Front sprocket

[Mark.S]

Could some one tell me how the front sprocket is held on. The shaft looks like there's a groove for a cir-clip (but no cir-clip is fitted) and there is a plate that fixes to the sprocket with 2 screws but that doesn't seem to be doing much. I can slide the sprocket up and down the shaft.

Any suggestions?

Cheers
Mark

[fallenmikethebike]

Look again Mark, the splined washer slides on, then has a half twist to align the bolt holes, thus securing the sprocket.
I have at my own risk replaced this factory arrangement with a large diameter cir-clip, to good effect.
Mike

[knackeredMk1]

If your splines are very worn then the whole sprocket and holding plate can come off. If that is the case you need to find a replacement drive shaft before the chain drops off and causes considerable damage. Mk2 and 3 drive shafts are the same and I suspect the AR is the same but havn't checked.

[fishtail]

mk1 drive shaft and sprock holding arrangement seems like a better design?
wondering a bit late in the day maybe whether possible to swop whole gearbox with MK1 gearbox? ( maybe next time )


i just bought the clip - but didnt come with any bolts. this is from LT...

any chance of a pic of your circlip mike? what size did u use?


maRt

[Mark.S]

Yes Mike, just had a look and i can see what you mean now, but mine must be badly worn because i managed to get the splined plate on and get the screws in without rotating it! With a bit of jigery pokery i managed to get it to work but the sprocket still feels loose on the shaft.

Knackered, looks like i will have to replace the shaft eventually, but will have to try and do a fix of some sort for the moment as i've got quite a few outings coming up.

I just tried a few things and found if i put the splined plate on first, this looks like it would position the sprocket in the right place to then be able to put a cir-clip in the groove, probably give this a go until i've got a new shaft/time to fit it.


Thanks for the advice.
Cheers
Mark

[fishtail]

u can always weld it on

thats what mine was like when I bought it!

[knackeredMk1]

The Mk1 looks on the face of it to be a good design using a dished washer and bolt through the middle but it comes loose all the time even with 'permanent' thread lock. I changed to a Mk2/3 drive shaft when I changed the gearbox ratios on my Mk1.

The sprocket should be quite loose on the shaft but with limited movement and certainly not able to slide up and down the shaft.

[fallenmikethebike]

The shaft is just under 25mm, so a clip of about 23mm should do. T.B.O., the clip I used was just one that came in a big box of clips, and was a snug fit. I always carry a couple of spares in case it goes AWOL, though it's been fine thus far.
Mike

[Mark.S]

Nice one Fishy!
Thanks all, I'll be on the look out for a new shaft.