# [EVDL] Some observations questions on going back to clutch



## EVDL List (Jul 27, 2007)

I know some have had the starter ring removed and the extra, unneeded
part of the flywheel machined off. I've also read that you should have
the whole assembly (motor, clutch, flywheel) balanced together.

On Sat, Apr 14, 2012 at 8:35 PM, Ben Jarrrett <[email protected]> wro=
te:
>
>
> Hey guys,
>
> As I mentioned in a previous message, I'm now going to put the clutch back
> in my Jeep EV. I'm doing this to make the Jeep more drivable in suburb=
an traffic.
>
> I spent the day rummaging my garage and shed to find the parts I needed. =
One
> thing that bummed me out a bit was that the flywheel and clutch together =
way
> 47lbs! The flywheel accounts for 27 of those lbs.
>
> So...
>
> I started second guessing my decision, but I plan to go forward with the =
clutch nonetheless.
>
> I know I have a heavy jeep, but I still try to save weight where I can (m=
y fiberglass
> hood and fenders saved about 35lbs, for example).
>
> I'm thinking I could have the backside of the flywheel cut down when I ha=
ve the clutch
> side resurfaced. Anyone think that's worth it? Might save 10lbs or =
so.
> I'd also like to not have the extra inertia.
>
> -ben
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere. Thanks.
> |
> | REPLYING: address your message to [email protected] only.
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-- =

David D. Nelson
http://evalbum.com/1328
http://2003gizmo.blogspot.com

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## EVDL List (Jul 27, 2007)

Hello Ben,

If you use a flywheel, make sure its for a internal balance engine, meaning 
the engine is balance by it self and the fly wheel is not use to balance the 
engine. Contact a auto parts store, and they can look it up in there 
catalogs to see if the flywheel for the engine is for a internal or external 
balance engine.

A flywheel that is use to balance the engine, will have a set pattern of 
bolt on to the engine crank flange meaning it can only bolt on one way.

Lets say you find that it's a flywheel for a external balance engine, then 
take it to a shop that does engine balancing or better yet, some electric 
motor shops also do engine and motor balancing. They can also remove the 
ring gear and machine it to the same thickness as it is in the center. 
Leave a little indentation in the center for the motor coupler to fit in so 
the flywheel center it self. If the not using the flywheel to flange 
indentation, then the fly wheel normally will have a centering pin hole 
install into the crank shaft flange and flywheel.

Do not relied on the flywheel bolts to center the flywheel, If there is a 
centering pin hole in the flywheel which is normally between two flywheel 
bolts, it is best to install a flywheel pin and drill the motor coupler 
flange to fit this pin.

My first flywheel which was for a GM 350 engine that weigh over 80 lbs. I 
ran it that way for about 10 years. Coming down mountain roads at speeds up 
to 80 mph, the EV could run out another 3 miles on the flywheel inertia 
only. In city if I see a light about to turn red three blocks ahead, I can 
let up on the accelerator and the EV will roll with the traffic up to the 
light.

If I have a quick stop, I push in the clutch which leaves the motor and 
flywheel spinning and then let out the clutch which reduces the motor ampere 
on start up.

Today, I am running a direct drive shaft that bolts directly to the motor 
coupler. The shaft is spline at one end at the motor coupler, so it is 
allow to float at least 3/16 of a inch in and out of the transmission. This 
replaces the torque converter for a automatic transmission which was 
converted to a manual transmission that does not use a modulator, governor, 
rpm or electronic control.

Set up for torque control which is ideal for a electric motor. Weighs about 
100 lbs less than the manual transmission and the performance is equal or 
better than the manual.

With the existing manual, I normally could only run in 2nd gear which was 
about 13:1 overall gear ratio. I had to shift into 3rd with a overall gear 
ratio of 5.57:1 to go over 30 mph which increase the motor amperes another 
100 amps.

With the automatic/manual, I had the transmission gear ratios size so I can 
stay close to the sweet spot of the motor in 1st to 25 mph, and 2nd to 50 
mph, can even shift to into 3rd after accelerating to any speed where the 
motor ampere is now 50 amps less than it was in the manual.

The sweet spot is where the torque and hp is at a maximum at a certain rpm 
for that motor. You want to be either at or close to the sweet spot when 
running the EV.

For my Warp 11 motor, the sweet spot is about 1800 rpm and for a Warp 9 
motor it is about 3300 rpm.

Accelerating to 1800 rpm in 1st gear, the motor ampere reads about 200 amps 
and comes back to about 100 amps. I then shift to 2nd and accelerating to 
1800 rpm which also reads 200 amps and comes back to about 150 motor ampere. 
Shifting into 3rd at 1800 rpm the motor ampere is steady at 200 amps at 
about 25 mph which is my normal city driving.

Here is a formula to calculate the mph or rpm or gear ratios.

RPM x Tire circumference
MPH = ----------------------------
Overall Gear Ratio x 1056

The tire circumference is measure by rolling the tire while its on the 
vehicle one turn.

The overall gear ratio is the transmission gear ratio times the differential 
gear ratio.

Roland








----- Original Message ----- 
From: "Ben Jarrrett" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Saturday, April 14, 2012 9:35 PM
Subject: [EVDL] Some observations questions on going back to clutch


>
>
> Hey guys,
>
> As I mentioned in a previous message, I'm now going to put the clutch back
> in my Jeep EV. I'm doing this to make the Jeep more drivable in suburban 
> traffic.
>
> I spent the day rummaging my garage and shed to find the parts I needed. 
> One
> thing that bummed me out a bit was that the flywheel and clutch together 
> way
> 47lbs! The flywheel accounts for 27 of those lbs.
>
> So...
>
> I started second guessing my decision, but I plan to go forward with the 
> clutch nonetheless.
>
> I know I have a heavy jeep, but I still try to save weight where I can (my 
> fiberglass
> hood and fenders saved about 35lbs, for example).
>
> I'm thinking I could have the backside of the flywheel cut down when I 
> have the clutch
> side resurfaced. Anyone think that's worth it? Might save 10lbs or so.
> I'd also like to not have the extra inertia.
>
> -ben
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere. Thanks.
> |
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
> 

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|
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----------



## EVDL List (Jul 27, 2007)

Hi Ben,

Be careful. If it is steel then you will be ok to a point - I'd leave it 1/2 inch thick min for your relatively heavy Jeep.

If it is cast iron - forget it! Even removing the normally heat-shrunk on starter motor toothed rim (thningy) is enough to weaken to the point where it might shatter at high RPMs with exciting (& potentially lethal) consequences.

You could always make one - see my blog below for details. Don't go thinner than 12mm mild steel tho. This may also make it easier to get the clutch in as it might take up less room along the axis of rotation than the stock flywheel. It should weigh only about 1/3 of the original I would guess.

Good luck. 

Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk




> Ben Jarrrett wrote:
> 
> >
> >
> ...


----------



## EVDL List (Jul 27, 2007)

The larger effect of having a flywheel is the increase in rotational inertia,
but it is not a huge effect unless you are shaving every second for racing. 
For example The flywheel weight in my Suzuki Swift is 22.5 lbs, or a mass of
10.2 kg, according to one parts distributor website. I guess its radius at
about 6 inch or about 0.15 m. The dynamic tire radius is about 10.5 inch or
0.27 m and overall gear ratios for first and second gear are 13.45 and 7.16
respectively. Vehicle mass is about 1027 kg. The equivalent mass of the
flywheel, m sub e = (m*R^2 * g^2)/(2*r^2), where m is the vehicle mass, R is
the flywheel radius, g is the overall gear ratio, and r is the dynamic tire
radius. This is 285 kg in first gear and 81 kg in second gear for the
Swift. "Equivalent mass" means the same work is done moving these masses
translationally as is done rotating the 10.2 kg flywheel, so with the
addition of the flywheel, during acceleration in first gear the vehicle mass
is effectively increased 100*(285)/1027 = 28%, and about 8% in second gear.

Accounting for rotational effects, the acceleration of the vehicle is A =
F/M where M is the effective vehicle mass including rotational effects. So
M equals the vehicle mass plus the sum of the equivalent masses of the
rotating parts. Acceleration with the rotating parts is A = a*m/M, where a
is the vehicle acceleration without the rotating parts, m is the vehicle
mass, and M is the vehicle mass including equivalent masses. Then if I
replace the flywheel with an aluminum one that weighs 7 lb, or 0.31 the
weight of the original, m sub e = 88 kg in first gear and 25 kg in second
gear. The rate of increase in acceleration would be about 15% larger in
first and about 5% larger in second gear compared to with the existing
flywheel. Eliminating the flywheel should give about 36% improvement, but
that requires a motor with enough torque for good acceleration at lower rpm,
and enough power to continue supplying high torque for good acceleration at
higher rpm without the benefit of a gearbox to change the wheel torque to
motor torque ratio. That cost more than I am willing to spend for the
somewhat higher acceleration rate. 

--
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## EVDL List (Jul 27, 2007)

They make Aluminum flywheels.


Sincerely,
Mark Grasser

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Ben Jarrrett
Sent: Saturday, April 14, 2012 11:35 PM
To: Electric Vehicle Discussion List
Subject: [EVDL] Some observations questions on going back to clutch



Hey guys,

As I mentioned in a previous message, I'm now going to put the clutch back
in my Jeep EV. I'm doing this to make the Jeep more drivable in suburban
traffic.

I spent the day rummaging my garage and shed to find the parts I needed.
One thing that bummed me out a bit was that the flywheel and clutch together
way 47lbs! The flywheel accounts for 27 of those lbs.

So...

I started second guessing my decision, but I plan to go forward with the
clutch nonetheless.

I know I have a heavy jeep, but I still try to save weight where I can (my
fiberglass hood and fenders saved about 35lbs, for example).

I'm thinking I could have the backside of the flywheel cut down when I have
the clutch side resurfaced. Anyone think that's worth it? Might save 10lbs
or so.
I'd also like to not have the extra inertia.

-ben

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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----------

