more about his experiences with his AC system in his Fiero. It's about the same weight as your Mustang, and he kept the manual transmission. I have this long list of EV suppliers and can never remember which one sells the AC kits.


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## DRAINSTURGEON (May 26, 2010)

Well, at first glance what I am up against here is fairly complex. I have made a decision, continue my restoration as planned, while planning my EV conversion for my other 65 rolling shell I have it waiting in the wings lol. I think I am a year or two out from having the knowledge neeed to take on a project like this. And I am still learning a lot about the restoration process. I absolutely love reading about these conversions and will try and limit my newbee questions as much as possible. I will assemble my funds and learn all that I can before I get too specific on technical matters. I have shared the initial findings with some very interested gear heads on other sites so hopefully they show up here with a better foundation than I had.
This Internet this is freaking sweet, I think I should buy stock!


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## PatricioIN (Jun 13, 2008)

here's another option:

Keep the transmission, use a warp 9 motor and go with Lithium batts. There should be no reason you can't have your goals with a 120 or 144 volt system and spending 6k (minus batts). You could do this with lead acid, but the car would be very heavy. If you can spring for the lithium, then you'll EASILY reach your range goals and more while keeping the car around it's original curb weight.


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## PatricioIN (Jun 13, 2008)

FYI - I converted a 2500lb Ford zx2 to a 120volt system with 15 8volt batts and easily got 35 miles of range even at the range of speeds you're talking about. I used a 8" motor and a small (400amp) Curtis controller. It weighed 3200lbs once converted.

If I were to do the same car again I would use a 9" motor and a higher amp controller. Just by adding another 24 volts (all else being equal), I figure it would have given me 20% more range.

A simple calculation shows I should have gotten 36miles with my setup and using the same figures (but with 144volts) I get 44 mile range. This is with normal everyday driving. You can extend or shorten your range greatly by your driving style, terrain and outside temps. The VERY simple calc I use for estimating range is:

(volts*amp hour rating of batts at 20hrs/watt hour per mile for vehicle/1.8 for lead acid/1.05 for inefficiencies) This is VERY SIMPLE, but fairly accurate. Now do the same calc for lithium (you don't divide by 1.8 for Peukert effect) and range jumps to 77miles. Figure a '65 Mustang would probably use ~350wh/mile. So if you did 183aH 8v batts for a 144 volt system (18batts) and drove moderately, then range would be ~ 144*183/350/1.8/1.05=39miles. If you did the same car with 180aH lithiums, then 144*180/350/1.05=70miles. Again, this is very general, but I've found it tends to agree with real world at least with LA. 

Don't over build and spend money where you don't have to. If you'd truly be happy with moderate acceleration, 70+ top speed and 40 mile range, then only build for that. However, if you have the money.. do something great.


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## DRAINSTURGEON (May 26, 2010)

PatricioIN said:


> Don't over build and spend money where you don't have to. If you'd truly be happy with moderate acceleration, 70+ top speed and 40 mile range, then only build for that. However, if you have the money.. do something great.


That truly is the trick isn't it. It is one of the main reasons I like my I6 ICE. Most everyone who restores these cars slaps a modded V8 in them, either causing a ton of other drivetrain replacements or repair issues later. 99.9% of the time all that extra power buys you a nice rumble out the exhaust pipe and $$$$$ at the pump. So it stand to reason that the same can be said about EV's. I really need to figure out what my short and long term goals are to find the perfect system. The Warp9 /1000A controller is way cheaper and may very well meet my needs. Thanks for the equation, I really need to find that spreadsheet I had. You could really tweak the parameters to zero in on what you wanted. I may have gotten rid of it because I was planning a motorcycle and it was specifically for cars.


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## vpoppv (Jul 27, 2009)

IMO, a Mustang is an excellent choice for an EV conversion. It can handle battery weight better than an econobox, plus you have a wide array of choices for suspension modifications to accommodate more batteries. And , if you choose to, you could lighten it by adding fiberglass body panels. Also, all parts are readily available and fairly inexpensive. I sure hope you decide to go through with it....


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## MJ Monterey (Aug 20, 2009)

Haven't done a deep comb through for details but of particular interest in this case as a starting place.  It is a school presentation so dig through for facts, and verify facts before assuming they are.

http://nbeaa.org/presentations/ev_intro.pdf


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## PatricioIN (Jun 13, 2008)

MJ Monterey said:


> Haven't done a deep comb through for details but of particular interest in this case as a starting place. It is a school presentation so dig through for facts, and verify facts before assuming they are.
> 
> http://nbeaa.org/presentations/ev_intro.pdf


This is a good illustration of my basic range estimator formula. This is a convertible they claim uses 375wh/m, which is probably very accurate. They have 12-12volt 100Ah batts.. so 144*100/375/1.05=36.5miles.. They claim to achieve ~40miles. They have a '66 Mustang with some form of Lithium batts. So figure a hardtop Mustang would have better aerodynamics and would get a better range with the same set up.


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