AVO inserts

[Steve Roberts]

I have just fitted a pair of AVO rear inserts to a rolling chassis (body off) and upon 'bouncing' the rear end there is a tremendous clunk on the rebound. The inserts are definately clamped correctly in the upright by using the right spacer washers underneath. I removed one and checked it against the original and the cylinder is the same length but the piston rod when fully extended is one and a half inches shorter. What this does is preload the spring when fitted and consequently the piston is fully extended even with my weight stood on the chassis. The clunk sounds like the piston hitting its maximum extension. There is no droop to the suspension when the chassis is jacked up, the rear wheels lift off the ground immediately. Putting the old insert back extends the spring by the one and a half inches and there is no clunk. Has anyone experienced this and is there a solution apart from trawling around for the correct length insert.

[miked]

Steve,
I have AVO rear inserts with standard springs. I had no troulble like this. Could it be that you have a set of race type inserts that have shorter pistons. As I understand TTR does same with Koni. It prevents droop and problems with the drive shafts at acute angles. If this is the case are you not meant to take off the big springs and fit the adjustable platforms for 2.25 inch springs etc. With this you can set your ride height and not be troubled with problem because of the short pistons. Lots of boys on here well clued on this, but sound right to me.

Mike

[miked]

Steve,
Just another point. The spacers you mention. Are these not trasit washers to prevent damage to the bottom of the shocks. These had me a bit confused. I put the insert in and the collar tighened right down and nipped the inerts fine. Still got the washer in the shed.
Mike

[sotul86]

Hi

I have a elan s4 with 2.25 springs and AVO inserts an I?ve exactly the same sound thats You describe have learned to live with it but now then reading this it all come back to me ???

If You come up with some solution I sure would be interested

Cheers

[miked]

Johan,

I dont think Steve has the 2.25 inch springs, reading his script. That is why I was wondering if he has clamped up the big old ones with the orginal chapman strut with the normal platform. Or have I read it wrong.
Mike

[tdafforn]

I have the same problem although I am not sure whether the shocks are AVO, they were bougth from TTR and are chrome plated with top adjustment.
In order to reduce the problem I am about to fit 2 wire restraints to prevent the shocks hitting the stops on full droop. I am also hoping that the restraints will have enough "spring" in them to decelerate the suspension more gently.
One of my reasons for doing this was that I was worried about the effect on the shocks of hitting the stops on a regular basis..
What do you guys think?
Cheers
tim

[Steve Roberts]

Thanks Guys, Yes every part I am using is standard including the original coil springs on standard uprights. Allowing the dampers to hit the upper stops as they are is like fitting a slide hammer and I'm sure as well as doing the damper no good it will put tremendous strain on the insert retaing nut on the upright. I guess I'm not prepared to continue the build until I sort this out. At the moment with the body off I can compress the spring, undo the top nut at the Lotocone, pull the upright away from the chassis mount and remove the spring followed by the insert in about 5 minutes. All that changes with the body on. I am going back to Chris Neils with the AVO's I think the solution is to source a pair of inserts of the correct length if there are such things. I did send one of my original inserts to SJ sportscars to use as a pattern for manufacturing new ones - maybe I'll give them a ring. I'll keep everyone informed Cheers.

[rgh0]

MOst shockers need a couple of strokes to properly prime and work after sitting for a while. The spring load at the end of the extension stroke is relatively low, especially at the rear, its actaully much greater at the front.

The shock with its damping action ensures the shock reaches the end of its travel at a relatively low speed and low impact. The shocks at both front and rear are designed to restrain suspension travel in droop for much heavier suspension than you find on a Lotus.

I only use a droop cable at the rear as the shock allows to much droop and does not prevent lockup on the CV's. Limiting droop with a shorter travel shock is OK in my opinion.

I personally would not be concerned about the "knocking" sound at this stage. You can get different shocks with longer travel that will not limit droop but then something else will and this may be even more of a problem.

Rohan