Final drive, front sprocket play on spline

Andy

Andy

Hero member
Location
Auckland, roughly
As seen in the video below, and probably seen by most here... I can see wear to both output shaft and sprocket (sprocket has 13,000km).
I assume that any play will accelerate wear. Is there anything I can/should do to reduce play apart from replace the sprocket?
I found THIS THREAD (which I couldn't resurrect) and it has some good suggestions: reverse the sprocket (chamfer to the outside), shop around for a tighter fitting sprocket, loctite, and even welding.
This must be an ongoing problem with all sorts of machines, is there a "standard solution"?


View attachment IMG_2724.mov
 
Last edited:
once I had this problem at the primary drive sprocket. A expierenced welder welded the crankskaft end with a special electrode, milled it and pressed a new spocket on it. I worked!
 
Many years ago I had mine metal sprayed and refinished by Duralloy Gears in Christchurch. Brilliant job.
 
Very timely, Andy. I encountered the same problem when building the SFQ - I had only very slight play, but it still bothered me greatly. I have three output shafts and brand new sprockets (two tried so far) are loose on every one of them, not backlash loose, but an easy non-inter fit - they used to be so tight owners could damage the cases trying to get them on. I preferred them like that.

Now it seems every sprocket made for them is a loose fit, ie they go on by hand, with or without slight backlash, even over the 'unused' part of the spline outside the retaining groove. A mate had a brand NOS SFC sprocket still in the vacuum pack and I used that. It wasn't a super tight fit, but better than others I tried and had no backlash. I fitted it with Loctite 620 after using the Loctite primer - probably make no diff, as it's a press fit repair, but added peace of mind.

AFAIC if there's even a hint of backlash, it's eventually going to end up like Monsieur Sock's example!
 
piranha-bro2 said:
Very timely, Andy. I encountered the same problem when building the SFQ - I had only very slight play, but it still bothered me greatly. I have three output shafts and brand new sprockets (two tried so far) are loose on every one of them, not backlash loose, but an easy non-inter fit - they used to be so tight owners could damage the cases trying to get them on. I preferred them like that.

Now it seems every sprocket made for them is a loose fit, ie they go on by hand, with or without slight backlash, even over the 'unused' part of the spline outside the retaining groove. A mate had a brand NOS SFC sprocket still in the vacuum pack and I used that. It wasn't a super tight fit, but better than others I tried and had no backlash. I fitted it with Loctite 620 after using the Loctite primer - probably make no diff, as it's a press fit repair, but added peace of mind.

AFAIC if there's even a hint of backlash, it's eventually going to end up like Monsieur Sock's example!
Click to expand...
Le Socks sample is as bad as I’ve ever seen. I wonder if there’s been any that have been so bad, to the point where there’s no drive?
 
I've got the same problem on the motodd. I replaced the worn original from a spare gbox I have when rebuilding the motor, 15000 kays later its showing wear. Hoping the 520 chain will go easier on it.
Are they still available new?
Red is manufacturing extended splines so maybe he could have some made.
Looks like there is a market for them.
 
If I was going to replace mine I'd be lashing out for one of Red's outrigger shafts - would have to go the hydro clutch at the same time, but I really like the idea of extra support at that power transmission point.

Be interesting to see how the SFQ fares with a few serious ks on the dial.
 
motoddrob said:
Hoping the 520 chain will go easier on it.
Click to expand...
A couple of educated guesses:

The 520 chain, being lighter than the 530 will have lower dynamic loads, but I think the dynamic loads are more relevant to chain wear than sprocket wear. The power transmission loads will be the same for either width sprocket.

I imagine a 520 sprocket will be harder on the shaft because it's narrower and will therefore have a smaller contact area and consequently higher contact pressure between the two parts.

But if it's a 530 sprocket that's had the teeth machined sown to 520 size, but the hub left full width, it should make no difference to shaft wear.
 
They need to be full size at the base for them to fit correctly. I ground down a 530 sprocket. As for chain wear, I fitted new 530 chain/sprocket on the replacement spline when rebuilt so done 15000 kays. I was surprised to see the spline wear when changing to 520.
 
When I changed from 630 to 530 on my Jota there was rotational movement on the output spline - I spoke to Keith who reminded me that it was 40 years old and there would be some wear and it would be an awful lot of work and time to replace !!
 
Paul Marx said:
A lot depends on how many thousands of miles a year you ride the bike.
Paul
Click to expand...
And how hard you ride it.

if a sprocket starts out as a nice tight fit on the splines I can almost guarantee it will stay that way - mine did for decades and 100s of 1000s of km. Once it has even a little bit of backlash it's going to start wearing the shaft, especially if you like hard acceleration in low gears. I'd be happier, much, going back to a tight fitting sprocket.
 
There was an argument made on the old forum long-long ago; for welding the 2 together, which I can see some sense in....

If your shaft is starting to wear then carefully weld on a new sprocket using a number of small-ish TIG tack welds. When it comes time for a new sprocket, just nip through the welds with a cutter and go again.
 
"If your shaft is starting to wear then carefully weld on a new sprocket using a number of small-ish TIG tack welds. When it comes time for a new sprocket, just nip through the welds with a cutter and go again."

not quite correct Haggis TIG is too slow, first be sure that the "slack" is taken up on the drive side to mimimalise the load on the weld, then (with the bike laid over) be ready with a small house type watering can filled with cold water, then GET IN THERE with a high carbon rod (Murex would be ideal) in a stick welder, use 2.5mm and about 150/170 amps, move fast and weld about a third, quench the shaft at the back of the sprocket, then repeat, 2nd third and again the last third, Have done it several times and never heard back from the owners.
CLEM

TIG would heat too slowly and destroy the oil seal before you had enough heat to melt the sprocket/shaft, stick = NO PREHEATING, just get in there a zap the fucker, it's a fillet (albeit a round one) so this works well.
CLEM
 
piranha-bro2 said:
And how hard you ride it.

if a sprocket starts out as a nice tight fit on the splines I can almost guarantee it will stay that way - mine did for decades and 100s of 1000s of km. Once it has even a little bit of backlash it's going to start wearing the shaft, especially if you like hard acceleration in low gears. I'd be happier, much, going back to a tight fitting sprocket.
Click to expand...
Yes, but if you ride 300 miles a year, you've got a few years before you need to worry.
Who on this forum rides his Laverda thousands of miles a year?
Paul
 
You must log in or register to reply here.
Back
Top