# Motor coupling: universal joint?



## jlsawell (Apr 4, 2008)

I've finally saved enough to buy a manual transmission for my conversion and am starting to put serious thought into the adapter plate/coupling issue.

KiwiEV says on his site that the motor had to be EXACTLY aligned with the gearbox but I'm wondering if a universal joint would neutralise the problem?










Not strong enough to handle 9" torque? Too complex?

If I'm making too much of the issue, can someone give me a pointer on how to make the adapter plate & coupler align perfectly?

Ta


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## DIYguy (Sep 18, 2008)

hey there....

Personally, I wouldn't go down this road. I was worried about the same issue until I got into it. I have access to digitizing and NC machines, but for this, I didn't bother... it was easy enough.

Here is what I did; When I split the motor and trans, I used the thin spacer to help layout the general shap of the adaptor on a large piece of plotter paper. You could do this without the sheetmetal spacer, but it saves some time making a template. (templates can be made with stiff paper and a thin smear of grease on the mating surface) Next, if you do some measuring and use a good straight edge, you will find that there is a relationship between some of the holes mounting the engine to trans and the centre of the drive input shaft. Most have two main dowels either separate from the bolts or incorporated with a through hole. Mine was super easy as the two main dowels were in-line with the drive input shaft. Additionally, it was centred at the exact mid point between them. If it's not, draw some lines between mount hole centre points... you will find the dimensional relationship. 
If you have the sheetmetal spacer, you can transfer the outer shape and trace the mount hole locations on the paper. Draw the intersect lines on the sheet and carefully measure to find the precise centre. NOTE; if you grab the trans input shaft and wiggle it, you will find that it moves 1 to 2 mm so, it's not that tough to get right. Once you get the paper marked, tape it to your Al plate and centre punch the hole locations, including the drive input centre. Once you have the centre point punch marked, you need to scribe the bolt pattern of your motor mount onto the plate. I used a digital caliper, set it to the exact radius of the circle and locked it with the little lock screw. Next I and placed the point of one of the caliper measuring "jaws", into the centre punched hole. Using the caliper like a compas, you can scribe a perfect circle into the Al plate that represents the mount hole centre line. Just determine the pattern orientation that you need for you motor and center punch and drill. 

My motor had a large centre hub, so I scribed this circle... cut it out with a jig saw.. polished it up with sanding hub till i got a perfect fit, and sat my motor on the plate. I used transfer punches to get the holes dead centre. It worked out just fine. If any of this (or all of it , is hard to understand) please ask for clarification) I have some pics of some of it also.

Of course you will need to jig saw out the profile and either drill or cut the larger centre hole for you shaft/coupler.... 

I'm having trouble with some of my pics... I loaded a few, but I have some others showing the work better. Will see what I can do...

good luck.

Gary


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## etischer (Jun 16, 2008)

I just took my parts to a machine shop had had them locate all the bolt and dowel pins with their CNC. 










Everything just pressed together perfect.


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## whtemple1959 (Apr 30, 2013)

Etischer,

I am just getting started on my research.
Would you please tell me about your coupling? Did you make it? Did you buy it?

Thanks,
Bill


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## gdirwin (Apr 7, 2009)

My transmission shaft did not jut out beyond the mounting surface, so a good trick can be used:

First cutout your aluminum adapter plate. Use transfer punches to mark the mounting holes to the transmission, drill and mount (tight fit with no slop). 

To find the shaft centre, a good trick is to attach a pencil onto the transmission shaft via elastic bands... It should extend a bit past the mount surface, so that it touches the adapter plate. Bolt on the plate, then turn the transmission - this will inscribe a small circle to mark the centre. 

My adapter plate was 1" aluminum - I used a hole saw to first drill the motor shaft hole. Then I cut off the heads on short bolts for the motor to adapter mount bolts and sharpened the tips - when the motor is placed onto the adapter plate, you can now transfer the hole centres to the adapter plate (think of how the motor should be rotated at this point - access to terminals, brush holders etc...). It is better to use transfer punches here (as Garry did above), but I think you would have to disassemble the motor to remove the front cover...

Drill the motor mount holes. Finally cut out a large centre circle (jigsaw with bosch blades and lots of oil) so the motor sits flush.


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## z_power (Dec 17, 2011)

If you're mating motor to FWD transmission/gearbox then there's a chance of having input shaft supported with two bearings in the case, it could be used as locating item then. Here: http://www.diyelectriccar.com/forums/showpost.php?p=293360&postcount=13 is a picture of my attempt; I have access to cheap cutting plotter for plastic letters, I've drawn first sketch in CAD, had it cut, then measured with dial gauge if large bore is concentric, corrected CAD drawing, again and again... It took 3 plastic templates and next 3 from 3mm lasercut sheetmetal, achieved result is 0.02 mm accuracy.


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## poprock (Apr 29, 2010)

gdirwin said:


> My transmission shaft did not jut out beyond the mounting surface, so a good trick can be used:
> 
> First cutout your aluminum adapter plate.
> Finally cut out a large centre circle (jigsaw with bosch blades and lots of oil) .


My apprenticeship was 45 yrs ago and the preferred lubricant for aluminium was milk. Or was that just reflecting the poor finances of the Australian military?


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## gdirwin (Apr 7, 2009)

poprock1 said:


> My apprenticeship was 45 yrs ago and the preferred lubricant for aluminium was milk. Or was that just reflecting the poor finances of the Australian military?


Milk - never even thought of that - but it may explain why I went through so many bits using oil!


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## Siwastaja (Aug 1, 2012)

Ethanol or isopropanol works as a cutting fluid for aluminum. Naturally, an oil-based cutting fluid works too, but I prefer ethanol because it's less messy and you don't need to clean it off.


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## JRP3 (Mar 7, 2008)

Any concern with fire as the metal heats up? I've often seen smoke when drilling.


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## alvin (Jul 26, 2008)

JRP3 said:


> Any concern with fire as the metal heats up? I've often seen smoke when drilling.


I have used the alcohol from under bath vanity. No fires. I think it keeps the bit cool. It drills alot easier.


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## Joey (Oct 12, 2007)

Siwastaja said:


> Ethanol or isopropanol works as a cutting fluid for aluminum. Naturally, an oil-based cutting fluid works too, but I prefer ethanol because it's less messy and you don't need to clean it off.


 At work we make parts for vacuum chambers and oil is a bad contaminant that is expensive to clean. The machinist uses isopropanol (IPA) on all aluminum parts, and there is never any fire or smoke. The alcohol evaporates quickly and keeps the cutting tools cool. He sprays it nearly constantly from a hand pump bottle and keeps the part wet. It also seems to lubricate, because the hand tap has less resistance with the alcohol compared to dry. Boiling point is ~80 deg C, and autoignition is 400 deg C (from wikipedia)


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## Siwastaja (Aug 1, 2012)

Yeah, if the part heats up so much that the ethanol is quickly evaporating, I think the cutting tool is dull or cutting parameters wrong to begin with. You need a lot of heat to heat up aluminum, as it conducts the heat away so well. With sharp tools and a squirt of ethanol, aluminum doesn't even heat up considerably. Unless it's a very small piece. Then just use more ethanol to cool it down.


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## jehan12413 (Feb 4, 2010)

JRP3 said:


> Any concern with fire as the metal heats up? I've often seen smoke when drilling.


The metal shouldn't heat up, if it does then you are not using enough coolant. There should be a constant flow to flood the part being drilled, and they use a water soluble oil. This has a milky color and is primarily a coolant not lubricant. You could probably get some from any machine shop.


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## Siwastaja (Aug 1, 2012)

I have mixed water, paraffin oil and dishwashing liquid in about 4:2:1 ratio in a tight spot. The dishwashing liquid is there to help form the emulsion of oil in water. Seemed to work pretty well, but did cause some corrosion to the tools because the anti-corrosion agent is missing.

Luckily, the ethanol is just perfect for aluminum with no downsides.


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