Question for the masses. My first run-in with the newly aquired SXV550MP (money pit) has given me my first scare.... On my way up to Riders in Bristol from the office thursday night - a mile out noise started to appear from the clutch side....then got louder then, transfered to the right footpeg...got to Riders, picked up my spares then nursed it the last mile home getting louder and louder (at this point im thinking big ends...) Long story short - rh side of the engine off and the final drive cog/nut had come loose causing the crank to float and said gear rubbing against the clutch basket hence the sound and vibration. All good, crisis averted, have to nip over to Fowlers at lunch time to get the holding tool to lock the engine so i can re-torque the nut to 160nm. And heres the question... two people have been a great help...the lad that i bought it off said "yeah it has happened before on numerous occasions to people that have rebuilt them - i always put loctite in there" on this occasion though its not stopped it. Another lad from the forum said "if its up to 160nm then loctite is not suggested by aprilia" as its torqued up to that value. What does everyone think and, if i do go for the loctite option which stuff should you use?
If the nut was previously torqued to 160 Nm and came loose, not sure if simply retorquing would be a proper fix. May be worth getting a new replacement nut to ensure no issues with the thread, and check the mating thread on the shaft. It may be the nut has some form of single use self locking feature? Do you have access to a workshop manual, if so what does that say?, can you contact Aprilia technical dept directly for advice. If you decide to go with loctite then you'd need to select one that's tolerant to running in hot oil I guess.
If it’s previously been secured to 160 nm (which is bloody tight) and with added loctite there could be shims missing or some sort of tolerance failure? Get a good parts manual picture and check all components in place that seat the assembly.
Righty....ive gotta go up fowlers at lunchtime...ill check stock to see if theyve got a nut in stock...with regards to support from aprilia thats going to be non existant id say - (production stopped 15 years ago) - that being said the build process has been refined over the years....eg theres a head gasket mod that now is done to fix the issue that was there back when they were in production.
Id say the assembly is fine. The lad that built the engine is one of two lads in the UK that everyone takes their bikes to... speaking to him over the weekend he currently has 4 motors on his bench that hes building so i trust his build competancy.
If that’s the case. Probably not an engineered solution. But you could increase the chances of it staying tight as follows. New nut. Degrease both threads with brake cleaner. Add stud grade loctite. Torque to factory spec. NUT TO BE HEATED IF EVER UNDONE DUE TO USE OF STUD GRADE LOCTITE!
I've no idea if a washer is used or if there is room for one under the nut but a Nordlock washer may be worth considering.
Nordlocks give excellent results. Only concern would be reducing the torque setting to allow for dismantle. Heating the loctite softens the bond, so the breaking torque shouldn’t be excessive. Not sure on the Nordlocks. They do have a very good tech dept you could contact for further advice though. Certainly worth considering. As Derek says make sure the shaft is long enough to take one first!
Thanks for the replies....as ive said in the build thread the engine hasnt even done a couple of hundred miles so the heavy duty loctite could be the answer.... so the lad tells me the normal refresh time for these motors is about 6k....im planning on no more than 1k per year so i might take that option....just looked at the NordLock washers - never seen those before...i might do the cleaning option and maybe loctite and see what happens...this bike is for short (really short) trips out and now i know what im hearing if theres an issue i know what it is....oil changes are every 500miles so if it gets to the next 500 i might get one of the washers on order and if it surfaces again try that... Edit: scarily that final drive gear costs 700 quid!
Sorry, just saw this, raced a 450 and a 550 back in the day. Everything needs to be clean, then clean it again. Red loctite, then torque it. Then crucially check alignment. Good luck, Cal (no not that Cal)
