Cush drive questions

[Drew Back]

Im working on a 1956 A10 plunger with the six spring clutch with the duplex sprocket..With the sleeve nut snugged down to where the cotter pin goes through it still seems loose and there is a lot of play in the sprocket is this normal ???Im also new to this sight just found it thank you for any help..

[a10 gf]

Hello, & welcome, am hoping you will find good help here. An introduction post in 'Bikes & Members' always appreciated.

play in the sprocket

What kind of play, longitunal, lateral? With the nut on and a spring in good condition there should be no possibility of play (except of course the normal movement possible under load). Are these the parts you've got fitted?  see picture in http://www.a7a10.net/forum/index.php?topic=7880.msg55430#msg55430

[Drew Back]

I can move the sprocket front to back about 1 inch the lobes dont seem to mesh tight.I know on the single chain bikes they fit together perfectly im not to familiar with this duplex chain all this stuff came off a basket case bike i will try to get pics in a little while..

[a10 gf]

I can move the sprocket front to back about 1 inch

With the spring fitted and tightened up ??? Should not be loose at all, but retain the possibilty to move under load (that's it's job), should initially feel tight then tighten more the longer it moves (angle of lobes > pressure increase of spring).

On mine here I've got approx 3 teeth movement on the sprocket (initial 'flat spot' of lobes) before the spring starts to compress. If that's what you got I'd say it's normal, but certainly does no feel loose in any way with the spring tightened.

[Drew Back]

Here are some pics

http://i691.photobucket.com/albums/vv276/monadrew/BSA%20PLUNGER/DSC_1076800x536.jpg

http://i691.photobucket.com/albums/vv276/monadrew/BSA%20PLUNGER/DSC_1075800x536.jpg


adm edit: please read rules for posting pictures. Thanks.

[a10 gf]

The 'flat spot' before compression looks normal to me, and similar to my plunger, maybe someone else here has some to compare with. From the engine scan, one also sees the initial flat surface followed by a quite steeply increasing angle.

[duTch]

 Hiya DrewBacca- welcome along, I hope you have a fun time...!

 I had a good look at mine when I had it apart the other week, and maybe it's optical, but the flat on your sliding sleeve looks a bit longer or flatter..but on mine I decided as the lobes mesh in snugly it'd be ok-ish- it's all I have anyway....

 Maybe have a look at the spring, I had to replace mine and the replacment I feel is a bit short and larger dia. than it should be, as discussed if you do a search for 'Cush spring' I think...??
 For the record off the top/side of my head my spring is ~44.5mm ID x ~45mm long....?? I reckon too short would not have enough preload, and mine makes sounds to that effect

[Drew Back]

From that pic all looks normal so maybe I just dont have it tight enough so I really need to drive it home..sorry about the pic thing I will do the thumbnails for now on>

[a10 gf]

May have some wear, but should not hinder the use of the bike imo.

Am curious, what's the spring size uncompressed\compressed? Here (very old one) starts at approx 48mm, and feels tight as *ell when compressed (point of allowing the fitting of retaining pin), ending at approx 38mm, must use quite some force to tighten it up.

[chaterlea25]

Hi Drew,
Your cush drive issue is caused by a mismatch of parts
The outer cush member is from a later 2 lobe cush where as the sprocket is 4 lobe as used on the earlier A and B models

HTH
John

[a10 gf]

the sprocket is 4 lobe

from the pics, seems to be a standard 2 lobe 67-2050 ?, let's see if Drew has some more info.

[Drew Back]

Well that explains a lot does anyone have any pics of what it should look like??My spring does not really compress and it is 1.5 inches long.

[chaterlea25]

Hi Drew,
Maybe I rushed into replying as the diagram posted shows a 2 lobe setup???
Whether or which the sprocket and outer cush piece should match profiles and fit closely together
The outer nutMUST be tightened fully and not just enough to fit the pin
Recommended torque is 65 ft/ lbs
HTH
John

[Drew Back]

There is one on ebay p/n 67-2055 is that the one that I need?? I will try to get pics of what I have.

[chaterlea25]

Hi Drew,
Look at this  link
http://www.ebay.co.uk/itm/BSA-CRANKSHAFT-A7-A10-CUSH-DRIVE-27-TOOTH-SPROCKET-VINTAGE-/171338804514?pt=UK_Motorcycle_Parts_13&hash=item27e496ad22
it appears that the lobes are much smoother than  the one in your pic??

HTH
John