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QD rear wheel, replaceable sprocket
#539833 04/25/14 1:06 pm
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My 1969 T120R has the quickly detachable rear wheel.

I´d like to be able to replace the sprocket, without replacing the brake drum.
(Bought a "520" x-ring chain kit with narrow sprockets, but the rear sprocket is of the detachable type)

I seem to remember that a qd drum exist, with detachable sprocket. (37-1779)?

Anybody with such a drum for sale, links or info, feel free to chime in;)

Regards
John


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Re: QD rear wheel, replaceable sprocket
Ducknaldo #539834 04/25/14 1:09 pm
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i had one for sale on eBay last week that didnt sell
Paul

Re: QD rear wheel, replaceable sprocket
Ducknaldo #539836 04/25/14 1:14 pm
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Hi Paul

Fast reply:)

Is it repro, nos or new?


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Re: QD rear wheel, replaceable sprocket
Ducknaldo #539838 04/25/14 1:18 pm
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it was on a bsa bike that i imported from the usa last year the brake lineing looks ok and it has 10 holes for the sprocket

Re: QD rear wheel, replaceable sprocket
paul67 #539839 04/25/14 1:26 pm
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Hmmm...
My sprocket is with 8 holes only.
Were there 8 AND 10 hole versions of this drum?


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Re: QD rear wheel, replaceable sprocket
Ducknaldo #539840 04/25/14 1:28 pm
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yes i beleive it was a A65 from the sixtys

Re: QD rear wheel, replaceable sprocket
Ducknaldo #539841 04/25/14 1:37 pm
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The BSA and Triumph QD setups are the same basic design but different parts so I doubt an A65 drum with fit a T120.

Re: QD rear wheel, replaceable sprocket
Ducknaldo #539842 04/25/14 1:46 pm
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AFAIK, the splines were different between the BSA and Triumph. Also the hub was different. I believe the whole set-up is different. It would be nice if John could post a picture of the hub and drum that his T120 has.


Bill B...


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Re: QD rear wheel, replaceable sprocket
Ducknaldo #539844 04/25/14 2:12 pm
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Here is the drum type that I use today.

[Linked Image]

[Linked Image]

This is the sprocket I want to be able to use.

[Linked Image]


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Re: QD rear wheel, replaceable sprocket
Ducknaldo #539859 04/25/14 5:37 pm
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That is the Triumph type and I don't think that it was available with a bolt-on sprocket. The BSA, late pre-unit and unit used a QD drum with a 10 bolt bolt-on sprocket.

Bill B....


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Re: QD rear wheel, replaceable sprocket
Ducknaldo #539909 04/26/14 2:54 am
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Hi John,

Originally Posted by Ducknaldo
I seem to remember that a qd drum exist, with detachable sprocket. (37-1779)?

Fwiw, I've been messing about with Triumph qd rear wheel bits on-and-off for something like twenty years and this is the first I've heard of a Triumph qd hub with a detachable sprocket. Are you sure that isn't a BSA part number? Bear in mind that, when Triumph part numbers were translated to the BSA format in the early 1970's, Triumph "W" became "37", but that prefix was one used by BSA already.

If there is such a thing, it's so old and rare, if you find a usable one, I suggest you also buy a lottery ticket. smile

Perhaps more practically, the two sprockets have the same number of teeth and aiui, the bolt-on sprocket you have is a standard conical-hub one that's been machined down for the 520 chain. Would it not be simpler just to have the qd hub sprocket teeth machined similarly?

Hth.

Regards,

Re: QD rear wheel, replaceable sprocket
Ducknaldo #539914 04/26/14 3:44 am
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That sprocket looks like 37-1499, to fit the bolt on non qd drum 37-1498. Not sure there was a qd version though.



Re: QD rear wheel, replaceable sprocket
Ducknaldo #539919 04/26/14 4:36 am
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[Linked Image]
[Linked Image]
[Linked Image]
this is the bsa one i have it was on a A10 Spitfire with a 58T sprocket

Re: QD rear wheel, replaceable sprocket
Ducknaldo #539950 04/26/14 10:10 am
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It would definitely be easier too "shave" the sprocket on the 37-1040 drum.
But I ´d really like like to be able to just replace the sprocket, as I have several of these sprockets lying around.

I guess I could ask a machinist of some kind to modify the 37-1040, to allow for the replaceable sprocket to be mounted.

I found a thread on triumphrat.net, mentioning the drum in question, but this guy could of course have misunderstood something.
http://www.triumphrat.net/classic-vintage-and-veteran/72396-qd-quick-detach-rear-hubs.html

("Slicktero" mention it about halfway down the page)

Edit.: The sprocket also seems harder and better quality than the original qd sprocket and I´m not sure a shaved original sprocket would last very long if shaved down to around half width.

Last edited by Ducknaldo; 04/26/14 10:15 am.

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Re: QD rear wheel, replaceable sprocket
Ducknaldo #540032 04/27/14 2:22 am
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Hi John,

Originally Posted by Ducknaldo
I could ask a machinist of some kind to modify the 37-1040,

But, unless you found someone familiar with what you want to do, you'd have to come up with the mounting arrangement that you want:-

. Risking telling you something you know already, it isn't a matter of turning the teeth off the drum and boring eight holes to match the sprocket; that would put the sprocket out of line. frown Afaict, the teeth have to be machined off the drum, then what remains must either match the i.d. of the sprocket or it must be machined too; then you've got to work out a way of fastening the sprocket edge-on to the drum.

. I'm not saying it can't be done, but I reckon you need someone more than just "a machinist of some kind".

. Years ago, I remember reading that qd drums were modified for different numbers of teeth; trouble is, it's so long ago I can't remember how it was done. frown Perhaps look around the www for a forum that deals with classic motocross and/or trials and see if anyone's still using and modifying Triumph qd drums?

Originally Posted by Ducknaldo
The sprocket also seems harder

Which isn't going to help any machinist. frown

Have you considered a standard 3/8"-width chain and lubricating it with something like a Scottoiler? whistle grin

Hth.

Regards,

Re: QD rear wheel, replaceable sprocket
Stuart #540033 04/27/14 3:29 am
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Hehe

I do use a Scott Oiler, but would like to ditch it:)

Now.
I´m not a machinist, but I reckon, that the modification wouldn´t be that hard for a well trained machinist.

The way I think it could be done is by fabricating a "mounting disc" that fits directly behind the existing sprocket, slide fit at first.
Then shaving off existing teeth on drum-sprocket.
Finally weld the mounting disc in place behind the now shaved sprocket.
Unfortunately the new sprocket, will not slide in from the drive side, because of the lip, but this could be overcome by either shaving this flange just a tiny bit or shaving the inside of the sprocket just a tad.

I´m not sure how much welding could be done on the drum, before it deforms, but probably this could be done.


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Re: QD rear wheel, replaceable sprocket
Ducknaldo #540036 04/27/14 4:07 am
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I'm just wondering how many miles you are going to do on this bike to warrant all the work involved? Those sprocket/drums last a long time, if you want to change the gearing then engine sprockets are relatively cheap, and easy to change.



Re: QD rear wheel, replaceable sprocket
Ducknaldo #540048 04/27/14 7:24 am
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Hi,

Originally Posted by tbird649
just wondering how many miles you are going to do on this bike to warrant all the work involved? Those sprocket/drums last a long time,

Originally Posted by Ducknaldo
Bought a "520" x-ring chain kit with narrow sprockets,

Originally Posted by tbird649
if you want to change the gearing then engine sprockets are
easy to change.

Ye-ea-ah ... after you've removed the entire primary drive ... Then, having changed the sprocket, you have to rebuild the primary (remind me, how many individual clutch rollers are there?) and, having finished, you have to hope it doesn't leak from one of the myriad gaskets and seals ... whistle

Originally Posted by Ducknaldo
I do use a Scott Oiler, but would like to ditch it:)

shocked

I don't mean to hijack your thread, but why?

Because, ime, (expensive) 'O'-/'X'-ring a hell of a lot longer if they're lubricated. Back in the 1990's, I commuted in all weathers on various old Jap bikes; ime, what did for unlubricated '-ring' chains was the rings hardened from being heated by the chain (feel the friction in it now, it doesn't get any better with use eek ), then they cracked and broke up, letting the lubricant out and water and grit in. frown In 1991, I fitted a Scottoiler with a new 'O'-ring chain-'n'-sprockets; in the following year, the bike covered about 10,000 miles. I still own the bike, those chain-'n'-sprockets are still on it, the rear wheel adjusters are about half-way along their travel.

The huge advantages I found when I used a bike every day were:-

. it was just a matter of adjusting the pump for more/less lubricant depending whether the roads were were wet/dry;

. I could, and did, get home late from work, put the dirty, wet bike in the garage, go on holiday early the next morning for two weeks and, when I returned home, the bike's chain would work normally, rather than being a rusty, seized mess. :bigt

Nowadays, I can leave a Scottoiler-equipped bike literally for months between uses and, when I want to use it again, one thing I know won't need any attention is the chain. I've been gradually fitting all my bikes with Scottoilers, with 'normal' chains (on Fraser Scott's advice) because the additional cost (and on Britbikes, the need to faff around with 520 chains and special sprockets wink ) of 'ring' chains isn't justified for the number of miles each bike covers.

Luck with your task, but I'd interested to know the problem that needs such a solution. confused

Regards,

Re: QD rear wheel, replaceable sprocket
Stuart #557787 08/11/14 5:28 am
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@Stuart

I decided to keep the scottoiler after all.

I investigated the claims that some o-ring chain(530) does fit these bikes and learned that DID make an x-ring chain that´s even slimmer as their o-ring chains, which also fit.
I kept my standard sprockets and bought a DID 530VX. Fits with lots of room to spare and keeps chain maintenance to a minimum.
This chain and the scott oiler makes touring more of a pleasure.


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1969 T120

Moderated by  John Healy 

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