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MG MGB Technical - Testting a front shock absorber

Guys, is there a way to test the front shockies off the car? I just bought a pair which were supposed to have been rebuilt 2 years ago but have been sitting on a shelf since rebuild. Can I check them myself some how? Also how do i up-rate them myself if I decide to do so? In other words change the valve and what rating is ideal for fast road/race?
regards
mark
Mark Mathiesen

I have heard tell of a force/distance/time spec but not what or where it is. They should offer smooth and steady movement throughout the range, and especially not a dead or sloppy spot when wiggling back and fore near the middle of the travel. I also understand that they have a two-stage valve giving softer damping with smaller movements, so paradoxically they should get harder to move when the force applied goes above a certain level.
Paul Hunt 2

Put it in a vice, slip a light hollow bar 3 or 4 feet long over the lever arm, with the lever arm uppermost.

It should come down under the wieght of the bar alone with a smooth movement from start to finish without no crunching.

If you time it, both shockers should take the same length of time to drop down if they are well matched.

HTH Liam
Liam H

Damping is a function of speed not applied load. The faster you try to move the arms, the greater the resistance. It just feels like they're load sensitive as the effect of you pushing harder is inevitably to try to move them faster which makes them harder to move (if you see what I mean).

They should come down under their own weight IMO. As above, valving makes no difference.

You can 'uprate' by changing the valves or the fluid.

Neil
Neil Lock

Yes, the arms should be able to move under their own weight. There is a tiny bypass groove machined for that purpose. Smoothness is key. Don't worry too much that they may feel "notchy" at the extremes, as your bumpstops don't allow that much movement. They should change direction without jumping. Peter C
Peter Caldwell

Also check for any wiggle in the bushings, since this is usually where the wear is. There should be none whatsoever. This is especially critical in the front shocks which have the pivots placed lower in the body of the shock. Once they start to wear the oil begins to seep past the seals, leaving less to lubricate the bushings and accelerating the wear, causing the oil to leak out faster, and so on.

Your easiest upgrade is a heavier shock oil, then competition valves. IIRC a 50 wt oil was close to the stiffness of the new valves with transmission fluid, so you have a broad range. Use something that won't foam or eat the seals.

Jim
Jim Blackwood

This thread was discussed between 28/01/2007 and 30/01/2007

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