The fight to keep the KTM 300 EXC gear selector tight

KTMphil

KTMphil

Senior member
Joined
Jan 11, 2011
Location
Chiang Mai, Thailand
Bikes
2007 KTM 990 Adventure Suzuki DRZ 400
An unusual arrangement on the KTM 300 EXC's gear shift selector from a lot of other bikes. The gear selector lever/ pedal, has a female, conical spline, that mates with the male conical spline on the engine. A bolt then tightens the lever onto the angled spline creating a tight/ solid fit.


The problem with all the vibration and gear change abuse is keeping the bolt tight, its come loose about 10x even with Loctite


ktm 300 bolt by Triangle Golden 007, on Flickr



Have been experimenting in the past with 2 nuts on the threaded bolt. The connection where the bolt goes in is threaded, then one nut acts as a locknut, the second nut is a double lock nut, everything including the full length of the bolt is loctited. Hopefully this will stay tight.


If anyone has any ideas of making this bullet proof, please let me know, i've consiederd expoxying everything too.


You can see the two lock nuts in the photo below:



20150219_171516.jpg by Triangle Golden 007, on Flickr
 
Phil, ever considered a tiny tag weld?
Another option is drill a small hole through the nut and bolt and secure it with a linchpin or monel wire.
Remember the old race Ducatis which had all engine bolts wired up.
 
What you've done there should work but I would swap the plain nut for a nyloc nut.
So it screws on properly, wing a bolt through it the correct way to pre thread the nylon section then put it on your bolt backward, if that makes sense.
Less change the nyloc nut will coming loose compared to a standard nut.
 
Thought about the nylock lock but backwards, but with all the vibration and hard kicks, wasn't sure they d be much advantage. Hopefully lots of blue loctite will be like glue. Might still epoxy everything.




Pounce said:
What you've done there should work but I would swap the plain nut for a nyloc nut.
So it screws on properly, wing a bolt through it the correct way to pre thread the nylon section then put it on your bolt backward, if that makes sense.
Less change the nyloc nut will coming loose compared to a standard nut.
Click to expand...
 
Try the nyloc, they are made for vibration situations, but still do it the way you have with 2 nuts. Flange nut as you have against the lever then the nyloc nut.
Go the red loctite, it's stronger & more permanent.
Welding, even a small tig tack weld will make everything harder to fix in the long run.
Epoxy is just overly mess & not that great.
 
Pounce said:
Try the nyloc, they are made for vibration situations, but still do it the way you have with 2 nuts. Flange nut as you have against the lever then the nyloc nut.
Go the red loctite, it's stronger & more permanent.
Welding, even a small tig tack weld will make everything harder to fix in the long run.
Epoxy is just overly mess & not that great.
Click to expand...



Ok .... this is setup for now, if it comes loose the nylock nuts will go on, good idea, thanks.
 
HT steel bolt Norlock washer Nylock nut and Thread lock would all be a waste of time unless all the components are cleaned with degreaser / cleaner ......
 
You should consider a 'common procedure' used in racing and aerospace, which consists of securing the bolt with a safety wire through the drilled bolt head and with the other end attached to a drilled washer tab (welded on a regular washer if you can't find the drilled tab washers sold for this purpose) which is at an angle over the gear shifter. Alternatively you can weld a second tab at a 90° angle which acts as 'hook' or 'stop' preventing the washer from turning when the bolt vibrates loose. The safety wire and drilled washer combination must be positioned so that the safety wire exerts a 'pulling' force in the 'tightening' or clock-wise direction on the bolt head, thus preventing it from turning loose. I can do it for you if you want as I have the required wire and tools. Just give me a call.
 
The reason this safety wire application is mandatory in racing and aerospace is because it is the best safest solution to secure fasteners as it does not matter whether the threads are clean and dry or dirty and covered in oil, which will affect the application of loctite. Another important aspect is that safety wire offers the advantage of easy visual inspection without having to apply a wrench on the fastener to check whether it is still tight.
 
I need you to give me the gear shifter assembly (lever plus bolt and washer). I'll be in the city later this afternoon as I have to do my 90 days renewal. Let me know if you'll be around at RC.
 
Methods mentioned above sound ideal for the conventional style of lever clamping . Would be interested in the results on the taper spline style especially if the shaft is worn .
 
The headache with the Conical tapered spline is that as the soft alum. gear shifter wears it is then allowed further in/ up on the tapered conical shaft, so you lose the tight friction hold from the lock nuts....then the bolt backs out from vibration as its no longer under tension....nasty setup.
 
With the remoteness of some of the places you get to this is extra important . If it was me i would get a machine shop to adapt a conventional un-conical splined end and go shopping for a similar shaped lever with the "crush" style fixing /
 
jkrfjessjess said:
With the remoteness of some of the places you get to this is extra important . If it was me i would get a machine shop to adapt a conventional un-conical splined end and go shopping for a similar shaped lever with the "crush" style fixing /
Click to expand...


I think the best solution might be a center drilled pin through the shaft and gear shifter. If its threaded, it would also deal with the taper wear problem kind of keeping everything fixed as one piece, what do you think?
 
Definitely better than off centre drilling .Think this would be best done in a machine shop with the shaft removed from the engine and insisting they use quality fixings .
 
brake034 said:
Another option is drill a small hole through the nut and bolt and secure it with a linchpin or monel wire.
Remember the old race Ducatis which had all engine bolts wired up.
Click to expand...

This... Lockwire one solution to vibing bolts that just works..
 
You must log in or register to reply here.
Thread starter Similar threads Forum Replies Date
KTMphil 2012 Ducati Streetfighter 848 retail USD$ 12,995 Bike Talk 2
Similar threads
2012 Ducati Streetfighter 848 retail USD$ 12,995
Back
Top Bottom