Wednesday, 11 July 2007

Rear damper problems?

Last year I did some work on the suspension of 't Kreng. One of the things that I changed then were the rear dampers. The old but reliable red Koni's Classic's were changed for a new set of adjustable AVO’s. Big advantage of the AVO's over the Koni's lies in the fact that they are adjustable on the car. Also on the AVO's you adjust both in and out going stroke, while on the Koni Classic's only the outgoing stroke is adjusted;

So far so good, although looking at the difference in length between the two I should have been warned! The car was used in anger several times after that without encountering any problems. While driving La Carrera Caledonia in June the rear did bottom out twice on the first day, but nothing worrying. So I stiffened up the dampers two clicks and the problem was solved. As the car performed rather well after that I didn't think much about it until I received an e-mail from a friend a few weeks later.
On my advice he had also ordered a set off AVO dampers for his TR7-V8. But while putting them under his car he found out that the rear dampers were too long. So I did check mine today. First thing to check was for marks where the bump stops had touched the back axle, but there were none! Checking the ingoing suspension stroke I measured 110 mm between axle and bump stop, should be more than enough;

This was confirmed after I removed the rear springs from the car and lowered it onto its bump stops;

Which wasn't possible as you can see, so the dampers are indeed to long. The gap between axle and bump stop is in my case approximate 20 mm. Which gives me an ingoing stroke of about 90 mm. Should be enough for the time being. But I think I will send an e-mail to AVO  in the near future, see what they have to say about it ...
It seems that the adjustable Spax rear dampers have the same problem. As Koni's are shorter they haven't.

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