Fitting front wheel MAC to fork - a few questions

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kiwipete   100 mW

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Fitting front wheel MAC to fork - a few questions

Post by kiwipete » Dec 25 2013 5:39am

I just received my MAC motor, and I've assembled the engine bits and have started fitting the wheel to the dropouts. First question I have is: On each side of the axle is a nut, a washer with a bent lug and normal flat washer (as per pic 1).
pic1.jpg
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My first question is: should the flat washer go on the inside of the dropout or on the outside of the dropout (behind the washer with the lug)?

Then after I started fitting the wheel I quickly found out that one side of the motor was rubbing against the inside of the fork (see pic 2).
pic2.jpg
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Obviously, the amount of space between the forks is very narrow. So I packed that side out with 3 washers on the inside of the dropout (pic3)
pic3.jpg
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On the other side I used no washer behind the dropout (pic4).
pic4.jpg
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The wheel now sits in the middle of the fork and spins freely without wobbling. I'd like to know whether thats a safe and acceptable installation? Or should I wedge the fork open a bit more and pack the other side out with 3 washers as well?

Or should I get a different fork altogether?

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Ricky_nz   10 kW

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Re: Fitting front wheel MAC to fork - a few questions

Post by Ricky_nz » Dec 25 2013 5:49am

I would want at least one washer inside the forks on each side to stop the axle shoulder biting into the fork.
If that fork has lawyer lips (ie originally had a quick release wheel) you need something to fill them in to give the nut a flat surface to clamp on.
The torque washers won't be particularly effective on most forks so what ever you do you should put a decent torque arm on. If your MAC as anything like my 10 turn rear one there is heaps of torque.
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kiwipete   100 mW

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Re: Fitting front wheel MAC to fork - a few questions

Post by kiwipete » Dec 25 2013 6:09am

Ricky_nz wrote:I would want at least one washer inside the forks on each side to stop the axle shoulder biting into the fork.
If that fork has lawyer lips (ie originally had a quick release wheel) you need something to fill them in to give the nut a flat surface to clamp on.
The torque washers won't be particularly effective on most forks so what ever you do you should put a decent torque arm on. If your MAC as anything like my 10 turn rear one there is heaps of torque.
Thanks Ricky_nz.

No lawyer lips (cheapo Diamondback bike from the Warehouse). Yes, I did buy a torque arm from Paul as well and will fit that next.

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dogman dan   100 GW

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Re: Fitting front wheel MAC to fork - a few questions

Post by dogman dan » Dec 25 2013 6:28am

That should work well enough, as long as the rim is not too off center.

Those are the cheap steel, pinched tube type shock forks. They are very forgiving, for a front hub install. Alloy forks would bind if spread any, but those won't. You will see how much they can deflect and still work, when you start riding. They will wiggle forward and back as you get on the throttle. Don't worry though, the forks are not about to break. They are actually quite strong, provided they don't have a welding defect at the crown. They cannot fall apart in use, and have one of the strongest dropouts I have ever seen on front forks.

Another way to get clearance for the motor on this type of fork, is to put the leg in a vise, and pinch it smaller. There is nothing vulnerable in the first 3 inches of fork. So you can pinch it more with no harm done.

The comment above on the need for an inner washer applies to the alloy front forks. On alloy forks, I use an inner washer, and often have to cut new axle shoulders to make room for the washer. The need for an inner washer also depends on how the axle is made. Some have wide shoulders and others have narrow narrow ones that tend to dig into soft alloy.

kiwipete   100 mW

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Re: Fitting front wheel MAC to fork - a few questions

Post by kiwipete » Dec 26 2013 6:56am

Thanks for the advice guys.

As it turned out the solution was obvious: I had bought but not yet fitted a grintech torque arm. So I looked at that a bit closer and thought "hmmm ... that has nice 4 or 5 mm thickness..." So I put the torque arm on the inside of the drop out (instead of the washers) and that gave me enough clearance to do the job.
pic6.jpg
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pic5.jpg
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Put a washer on the other side on the inside of the dropout and "bob's your uncle"...

Cheers..

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dogman dan   100 GW

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Re: Fitting front wheel MAC to fork - a few questions

Post by dogman dan » Dec 26 2013 7:21am

Easy to remedy, with those bendable steel forks. Need it wider, step on one tube and yank. Viola, the tires back in the middle.

Weird to watch the fork flop when you power up the motor, but you soon get to just ignoring it. I did at least 4000 miles on such cheap forks, and never had one break. I eventually upgraded to better shocks because the bumps in my town would bottom out the cheap ones.

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