Protech shock bushes

[Scooterdude]

Ok so I just fitted a new Protech rear shock only problem as I can see it is the inner bushes are slightly longer than the bit on the thread were the nut tightens up so when tight the nut pinches the metal inner bush so in effect holding it in a fixed position so any flex will be between the rubber and the shock body, anyone else noticed this and have you done anything about it? For example filling down the bush?

[Adam_Winstone]

I noticed the same but assumed that it is so that the unit can flex on the rubber bushes. My thinking behind this is from reading about R1s and others being held tight, especially if brass bushes are fitted rather than nylon, and finding that they can suffer piston/rod failure as there is no flex/rotation. I notice that people have suggested that not doing the nuts up tightly on the R1 conversions can alleviate the breakage issues by allowing this slight rotation.

In light of the above, I'd have thought the Protech design was longer on the centre collar so that the nuts can be done up tightly, fixing the shock securely, but not clamping down on the outer eye, thereby allowing the movement necessary to avoid the breakage issue detailed above.

The above it total assumption, based on limited knowledge of a recognised problem, so I could be 100% wrong!

Adam

[Scooterdude]

Now I've had time to think about it I'm going to whip it back off tomorrow and compare the length of the steel bush with the original Lambretta one, if it's longer I'll reduce it to the same length. If I leave it I can see the rubber getting ripped out before long.

[Grumpy225]

Ok so I just fitted a new Protech rear shock only problem as I can see it is the inner bushes are slightly longer than the bit on the thread were the nut tightens up so when tight the nut pinches the metal inner bush so in effect holding it in a fixed position so any flex will be between the rubber and the shock body, anyone else noticed this and have you done anything about it? For example filling down the bush?

The nut has to go against the inner sleeve otherwise the shock wouldn't be able to flex with the motor. If the nut went against the outer it would remove any flex from the motor (and act like a solid bushing R1).

[Scooterdude]

Ok took it back off and tightened one end up at a time so I could swing the shock to see if we had movement, top one was fine but the bottom one needed the outer face of the bush filing down so the nut and washer would tighten against the inner sleeve, waiting for the rain to stop so I can set the preload and rebound up.....

[Scooterdude]

Ok an update on this. Found a bit of movement between the inner bush of the shock and the top mount on the frame. Frame mount diameter is 18.03mm and inner shock bush is 18.26mm resulting in a bit of slop, now before I start building the frame mount up by welding is there a quick fix I can do to loose the gap?

[theageofindustry]

Ok so I just fitted a new Protech rear shock only problem as I can see it is the inner bushes are slightly longer than the bit on the thread were the nut tightens up so when tight the nut pinches the metal inner bush so in effect holding it in a fixed position so any flex will be between the rubber and the shock body, anyone else noticed this and have you done anything about it? For example filling down the bush?

The nut has to go against the inner sleeve otherwise the shock wouldn't be able to flex with the motor. If the nut went against the outer it would remove any flex from the motor (and act like a solid bushing R1).

Just as Mike has said. The rubber in the bushes is what is supposed to twist when the shock is compressed. They work the same way that engine silent blocks work. The metal spacers are not supposed to move on the frame or engine mounting pins.