Not had a particularly lucky time on three wheels recently...

A couple of weeks ago took the S-327 out on a weekend for a gentle ride - and the rear tyre (Schwalbe Marathon) had a bead wire failure - 2 mile walk home.

Yesterday was out again with a group of friends and a mile or so from home I went over a bump a bit faster than I should have - there was a sickening crack and the rear wheel was rubbing up against the seat. Rear suspension had given way - the titanium bolt which supports the rubber 'shock' had pulled right through the aluminium block at the back of the frame:



Walked home :-(

Looking at the fragments I think it had corroded quite badly over the years, so that bump was just the final straw...

It's not _quite_ as bad as I feared - it looks like I may be able to salvage matters by making a plate to fit over where it's broken through. Other options are maybe having it welded up then re-machining, or as a last resort making at entire block anew from a large lump of aluminium.

Thats why you need extra trikes - I only have one of my trikes on the road at the moment - must fix at least one on the other two so I have a spare ready to go.

John Turvey

Peter:

Is the broken bit integral with the main frame? (It's hard to tell from the photo or a quick glance at my Zenit, which I know has a different rear arm design.)

Further thoughts on how to go about the repair?

I wonder if you can make any sort of wild guesstimate how many miles/km are on your S-327. Could aluminum fatigue have anything to do with the failure or are you convinced it was corrosion?

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Here, snow, cold and 'reluctance' still prevail, but another calendar month should make a difference, both in the weather and my outlook.

Have it good.

Peter B.

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John - good idea - alas no space!

Hi Peter - on mine the rear block is not welded to the frame - it slides inside the main rectangular frame and is secured with titanium screws and (I think) glue. Some former owner seems to have tried to remove it - the screw heads are quite mangled. You can see one on the last pic below... and as you'll see there's so much corrosion I'd certainly suggest that as the main cause. No idea on total miles - I probably put a few thousand on it at least, then it seems to have been used hard when out of my hands...

Anyway, just fixed it for now...

Propped the trike up on a Workmate, removed the rear shock and pivoted the swingarm up to reveal the damage:



Closer up you can see the steel bushing has been pulled right up through the plate. The white powdery stuff is corroded aluminium - the edges where it cracked off were covered in it, and 'veins' seem to run back each side of the broken out area. These seem to have 'spread' the whole block - at the rear end (where it broke) it's about 2 mm wider than where it fits into the frame. Nasty stuff corrosion - as aluminium oxide is greater in volume than the normal alloy it can burst stuff apart :-(



I've now knocked out the steel bushing and filed away some of the worst of the corrosion. It was quite bad on the underside too - and you can see where it's eaten away at the rib to the left on this pic. I basically filed the underside back to flat, or close to it. Plan is to fit a bit of 10mm alloy plate in to support the bushing - I'm hoping there will be enough strength left in the original to hold it.



Finished the plate - the big bevels on each side are to clear the nice stress-relieving radiuses which the Russians used when they machined out the gap where it's to fit. The stainless steel bushing which forms part of the suspension unit's 'ball joint' is still in almost perfect shape after a quick clean.



Test fit. I was thinking about cross-drilling the whole thing and putting an M5 or M6 stainless bolt through it to counteract any further 'spread' of the rear end - loads from the new plate could tend to lead to this. But the bolt couldn't be very far back (because of the steel bushing) so it probably wouldn't have much effect anyway, so I decided to omit it.



Finally slathered everything with extremely copious grease to try to prevent further corrosion, and did the shock bolt up.



Seems OK after a test sit, but time will tell...

Ingenious repair method and very nice work, Peter.

I'll be curious to know how it holds up.

Peter B.

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