Author Topic: 36T Rear drum/sprocket for C5  (Read 394 times)

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JohnnieK

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on: June 07, 2021, 08:31:55 am
Hi

The rear sprocket/drum on my 2011 C5 has 2 broken teeth. I came across this 36T rear sprocket/drum in our local classifieds. Now the question is if this will fit my C5 ? Has anyone used a 36T rear sprocket on their C5. The standard sprocket is 38T. The inside is 152mm and the outside is 188mm.

Thanx


JohnnieK

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Reply #1 on: June 07, 2021, 08:45:09 am
Another pic with the measurements. Teeth edge to edge is 16.6mm


Haggis

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Reply #2 on: June 07, 2021, 02:09:27 pm
Never seen a 36 before.
Seems to measure up the same as my spare 38.
Obviously the od is smaller on the 36.





I also have a drum that I machined down to take a bolt on sprocket,  still a 38 though.
« Last Edit: June 07, 2021, 02:13:06 pm by Haggis »
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JohnnieK

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Reply #3 on: June 07, 2021, 02:59:25 pm
Haggis

Thanx for checking the measurements. I'll fit it over the weekend and see if it makes a big diff.

Johnny


hpwaco

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Reply #4 on: June 07, 2021, 11:05:21 pm
If it fits it will be a little harder to pull top end.  About like going up 1 on counter shaft.


jvb

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Reply #5 on: June 08, 2021, 12:17:09 am
Different size brake shoes?


axman88

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Reply #6 on: June 08, 2021, 05:45:14 am
I certainly wouldn't expect a lot of difference.

Going down 2 teeth from the standard 38 rear is just 2/38 = 5.2%

Just about the same as going up 1 tooth from 18 to 19 in front 1/18 = 5.5%

I've spent the last several years defending my choice to retain the standard 18 tooth front sprocket on my C5.  I liked the acceleration and low end pickup and didn't really feel I needed longer gearing since I almost never take the bike on the highway.

Eventually,  I actually looked under the side cover, counted the teeth on my front sprocket, and found 20 of them.   Oops!  I have the standard rear sprocket, with 38.


JohnnieK

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Reply #7 on: June 13, 2021, 05:36:08 pm
I fitted it today and it does not work. While it fits well, the chain runs up on the teeth. It seems like the teeth are just a fraction too far apart for a new chain to properly fit. So after half a rotation of the sprocket, the chain climbs onto the top of the teeth for about 7 teeth and then drops back into place.
So back to the shop for a new 38T drum, bearing, seal and a new chain as I already cut the new chain. Bummer.


Haggis

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Reply #8 on: June 13, 2021, 06:51:51 pm
Interesting, I wonder if its and old imperial spec,
BSA/Triumph Bantam/Cub and similar earlier lightweight British motorcycles need a Original 1/2 X 3/16 inch chain. This is because metric equivalents, although having the same pitch has different size rollers which will not correctly seat into the sprockets and will very quickly knock the tops off the sprocket teeth.
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Haggis

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Reply #9 on: June 14, 2021, 01:11:01 pm
Just measured my spare 38.
You sure you have s standard 530 chain fitted?
Maybe your chain is stretched?
« Last Edit: June 14, 2021, 01:14:15 pm by Haggis »
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JohnnieK

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Reply #10 on: June 14, 2021, 02:05:19 pm
Haggis

I put on a new 530 chain. The chain fits perfectly on the 38T drum. Just does not fit on the 36T.

JohnnieK


JohnnieK

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Reply #11 on: July 17, 2021, 03:17:38 pm
Just to finish off this episode I have take pictures with the 38T sprocket and a new 530 chain and also of the 36T sprocket and the same new 530 chain. You can clearly see how the chain rides up onto the teeth of the 36T sprocket. Just glad I can ride again.


axman88

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Reply #12 on: July 17, 2021, 07:11:02 pm
That's something I've never seen.  It's like 18 pins on the chain correspond to 17 teeth on the sprocket.  That works out to .662" or so as the pitch of the sprocket, which is  about 16.8 mm.

Is there such a thing as metric chain with a 17mm pitch?

Does it look like the 36 and the 38 have the same pitch diameter?  That is, when the link is lying in the gullet, is the pin at the same radius from the center of the hub for both sprockets?

Where did the seller say that 36T came from?


JohnnieK

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Reply #13 on: July 20, 2021, 09:47:36 am
I measured the outside diameter of both sprockets. The 36T is 187.3mm and the 38T is 197mm. This results in a difference of 0.085mm pitch between the sprockets. I guess that is what is causing the issue.
The seller said he got if off eBay from India


Haggis

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Reply #14 on: July 20, 2021, 10:58:48 am
I think someone has had a go at making their own sprocket,  and got it wrong.
Looking at your photos,  the 36 has a bigger pitch than the 38.?
The standard 38 runs a 530 chain which has a pitch of 0.625" or 15.88mm.
Looks like you have a collectors item...??
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