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MG MGB Technical - Testing Rear Dampers

I have both rear dampers off the car and on the bench. I've replaced the shock fluid in both. The arm on each provides good resistance both up and down when exercising them. However, neither arm "rebounds" by itself after pressing it down. I know that tube shocks rebound when you work them by hand, and you can see the action, but do the Armstrongs noticably rebound when worked by hand?

Thanks in Advance, Greg.
Greg Peek

I do not believe that the original types of shocks on this car rebound at all. They are even called dampers because they dampen or slow down the movement of the springs but do not effect where the spring position is at. Bob
Bob Ekstrand

I had a leaking rear damper a couple of months ago and bought a reconditioned replacement. I can confirm the lever has no rebound.
Geoff Everitt

There is no gas pressure on lever shocks unlike most telescopic shocks sold now. Hence, the shock does not rebound back to the original position.

If I remember right non-gas filled telescopic shocks did not rebound either.

If you have good resistence and they don't leak they're probably okay. There is a fair amount of friction dampening in leaf springs so less than optimal performance may be hard to notice on the road.
Robert McCoy

Thanks much! Any thoughts as to whether you can replace just one damper (one makes a grinding noise at the end of the arm's travel) or is it advised that you replace both sides?
Greg Peek

Suspension units containing both spring and damper will return (if you can compress them!) but pure dampers won't, and that goes for the standard lever arms on the MGB.

I've never found a problem with replacing just one lever-arm damper (not that I've had to change that many!) This is in contrast to tubular dampers which *have* needed to be replaced in pairs. After the 2nd set on my V8 showed signs of failing I went back to the standard lever arms.

As well as steady resistance against movement throughout the range position ther arms at the mid-point of travel and gently try and waggle the up and down just a little. If there is any free movement before damping starts they are faulty. That goes for testing replacements before fitting, new or rebuilt, I've had one that failed that test.

These tests are really only crude go/no go tests, the real tyests are much more sophisticated than that. For one thing the lever arm has a two-stage damping effect whereby if you try to move the arms faster than a certain rate i.e. over a big bump or at high speed a secondary valve closes to apply even more damping. This gives a more compliant ride under 'normal' conditions but more resistance to bottoming or rebounding under extremes.
Paul Hunt

Thanks Paul! Glad you are still prowling these posts!
g
Greg Peek

This thread was discussed between 05/07/2008 and 06/07/2008

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