[sifawangiaEV]

Hi everyone,

I recently purchased a set of love joy couplings before realizing that it wouldn't work out because it was too small for the Warp9 motor I'm using. Here are some pictures to show what I'm talking about:

The motor shaft is too long for the coupling so it sticks out (shown in first image) so when I put the second part of the coupling on, it doesn't sit all the way on properly leaving space in the middle (shown in second image). If I lift the bottom up, then it fits properly but it's elevated from the motor (shown in third image). If I put a key in and used the hex screw to jam the key in place, would that keep the coupling safely elevated and connected or is that not reliable?

My other option is buying a whole new lovejoy coupling that is larger. I've been looking on eBay and I can't seem to find the right one though. The Warp9 motor shaft is about 30mm tall so the coupling needs to be at least that tall. And the coupling can be 95mm in diameter maximum because that's the size of the small circle platform that it's sitting on. Please let me know if you have any links to lovejoy couplings that I can buy or if there's any way I can make what I have work.

Thanks,
Sifa

 

[sifawangiaEV]

After much research, I have come up with a better solution to the problem that I am facing. I will be using an L150 lovejoy coupler with a bore size diameter of 1.125 inches.

Why the heck are you using a Lovejoy coupler? Im assuming you are putting this in an on road vehicle. No, Don't. Get a proper coupler that will hold up to the torque the Warp9 can dish out. You will destroy that Lovejoy and it won't be joy any longer.

I chose to use a Lovejoy coupling because I'm following Rich Rebuild's Mini Cooper conversion where he also used an L150 lovejoy coupling and while I know that this conversion was pretty quick and dirty, it worked and was road worthy which is good enough for me. Also, according to the spec sheet below, an L150 coupler (which is larger than the L100 I am using currently) will be able to hold up to the torque of the Warp9. Here is the spec sheet for the L150 lovejoy coupler:

**Small note: the SOX(NBR) is the spider piece that will be going in between the two lovejoy couplers and the torque rating is somewhat dependent on that.
So according to the L150's torque rating of 1,240 in-lbs, I believe that it will be able to handle the Warp9's torque rating of 840 lbs-in. Please let me know if you think otherwise.

In this image that highlights the specs of the of the Warp9 motor, I've also highlighted the Warp9's RPM of 5,500 because the L150 apparently has a max RPM or 5,000. Here is the spec sheet:

So is this difference in max RPM's a problem or not? Someone please let me know.

What are you connecting this coupling to? We need to know to come up with a better coupling.

I will be using a 2006 Mini Cooper S Manual transmission shown below.

Why are you insisting that the motor side of the coupling sits against motor case? Of course it can't touch the case because it would rub; the coupling is mounted on and located by the shaft, locked in place by the set screw, not the motor case or any step in the shaft diameter.

Yes, I just realized that. In looking at Rich Rebuild's Mini Cooper conversion, I thought that the coupling was sitting on the motor base, but now I know that the coupling will need to sit up from the motor.

So...what does everyone think that using the L150 lovejoy coupling will work? Any more feedback is appreciated.

 

[sifawangiaEV]

You said "at 2000 amps" but my motor will be getting, maximum, 500 amps, so I believe that the lovejoy should be sufficient, right?

 

[sifawangiaEV]

Motor torque output is basically proportional to current. The combination of 72 volts and 335 amps is enough electrical power for the 32 horsepower listed, but that combination of voltage, current, and power won't occur at either 5,500 RPM (that will be maximum speed) or 70 lb-ft (that will the maximum torque, at a lower speed); the 32 HP is a rated power for some condition that they think can be sustained, and perhaps the 70 lb-ft is for another sustainable condition, but the peak torque and power are both higher. The performance data for the WarP 9 at 72 volts shows 100 lb-ft (1200 lb-in) at 500 amps. That puts the Lovejoy L150 right on the edge for a WarP 9, and of course with more voltage and a controller able to handle more current both torque and power can be higher.

Thanks this is very helpful. I have a 500A semiconductor fuse so even if I hit 500A, the fuse will blow, cutting off all power. Considering this and the fact that my system will be running on 88V nominal (96V peak), I think I'll be safe using the L150 lovejoy coupling. Do you agree?

 

[sifawangiaEV]

Im thinking you will eventually not be joyous when the Lovejoy coupler dies. As a matter of practicality I think you should not cut corners when building an EV. You don't need to break the bank but you do want your parts to hold up and don't underestimate the the torque these motors dish out. For a stationary motor powering some belt driven device at low rpm the Lovejoy is perfect but for an on the road vehicle it is not practical. For a quick test of something maybe but for daily driving, I do not recommend under any condition for a DIY EV build. It is not the first time seeing someone wanting to use them. I even thought about but that was a rather fleeting thought. 500 amps or 2000 amps the motor dishes out lots of torque in ft lbs not in pounds.

Ok, so I would not like my coupler to die but it seems like in this case everything works out fine. I'm using a Zilla controller and I'm setting the motor max amps to 450A (starting out at 300A max) so my amps will be relatively low. My max voltage is 96 which is also pretty low. The L150 coupling is also able to handle the max torque of the Warp9. So with all of these considerations, I don't really understand why it won't work. It seems near perfect to me. What do you think? Also do you have any other suggestions for couplings?

 

[sifawangiaEV]

I guess you are fully set on the Lovejoy so I can no longer persuade you to see. Experience is a good teacher. I await seeing your project on the road. I await your responses to your choices a year from now.

I am not fully set to Lovejoy. As I'm making this tough and important decision, I find it helpful to weigh the pros and cons based on facts so that I can make a better, more informed decision. I listed the facts that I have above in my previous post (mainly pros), but if you felt that something was off or that there was something that I was missing, please let me know because that would be a valuable part of my decision. I don't know about you but I would not like to have my EV fail after a lengthy conversion so I am willing to make changes if those changes are for the better, so please let me know why the Lovejoy won't work for my conversion and I'll take that into consideration.

 

[sifawangiaEV]

The teeth of the love joy, 3 per side is a weak point as well as the rubber center. Constant stop and go will eventually cause the center rubber piece to be slowly crushed and as the gap increases the degradation happens faster. The teeth of the Lovejoy are also a shape that can fail due to fatigue of the edges. They are not designed for constant stop and go hard torque situations. They are designed for light duty or for constant speed and use. So a motor that is always moving without high torque applications constantly beating it to death will last much longer. I think you might be underestimating the power of the torque from these motors. Im sure some Lovejoy couplers might work but using the original vehicles means to couple things together with a clutch or auto trans is best. The solid couplers are best. I chose to use my VW's clutch and pressure plate. I'll be putting in two induction motors for a 167 hp and 173 ft/lb torque at the motor but much more at the wheel. I want to be sure it all holds together. My flywheel will have two clutch discs and a floater plate for the clutch so a stock pressure plate will suffice for the pressure and double the surface area of the clutch disk. 144v and up to 1000 amps combined.

I don't know any who actually had any long term success with them.

Thank you for your input. I see the problems with a Lovejoy being used on an on road vehicle and I definitely do not want to deal with that. I've come up with two alternatives after a bit of thought:

1) Remove the spider from an L150 Lovejoy coupler and have a machine shop weld the two parts together including filling in the middle so that it's just one solid structure. Would this work or no?

https://www.mcmaster.com/shaft-couplings/high-torque-set-screw-flexible-shaft-couplings-10/

2) I clicked on this link and found a coupler that works great with misalignment issues and is made for forward/backward and starting and stopping motion. It's also has a 2,075 lbs.-in torque capability and can go up to 9,000rpm. What do you think about using this coupler for my conversion? Is it up to take the abuse of an on road EV?

Out of option 1 and 2, which one do you recommend?

 

[sifawangiaEV]

Question, Does your vehicle use a clutch?

I'm not using a clutch for this conversion, so it's going to be clutch-less.

Unless your welder is top notch and can assure perfect alignment and a super solid connection then I'd say no and to afford someone like that defeats the purpose of saving a buck.

I think I'll go to the machine shop and see if they can give me a quote for welding the Lovejoy together with perfect alignment and a solid connection because I think that this may be the best option.

 

[sifawangiaEV]

maybe I misunderstood the idea, but if you're welding the two halves together, isn't it easier just to machine a solid shaft coupler to begin with ?

It probably is but I have no clue how to do that and do it right at that. Do I just give the machine shop the clutch plate with and the motor shaft dimensions, tell them to make a coupling and leave it at that?

 

[sifawangiaEV]

I agree with you here. If you are going to do a solid coupler buy one for that purpose.

I agree with that as well. I am asking how I can get one made. That's what my last post was asking. How can I get a solid coupler made? What do I need to provide the machine shop with so that they can make one? Please know that I am learning and I am very apt to change and persuasion because I am new to this. I have listened to what others have said which is why I am asking how I can do what is being recommended: get a solid coupler made specifically for my vehicle. Please let me know if you can help me answer this question and how I can get the job done right.

 

[sifawangiaEV]

So others may be able to point you to an existing product.

Does anyone have a link to this existing product?

sketch it up in CAD and bring them the drawing. If you draw it up in CAD you will be able to get quotes from shops that take orders online too.

I think I might try my hand at making a CAD file of the coupler. I'll make a new thread for that and include the link to it here.

 

[sifawangiaEV]

I'm thinking of using an existing product for my coupling to make things more reliable and easier.
I made a new thread here: Finding a Good Coupler.

 

[sifawangiaEV]

First a caveat, I skipped probably the last 15 or 20 posts to just get to the end of this thread and add my 2 cents, so if this has already been settled or whatever, please excuse.

I highly recommend not using a LoveJoy coupling in (most) EV conversion applications. How do I know? Because I tried it myself, and it ended bad. I'll spare a lot of details, even though I know details matter in such things, but the long and the short of it is that LoveJoys are very good at lower RPMs and torque loads that rise gradually (relatively speaking). In real world conditions of an EV, you've got neither of those, and the pliable center "spider" just eventually gets chewed up. Additionally, the little bit of "play" that you get with a LoveJoy that is seen as one of its advantages in many of its applications turns out to not necessarily be to your advantage, again, in a typical EV conversion. You end up with unwanted unbalance. A solid coupling between your motor and tranny is most desirable. Think about it like this, if a LoveJoy-like connection was what was best between a motor and transmission, then automakers would have been using them (or again, something like them) for a long time now.

These I've found to be great:

Climax Part CC-112-112-KW Mild Steel, Black Oxide Plating Clamping Coupling, 1 1/8 inch X 1 1/8 inch bore, 2 1/8 inch OD, 3 1/4 inch Length, 1/4-28 x 3/4 Set Screw: Industrial Products: Amazon.com: Industrial & Scientific

Climax Part CC-112-112-KW Mild Steel, Black Oxide Plating Clamping Coupling, 1 1/8 inch X 1 1/8 inch bore, 2 1/8 inch OD, 3 1/4 inch Length, 1/4-28 x 3/4 Set Screw: Industrial Products: Amazon.com: Industrial & Scientific

www.amazon.com

(Not getting any kickback from Amazon or anything like that, this was just the quickest link I could find)

Good luck!

Thank you for the feedback! I decided that a LoveJoy coupling wouldn't be reliable but now I'm stuck between getting a rigid coupling like the one you linked to or a flexible shaft coupling. Quick note: I will be driving clutchless so I need the best coupling for a clutchless application.

Some drawbacks to the rigid coupling is the fact that I'll have to get it perfectly aligned with the motor and transmission shafts and I don't know if know if I have the tools for it. 57Chevy said this in my other thread about couplers:

if you make it rigid then your alignment needs to be absolutely perfect and you need to 'clock' the shafts to each other first by putting a DTI on one shaft and rotating it around the other in several places to ensure it is both parallel and concentric. This is not an easy task if your coupling lives hidden inside a bellhousing and even harder if you don't have a shimming/adjustment system. The jaw couplings allow easy assembly plus have a stated acceptable misalignment amount. Any misalignment in the shaft that is forced into alignment by tightening a rigid coupling will cause extra stresses and lead to something failing.

How did this process work for you? Was it easier?

My other option, the flexible shaft coupling, seems like it might work well. Here's the link to it: McMaster-Carr. What do you think of this option (specifically the one rated for 2075 in-lb of torque?

 

[sifawangiaEV]

I've not seen that other flexible shaft coupler, but it does look a bit more stout than the LoveJoy. (And again, LoveJoy's are great, just not the best for this application IMHO.) That someone has used it successfully in an EV conversion is promising.
With all of that being said, I'd still lean pretty heavily towards a rigid coupling. Yes, it is definitely correct that the alignment needs to be very, very tight (and that is not only the X and Y axis, but also the Z). And I hear that you're going clutchless, but there are approaches to getting that alignment to where you need it. And finally, again, sorry I didn't read all the posts, just don't have the time right now, but for all of the reasons to go clutchless, in the end, overall, I fall in the camp of generally keeping a clutch. Yes, you loose some efficiency with the flywheel, but it really isn't as much as many make it out to be. And even though you end up using the clutch very little (compared to the ICE setup), it does make a few situations much easier when you have it; and the alignment issue becomes easier with a clutch setup (not "easy", but "easier").
Not trying to talk you out of your approach, as we've all got to pull these together our own ways; just letting you know my experiences.
Good luck!

I’m pretty set on going clutchless but I would like to try using a rigid coupling. How might I go about doing that right? Could I just send my motor and transmission and coupling to a machine shop and have them do it? What are your recommendations?