Continuing my ETEK anatomy thread, just found this video showing the Lemco motor:
Skip to 4:38 to see the inside bits.
Category: the ETEK thread
Well, view. The exploded view.
Them are the partz. This is how they go together:
The two collars are what holds the rotor.
So, yeah, in the process of discovering how to take the thing apart, I broke a 12-ton press and damn near busted my thumb with a sledge. Broke my BFH too. Had to cut the collar nut off, then realized it was coming off the wrong direction, over a collar that was just a wee big too big. If brute force doesn’t work, you’re not using enough.
Will Ted be able to put it back together? Will the ETEK ever run again? Don’t change that channel…
(Sorry about the abbreviated posts, I’ve got two story deadlines this week… had to get these posts up though to keep me honest. I’ll be back and flesh them out a bit after the stories are done.)
Here’s how the collars go together:
Here you go. Start to bitty parts, how to tear down an ETEK (or Manta) motor. (Even sparing you the tacky voiceover or obnoxious music. Don’t thank me, no, you’re too kind… )
OK, I ran my ETEK for a bit and the rotor started binding on the brush-side magnet. So I started looking for slop.
The magnets are located on the two housing halves. The rotor is located between them with the bearing and the shaft, along with some shims and a bearing lock plate, on one end only- the sprocket end (as opposed to the brush end). So, there’s where I figure there has to be some slop.
As far as I can see, the shims and the circlip seem OK. The shims measure out at a perfect .010 each, and the circlip fits snugly in it’s little circlip groove. The bearing has a bit of slop from side to side, so I’ve ordered a new one. I’m going to hazard a guess that it’s moving .015 or .020, at the most. I figure it can’t hurt to just plop a new one in.
But here’s what I found that may actually be significant. The bearing locking plate, on the inside of the housing, doesn’t seat up against the housing. Here’s what I mean.
This is the bearing sitting in the housing.
The outer diameter of the bearing is flush with the face of the housing. Here’s the plate, sitting over that face:
That, once it’s bolted in, should hold the bearing flush with the face. The problem is, it doesn’t. The plate is slightly larger in diameter than the faceplate relief. Here’s what it looks like from the other side, with the bearing removed, showing the space between the plate and the face. It measures out to about .035.
…corresponding to the same depth of the relief on the inside between the outer casting (where the plate is sitting) and the inside face (where the plate should be sitting):
So, it should be a simple fix to just grind down a little of the edge diameter of the locking plate so it has a better fit. I’m not at all convinced that this will be enough to keep my rotor from binding, but it certainly isn’t right. Stay tuned.
For the record- this is a “Manta” ETEK motor from eBay- reportedly never used, and “remanufactured”.
Want to open up the ETEK? Piece of cake. Here’s a great 3-step post on it, via TeamHurtz.com. Great suggestions on when to mark the positions of the parts you’re taking off, too.
Also found this manual: etekmanual Form #275225 ETEK Manual
Now. Here’s what I did. I don’t have photos, because, frankly, I was more interested in doing the repair than showing how to do it. Sorry.
First, I pulled the cover as shown above. I can’t rave too much about the sweetness of having a good puller. The one I have is a basic three-leg gear puller, and by taking everything off except two of the brackets, I was able to reach below the legs of the face plate here and toss a pin across the two puller bracket holes. The cover came off in a heartbeat.
All you’ve done at this point is to pull the cover off. The magnet got sucked into the rotor when you undid the bolts.
Going to the other side, undo the circlip on the shaft. There are a few shaft shims, take them out, and then, with a rubber mallet give the shaft a bunch of hard whacks (after you’ve undone the bolts on that side too). The shaft should move out of the bearing at that point, and the rotor will come out, with the magnets stuck to it.
I then reconfigured my puller with a couple of brackets bolted to the magnets, and used that to pull the magnets off. I had a few pieces of wood to stick in there between the rotor and the magnet as it separated, and once it got to about an inch and a half away, I could grab the magnet and pull it off.
Watch your fingers.
I was pulling the thing apart because there was some significant binding when the motor turned. The first thing I saw was something that looked like this, which freaked me out:
The corner of the rotor was all ground off, on one area. I figured my motor was toast. I then found this video, showing the same thing, and so I figured that grinding was done in the factory to balance the rotor. Remember to breathe.
I cleaned everything, checked stuff, noticed the rubbing was on the brush-side magnet from the outside of the rotor, and checked the rotor for wobble. Sure enough, there was a little run-out, and I tried tapping it gently with a rubber mallet where it was a little proud. It brought it in, remarkably, and it ran fairly true. I have no idea why it was like that, and no idea if the problem will come back, but after reassembling the motor it seems to have taken care of it.
The one trick to re-assemble the motor is to bolt the magnets into the housings before you put it back together. If you don’t you’ll be trying to place the magnets on the rotor and get them centered. That ain’t easy. Then when you try to bolt it together again you’ll have a reach to get to the threads, and be pulling the magnet off the rotor with your little bolts and not a lot of thread. Not easy either. If you place the magnets in the housing halves, bolt them in, then assemble them, the magnets get firmly seated, the bolts don’t get stressed, and the magnets help you by pulling the whole thing together.
Yeah. On that. When you’re putting the brush side housing on (after you’ve put the output side on and replaced the shims and the circlip) keep your fingers out of the way. It doesn’t go in gently. It snaps it right in…
Total ET of the teardown, without messing with the puller for the first time? About 5 minutes, including sipping coffee. Reassembly? About 3. Don’tcha love a motor with one moving part?
It doesn’t take more than a few hours of looking into building your own electric vehicle before you see the name Etek. The original Etek motor seems almost legendary, and the fact that the Briggs and Stratton name is associated with it makes it all the more interesting. After a while, though, a few things become apparent… the original Etek is pretty much not available, it seems to have been replaced by two newer models, the Etek R and RT, and as you delve a little deeper the confusion mounts.
Cedric Lynch designed the original Lynch motor, started LMC, which appears to still be around, went on to found Agni Motors, and there are rumors about technology from Lynch’s design being licensed to Briggs and Stratton for the new Etek R and RT. Depending where you look, you can find Lynch “LEM” motors listed, Agni motors, original Etek motors, new Etek replacements, even listings on Ebay in the Briggs and Stratton Outlet store for Etek motors. Then, there’s Mars.
Through a conversation with Steve Lorenz at Sevcon, I got in touch with John Fiorenza at Mars Electric LLC. John was a great help in answering some of my more pointed questions- in particular, solutions to the old “permanent magnet DC motors running regen and blowing up” issue- (John’s answer- “Sevcon MilliPak 4Q control was developed for PM motors. It will not blow up.” ) but in the meantime, we got into a conversation about the history of the Etek motor and the current situation. Yeah, I can’t stop myself from making that pun. But here’s the deal.
The original Etek motors were developed by Briggs and Stratton for OEM use, and actually, they were not allowing sales of the motors to any 2 or 3 wheeled vehicles capable of over 20mph for some reason known only, probably, to the lawyers. The early motors were purchased by EV guys resourcefully, through the Service channels. This is how legends are born.
The so-called Etek R and RT are actually Mars motors, designed by Mars (John, actually) without Briggs and Stratton or Cedric Lynch, either. There’s no licensing from Agni going on. Originally there was licensing from Lynch to Briggs and Stratton for the original Etek design- obviously a major source of the confusion.
The Agni, as well as the original Etek, by the way, is an axial air gap motor- see the previous post. The Mars is a radial air gap- a much more traditional basic design. The names, Etek R and Etek RT are names coined by some of the resellers- actually discouraged by Mars and probably an infringement of the Briggs and Stratton trademark.
The bottom line is that the Mars ME0708 and ME0709 motors are what you want, and what you’re going to be sold, if you’re looking for a new motor of “Etek” design. You want the best deal on them? Buy them from John, at Mars Electric LLC. If you want a kit or a package, and the support that comes with that, and are willing to pay a bit extra (usually only $25-50 more) then go with the resellers. (I’m a big supporter of dealers, and the service they provide- but you should know what you’re buying.)
As a little aside- you have, no doubt, heard about the Perm PMG 132 motors? Well, there’s a dirty little tale there, too- that company started as Cupex and was working to help act as supplier for Lynch. Instead, the company got their hand into the cookie jar- they started producing their own motor, the 132- an axial air gap design- and have been accused of infringing Lynch’s patent. The story goes that they don’t deny the design, they argue that the patent is invalid. As far as I’ve heard, it was never resolved in court, and they continue to produce the motor. (Update from Travis: the patent ran out in April of this year…)
From John:
“As to Mars Electric LLC, we are a niche motor designer and distributor for low voltage, high efficiency motors and controls. We design the motors in the USA, and have them made in China to reduce the product and tooling costs. We have been in business since 1997. Our core focus is to develop specialty motors for OEM applications, but we also sell motors to a few dealers in the EV markets. Our warehouse is located in Mequon, Wisconsin, and most of our orders are drop-shipped directly to the customer.”
Oh, and those motors on Ebay sold by Briggs and Stratton? Those are some leftovers from a failed outboard motor project- and with some questionable specs listed, to boot.
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