Trouble Fitting Swing Arm to Gearbox Cradle

I have a '74 Roadster with the felt wicks in the swing arm with blanking plugs and no long bolts passing right through the complete assembly.

I have purchased and fitted the pivot seal onto the bushes and pressed them into the swing arm all the way. I know they are all the way home.

I also purchased a new gearbox cradle -- the one to fit the '74 with the two cotter pins and slots for gearbox adjustment.

When I went to fit the swing arm to the cradle I found it would not fit. The cradle was wider than the distance between the two swing arm bushes.

There was .040" difference as best I can measure it that the swing arm distance needs to be reduced by to be able to fit.

I thought the swing arm would slip over the cradle and I would actually have to shim the bushes out a bit to get a good fit so the swing arm would not move around in the cradle and give me movement at the back wheel and affect the bike's handling.

I hope this all makes sense.

Are there any suggestions as to how I would accomplish this. BTW I do not have a lathe, mill, or other fancy tooling to help in this regard.

Thanks Don

Does the new cradle have the proper unpainted areas for the swingarm pivot as well as the centerstand and engine tabs? These areas should be bare metal for things to fit properly.

I am getting ready to sandblast and paint a frame and associated parts so I took photos of the bare areas to mask off before paint.

The two faces of the cradle that slip between the bushes should have been machined to the correct dimension. Are there any machining marks on those faces? I'm wondering if the machining process was missed. Do you have the original cradle to compare dimensions with?

Thanks for the replies guys.

The cradle is an Andover Norton one - supplied to me by Mick Hemmings.

It will be apparent from the pictures below that these areas are painted or I suspect powder coated which would have some thickness to it compared with a coat of paint.







Any suggestions on how to remove powder coat.

Any comments welcomed.

Thanks

I found out by accident when cleaning my carbs that STP carburetor cleaner made the powder coating soften. You could try spraying some on a rag (away from anything you don't want to remove or spoil finish of) and rub it on area in question to see if it affects your (which may be different) coating. I am very careful when using the stuff these days.

I tried CRC gasket remover to see if it would remove the substance on the cradle. I didn't know if it was powder coat or heavy paint.

The gasket remover seemed to work ok as evidenced in the pics below. I know I made a bit of a mess removing the coating but it was hard to mask up the area as the gasket remover melts everything in the area including masking tape.

I think I will try and rub it back with some emery to get edges smooth and then give it a light coat of spray can paint before I try and refit the swing arm with bushes fitted.

BTW you can see the machining marks on the cradle now the coating is removed.





Thanks Don

That was DEFINITELY powdercoat.

I use Rust-O-Leum gloss black spray paint in a rattle can, it works great.

grandpaul said:

That was DEFINITELY powdercoat.

I use Rust-O-Leum gloss black spray paint in a rattle can, it works great.

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Did Rick's MK III get a Rustoleumed frame job?

The $50,000 question is, does the swinging arm fit now?

Danno said:

Did Rick's MK III get a Rustoleumed frame job?

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Only on the spots where the powdercoat is cleaned off.

There is no better paint / touchup for bare metal cycle parts than Rust-O-Leum.

gripper said:

The $50,000 question is, does the swinging arm fit now?

Click to expand...

I have to remove the powder coat from the other side of the cradle, then press the bushes back into the swing arm and then I can try again to see if it fits. Maybe tomorrow afternoon.

Thanks everyone for comments.

thunderbolt said:

gripper said:

The $50,000 question is, does the swinging arm fit now?

Click to expand...

I have to remove the powder coat from the other side of the cradle, then press the bushes back into the swing arm and then I can try again to see if it fits. Maybe tomorrow afternoon.

Click to expand...

If it isn't enough you could rub down the bush flanges on a flat sheet of 'wet & dry' paper?

It doesn't seem to have been mentioned yet.
We can't quite see all the cradle in the pictures but you need to do the powder coat removal thing on anywhere there is a bolt head or washer or nut face as well as the area where the engine and gearbox cases meet with cradle. If you don't, things like the engine mounting bolts will work loose in use with bad consequences. I'm a bit surprised AN supplied the cradle with so much powder coat on it. I guess it stops it rusting when sitting on the shelf.

thunderbolt said:

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This is why I don't like powder coat. There are different chemistries of powder and some have better adhesion to metal than others. Some tend to "encapsulate" the part rather than adhere. As can be seen in the pictures there are now edges where rust and corrosion can travel under the powder. (There is no primer to protect it). You may have luck with a modified alkyd like Rustoleum, but a good coat of epoxy primer down first would give more protection.

For my money I would rather strip the entire piece to bare metal and lay down an epoxy primer and black acrylic urethane topcoat.

Ron L said:

thunderbolt said:

Click to expand...

This is why I don't like powder coat. There are different chemistries of powder and some have better adhesion to metal than others. Some tend to "encapsulate" the part rather than adhere. As can be seen in the pictures there are now edges where rust and corrosion can travel under the powder. (There is no primer to protect it). You may have luck with a modified alkyd like Rustoleum, but a good coat of epoxy primer down first would give more protection.

For my money I would rather strip the entire piece to bare metal and lay down an epoxy primer and black acrylic urethane topcoat.

Click to expand...

That is my plan for the flood victim's black parts. I have taken pictures and made notes about the areas to be masked and left bare and relevant measurements.

Ron L,
Are the primer and top coat paints you speak of multi-part systems or otherwise not available in spray cans?

Ed

Ron L said:

You may have luck with a modified alkyd like Rustoleum, but a good coat of epoxy primer down first would give more protection.

For my money I would rather strip the entire piece to bare metal and lay down an epoxy primer and black acrylic urethane topcoat.

Click to expand...

Ron can you give a further explanation of the paints you have mentioned above please. "A good coat of epoxy primer" -- is this brushed on, spayed on from a can or spray gun, etc.

"Lay down an epoxy primer and black acrylic urethane topcoat" -- again is this spayed on or brushed? If sprayed what is the procedure. I will have no trouble removing the powder coat - if the CRC is left long enough the epoxy just crinkles up and practically falls off. I did not leave it quite long enough on the first side I did and a bit of scraping was involved, but on the second side it just fell off.

When painting the cradle are the attachment points for the crankcase and other places left unpainted or is the thin coat of paint compared to the thick powder coat ok. BTW removing powder coat from one side of the cradle reduced the thickness of the plate by 0.013", so 0.026" overall and the swing arm did fit on with 0.006" sideways movement measured with a feeler gauge.

I had previously removed some material from the flange of the bushes earlier in the piece as suggested by Les (LAB). I had reduced each bush by 0.010", so increased the distance between the bushes by 0.020". So I would have had to remove some material from the bushes anyway.

Is 0.006" too much sideways play on the swing arm when mounted in the cradle. I could put a shim behind one of the bushes if needed.









I have been disappointed by the quality of the AN parts. They couldn't be bothered to mask up the cradle before the powder coat process. I would have preferred it was painted. The cotter pins do not fit the cradle and had to be filed to fit. I was expecting it to fall together with ALL new parts, but it has been a battle every step of the way.

All comments welcomed.

Thanks Don

Thanks to all those who have posted replies to me. All have been valuable. Please keep them coming.

Cheers Don

thunderbolt said:

Is 0.006" too much sideways play on the swing arm when mounted in the cradle. I could put a shim behind one of the bushes if needed.

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Yes, shim it to remove all play.

thunderbolt said:

I have been disappointed by the quality of the AN parts. Couldn't be bothered to mask up the cradle before the powder coat process. I would have preferred it was painted. The cotter pins do not fit the cradle and had to be filed to fit. I was expecting it to fall together with ALL new parts, but it has been a battle every step of the way.

Click to expand...

That happens all too often, unfortunately, but I suppose we should be thankful these parts are available, although it's no consolation when you've just spent a considerable sum of money buying 'genuine parts'.