R1 Shock Snapped !

[Rich_T]

You might want to consider that this metal fatigue failure is not down to the mounting bushes but actually more to do with the engine mountings.

The Lambretta engine rotates not only around the engine mount bar but also side to side as the engine twists over uneven surfaces and during acceleration and breaking. This side to side movement is not taken up in the solid R1 mountings and therefore stresses the metal, essentially it is the shock that is attempting to hold the engine straight. The R1 shock never had to deal with side ways movement because the swing arms all run in bearing, nice an colinear, not exactly like a Lambretta.

The only way you'll get round this is to either 1. make an elastic rubber bush for both ends of the R1 shock or 2. work out some rose joint system if someone sends me the the internal dimensions of the shock mounting (ID and length) I could sketch something up on CAD and post it up for a rose joint solution.

The other option is solid engine mounts, and have your teeth rattled out (not really a good look).

[tony]

There you go. Rich has the idea. Maybe its worth a close examiniation of the the shock to see which plane the bar snappped in. This will give you a good idea if Rich is on the money and/or the thing was bolted up solid anyway.

[soullad]

Jaime - yes i too thought these were the answer but maybe they aren't?..................
unfortunately i do not believe that there is enough room left in the top or the bottom aluminium housing on the r1 / r6 design to fit any useful depth of rubber into - theres certainly not enough meat left to drill a larger diameter hole. Whatever product you use there has to be enough "give" inherent in the material to allow flexing in all axis.
By that I mean that if you remove your rear shock the engine can actually move side to side fractionally too ....thanks to the rubber in the engine mounts. This side to side movement is also possible in the rubber rear shock mounts too. It cannot be possible in urethane, ptfe or brass obviously as they are too hard a product. In effect the traditional lammy rubber mounted set-up allows movement in all axis.

Exactly Rich, and the ill fitting smaller springs just exacerbate the side to side intolerance.

[Supereibar]

Whatever is the solution folks, does not seem like an easy one so far... Getting far and far more disapointed with the R1. Due to it being over engineered it will defo. do the work an X amount of time but how long?

[Rich_T]

My appologies, I was too lazy to read the entire thread but after seeing one of these R1 set ups at Stuart Owens it was the first thing that occured to me. Clearly there are a couple of others who are on the same train of thought.

If a rubber joint is not possible the only other option is a split rose joint construction. It is a piece of cake to draw up and easy to CNC machine (not pssible on a standard lathe). All I need is the length of the R1 mounting boss and the maximum bore in the R1 mounting boss. If I can get a rose joint solution to work then I'll post the drawings/installation notes and you can decide what to do. I can get them made ot others can get them made, call it shared design for the better good.

[soulsurfer]

It is a piece of cake to draw up and easy to CNC machine (not pssible on a standard lathe). All I need is the length of the R1 mounting boss and the maximum bore in the R1 mounting boss. If I can get a rose joint solution to work then I'll post the drawings/installation notes and you can decide what to do. I can get them made ot others can get them made, call it shared design for the better good.

Top boss is 23mm long, 24mm dia.
Bottom boss is 25mm long, 22mm dia.

[shocky]

hi richard i supplied a fair few of these shocks over the years and have always left my nuts slightly loose i am interested in your rose joint system the dimentions are
top eye ; 23.45mm wide and 23.99mm bore
bottom eye ; 25.07mm and 21.99mm bore
measurment taken with a vernier so might be slightly larger but not much

[Rich_T]

Bad news guys. The absolute minimum bore size you can get away with is 24mm. I'd prefer 25 but you could squeeze 24mm at a real push. The bottom bush nails the job because both joints must have the same movement. Is it possible to bore the bottom bush? is there enough meat on it?

I did some CAd models on this last night, I will mail Mike Maxwell with a couple of screen shots and a drawing of the closest I can get. The principle is to have a bush with a spherically barrelled ID. This bush fits inside the shocker.

The bush for the frame mounting comes in two top hat shaped pieces, the two pieces face each other and the key is that at the junction of the two top hat bushes is a spherical seat where the barrelled bush sits. The R1 shocker may slide over the barrel bush a little but it is retained by the top hat ends of the other two bushes. I'll send Mike a general arrangement drawing to post if you don't understand where I'm coming from.

[shocky]

the bottom eye is 5.7 mm thick at the bottom but this reduces to 4 mm closer to the hole i wouldnt want to bore it

[soulsurfer]

I looked at the possibility of boring the top mount out a few years ago when I first got one of these, even if to make it the same size as the bottom, but came to the conclusion that it would be too thin.