Motobecane AV7 crankcase bearing and oil seal removal.

Christopher Manning /

I am trying to rebuild this AV7 and I need to replace the crankshaft brearings and crank case oil seals. Whats the best way to do this? I found this tool (https://www.1977mopeds.com/Motobecane-Crank-Bearing-Puller-p/3157.htm) but its out of stock and I would rather get a universal bearing removal kit. Any suggestions for what kind of kit I should get? As far as removing the bearings go, I have read about people heating the crank case in the oven and popping the bearings out. Is this an alright method or should I shoot for getting a universal bearing removal kit?

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Re: Motobecane AV7 crankcase bearing and oil seal removal.

Heat up the cases then use a socket and a press or a mallet to tap them out. Heating the cases also helps with installing the new seal too. Its pretty easy to botch it your first time so be careful.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

Christopher Manning /

So use a socket that doesn't fit through the bearing to tap it out from the other side? I just tried heating up in the oven at 325 convention bake for an hour. I had no luck getting it out.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

Blind hole puller.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

> Christopher Manning Wrote:

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

> So use a socket that doesn't fit through the bearing to tap it out from

> the other side? I just tried heating up in the oven at 325 convention

> bake for an hour. I had no luck getting it out.

Maybe because you didn't have the temp high enough .

I use a small propane grill . Crank the heat to 400° , put the case in . Remove the case about 15 minutes later .

Bearings fall out with the slightest touch .

If you're quick enough , the new bearings pretty much fall into place , as well .

New seals go into place while the case is still very warm to the touch .

Re: Motobecane AV7 crankcase bearing and oil seal removal.

What Stephen said. I've had to use a blind-hole puller bit as a "surface" and a regular puller to "push" the bearing out (I wish I'd taken pics of the "rig"). Make sure you get the cases really hot. and support on a wooden surface (a 2x4 in a vise with a hole big enough for just the bearing to come through when it comes free) so you don't damage the case surfaces.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

Dirty30 Dillon /

Heat

Blindhole puller

Slide hammer attachment

Thick ass glove

Re: Motobecane AV7 crankcase bearing and oil seal removal.

I rebuilt mine earlier this year. The MB factory service manual I was using called for a propane torch to heat the case. I used a heat gun, and a temp gun. Everything started coming loose around <Edit> 220C (like ~400F on the grill above degrees), basically until everything just started to smoke. One side fell out while I was heating it, the other dropped when I tapped it on the work bench. Assembly is reverse. I did cool new new bearings in the freezer for a couple of hours and put some assembly lube on the bearing before I started heating the case. You can seat with a socket that mates the outer surface of the bearing. Yes, do wear gloves.

This guys explains it well:

The seals aren't hard to get out. Just don't mar/gouge the seating surface on the case or the crank hole. You can grab 'em with some needle nose pliers and give 'em a good tug. Clean the case well afterwards, there will probably be some old gunky seal material left behind on and case.

As far as new seals... IIRC, I ended up using these, based on a post elsewhere:

https://www.avxseals.com/Shaft-Oil-Seals-TC15x21x4-p/tc15x21x4.htm (edited)

Re: Motobecane AV7 crankcase bearing and oil seal removal.

mike thompson /

There is this guy on youtube that has done a whole mulit part video series on Moby teardown and rebuilds. They are excellent. He shows exactly how he did what you are asking. Each segment is called "david fixes his shit" but don't use that as a search. Actually, here is a link to one of them (I don't think what you need is in this specific one though. I think it may be in the one before this one)

Re: Motobecane AV7 crankcase bearing and oil seal removal.

That dude is fun to watch. I watched his whole rebuild series before I started on mine. Revisited a couple of times when I had gotten myself totally confused.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

kevin Smellaflange /

rebel moby puts dave to shame...ie; cigarette carton base gasket.brake pad mod.etc,etc,etc.

dave is a good, because u see his mistakes & can learn from them.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

Shave the cases so you can install the seals after the cases are assembled. It's so awesome.

I despise not being able to install or pull seals from outside the cases

Re: Motobecane AV7 crankcase bearing and oil seal removal.

kevin Smellaflange /

200* on the aluminum carters

crank wrapped up in the freezer

...dirty30 thick ass gloves

Re: Motobecane AV7 crankcase bearing and oil seal removal.

Christopher Manning /

Alright guys, I had to use a propane torch and got around to popping out the bearings. These bearings didn't come out easily and it definitely did not work leaving it in the oven at 400f for at least 30min. I did it on a set crankcases that I'm not using on the main motor. However, I do feel more comfortable with the process even it felt a little bit too destructive with the crankcases I practiced on.

Are the seals supposed to pop out easily with the bearing? I imagine the case should be heated up as well?

I can also assure you guys that I don't think using a socket to tap them out is the best method. It left a noticable ring on the crankcase. Thanks for all the help!

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Re: Motobecane AV7 crankcase bearing and oil seal removal.

The seals come out with a screwdriver . No heat required .

And , post a pic of the ring left on the case from the socket .

Re: Motobecane AV7 crankcase bearing and oil seal removal.

goes without saying but heat expands, to remove the bearings with "heat" u don't blast the bearing but the case where the bearings sit expanding that. basically heat the back side/outside till smoky and tap on a block of wood.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

For a really stubborn set, put a 2x4 in a vise and drill a hole big enough for a blind-side bearing puller shaft and bearing to go through set the puller up, heat the cases and a few good slams and they will usually come out. you want to pull through the 2x4 so the case halves aren't damaged.

IF that doesn't work, tighten the bit from the puller into the backside of the bearing, without the slide-hammer attached, place over the hole in the 2x4, set up a bearing press so it pulls against the 2x4 as it pushes the bearing out.

(I was wondering when I'd have to explain how to do this). Or, you could buy another st of cases on ebay, but, I can just about promise, they have bearings (seemingly) hopelessly stuck in them.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

Folks,

I’m in the beginning of an AV7 rebuild and ordered these AVX seals based on this thread. https://www.avxseals.com/Shaft-Oil-Seals-TC15x21x4-p/tc15x21x4.htm There is no metal outer-band, super easy to order and install, with free shipping.

Now I’m doubting myself. Regarding the lip type, in another post Rebel mentioned:

"Go for the A, you dont need the double lip which would prevent oil from lubing the seal with the garter spring. Install them garters facing OUT!"

The ones I ordered and suggested in this thread are type TC which is "Rotary Shaft Seal Double Lip"

Do I need to re-order A’s as any double lip seals are really not good in the AV7 ?

cheers (edited)

Re: Motobecane AV7 crankcase bearing and oil seal removal.

when I got home from work i checked the actual AVX seals themselves, they were not TC, but rather "SC". In the thread by Moby, linked above, he said he uses SC himself. I am confused about the double lip/oil remark and why the AVX cart, and website says you're getting TC, but happy. Shipping by the way isn't free, but a reasonable $2.50 Just wanted to thank J D for the AVX link and let everyone know that if you order TC, you get the recommended SC. (edited)

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Re: Motobecane AV7 crankcase bearing and oil seal removal.

the second lip.... (edited)

Screen Shot 2020-01-09 at 9.57.04 PM.png

Re: Motobecane AV7 crankcase bearing and oil seal removal.

I've done a few removals on some engines here and i just warm it with a propane torch and they literally fall out. No need to tap or do anything.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

Pushrod Fifty /

Heat gun the case outer and slam it onto a wooden bench and the bearing will come right out. Any more heat than a heat gun would produce will alter the temper of the alum or warp it, whichever comes first.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

I don’t know who this is but he’s a legend.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

"Dave (fixes his shit)" is fun to watch, but (as noted) you have to learn from his mistakes. The guy above with the hammer and torch, happens to have a case where the bearing came out of the case, (at least) 90% of the moby cases I split, the bearing comes off at the crank, leaving it stuck on the cases. Hammering on the naked end of a crank is an amateur, ham-fisted move. The method I outlined above has worked flawlessly, and left the cases damage-free.

Cases are magnesium (not aluminum) , by the time they're hot enough to distort, they'll burst into flames.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

I’m doing a full rebuild on a AV7 motor right now. I just popped them in my toaster oven insides down... let it heat up. Bake for 5mins and the bearing fell right out. They are pretty easy. Heat is your friend. Don’t ever force them out. They may never want to seat properly again.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

Richard Eberline /

I always use double lip seals (TC) the outer lip barely touches the shaft. It's mainly for a blocker of oil/dirt.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

I heated my av7 with a torch and was able to tap the bearings out pretty easily. But the seals are completely stuck- can’t get them to budge.

Any other tips or tricks?

Re: Motobecane AV7 crankcase bearing and oil seal removal.

Steven Bolduc /

Sockets are a good usable tool.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

Just manned up and yanked 'em out with pliers.

Re: Motobecane AV7 crankcase bearing and oil seal removal.

you can cut your case lip so you can install remove from the outside.

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