Scooterotica

Bike felt a little uneasy at speed and defo something amiss so pulled over to check and ........could have been very nasty.
As you can see the threaded rod, approx 10mm diameter has snapped off within the upper housing. This is a screw thread fit.




You can also see how its been wearing away at the top after it came apart, enlarging the hole. It has also been catching the rear mudguard and original CDI bracket (Series 2) after it broke.
Shame as I had thought I'd found the answer to my Lammies rear suspension set-up. Question is what to do, is it fixable? It obviously comes with no quarantee as they are all secondhand anyway.





It had previously been on the scooter for approx 18 months with no probs at all.

never seen that before

what i dont understand bout these shocks is how they pivot on the brass/nylon bushes when the shock is being compressed. do you leave the nuts loose so shock can move or just tighten it up so all pivoting movement puts an extreme strain on the shaft .the genuine shock has a rubber bush that can twist under compression.
you are lucky bloke ian

mark wrote:what i dont understand bout these shocks is how they pivot on the brass/nylon bushes when the shock is being compressed. do you leave the nuts loose so shock can move or just tighten it up so all pivoting movement puts an extreme strain on the shaft .the genuine shock has a rubber bush that can twist under compression.
you are lucky bloke ian

That's a very good point, and I wouldn't be surprised if that's what happened here I have the PTFE type, what we really need are rubber bushes. But what's the alternative, has the leaking problem with the BGM been isolated/sorted? I heard there was an "off" at Lincoln due to fluid running on to the rear tyre

Glad you're okay Ian

i think the alternative is to use a shock that was designed fo a lambretta not a monoshock sports bike.
i was horrified to see a r1 shock a chap wanted fitted to his bike had a thinner spring fitted to it and this allowed the spring to move 15mm approx inside the spring cup/support. this meant it was rubbing on the mudgaurd and not compressing eveny. we fitted a std escort for him

soulsurfer wrote:That's a very good point

yes, never thought of that, and probably explains why my nuts do come loose quite regularly...
think I need to rethink my rear suspension....

cheers guys.....
I can visualise how some sort of pivot / rotation is needed in a swing arm suspension set up but can the R1 shock setup differ from say any other shock thats done up tight. These do not pivot / rotate on the mounting lugs either. Are you saying that the approx 5mm of compressed rubber within a standard type shock at the mounts absorb this rotational movement / stress ?

So is the R1 / R6 just so overspec'd for the job that they are able to cope with this normally - i mean theres hundreds n hundreds of folk using them and this is the first I've known snap? Or are they fundamentally wrong then?

the original shock has a metal sleeve to fit the shock mount then a bit of rubber then another metal sleeve attached to the shock itself . this enables a rotational movement that is needed as when a shock compresses it gets smaller and seeing as its fixed between to points that swing together (pivoting on the engine mount ). the rubber takes the rotational force and absorbs it . brass / nylon bushes dont absorb this and the force needs to go somewhere i know its only a small movement but its a movement . hagon,bgm ,escort and the alloy taff/readspeed shocks all have these mounts for a reson,if it was cheaper to use solid mounts then manufactures would but they dont .
the r1 shock is great on a r1 where it was designed for and it uses rubber bushes ,yamaha dont do that s**t for fun they do it cos it needs it

the rubber "inner" at the top and bottom of a standard shock also acts as a vibration damper- as per engine mounts. Putting direct metal to metal contact at those points can only increase the engine vibrations.

Chris

As its in bits i will examine the loose spring / collar issue too n post up pics. Im beginning to see that the common conversion for these otherwise top pieces of kit may only be half a job, and potentially dangerous at that