Worn drive sprocket splines

1200ts

1200ts

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I there any good fix for the front sprocket being loose on the splines? Other than taking the gearbox apart and fitting a new gear?

I have heard this problem only happens when fitting pattern sprockets rather than factory ones. Well as there are most likely no factory sprockets left what can be done the prevent a recurrence? I have seen Laverda's where the sprocket is almost impossible to get on and also to where it just falls on. What was the factory specification for the spline clearance?

Bruce
 
Bruce

One thing that you could try is fitting the front sprocket backwards.

A lot of sprockets have an overly large chamfer and hence only half the splines are being used / worn out.

When my RGS went past the 100,000 mile mark I had to start fitting my sprockets backwards...

T.
 
Interesting question, Bruce.  Your experience is counter to mine.  When I fitted new sprockets and a drive chain on my RGA at Wolfgangs a  couple years back, the sprocket was too tight, not too loose.  At this year's rally, Wolfgang mentioned this again. Apprarently, the manufacturer of the sprockets he was sourcing was using old machine tools and were no longer able to hold their tolerances.
 
If there were enough interest I could get a batch spark eroded.

I had a Triumph triple front sprocket made the other week and the results were very impressive.

I would need a good sprocket as a pattern tho.

Andy
 
You would not need to spark erode a new sprocket, the centre splines are broached before hardening to a common standard, I've got it written down somewhere. Individualy spark eroding pre hardened platewheels is probably best reserved for specials and one offs.
If your sleve gear splines are totaly shagged you may get another bite of the biscuit by using Tony's method. In an ideal world the sprocket should be a tight push fit on the sleve gear, that is why we have engineering standards, but alas, the world is not ideal.  ::)

  Keith.
 
Hi Bruce

the proper fix is to pull the motor, flip it upside down, remove the bottom case half to get at the transmission, and replace the 5th gear output shaft with bearing and seal. Not what you want to hear, you already made clear.

you didn't hear this from me, but a bodge fix would be to source a brand new sprocket, fit it on the worn output shaft, then tack weld it in place onto the shaft.........the bodge will last the life of a couple of front sprockets, just grind off the tack welds each time you need to fit a new sprocket, and tack weld the next one on as required. The tack welds will keep the sprocket from "rocking" on the worn splines.

I can already hear the screaming from other list members, but the output shaft splines are already buggered, just keep the tack welds small and at a low a heat as possible to avoid cooking the output shaft seal. If you sell the bike, you should disclose the bodge!!

I ran my 79 1200 for the balance of a summer several years ago with a new front sprocket tack welded into place on an output shaft with badly worn splines, kept the bike on the road until winter hit and I could then pull the engine and replace the output shaft at my leisure while the bike was off the road for the winter anyway.....

Paul LeClair
 
Before you do any tack welding, remove the clutch pushrod seal from the end of the countershaft. If you do it carefully you may be able to re-use the seal. But if not, Wolfgang has the seals.

I just fitted a new sprocket to my brother's 3c on Tuesday nite. At the time, I was thinking it was a bit tight, needing gentle tapping with tubular drift (actually a big socket over the end of the shaft). But Keith's comment that it should be a tight push fit has reassured me that all is well. The bike has only done 65,000 km so the spline shouldn't be worn out, especially since there was no retaining plate on the old sprocket and it was sitting on the outer end of the spline!

Cheers,
Cam
 
My 1200 spline is also worn and when replacing the sprockets last year Wolfgang suggested fitting one of his "tight" sprockets onto the spline. Turned out there was way less slop on the fit so all in all a successful outcome. Might be worth talking to Wolfgang to see if he has anymore of the "ill fitting tight sprockets".
I was lucky enough to buy a set of 1200 gear clusters complete on ebay several years ago for I think 60 quid. The spline is in good condition so now I'm waiting for the crank big ends to give up to justify splitting the cases to replace the shaft. Motor has done 170,000 and the cases are virginal. Problem is, still no sign of crank wear!!! and I'm from the "if it aint broke don't fix it" mold so who knows when that'll be.
 
I fit one of Wolfgang's "tight" sprockets about two years ago, and man, was it tight! A little too tight, me thinks. To install it, I had to bake it in the oven and get it fully, wholly hot - like 350 degrees F hot - and even then had to use a large socket to drive it home. Only once I had it on did I stop to think, "okay, when it wears out, how the hell do I get it off?" Personally, I'd rather have tack welded a sprocket on, because I'm certain the sprocket I've installed is going to have to be cut off when it's time to replace it. That said, I doubt it'll ever loosen up!
Richard
 
What I was thinking was chop the teeth off an old sprocket that was ALMOST aligned with the orignal 6mm bolt holes...
    So that when the bolts where tightened a shear affect would take place....Cheap and effective....A 0.5 msallignment and blob of Loctite should do the trick

    I thought it a good idea at 4.30 am Thursday morning after hours without sleep .


            BEST WISHES

              Tim
 
you've got a point Tim, but the problem must be that by making the sprocket centre wider, there would be no way of installing the twistlock plate and the two 6mm bolts, not a bad idea to use the spline area either side of the lockplate fitting groove, because that part doesnt wear,it might work as a "slightly better" bodge than just welding on the new sprocket, but you would still have to weld on your double thicjkness sprocket.

Lets hope it wont be long before someone makes a new splined shaft, they are surely needed already.
CLEM
 
Crikey! Nobody has mentioned my favourite fix bodge for worn splines!

I am a big fan of Loctite products as 'imho' they are better than the claims made for them.

Loctite 660 Quick Metal is specifically designed for worn splines/keys/bearing seats and can compensate for gaps up to 0.5mm.
Of course a good puller will be required for removal-remove the clutch rod and put an old nut in the centre to prevent damage to the shaft.
I will readily admit there may be some awkwardness in having to remove the chain first (maybe not?).

http://www.loctite.co.uk/cps/rde/xchg/henkel_uke/hs.xsl/Loctite-4087.htm?iname=Loctite+660&countryCode=uke&BU=industrial&parentredDotUID=productfinder&redDotUID=1000000J02K

You may have guessed that I have worn splines on my 'donor' engine, and this is my chosen method.
The main idea is to remove fore and aft movement of the sprocket ro prevent further 'fretting' of the spline.

I'm not sure about tack-welding sprockets on, I have seen a few emergency weld repairs in industry and usually the welds break eventually.

I am ready to be shot down in flames.

SimonR

 
SimonR501 said:
I'm not sure about tack-welding sprockets on, I have seen a few emergency weld repairs in industry and usually the welds break eventually.
Click to expand...

  Maybe you need to try some of Pauls "low heat" welding    :D

    Keith.
 
Keith

I had the Triumph one from an E8 06B-2 sprocket, cost about ?55 including the sprocket, spark erotion does away the need for a broach.

I do not know the tech bits behind it all but the sprocket was good and still operating even tho it was not hardened.

Andy
 
I can vouch for some of the Loctite products as well.The crankshaft spline and sprocket on Nickdav7's Jota were badly worn, due mainly io haveing been run with the jesus nut less than "up till it strips" tight, a new sprocket was purchased and the internal and external surfaces cleaned with degreaser, then petrol, then methylated spirits.Loctite activator (7649) was sprayed over both surfaces and then Loctite "quick metal" (no number on the pot, I just looked) was coated onto the spline, fit the sprocket, scrupulously clean the thread and the jesus nut, Loctite on the threads, plus a new lock washer and tighten up using my home made locking tool and a three foot tommy bar.Has'nt moved yet, shouldnt be "wearing" and we wont be taking the sprocket off if we can help it.The cost of the two Loctite products even from a known good source (Capitol supplies, Croydon) was eye watering, but at the seventy odd quid, is it not actually very cheap, compared to fitting a new end on the crank, and the repair does seem to be fairly permanent (maybe I shuld not have said that !) I am not sure it would work on a sliding fit gearbox sprocket, because there is no nut to tighten the whole plot up.
CLEM
 
Clem,
I think that Loctite Quick Metal 660 is much more competitively priced now, I bought some from Ebay for ?12.50.
The activator was ?2.99 from ebay also.
The activator speeds up setting, especialy when temperature is below 15oC.

SimonR
 
Back in the '80s we had some guys here who welded these things on for racing.  Never had a problem getting them off again, just stole another bike!  But maybe this option isn't available to you.
 
laverdakeith said:
SimonR501 said:
I'm not sure about tack-welding sprockets on, I have seen a few emergency weld repairs in industry and usually the welds break eventually.
Click to expand...

  Maybe you need to try some of Pauls "low heat" welding    :D

     Keith.
Click to expand...

I knew I would take some hopefully friendly abuse for that post........

I used a MIG welder, four quick tacks, lowest amperage setting I thought I could get away with, not a lot of heat buildup on the output shaft and it got me through the summer's riding season, no problems. Not enough heat from the quick tack welds to bother the output shaft oil seal. Hey, it worked.

Paul LeClair
 
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