Frankencar1

Okay here it goes:

1. I am converting a 1986 Mazda Rx7 Non-Turbo to run on electricity.

2. I am told that I can't use a standard replacement flywheel. This is due to the nature of the rotary engine and the counterweight on the stock flywheel. I was told by an EV conversion company that I need a non-counterweighted flywheel, and that it would cost $500.

I said that was twice as much or more than what other flywheels cost and called BS. They looked around for me and found another one that they said would work for $300 (some markup of course). I said fine.

3. For many reasons, I didn't get around to doing much on the conversion for about a year and two months since I bought the flywheel. I recently discovered that the flywheel (an ACT flywheel) was much larger than the Exedy clutch kit I purchased around the same time. They won't fit together.

4. After much google action, I finally called ACT who informed me they do not make a flywheel for non-turbo Rx7's. So my assumption is that this is the source of the problem.

First question: Does that seem correct? The Turbo flywheel would be larger than the non-turbo flywheel? Manual, of course.

Second question: Would it be possible/wise to use the turbo flywheel on my non-turbo Rx7 and swap the Exedy clutch kit for a turbo kit? Doesn't seem smart to me.

For the rest of the story - I contacted said EV conversion company and they suggested the latter (return clutch kit and use incorrect flywheel) but that doesn't sound smart to me, nor safe, nor does it help me monetarily. Any thoughts/solutions/answers? Thanks!

jjcobm

iTrader: (18)

You need a couterweight, regardless of the flywheel you use. It seems like you got a TII aftermarket flywheel. You need to get a couterweight off an automatic S4 RX7 along with a TII clutch and a TII transmission to run that or just run the stock n/a flywheel.

The turbo flywheel is much larger than the N/A. You can't use the TII flywheel with an N/A transmission. The bellhousing is different on the N/A and will not work with the TII flywheel, specifically the starter location, and the bellhousing on the N/A cannot be removed unlike the TII transmission which you can remove and swap around.

They told you wrong, you need a counterweight regardless. Otherwise your engine will not be balanced out when it runs which makes no sense for them to tell you that. Aftermarket flywheels all use counterweights off automatic rx7's which is not built into the flexplate like the stock flywheel has the built in counterweight.

A flywheel is a flywheel. It serves to provide a surface for the clutch to grab on to. Even if you get an aftermarket flywheel, it will still be to specifications of mazda as far as thickness and diamater. It may be lighter and made of a different material but thats about it

Frankencar1

Really? Weird, it seems right to me to not want the counterweight. It seems like the counterweight would throw the electric motor OUT of balance...maybe you could help me understand that better?

There's no way I'm trading out the whole transmission thought. That's nuts. I just need a flywheel that fits my car, sounds like.

jjcobm

iTrader: (18)

Are you running a straight electric motor, and replacing the 13b? The counterweights are ONLY for the 13B engine. The e-shaft spins around. It has rotors rotating around the housings. Without counterweights on the front and rear of the engine the rotors would not be stable and balanced when rotating at speed. The e-shaft when balanced, will not wobble around at all making the output side of it (side that goes into transmission) not move around and will spin around the rotating axis. That will not effect the "balance" of the transmission at all.

Frankencar1

I am using an electric motor directly coupled to the transmission (through a flywheel adapter that I bought from the same company who sold me the wrong flywheel).

So I think they're right about the counterweight. That said, I noted that the counterweight seems to be a separate piece from the flywheel so...couldn't I just order any aftermarket flywheel and just NOT order the counterweight? Or is there some kind of cutout to fit the counterweight on the back of most flywheels (BTW, I don't have the original flywheel...kid I bought the car from sold it with the engine before I could get my hands on it).

If anybody can point me to a flywheel they think would work, it would be appreciated.

jjcobm

iTrader: (18)

Yes, in that case, they are right about the flywheel. Their motor must be already balanced and not need counterweights. And yes, you need to order an aftermarket N/A flywheel and bolt it on the motor and you will be set from there. The original flywheel will not work in your case since you need one that doesn't have the counterweight, or it will throw your electric motor out of balance.

Go to racingbeat.com they have N/A flywheels. I am 99% positive those require the seperate counterweight, which is what you need, but give them a call to make sure before you order.

jjcobm

iTrader: (18)

Almost forgot to mention. The aftermarket flywheels do not have a taper fit on them (it is acquired using the automatic counterweight bolted to the back of the aftermarket flywheel). Meaning, the electric motor should have a way to bolt this up, unless the output-shaft on it is shaped like the 13b one. In that case you will have to figure out someway to replicate the taper section on the O.E. flywheel or automatic counterweight, so that it will fit the output shaft and stick out the flywheel the required distance to properly have the transmission engage and disengage the clutch.

Frankencar1

Thanks, checking it out now.

eage8

iTrader: (9)

racingbeat.com sells flywheels for non-turbo rx-7s but I think they come with the counter weight. you might have able to talk to them and get one without a counterweight for a lot cheaper.

Frankencar1

I just got a reply from the company, looking for advice. Here's what they say:

"Nobody makes the special flywheels for the non-turbo RX7s because nobody races those. Listings for racing flywheels, never even specify "turbo" because it is assumed. All the RX7s, turbo or non, used the same transmission bell housing, so the flywheel should fit. All used the same clutch release bearing. The turbo and non turbo clutches for '86 both have the same stack height. The only difference seems to be a larger friction surface for the turbo. So the solution seems to be to use a turbo clutch with the flywheel in your transmission."

They offered to split the cost of a $160 clutch kit that will match the flywheel with me. I guess I can probably sell the clutch kit I bought before to cover the cost of this one (it's still brand new, it's just been sitting around for a year).

Could there be any negative effects from using the turbo flywheel in my non-turbo transmission housing?

jjcobm

iTrader: (18)

Really? Interesting, I guess the flywheels from racing beat and other companies is all part of my imagination.... I think its more of a bad marketing decision from whomever you bought the flywheel from...

All true stories....

This is the chevy mentality. Since it's been the same block since the 60 or whenever they started making the 350's, then all 350's use the same spark plugs. Wrong. There are differences in the heads, just as there are differences between a TII and N/A transmission bell housing.

Save yourself the time, unless they offer to throw you in a TII transmission with that deal or you don't need a working starter motor for the flywheel.

Yes, you will have to push start your car everytime you need to start it. If you don't need a starter (it is an electrical motor so I am assuming it may have the capability for starting on its own), then going with the TII flywheel and clutch mated to a N/A trans will work. If you need a starter, this will not work. The TII transmission has the starter located differently than the N/A transmission. The N/A starter will not spin the TII flywheel as far as I know.

http://www.rotaryresurrection.com/2n...in_differ.html

Hope that helps...

RotaryRocket88

iTrader: (7)

Huh? Someone at Racing Beat told you that, or someone at this EV conversion company? Of course there are people racing N/As. And if you go the RB's site, they have FOUR different non-turbo lightweight flywheels (steel & aluminum) for sale. They're not the only company making them either.

SoloII///M

iTrader: (13)

He's running an electric motor. So there is no starter. I'm confused about why he would need a starter.

RB sells flywheels for NA RX-7s and for turbo RX-7s. Since you don't care about the overall diameter of the flywheel (again - no starter), you can use either one and it will work with your transmission. Just make sure you get an NA clutch if you use an NA flywheel. Simple.

Now the tricky part is going to be the counterweight. The counterweight is to balance the rotating assembly inside the motor. Your electric motor will be balanced so you don't want a counterweight. The trick will be mounting the flywheel to the electric motor. Does the motor use a large non-tapered shaft with a woodruff key? If so, it should be very easy to take the flywheel and motor to a machine shop and have a machinist make you an adapter plate. That's what I would do.

I've driven quite a few home-brewed electric cars and one recommendation I would give you is run the lightest flywheel you can. Most of those electric cars used stock flywheels (on the order of 20-40lbs in most cars) and they are just too heavy. The electric motor takes long enough to spin down on its own as it is, you don't want a bunch of extra energy stored in the flywheel. It makes braking with the clutch engaged rather interesting.

Keep us posted on how this goes!

Frankencar1

Thanks everyone. Sounds like I'll just be taking their deal, then try to sell the clutch kit I bought to save on the cost.

Yeah, RB looks like it has what I need. The reason that I bought the flywheel from them was because they provided me with the motor-to-flywheel adapter that's going to make all this work. So I wanted THEM to tell me that it was all going to fit together.

Correct in assuming there's no starter. So it sounds like they're both right and wrong. They probably just don't want to fork out the extra hundred bucks or so to take back my flywheel and upgrade me to an RB or other (though to be honest I didnt find anything outside of RB).

Also correct that there's no counterweight. That's where finding a flywheel got tricky...I wanted no cw, and no groove for it so the flywheel was balanced. I think the RB flywheels are like that, but again, about $140 more than what I paid for the ACT flywheel I have now. So it seems like using the clutch kit for the turbo is going to be the path of least resistance.

ScrapFC

iTrader: (5)

How much power are you planning to run? With an electric motor's torque, you may be better served by a turbo drivetrain anyway. The NA drivetrain can be a little...delicate.

Frankencar1

Okay, update time. It's been a long and grueling process, but I finally have what I need. I have the turbo flywheel I originally ordered, as well as an ACT clutch cover for a Turbo, and a Turbo disc with custom splines to fit my tranny. It's been crazy, but I finally have it.

Just thought I'd post that and give you all an update who were so helpful with your information. Next step is to get it all installed. Any other considerations I need to be aware of? I'm just looking at some information and, while my process is a little different than replacing a clutch with the standard engine, it looks like there's a lot of things to consider here. I just mounted a new slave cylinder, but not being a car guy, I'm about to be lost again. Luckily, I have car guy buddies, even a Mazda guy buddy to help me out, but any general warnings or other input will always be appreciated. Thanks!

RotaryEvolution

iTrader: (30)

i would convert it to a turbo 2 transmission and use the modified driveshaft from mazdatrix. the rear end should be able to hand the torque of the electric motor so long as you don't do any drag launches with stickies.

Hazard15301

iTrader: (5)

They are ******* stupid asses. As has already been stated, turbos use a larger flywheel, and therefore a larger bell housing. Stop dealing with whatever company that is because they are talking out there asses.

RotaryEvolution

iTrader: (30)

the bellhousings are different, the n/a bellhousing for example is not removable because it is part of the transmission itself... if by the same they mean the bolt pattern is the same for the engines then they do have 1 fact correct.

jjcobm

iTrader: (18)

You bumped a topic that has been resolved already (well at least the argument part : ) ). He is using an electric motor with a TII flywheel on a N/A transmission and no starter. All is good.

As for switching the N/A Transmission to the TII transmission. Really up to you. I wouldn't worry about it until you start breaking things. All you need to worry about now is having the flywheel, clutch, throw out bearing and transmission back in the car. You should already have the N/A driveshaft to mate the transmission to your diff. Then all you need is the slave, and clutch cylinders and lines to connect them to the transmission.

TheAbsence

iTrader: (19)

I came here to say this, although it really depends on how much torque you're looking to put out and what driving style you're going to be placing this car under.


The OP bumped his own thread so its ok.

misterstyx69

iTrader: (142)

I couldn't grasp this Thread until I read it over again,and again
..Holy Smack!..a Mazda RX7 Electro-Car! NO 13b.!..
God!,I thought everyone was a Little bananas saying that you wouldn't need a counterweight..then I realized,there will be NO Rotary Engine,So therefore you dont need a Counterweight!.I gotcha now!

Skidtron

iTrader: (1)

crap i was gonna sell you a lightweight na flywheel for 100 bucks I just dont have the spacers for the clutch. oh well lol

Post up some pics of the motor and stuff when you get it in the car. electric conversions are cool

Aaron Cake

iTrader: (1)

Any specific reason you are going to use the clutch? Going clutchless would save you some serious hassle. I realize that clutchless can be a bit annoying, but you will probably be in 2nd gear for 90% of the time.

Might want to just use a stock flywheel and then have a machine shop lighten it up for you. Lose the ring gear, and then have them machine down the back. Shouldn't be anywhere near $500 to have this done. Hell, the ring gear just pounds right off with a hammer and it would only be an hour on the lathe for the co-op kind to turn down the rear of it.

However, depending on your motor (what are you using?) you may have to have the shaft machined to accept the RX-7 flywheel because it is a taper fit. Then you'd need to have it threaded to accept the flywheel nut.

Pele

iTrader: (28)

Why would you want to use a clutch in the first place? Directly couple the motor to the input shaft and just power off the motor before a shift. The mass of the armature would be accelerated or decelerated by the synchros and it might result in a little excess wear because it weighs a little more than a clutch disc... But that would be countered by the limited amount of shifting that would be going on...

Or you could tie into the vehicle speed sensor for the factory cruise control system (in the gauge cluster) and have a microcontroller to accelerate or decelerate the motor to preprogrammed speeds between shifts... These would be fixed numbers based on the gear ratios. Motor should change speeds without load pretty quick. Clutchless shifting.

Or just ditch the weight of the transmission and driveshaft all together and just couple the motor directly to the diff. Replace the ring and pinion with gears selected in accordance with your desired speed and acceleration, taking your motor's specifications into consideration. Hang the motor controller and charger back where the fuel tank used to be and fill the engine bay with the batteries.



I dunno, it seems as though just throwing the motor in where the original internal combustion engine was, leaving all the accessories that used to support the engine's weaknesses (limited powerband needing gears) is poorly thought out.