Removing backlash from QD rear hub

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Removing backlash from QD rear hub

Postby Halfwhelk » Tue Mar 12, 2019 9:26 am

Is there any way to eliminate a small amount of backlash between the lugs on the hub and the holes in the brake drum?
The PO had it pasted up with some sort of gunge ( although it may have been 60 years accumulation of greasy mud).
The movement is small (<1mm) but I'm sure its going to clunk.

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Re: Removing backlash from QD rear hub

Postby Rob Harknett » Tue Mar 12, 2019 10:33 am

They did it brand new. But only really felt at low speed, which could be eliminated by dropping a gear so the bike pulled. The full width hub was smarter than the old cotton reel type, and so much easier to remove. Great loved the bike, still do. When the bike was new I was unable to compare it with anything 65 years into the future. Let alone buy one. That can be done now. A 65 year old bike is what it is. Most people buying such a bike, do so for that reason and want it totally original. I assume you must have the first 1955 full width hub. Perhaps quite rare now. Some one may like to have just as it is. I have a 55 bike with later rear wheel which does not have the snatch problem, my almost new 55 bike had back in the 50's. Perhaps you would be happier with the wrong wheel fitted as an option. Or perhaps what you have just needs worn parts replaced. You do need some tolerance or it could be very difficult getting the wheel back in.

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Re: Removing backlash from QD rear hub

Postby Halfwhelk » Tue Mar 12, 2019 12:57 pm

Thanks Rob,
No, its fine just as it is. I just wanted to know there was not some trick I was missing.
After six Triumph twins the AMC way of doing things is a bit 'different'.

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Re: Removing backlash from QD rear hub

Postby Rob Harknett » Tue Mar 12, 2019 1:25 pm

Halfwhelk wrote:Thanks Rob,
No, its fine just as it is. I just wanted to know there was not some trick I was missing.
After six Triumph twins the AMC way of doing things is a bit 'different'.

What you have may need worn parts replaced. As for a trick, with the 55 only hub that had no rubber, just metal pins in metal holes, the only trick was drop a gear and keep the bike under load in traffic. It will not snatch if it has to pull. I soon discovered this when a teenager riding my 55 G3LS. Also keep the chains at correct whip/tension. A loose / worn rear chain will encourage it to snatch also.

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Re: Removing backlash from QD rear hub

Postby clive » Tue Mar 12, 2019 6:30 pm

A trick is to turn all the pins through 90 degrees if it has not already been done. This will halve the backlash as there will still be wear on the drum. The factory fix was to replace the one piece metal pin with a bolt and slightly oversized collar. You need to open up the sprocket holes to a circle again as the wear will be fore and aft. Les at Russell used to have these but wanted you to bring in the sprocket/brake drum to test the collars against as they were made in a number of sizes. If you have machining facilities you could make your own. I would try the bike with one mm play and you may find it does not rattle much. If they are too tight its a pig to get the wheel back in. A trick to do this is to replace the wheel and spindle without the spacer nearest the swinging arm. This allows you to rotate the wheel whilst pushing it across to locate the pins. Once fully located remove the spindle and replace it with the spacer in place this time.
clive
if it ain't broke don't fix

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Re: Removing backlash from QD rear hub

Postby 56G80S » Tue Mar 12, 2019 7:37 pm

I replaced the bolts and collars with ones from Les. This is about the only non standard for year part I found on the Matchless apart from the barrel missing the cut-out for the SR1. Machinist left almost no tolerance and I had to open out the holes in the drum a bit.

No backlash but getting wheel off a bit more tricky and worse replaceing - Clive's tip been given by him before and works a treat!

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Re: Removing backlash from QD rear hub

Postby Rob Harknett » Wed Mar 13, 2019 12:27 am

clive wrote:A trick is to turn all the pins through 90 degrees if it has not already been done. This will halve the backlash as there will still be wear on the drum. The factory fix was to replace the one piece metal pin with a bolt and slightly oversized collar. You need to open up the sprocket holes to a circle again as the wear will be fore and aft. Les at Russell used to have these but wanted you to bring in the sprocket/brake drum to test the collars against as they were made in a number of sizes. If you have machining facilities you could make your own. I would try the bike with one mm play and you may find it does not rattle much. If they are too tight its a pig to get the wheel back in. A trick to do this is to replace the wheel and spindle without the spacer nearest the swinging arm. This allows you to rotate the wheel whilst pushing it across to locate the pins. Once fully located remove the spindle and replace it with the spacer in place this time.


I have never had problems getting the 55 wheel located to fit. ( metal pins in metal holes ) Not so with the 56 on version with rubber inserts. This is where Clive's mentioned trick comes in handy. e.g feed the spindle in from the R/Hand side, with the wheel on it, leaving out the stepped spacer. I usually use both hands holding the wheel, jerking the wheel a little round back and forth, it will eventually find its way on. Just with draw the spindle and replace adding the spacer. If adding the spacer is difficult, you have not got the wheel rammed fully on. If you do not use this method try it. As having the wheel on the spindle holds it vertical with the drum side, which is difficult to do with out the spindle in. Without it you also have to hold the weight of the wheel, while trying to line up the fitting.

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