A Tale of Two Dampers

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A Tale of Two Dampers

Postby Geoff Butcher » Sat Jun 23, 2018 9:54 pm

A while ago I had a pair of Leda dampers custom made to my dimensions, corner weight, spring rate etc. which cost about as much as the car is worth. Not long after, one of them failed, so I sent them back and was told it was my fault because I had let it bottom out. This seemed unlikely as they had nearly two inch thick bump rubbers. They had the gall to charge me for the repair, and they came back with even more bump rubber; putting a ty-rap round the stem showed that unsurprisingly it was hitting the stops as the travel was now minimal. I've now got round to removing the damper and taking the bump rubber off to see just how far it compresses before bottoming out. From the photo you can see that my spring would have had to compress to slightly less than half its free length, in the process squashing a 47mm bump rubber into a 20mm space. A tad unlikely, I feel? The original rubber is next to the damper along with replacement one.
I could go on about my Protech dampers, but I'll save that for another day...

ImageLeda damper and spring by geoffb7, on Flickr
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Re: A Tale of Two Dampers

Postby Hans Efde » Mon Jun 25, 2018 8:36 am

I have the theory the rear dampers have a short life (any brand) because they are mounted fixed at the top, while the bottom makes a curve when the suspension arm swings up. This causes a momentum on the damper for which it is not designed. The momentum puts pressure on the seals on 1 side, so that suffers from excessive wear. Obviously the front has the same setup, but perhaps length and geometry play a part. Else I can not understand why they all fail. My Spax at the rear have emptied themselves again long ago. But I have strong springs with pre-tension at the back. Combined with the lightness at the rear, the car seems stable and the rear doesn't dance around.
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