Is it OK to run a MAC without an inner washer?

Trying to finish my FatMAC build. Aluminum 170mm rear, BB5 brake.
If you don't want to read the below, my question is simply:
"Is it okay to run a MAC with no inner washer on the disk brake side?"
The brake fits with 1 disk spacer, and no inner washer.

Backstory (if interested. if too long, don't read don't complain):
The motor's disk mount was too short (even adjusting the BB5).
It needed either:
2 disk spacers (bolts then scary short),
or
1 disk spacer + removing the Inner Washer from that brake side.

I don't know where to get longer bolts to account for the 2 spacers (advice appreciated, or what do I search for).

My solution was to remove the inner washer. Now it fits w/1 spacer. But I have read (in a general sense) that inner washers are 'necessary', due to the narrowness of the axle pushing on the frame. Is it safe/okay with no inner washer on that side?

I didn't want to waste people's time, I asked the vendor (EM3EV) close to 2 days ago, they have never ignored an email, and I believe they will answer--but this is my most-important question (I asked them others), and I wanted to get y'alls opinions as well. BTW, EM3EV instructions are not just poor, they have entire sections/topics missing from the instructions. Very importantly, they lacked a photo of the a finished mounted product (closeup of the order of the washers, on both sides, plus where torque arm would go, what's necessary vs what's 'extra if you need it', etc). I just got a bag of unnamed hardware (washers/nuts).

Joseph there pointed me to a great free article on EbikeSchool.com on ebike washers. It was exactly what I needed (and hadn't found in searches), but that author says an inner washer is necessary. EM3EV NEEDS to be including this info w/their kits, desperately. Joseph said they're 'working on it'; that's what they said 2 years ago, before Joseph was even hired. Their 'support' page, literally, STILL has nothing (but filler text), and they've been in business a long time. I'm not flaming, so no need to swoop in and defend them or anything; what I'm saying is true, and I wish I knew before I ordered. Honestly, I was insecure, thought I just had no aptitude and wasn't sure what to even ask, so I put it aside, not confident the instructions were inadequate. But the EbikeSchool article proves there is a need and demand for this info. Even from regular users, surprisingly I found no "how to assemble and mount a MAC motor" video tutorial or article. I would have considered doing it, but it's a catch-22. I suggested that they approach our community for basically crowdsourced instructions (video and/or written). Anything from a contest, or privately approach a trusted member to write good instrux for store credit, or even just put out a general call for someone to help. I said people will help you. My suggestion was basically ignored, just "we're working on it", and "soon". So, I'll put out the call myself. Any help would help all parties.

In the meantime though, simply, is it okay to run with no inner washer on the disk brake side?

You mean the 'axle' washer? http://www.ebikeschool.com/install-hub-motor-washers/

This is a dilemma I came across recently when putting my mac mtr into another frame. I'm not going to be of much help. But I ran the mac in my first bike for around 3000 miles without the axle/inner washer...

It's obviously a better setup to have the larger clamping base of a washer against that inner frame surface/shoulder. I had planned to look around for a very thin washer as i'm maxed out pinching space from other areas (inc a 5mm disc spacer)

Not sure if anyone would say otherwise, that the washer 'isn't' needed.. other than anecdotes like mine, of 'done it without drama'.

I wouldn't recommend it with an aluminum frame.

Don't use either of your stated options - instead stick in the axle washer then pop a couple of 6mm washers on each bolt between the brake mount and caliper adapter to move the caliper inward the thickness of your axle washer (probably about 3mm). Done.

Your local Ace Hardware Store should have a fastener aisle with lots of metric bolts and washers to do the job. I find the 'average' stainless 6mm washer to be about 1.5mm thick (your mileage may vary...).


For the axle, stainless washers tend to be pretty thin and are a good choice if you can get one to fit. The issue is that the inside of the dropout often has a circular indentation cast in - the washer or spacer must fit within that indentation and lie flat on the dropout surface (not bridge the recess) so a small outside washer diameter is necessary. The axle spacers from the ebikes parts vendors are small diameter and a great fit even if they're a little on the thick side - I always tack a few onto other orders since they will essentially ship for free and are handy to have on the shelf. Another 'gotta have it today' solution is use an SAE 1/2" washer (these have smaller OD) and enlarge the opening a trifle with a Dremel.

All these little nuances of fit are specific to the mix of individual frame, caliper, and motor and are why parts houses sell parts, not 'detailed instructions' as a substitute for mechanical knowledge and experience. There is no single cookbook solution and you just can't Google experience (or expect it will come in the box with your parts order). And, as you can see from the picture caption above, this is an issue that is not MAC-specific...

So, buck up - now you have a little experience with axle washers and mounting calipers...

Thanks, both. Yes, it is the "axle washer". I don't know how Micah knew that vocabulary; I didn't find the info online elsewhere, and it certainly wasn't included with my kit. Smart man. BTW that page was just so needed.

I did think about trying to take that little washer on the caliper mount, and switch it to the other side, to try to push it out. But, I figured it was on that side, for a reason. If I got you right, you are basically saying, to get a washer like that, only thicker, and use 2 if necessary.

So now I need to check my Axle Washer to see if it fits into any dropout 'pocket' the way you said it should. I remember when it was in, looking at it and wondering if it was a little 'cockeyed', and not being able to tell, or if so, if that was important.

I still have yet to hear WHY 'not' having an inner washer would be bad, or what specific risks that would entail, with the axle shoulder torqued straight to the inside of the dropout/frame. And whether any of said scenarios have actually happened. I don't know if I have bigger dropout openings than most, but I did not put Torque Washers on, because the little 'tab' for the Torque Washer did not engage any frame metal. Instead, I put a Grin TorqArm4 on each side (dual torque arms--maybe overkill), lying flat against the outside of each dropout. It didn't fit right if it was in front of a washer (on either side), even though EM3EV told me it was supposed to go in front of the torque washer. And on the brake side, the TA did not fit very well anywhere, and I kind of had to kluge it (did not fully line up with a tube, but I got it close enough I think it might count).

I hope that's okay (torquing the TA straight down to the frame with no further washers). So while I'm at it, I might as well ask... I don't know if I need a washer to go between the outer Torque Arm and the Axle Nut? Don't know if this is "wrong"? If wrong, I'd like to know why it is 'wrong', i.e. what bad situation that could cause.

I really appreciate the information and photo you posted. It was enough for me to follow. Maybe I'll take in the brake caliper's bolt (and its little washer) to a hardware store (not too easy for me to get to).

- I measured my Disk Spacer: it's a hair shy of 2mm. I bought 2 of them.
- The Axle Washer is 2.5mm, and slightly round on one side. I assume the curved side is supposed to go into the 'pocket' of the dropout (more universally useful information that could be included in INSTRUCTIONS).
I don't know yet if I need 2mm or 3mm, but I know now that it's right in that range. I'll take my calipers with me to the hardware store, too.

So maybe 1-2 of those 6mm (wide, not thick) washers on each mounting bolt will do the trick. I hope the caliper mounting bolt will still be long enough. I think it will be. Might even find something like that in some inherited hardware in my home.

I still though completely rebuke the assertion that my stalling was due a lack of buck-up. I have tried to 'buck up' before (translation: trying without asking for help/instructions), and done stupid things; BTDT. And this is a safety issue. So I appreciate you guys helping me. I was actually being nice to EM3EV in my OP. I could've been a lot more 'honest'. The more-frank truth is that on a professional level, it's inexcusable to:
- Not include a parts list
- Not identify the names of the parts (if such vocabulary is important to know)
- Not say which washer goes inside of the dropout, and which on the outside, or which orientation--even if it's just general guidance to get one started
- Throw a bunch of various washers in a bag, and include no information whatsoever about them in a kit you paid hundreds of dollars for.
- NOT EVEN SHOW A PICTURE OF THE FINISHED PRODUCT. Really, even just a photo (either side), might have been enough to be confident I wasn't going to hurt the kit or me. This is serious business, nothing to f around with. And yes I did look online. And on their website.

The reason EM3EV has no time to write proper instructions, is because they are too busy answering all these emails, caused by a lack of proper documentation. I have a close friend who'se committing suicide-by-work. I keep telling them to look for a different job, and they say they can't, they're too tired due to the crappy job. It's the same argument. That's why I brought up the crowdsourcing. I thought it was a good idea. They should just admit that they're not gonna do it, and ask for help. Way past time.

There was actually acceptable info on the Controller/connections, and putting the motor together. You see I couldn't get that far, b/c you have to mount the motor first. It's not too much to ask for a video either--I know, now I'm really asking for the moon, right? I feel like I should hide under a couch for saying it. Plenty of supposedly lower-end vendors have assembly videos. I actually had those other-vendor videos to try to get a clue, but they were different (larger shoulders, different or fewer included washers, etc).

By the previous post's argument, EM3EV shouldn't have bothered to include the controller info either, nor Cycle Analyst info... just buck up, eh? It would be like selling a kit of a put-together shelving unit or other piece of put-together furniture. You include a freakin' photo of what it's supposed to look like at the end; you also include a parts list with pictures of the parts. That's standard, and anyone who knows how to write instructions, knows that. Not doing that is called "bad instructions". They don't get a free pass because it's ebikes because some bikes are slightly different. You don't just sell the parts and include of piece of paper where it has written, "Instructions: Step 1: Buck up! Step 2: See Step 1, you crybaby ungrateful stooge of a customer who puts food on my table! Figure it out, girly-man! Now make me a sandwich!" (not that they did--don't want to put Teklektik's words in their mouth).

As well as you are capable of explaining things, and you are, you should know that. I didn't want to be baited into the post becoming "should EM3EV include instructions with their kit", the answer should be obvious, but I don't mind at all pushing back when pushed on this issue due to what I went through; I'm standing my ground. Writing is part of what I do for a living, and I know acceptable and unacceptable instructions/writing. You are, literally, genius level, I have been amazed by you for years. And you are definitely in the [extreme] minority, in terms of aptitude, and my guess is you have been able to make a career off that aptitude. B/c it's so disproportionate. I am like you on other stuff, just not this. I'm really grateful guyz like Ozzz and Teklektik and Neptronix and others are out there and helping the community. Believe it or not, coming here and exposing my ignorance to belittling in all vulnerability, risking someone telling me to buck up, IS me bucking up. I just don't want to kill myself, not too much to ask. I won't risk my life for anyone's pathetic sex-role definition of how a "man" is supposed to act (among them: never ask for directions; die first, ask questions later). I'd rather ask, than do something stupid and die. BTDT, seen others do it too. Stranded myself, nearly died, seen others destroy things accidentally, whatever. I now ask. And I SO freakin' appreciate the info so far, seriously; this post shall not to be taken any other way. I can handle it... but will defend myself intelligently.

I haven't ridden the bike yet. But Ozzz's post made me worry less, if I do go out for some test rides before I get to the hardware store.

Iv'e been a bit frustrated with em3ev info too, it's led to needing to learn, which isn't such a bad thing but some simple instruction would save a lot of time, maybe some initial non-safe cockups as well.

Just wanted to say that my mac was in an alloy frame but removable dropouts, it can only be preferable to have a axle washer to spread the load.

You can get 1mm rotor spacers..

I found the stainless washers (mentioned) are much thinner. I'm thinking the load on the axle shoulder is on such a small area that the thin-ness wont be an issue(?).

Anyhow, if you are using those torque washers with the tab you should [strike]hammer[/strike] bend the tab down so it seats in the gap, it's in another of those (very good) articles on ebs.

SprocketLocket said:

I still have yet to hear WHY 'not' having an inner washer would be bad, or what specific risks that would entail, with the axle shoulder torqued straight to the inside of the dropout/frame.

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There's different potential issues depending on the dropout design, axle shoulder width, materials of each, etc.

With a steel frame, it's not as big a deal, because the steel is just going to slowly deform if it's soft, whenever there's pressure in a tiny area around the dropout edges (like fi there's a narrow axle shoulder, and no washer to help spread the force across a wider section of dropout face). The dropouts might spread, but they won't crack or break off suddenly.

With an aluminum frame, a narrow shoulder could cause pressure in a way that forces the dropouts apart, whcih can crack them and cause them to break off, made worse if the axle is able to rotate. A wider shoulder (or steel washer simulating this) will spread the load across the face of the dropout to prevent that.

And whether any of said scenarios have actually happened.

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It's definitely happened to front forks. It's probably happened to rear dropouts too, though I can't remember a specific instance ATM.

Ozzzz said:

If you are using those torque washers with the tab you should [strike]hammer[/strike] bend the tab down so it seats in the gap, it's in another of those (very good) articles on ebs.

Click to expand...

With my dropouts, it's not a matter of the tab not bending down far enough, it's that the tab is actually not Wide enough to contact the dropout. I'm not very familiar with dropout shapes, but mine are mostly vertical, and kind of funnel-shaped (upside-down funnel) at the opening. So, the axle would have to turn catasrophically before such a tab even would begin to contact. That is, if I understood you correctly. I'll have to look for that article.

My dropout has metal on one side, I'm not sure if that is a 'removable dropout', or a derailleur hanger, or both, but it's chromed and appears bolted-on and removable on the derailleur side. While the disk brake side is definitely just pure aluminium.

Don't want to give them free advertising, but for reference, it's B*kesD*rect, the Grav*ty Bulls*ye series. (Oh yeah now they're selling ebikes too, for over 3 grand--active topic in this forum right now. Don't tell 'em of your conversion plans with their regular bikes.)

SprocketLocket said:

I did think about trying to take that little washer on the caliper mount, and switch it to the other side, to try to push it out. But, I figured it was on that side, for a reason. If I got you right, you are basically saying, to get a washer like that, only thicker, and use 2 if necessary.

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yes.

SprocketLocket said:

So now I need to check my Axle Washer to see if it fits into any dropout 'pocket' the way you said it should. I remember when it was in, looking at it and wondering if it was a little 'cockeyed', and not being able to tell, or if so, if that was important.

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yes. But the 'cockeyed' part makes me wonder if you have a another fitmeant issue - dropout depth so the axle is centered in the indentation (nearly) as it was originally.

Here are two posts/threads that you may find useful - they relate to filing the dropouts to get better axle seating and to get the axle centered in the depression so you can add a inner washer and have it lie flat against the dropout.

https://endless-sphere.com/forums/viewtopic.php?f=3&t=82721&p=1213888#p1213921
https://endless-sphere.com/forums/viewtopic.php?f=3&t=75857&p=1145413#p1145413

SprocketLocket said:

I still have yet to hear WHY 'not' having an inner washer would be bad, or what specific risks that would entail, with the axle shoulder torqued straight to the inside of the dropout/frame. And whether any of said scenarios have actually happened.

Click to expand...

Well, you actually didn't ask that... AW answered it above and it's a discussed in one of the thread links above.

SprocketLocket said:

So maybe 1-2 of those 6mm (wide, not thick) washers on each mounting bolt will do the trick. I hope the caliper mounting bolt will still be long enough.

Click to expand...

Yes, you have the idea. Remember to use blue threadlock on any brake bolt that you replace (or re-insert). Follow the application instructions.

Regarding 'too short' bolts for the brake disk and spacer: The threaded holes in the hub have a bottom and you should screw in the bolt finger tight and check the hub to bolt head clearance against the rotor and spacer thickness. If way short you may need longer ones. If your replacments are too long you will need to either shorten them or slip a washer under the head. Do not blindly replace the included bolts with longer ones - if too long they will fracture a chuck of aluminum from the inside of the hub which will do all manner of devilment with the motor gears and whatnot. Remember threadlock again...

Now - about the rant:

SprocketLocket said:

I still though completely rebuke the assertion that my stalling was due a lack of buck-up. I have tried to 'buck up' before (translation: trying without asking for help/instructions), and done stupid things; BTDT.

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Well gee. To start, 'buck up' is a common expression that means nothing like like what you claim.
Let's try Google:

View attachment 1
I frankly cannot fathom how that encouragement got twisted into your rant about attacks on your manhood or suggestions that you are being baited. As for the rest of the rant, well, that's between you and all the parts vendors in the world.

I'm done here. Good luck with your build.

I want to apologize to teklektik for mistaking the meaning of what he said, and for not sending this sooner (I was unavailable last night). I actually did not understand that he meant it as positive. Where I grew up (I think this is a regional thing now), I only ever heard it used in the negative, like mean coaches who yelled at kids, and when a kit got hurt they'd tell the kid to 'walk it off' because they didn't care the kid got hurt, and wanted the kid to go away. teklektik was in no way doing that, and I realize now he was actually trying to be encouraging and supportive. I've sent a PM with a longer version of this, and I hope he can forgive me and not swear me off (or this thread FTM).

I also want to give teklektik a big thanks, both for the brake mount washers tip, AND for the heads-up about the fact that the axle might not be seating fully. I had actually wondered this while putting it together, as the axle seems down in the dropouts fine, but there is a little crescent or partial circle between the curve of the axle, and the curve of the end of the dropout. I wasn't sure if there should be ANY gap there, or if it is supposed to be nestled down in there perfectly. (I'm not even sure if the shapes are exactly the same.) I always thought the people who sanded their dropouts, were ones where the axle just refused to go in at all. When assembling, I didn't know if this was even something I should ask about, didn't want to look like I was asking a stupid question. I think I will try to get photos up here, but it will take me some time and I will use a real digicam with a good macro. I also need time to read those threads teklektik posted (thank you for looking that up).

I also actually found some little washers like teklektik had described. I think they're a little wider than 6mm, but the hole is what counts, and that seems to be about perfect--they seem to fit fine! And I happen to have plenty of them. I'm sure it'll take multiple times re-mounting my wheel and experimenting whether I'll still need a rotor shim, but I think that'll do it. Noted on the threadlocker. I'll lock everything when I have the recipe down.

If I felt like I had the knowledge (I don't yet), I wouldn't mind putting forth the work to write some greater tutorial both basic mounting, plus troubleshooting things that can come up. I haven't found anything like that, and I think a lot of people (including myself) could use something like that. This is wearing me down, but I'm determined to finish this. I appreciate ALL of y'alls help, really do.

Because teklektic seemed to know what problems I was experiencing more than I did, without even seeing it, I have a new title for him: the e-bike whisperer.

SprocketLocket said:

(I'm not even sure if the shapes are exactly the same.)

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They're not, because the diameters of the normal bicycle axle and that of the hubmotor are not the same.

Generally if it fits tightly on the flats and has plenty of interface surface area between the two, it is probalby ok, especially with well-secured tight-fitting torque arms.

But if you don't intend to use a regular bicycle axle on that dropout later, then filing it to fit the curve of the motor axle will let the axle sit just that much deeper in the dropout, that much farther away from the open end, and that much less able to apply it's twisting forces to spread the dropouts.

The only thing I can think of that makes it completely pointless to do is if the space between the axle end of the dropout and the frame is already smaller than the space the axle nut or any washers on the axle will need between the axle and the frame. If so, then the axle will be held away from the frame/axle end of the dropout anyway, so there's not actually a way to close that gap (short of filling it with weld and refiling it to fit the axle shape and depth).

When assembling, I didn't know if this was even something I should ask about, didn't want to look like I was asking a stupid question.

Click to expand...

The only stupid question is the one you don't ask.

Having done both myself, I'd rather look dumb by asking than make a mistake that proves it cuz I didn't ask first.

If I felt like I had the knowledge (I don't yet), I wouldn't mind putting forth the work to write some greater tutorial both basic mounting, plus troubleshooting things that can come up. I haven't found anything like that, and I think a lot of people (including myself) could use something like that.

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I'd recommend posting it in the ES Wiki as well as any thread you make for it. See the top of any forum for sticky threads that point to the wiki.

I should correct what I said, the drops on my norco were just alloy/aluminum. I don't recall any damage but then wasn't looking for it, and may not have been able to see it.

Another thought about the torque washers (and the arms) is to get the tension on them when tightening- tensioning down towards the torque side to take up any play in the fitting.
(something someone else more experienced than I wrote here somewhere once )