Motobecane front wheel bearing upgrade

I know that there are already some bearing replacement and rebuild tuts on the site. I already looked and if this information is elsewhere, my apologies and I appreciate any navigation assistance that you may be able to provide.

So, I've got an old AV88 and am currently working on rebuilding the wheels. The rear bearings were easy enough to find replacements for. The front hub has bearing cups. The recess into the axle/bearing seat (sorry, weak on terminology here) is rounded to accommodate the bearing cup so I am assuming that a replacement bearing would bottom out at the beginning of the contour, at 10mm. The axle is also tapered where the threads start so, the left and right side diameters (d) would presumably be different.

Dimensions of the hub recesses and pics follow:

Brake side (d=inner, D=outer, B=width):

d=11mm, D=31mm, B=10mm

Speedo sender side:

d=12mm, D=30.5 (probably also 31), B=10mm

Bearing cup in pic is representative of the one I knocked out of both sides. Dimensions (cup and outer race) were:

d=15 (cup), d=21(outer race/lid/whateveritscalled), D=31, B=15 (rounded)

Maybe a 6200 or 6201 might work but would require a new axle.

I'm also guessing that acorn nuts would have to be replaced since they wouldn't be acting as a part of the outer race and packing the bearings into the cup anymore. Maybe just a flat washer behind a hex nut as a replacement?

Whaddaya think?

SpeedoSide.jpg
brake(inner)Side.jpg
BearingCup.jpg

Re: Motobecane front wheel bearing upgrade

6201 wouldn't work if the OD of the cup is in fact 31mm.

6200 would likely work but you'd need to add a .5mm shim to take up the slack. Something similiar to this.

Then you'd need a 10mm axle, and a spacer to fit inside the hub.

As for axle nuts, yes just a flat washer and nut would work. As long as you're only tightening against the inner race and not the outer race of the bearings you're good.

Re: Motobecane front wheel bearing upgrade

Thierry Marseille /

Hello

Référence : 20706

Roulement de moyeu de roue et boite relais 6001 LLU (12X28X8) Mobylette Motobécane Motoconfort

Taille :

Ø extérieur : 28mm

Ø intérieur : 12mm

épaisseur : 8mm

Re: Motobecane front wheel bearing upgrade

Thanks to all for sharing the dimensions, specs and ideas.

Seems simple, but what am I missing.... just swap over to a 10mm (6200) or 12 (6001) mm axle like spudley and Zappa suggested?

As far as width (B/épaisseur) goes, how would I add spacers? I'm guessing either cut a longer spacer for inside the rim or add spacers between the bearings and the center of the hub. I would think that spacers (washers or similar) between the inside of the bearings and the hub would be more stable than a longer tube spacer to take up the slack. Thoughts or other suggestions?

Thanks!

Re: Motobecane front wheel bearing upgrade

You know, on the same note....why are the front wheel bearings loose while the rear are sealed from the factory?

Is the speedo sender an odd size, limited the sealed bearing options? Are loose bearings more suitable for the forces at play when the front wheel steers while back wheel just follows? They did it this way for a reason and I don't presume to be smarter than the French dudes that were making mopeds for a living in 1959. I can't see that it was based on cost savings because it added time and parts inventory to the production process. So, what for they do it that way?

Re: Motobecane front wheel bearing upgrade

You need a spacer within the center hub between the bearings that only rests on the inner race of the bearings and does not touch the hub. This is needed because if you were to tighten the axle nuts without it there would be too much pressure on the inner race of the bearing. It cannot touch the hub because once the axle is tightened it does not move. Think of the inner wheel bearing race, axle, and inner spacer as one piece which the hub/ wheel rotates around. Does that make sense? Needs to be one long piece.

And you'd need the .5mm shim to take up the slack since your ID is 31mm and bearing OD is 30mm. Can't just stick it in and say fuck it, have to take up that extra slack.

What size is the original axle? And how does the speedo drive tie in? You can probably keep it if you space everything out right.

As for why loose and not sealed bearings... I'm not sure. Loose bearings might be cheaper, and IIRC sealed bearings can take more weight which is why they'd be in the back. And let's be honest, Mobys aren't engineered perfectly in the first place.

Re: Motobecane front wheel bearing upgrade

Here is my write up for the exact same issue on my peugeot. I seem to remember having to drill out the speedo drive by 1.5mm to take the new larger axle but the sealed bearings have been in a 1000 mls now with no issues. With cup and cone i was constantly tightening the peugeot and mbk use the same leleu hubs. https://www.mopedarmy.com/forums/read.php?6,4098060

Re: Motobecane front wheel bearing upgrade

Thanks for all the experience shared. I'm thinking that I'm just going to get some new parts and put it back together the way it was originally. Seems like too much screwing around with shims, adhesives and the like to make sealed bearings work.

Re: Motobecane front wheel bearing upgrade

Fail

Re: Motobecane front wheel bearing upgrade

Definitely not my first.

I honestly think that it has something to do with sheer forces. Just like needing a spacer to take up slack in the hub, the forces at play on the front wheel are greater than the rear since that's where the turn begins/ends. The rear wheel only follows where the front is leading. Cup bearings probably have added strength from the cup. Sealed bearings would have the force exerted on the inner and outer races, with only the bearings to hold them together.... while they have to keep turning freely.

But I'm not an engineer so I can't affirm these beliefs...also not engineering a replacement.(edited)

Re: Motobecane front wheel bearing upgrade

If that^ is the case , then , why do all big motorcycles have sealed bearings in the front hub ?

Re: Motobecane front wheel bearing upgrade

> P D Wrote:

> -------------------------------------------------------

> If that^ is the case , then , why do all big motorcycles have sealed

> bearings in the front hub ?

Yeah, who knows? Everything happens for a reason. Like I said, not an engineer. As stated, I am moving on (or, maybe backwards?) to the original setup.

Re: Motobecane front wheel bearing upgrade

I was just questioning your reasoning . There's nothing wrong with cup and ball bearings . Just that there are 'better' options .

I'm in the same boat as you as I chose to stay with cup and balls in my '57 Simplex .

Worked good then and still does . ;)

Re: Motobecane front wheel bearing upgrade

Sorry, didn't mean to come off as flippant. Just guessing as to why. My original thought was/still is that there was a reason. Having sealed bearings in the back and cups in the front means a more diverse parts inventory=$, the time necessary to assemble using loose bearings vs popping sealed into place = labor=$. I have no idea how many other manufacturers used those hubs, maybe they were limited on options.

I also liked to you all. I'm still thinking about it. I looked up SAE bearing sizes and saw that a 1-1/4" is only about .5mm too big. Maybe I could drill or ream .5mm out of the hub.

.....so, maybe?

Re: Motobecane front wheel bearing upgrade

> J D Wrote:

> -------------------------------------------------------

>

> I also liked to you all. I'm still thinking about it. I looked up SAE

> bearing sizes and saw that a 1-1/4" is only about .5mm too big. Maybe I

> could drill or ream .5mm out of the hub.

>

> .....so, maybe?

I 'lied' to you, I'm liar. Spell chuck sicks

Re: Motobecane front wheel bearing upgrade

> J D Wrote:

> -------------------------------------------------------

> > J D Wrote:

>

> > -------------------------------------------------------

>

> >

>

> > I also liked to you all. I'm still thinking about it. I looked up

> SAE

>

> > bearing sizes and saw that a 1-1/4" is only about .5mm too big. Maybe

> I

>

> > could drill or ream .5mm out of the hub.

>

> >

>

> > .....so, maybe?

>

> I 'lied' to you, I'm liar. Spell chuck sicks

And here I thought I had a new friend .

No worries . It's all good . ;)

Re: Motobecane front wheel bearing upgrade

kevin Smellaflange /

H-D has repack-able bearings.

i repack every tire change.

Re: Motobecane front wheel bearing upgrade

H-D=Home Depot?

I actually was meaning to get back to this thread.... I found a full write-up (with a bunchopics) on the mabecane mobylette forum posted by none other than rebel Moby hisself. It was spot on with MPB Andrew's explaination, but easier for dummies like me to understand since he used playdough and took lots of pics.

Re: Motobecane front wheel bearing upgrade

kevin Smellaflange /

the rebel moby is the guru...

the play-dough way is the best...

11 bearings in each side tape them up/flip over to not drop what you just worked on...

Re: Motobecane front wheel bearing upgrade

Usually the rear cup/loose ball type bearing fails and the front is just fine. I'd probably just worry about the rear bearings.

Re: Motobecane front wheel bearing upgrade

Rick Bergsma /

> Don Ohio Wrote:

> -------------------------------------------------------

> Usually the rear cup/loose ball type bearing fails and the front is just

> fine. I'd probably just worry about the rear bearings.

Don , the guy already has the wheel apart so you're kinda missing the point .

Also , why would you ignore the front wheel bearings ? The moped is probably 40 + years old and the grease is likely dry and turned into something more like wax .

I've also seen front wheel bearings where all the balls were rusted.

To the original poster , the stock loose wheel bearings are fine , just repack them with new grease . A cone nut wrench is a big help when your putting the cone nuts back on .

My 2 cents

Re: Motobecane front wheel bearing upgrade

I just meant he doesn't have to do a front bearing MOD at all. The rear takes much more abuse and weight and in my experience, the rear cup or balls will fail twice before the front ever fails at all.

Re: Motobecane front wheel bearing upgrade

The shimming stuff in this thread is way overcooked

Just smack the bearing in with a slice of a soda can to shim out the extra space.

Re: Motobecane front wheel bearing upgrade

I think a beer can is the way to go. I tried a piece of sheet metal but it ended up being too thick. With a tin can, you could pile up a few layers, within reason.

Regarding the rear bearings, they were sealed from the factory. But, I ended up finding some cracks in the rear hub so will have to start anew and see what the replacement hub takes...... looking at this one: http://m.1977mopeds.com/item/3339313834

The freewheel was busted and seized on the hub anyway. Bearings in the freewheel were shot as well. Without that thing working I think it would have been all "mo" and no "ped".

Re: Motobecane front wheel bearing upgrade

So I got around to making shims. The beer can method seemed like it take too many shims. This is 16ga steel and three beer can shims. Thoughts? Seems a little ugly to me but everything is tight.

Thoughts? Would you ride it?

IMG_20190308_165958505_noexif-1536x2048.jpg
IMG_20190308_170007061_noexif-1536x2048.jpg

Re: Motobecane front wheel bearing upgrade

Nope! YOU go first! LOL!

Re: Motobecane front wheel bearing upgrade

Yeah, I guess of I have to ask then I have my answer... Call it a work in progress

Re: Motobecane front wheel bearing upgrade

No beer cans. Two shims, 22ga steel. Seems solid.

IMG_20190310_170737354-1536x2048.jpg
IMG_20190310_170800760-1536x2048.jpg

Re: Motobecane front wheel bearing upgrade

That does look better .

Re: Motobecane front wheel bearing upgrade

Its a Motobecane....I'd ride it! :) This is an interesting read.

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