# Just Another Geo



## vpoppv (Jul 27, 2009)

I will follow this project closely!!! Those are some really beautiful motors...


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## dtbaker (Jan 5, 2008)

so..... WHY are you going with direct drive to each wheel? Just to get more HP?

Do you have any monitoring/control between the motors to compensate for slightly diferent speeds? How about if one wheel breaks loose? I just would be pretty concerned about 'torque steer' if one motor is pulling and the other loses traction....


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## grayballs (Aug 27, 2008)

dtbaker said:


> so..... WHY are you going with direct drive to each wheel? Just to get more HP?
> 
> Do you have any monitoring/control between the motors to compensate for slightly diferent speeds? How about if one wheel breaks loose? I just would be pretty concerned about 'torque steer' if one motor is pulling and the other loses traction....


No monitoring,,, I just don't think that torque steer is going to be a major issue,,, or turning corners at slow speed,,,, my thoughts are that the less loaded motor will just turn faster. I may get some real surprises, here,,,, and just in case, I have a plan 'B'. My initial idea is to provide total redundancy, in case of component failure,,, one could still limp home. If my idea fails, I figure to wire the pack in series (144v), wire the motors in series (they then act as a limited slip diff.), new controller, and so much for redundancy.
I have seen so many threads on this forum, asking about the possibility of this approach, I decided it was time to give it a try. I think the idea has merit and since most of the expensive parts I had laying around,,,,, (still need batteries),,, you get the idea.


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## Salty9 (Jul 13, 2009)

I have considered a similar drive system and wondered if proportional control could be used with the angle of the steering wheel used as input.


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## dtbaker (Jan 5, 2008)

interesting concept for sure.... I'll be following along. I am thinking that the one-speed gearing is going to give some pretty sluggish acceleration, but perhaps w/ 144v and the dual motors you'll be ok.

I am not familiar with those motors, what is the rated torque/hp at 144v?
What batteries are you planning for 144v? You must be planning to sacrifice the rear passenger/cargo area completely?


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## grayballs (Aug 27, 2008)

dtbaker said:


> I am not familiar with those motors, what is the rated torque/hp at 144v?
> What batteries are you planning for 144v? You must be planning to sacrifice the rear passenger/cargo area completely?


They are 6.7" ADC's,,, about 8 hp [email protected] 72v,,,, 22 hp momentary. I'm guessing there won't be any issue getting this thing moving. 

I'm planning for LiPo4,,, 2 paralell packs of 160 - 180 ah each, depending on what I can afford at the time. No back seat,,, this is going to be a 2-holer commuter,,, the batteries taking the space where the seat and tank used to be,, maybe a package shelf over them


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## grayballs (Aug 27, 2008)

I got some time, today, so I decided to try to run in the brushes on my motors. At 12v they are drawing 14.3 a and running 2272 rpm. After an hour they are getting very quiet. Not having done this, before, I guess I didn't know exactly what to expect,,, still don't know how long it will take to fully seat the brushes. Any ideas?

http://i195.photobucket.com/albums/z20/oldguysrivi/MVC-009S-1.jpg

The picture also shows some of the buss that I came across, today. I'm guessing I scored about 110# total,,, some of it up 7' long,,,, all in all, a great day


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## grayballs (Aug 27, 2008)

Started the 'transmission' parts, today. mostly playing and shedding weight.
http://i195.photobucket.com/albums/z20/oldguysrivi/MVC-001S-1.jpg
The one on the left is the stock hub, as it comes from the manufacturer. It weighs in at 12 lbs. 13.6 oz.
http://i195.photobucket.com/albums/z20/oldguysrivi/MVC-013S-1.jpg
This is after some playing. The cast hub was cut out and replaced with a 1/2" 6061T6 plate and then attacked with the mill.
Now that the programming is done, the other is just time,,,, it would be quicker if we knew something about optimizing the tool path (soon enough, I guess). The drive hubs are roughed out and splined, ready for final, then trial assembly.
Case next,,, I hope-


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## grayballs (Aug 27, 2008)

Yesterday was a good day, production wise. We got the drive hubs made and test fit.








I had no luck finding a broach to cut the splines for the hubs so we took a different approach. The splined gears were removed from the differential and the teeth were ground off, then machined to size. We then silver soldered the splines into the hub and for good measure (translate that as I chickened out) ran a tig bead around the end. 'Back into the lathe to finish sizing and into the mill for the bolt circle. I was surprised how many steps were required, but very happy with the finished product.
















Last picture shows the assembly waiting for bearings and housing,,,,, next week, I hope


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## grayballs (Aug 27, 2008)

OK,,,, 'Finally got time to get back to my project. This shows all of the individual parts for one of the hubs










Hub assembled










Geo axel will snap in just as it did in the original trans. differential










Tool paths are defined, one of the side plates for the drive is clamped into the mill,,,, all I need is time to tell it to go. Then it should start to look like something other than parts.


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## electromet (Oct 20, 2009)

Grayballs,

I've got to say that you've got some crazy machine shop skills. You're going to have to put plexiglass front body panels on your Geo so that everyone can appreciate the beauty inside. I can't wait to see the finished product.


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## grayballs (Aug 27, 2008)

electromet said:


> Grayballs,
> 
> I've got to say that you've got some crazy machine shop skills. You're going to have to put plexiglass front body panels on your Geo so that everyone can appreciate the beauty inside. I can't wait to see the finished product.


Thanks, but that's not entirely true,,,just trying to learn as I go. Each piece takes an amazing amout of time and I find that I turn a bunch of good stock into nothing more than chips, occasionally. (things like turning a perfectly good drill into a punch,, because I forgot a zero also happen)

I actually have the hood trued to the point that I can use it for a mold. I need access to an oven or I need to build one to make it happen. Hopefully, it can be arranged so it's not too 'busy' under there to be worth showing off.. I've seen some beautiful work come from members of this site,,, just trying to measure up.

Right now the focus is on the drive parts and the fiberglass and plexi rear hatch.


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## MalcolmB (Jun 10, 2008)

I'll be following this very closely too as I'm planning a very similar approach for my mini conversion, though with a single controller driving the motors in parallel. I like the idea of having complete redundancy, but like you I'm curious to find out how things work out in practice. There are so few conversions of this type around. My main concern is long-term reliability of the belts and making sure there's no chance of overspeeding if one of them fails.

What pitch/make of belt are you planning to use? It's hard to gauge from the photos.


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## grayballs (Aug 27, 2008)

The belts are 'H' Gearbelts, 1" wide. With 6, or more teeth engaged they're good for 20+ hp each.
I'm hoping to use a couple of shift light tachs to control overspeed. I think they would be easy to adapt and use the light circuit to actuate a latching relay on the control side. If not, I have room to install a spring loaded follower on the belts to serve the same purpose.


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## grayballs (Aug 27, 2008)

This is one of those OPPSDAMNIT!!!! moments. Result,,, bruised chest,,, bruised ego,,, $45 end mill turned to junk. 










Two of the parts that make up the passenger side of the 'transmission'. Hopefully, by Monday I'll have some of it assembled, or, at least test fit. it doesn't look like much, yet,, but I'm excited


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## Tesseract (Sep 27, 2008)

grayballs said:


> ...
> The plan is for a twin motored (one driving each front axel), twin controller Geo. The donor is a '95 Metro that is next to perfect, except for the tranny.


Easily one of the most innovative, and gutsy, projects I've seen yet. I'm subscribing to the thread just for the helluva it! 

Looks like you are using Curtis 1221C controllers, correct? Sounds like a good match for the 6.7" motors, power-wise, but these basic analog controllers are unlikely to have very good matching with respect to motor current vs. throttle position. I.e. - 3k might result in 200A from one controller and 250A from another. Also, I don't think you'll be able to use a single potbox for both controllers since they use a two wire input. Maybe a couple of Alltrax 7245's would be a better choice for the controller because they can be set to 0-5V input and individually calibrated so you have a chance of minimizing torque steer.




grayballs said:


> ...The bolts extending from the tail shaft are for the tach pick-up that is yet to be installed. The plan is to try to use pulse driven tachs with shift lites to operate a control relay in the event of a broken or slippped belt. After searching the forum, I found what I thought were the parts I needed, but when I contacted the manufacturer, I was told that I needed at least 36 teeth to generate the pulse. I think maybe I don't understand everything I need to know, here. If any of you care to share a similar solution, with part descriptions, I would appreciate it.


Couple of things here... first, the aftermarket tach kits I have messed around with typically pick up the signal from a spark plug wire or the ignition coil. In newer vehicles (newer than yours), a 36 tooth wheel with one tooth missing (ie - 35 teeth with an extra space marking TDC of cylinder 1) is very common. You have no hope of using a simple circuit to read THAT signal. However, there's probably not much point because if a belt every breaks under load the motor is guaranteed to go ballistic way faster than a human could respond to it. In other words, a light telling you the belt has broken is more or less a useless light 

I'm not sure about this, but if the Alltrax 7245 also has a tach/rpm input for overspeed protection then that's yet another point in it's favor.

Good luck!


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## MalcolmB (Jun 10, 2008)

Tesseract said:


> if the Alltrax 7245 also has a tach/rpm input for overspeed protection then that's yet another point in it's favor.


It doesn't unfortunately. Another possible issue with the Alltrax controllers is the throttle response, which is based on voltage control, rather than current control. In other words each throttle setting corresponds to a given speed and the controller immediately tries to reach that speed. This results in very twitchy low-speed control, at least on my motorbike, which admittedly weighs a lot less than a Geo.

The Kelly controllers, for instance, reportedly give much smoother, current-based control that mimics the original throttle response of an ICE. I don't know about the Curtis controllers.

My own choice, for running a pair of motors in parallel, is likely to be a Zilla because of the dual motor control options and the overspeed protection.


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## Jimdear2 (Oct 12, 2008)

Tesseract said:


> Easily one of the most innovative, and gutsy, projects I've seen yet. I'm subscribing to the thread just for the helluva it!
> 
> Looks like you are using Curtis 1221C controllers, correct? Sounds like a good match for the 6.7" motors, power-wise, but these basic analog controllers are unlikely to have very good matching with respect to motor current vs. throttle position. I.e. - 3k might result in 200A from one controller and 250A from another. Also, I don't think you'll be able to use a single potbox for both controllers since they use a two wire input. Maybe a couple of Alltrax 7245's would be a better choice for the controller because they can be set to 0-5V input and individually calibrated so you have a chance of minimizing torque steer.
> 
> ...


I beleive Jeff has a good idea about using a 0 to 5 volt throttle instead of a resistor type throttle. A trim pot on each circuit should allow fine tuning.

I can tell you from experiance that the Alltrax DOES NOT have a RPM input. I am using an Alltrax on my pulling tractor and because things break I needed runaway protection. What I did was take a simple racing tach with a shift light to drive a latching relay that controls the main contactor operating circuit.

*Normal Operation* the main contactor power runs through the latching relay NC contacts.

*Trip Operation* the tach shift light comes on and operates the latch relay which opens the main contactor circuit.

*Reset* Turning the key ON switch OFF then back ON 

I used an aftermarket 5 inch tach with an adjustible shift light trip point.

These tachs have settings for 2, 6 and 8 cylinders. You need a simple pulse generator circuit to drive the tachs. It takes 2 pulses per motor RPM to drive the tach when set into the 4 cylinder position (3 pulses per RPM for the 6 and 4 for the 8 cylinder). I used a piece of 1/4 by 3/4 flat stock mounted (suitably shaped and centered) to the tail shaft. and a good quality proximity sensor to produce the signal.

This circuit works quite well. I've already had a person get on and REV the motor in neutral to hear what it sounds like. Worked like a charm.

A caution, for the latching relay use a DPDT relay with Very low coil resistance. Some of the cheaper tachs use VERY low power to drive the light. Second caution watch out and be sure the shift light DOESENT have a flashing shift light.

The curcuit works well, we have it on three different tractors using three different Tachs. A little fine tuning and they all came into place.

A side note if you don't want a tach for each motor in the car, there are adjustible rpm sensitive control switchs uses on race cars to trip things such as nitrious stages.

A final question, Why not save on expense and complexity and just run the motors in series. If they are not matched closely enough, you could possibly fine tune them with field weakening by parelleling resistors to the field on one motor (an Idea I heard elsewhere but sounds right). 

This is really beautiful machine work.


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## grayballs (Aug 27, 2008)

Jimdear2 said:


> I beleive Jeff has a good idea about using a 0 to 5 volt throttle instead of a resistor type throttle. A trim pot on each circuit should allow fine tuning.
> 
> I can tell you from experiance that the Alltrax DOES NOT have a RPM input. I am using an Alltrax on my pulling tractor and because things break I needed runaway protection. What I did was take a simple racing tach with a shift light to drive a latching relay that controls the main contactor operating circuit.
> 
> ...


The tach/control circuit is exactly what I had in mind. 'Hadn't given it much more than casual thought,,, just trying to stay busy and make the Geo look like a project rather than a pile. The holidays put a quite a dent in the finances,, everything else is stuff I've had on hand from other projects or just acquired/traded for along the way.
I have a Plan 'B', a series connection @ 144v (Paul and Sabrina's kit?) if this doesn't work out like I want. It's all just a big learning curve for one old guy and a couple of my friends.


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## grayballs (Aug 27, 2008)

I took my Granddaughter home last nite,,, got home about 11:00pm, and thought I'd walk through my shop on the way into the house. BIG mistake! At 3:00am I realized what time it was and that I have to work today. (I leave the house at 5:00am). I'ts proving to be a long day, already. Fortunately, Most of what is on the schedule for this morning is progress reports for my apprentices. The office believes that we are cave-people so "He dun gud" ought to handle it, from my end.
Anyway, last nite's progress;




























This is the driver's side end plate. Somehow I got out of sequence for my parts,,,,,
Let me know when I reach 'Enough Already!' I'm excited, and as long as I can pay the electricity bill and make the camera work, more is the word


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## grayballs (Aug 27, 2008)

Clean-up drill and tap, then the hub bolts on,,,,,,, sound real confident, don't I?


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## Jimdear2 (Oct 12, 2008)

Nice work, I can't do that good during normal woking hours, never mind 3:00 am.

WOW I wish we could all have a CNC mill in our workshop. I am for sure green with envey.

This EV of yours will absolutly need a Lexan hood. Even if it didn't move it looks like it will still be eye candy.


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## grayballs (Aug 27, 2008)

My ex daughter in law used to have a saying about her Toyota 4x4,,,, (48" tires, over 10' tall,,, scary!) it didn't move worth crap but "it sat pretty". I'm hoping not to build a show-piece, but rather a functional test bed for a few ideas I've heard. No vaporware or un-obtainium batteries on this toy,, just build and play and if that don't work,, build again


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## GT2 (Jan 3, 2010)

Very nice work!
Dont take this the wrong way, just a word of caution.
Speaking from my personal experience driving front wheel drive race cars with locked differentials.
If you loose a belt from one motor at high torque/ speed, be ready for a wild ride! The torque steer from the other motor will put you into the next lane faster than you can blink.
I've been spit off the track a few times by broken axle's, cv's, and diff's.
Hopefully this wont be a problem for you!


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## grayballs (Aug 27, 2008)

GT2 said:


> If you loose a belt from one motor at high torque/ speed, be ready for a wild ride! The torque steer from the other motor will put you into the next lane faster than you can blink.
> I've been spit off the track a few times by broken axle's, cv's, and diff's.
> Hopefully this wont be a problem for you!


This forum is a tough group to play to an any given day,,, I don't take anything "the wrong way". I appreciate the input. 
I have considered the torque steer issue and, from my perspective, I don't think I'm going to have enough torque/speed to do a great deal of damage. (I HOPE) 
I might get surprised and this thing is zippier than my wildest dreams,,,,, Yeah, Right! 
It's just a commuter,,,, 45+ mph top speed, if my calcs are correct.

I was told that this part looks like a tree frog so I'm doing double green, today. This is the last of the side plates,, assembly next,, then the spacers have to be rolled and fit to the plates.. Soon,,,, I'm not going near the shop, tonite


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## Amberwolf (May 29, 2009)

GT2 said:


> If you loose a belt from one motor at high torque/ speed, be ready for a wild ride! The torque steer from the other motor will put you into the next lane faster than you can blink.


Not to go too far OT, but if I have a tadpole trike setup with one brushed motor running on each front wheel, both wired in series running from the same controller (as an electronic differential), and the motor-to-wheel connection suddenly broke on one side, what do you think would happen? 

I'd like to be prepared for many, if not most or all, of the possible problems that could arise on this thing *before* I take it on the roads. If I know what the result might be, I might be able to build a sensor and cutoff for the expected problem that will still let it operate in normal conditions.
________
Club Royal Condo Wong Amat


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## GT2 (Jan 3, 2010)

Amberwolf said:


> Not to go too far OT, but if I have a tadpole trike setup with one brushed motor running on each front wheel, both wired in series running from the same controller (as an electronic differential), and the motor-to-wheel connection suddenly broke on one side, what do you think would happen?


With apologies to OP, I will answer.
My experience comes from light weight front wheel drive race cars with about 175-200 hp and wide slick racing tires.
These specs magnify the torque steer problems.

My gut feel says that in low torque / low traction applications ( your situation?) torque steer shouldn't be much of a problem.
Tim


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## grayballs (Aug 27, 2008)

Max torque at low rpm,,,, I think most of the carnage should be with start up, so speed should not be an/the issue, unless there are design or mechanical weaknesses. 
The other issue,,, the series connection,,,,, one of the reasons I decided to go with the parallel connection was that I couldn't figure a way to stop one of the motors and still have the other operate, ,,, (to get to the side of the road or out of the intersection or ?????) in case of belt or mechanical failure. I'm hoping the redundancy allows that. If not, I'll have an answer for the numerous threads that have asked the 2 motors, 2 wheel drive question. Call it a beta test,,,,,


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## Amberwolf (May 29, 2009)

Thanks for the answers. 

On my system I'll be carrying a shorting plug that I can put on the connector to the motor (at the controller end) in case something goes wrong with a motor or it's drivetrain along the way, so I can still limp home. I already know these motors can take the full pack voltage (48V); I'd just have to be careful with the throttle (or put a limiter switch on it for single-motor mode).

I have also considered having a plug setup so that I can use them in parallel *or* series, depending on the result I am after. I'd rather use a switch/contactor setup, but I don't have any rated for that duty and can't afford to buy any. 

Maybe I'll put a simple interrupter sensor in the driveline path so that if the chain or belt breaks it'll shutdown the controller, or at least throttle it way back. 

I don't have any worries about motor overspeed with these wheelchair motors  but I am still concerned about the vehicle's reaction to such an event.
________
UKGal_22 cam


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## grayballs (Aug 27, 2008)

Finally,,,,,,, time to get back to my project. 'Started bending the spreader pieces for the "transmission". 
I've done some fab work with alum. in the past, but it was 50 series stuff and for car bodies. This 6061-t6 stuff presents all kinds of problems. Today's task was to roll a 1/2"x4" flat into a circle, 3 11/16" radius. I was not even close, the first attempt,,,,, cracked all to Hell. Second attempt was much better, I took to annealing the work piece about every 3 passes on the rolls. Pictures tomorrow after I get the larger radius bent,,,, at least, then it will look like something. 
It's a good day when something is learned,,, I guess I ain't too old


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## grayballs (Aug 27, 2008)

One might think that after 35+ years of working with metal, I would have some idea of what I'm doing. After another 2 hours of annealing and bending, I was busy trying to square the 2 pieces that make up the spreader for the drive (transmission?). Notice I said 'trying'.,,, The piece was in the lathe and evidently not tight enough. Springy little bugger made it all the way across the shop, before it quit bouncing. In a matter of seconds I managed to turn all that work into more junk for the scrap bin.
Hopefully I will find time to start over, again, and be able to get it trued and assembled this week,,, then pictures for those of you that are watching..... Maybe I shoud start a thread on how not to go about this


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## grayballs (Aug 27, 2008)

After a week, or so, away, time to get back at it. I finally figured out how to roll the 6061-t6 without cracking it. (For those interested; heat to 650 Deg.F and quench. This will give about 2 hours of good work time. 6061 actually begins to harden with time or work). I actually annealed the pieces 2-3 times during the process,,, I just chickened out after the last failures. Work with/along the grain of the product,,, across will break it even with annealing.










I should get them welded up before the day is out and then back into the mill to true the faces and machine the offset.... FUN stuff,,,


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## grayballs (Aug 27, 2008)

Got a chance to test fit some pieces, today




























'Looks like everything is going to go together, as planned


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## dtbaker (Jan 5, 2008)

wow, artwork!
can't wait to see how that engine bay fills up!


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## grayballs (Aug 27, 2008)

I'm getting a bit excited about that, myself,,,, the package measures, front to back, just over 18". the plan is to locate it to fit the drivers side drive shaft and cut the pass, side shaft to fit. Off the top of my head, I'm guessing that trims about 2 1/4" off the shaft.
The next big fit is the outboard motor mount... the plan is to incorporate some ducting, for cooling, along with support. One suggestion is to press the internal fans off the motors, trim the outlet vanes, and reverse the air flow to the motors, (carrying the carbon dust to a filter or ?). I guess the idea is to run the blower speed inverse to the motor speed, somewhat. I assume the larger amp draw will be at lower RPM, needing more cooling. I'm real open for ideas or discussion, here,,, hopefully the resident motor guru will weigh in
Anyway,,,, drilling and threading and bolting and fitting will consume the next few sessions


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## grayballs (Aug 27, 2008)

Things are starting to go together,,,, even though I was certain about pitch lengths. and such, I'm relieved to finally assemble and know the belts will fit and run true. Soon it goes in the car, and I can sit there and make those MMMMMMMMMMMMMMM noises


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