Rear Suspension improvements

[moggiegeek]

I have recently fitted Spax adjustable shock absorbers all round. The front is great using deactivated original levers as top link, front anti roll bar and 10mm spacers as tyres perilously close to upper trunion.
The problem is the rear which has a transverse bar below boot floor with shocks nearly vertical. (with cut down bump stops) Even at softest setting the rear crashes about over speed bumps and pot holes.
I have thought it is too stiff at rear so is it possible/desirable to reduce stiffness of (new) springs?
I have considered rubber bushing the transverse bar rubber pads on either side of its attachment to the boot floor.
Any ideas appreciated

[philthehill]

A picture or pictures of your rear axle set up would be appreciated.
What you have described as the transverse rod is most likely a Panhard rod which stops the axle moving sideways relative to the body.
The angle of the rod relative to the body and axle is most important as if not correct will stop or restrict the axle moving vertically.
https://en.wikipedia.org/wiki/Panhard_rod

This is the preferred type of axle location mechanism:-
http://www.frontlinedevelopments.com/pa ... trol-link/
See fitting instruction for full details.
Or a Watts linkage:-
https://en.wikipedia.org/wiki/Watt%27s_linkage.

I had a Panhard rod on my Minor many years ago but removed it as the axle was located sufficiently tight so as not to be an absolute requirement - so been there done that.
The springs can be re-set. The seven leaf springs on my Minor had the short leaf removed and the spring re-tempered professionally to suit my requirements. They were also reset to give a 2" lower ride without resorting to spacer blocks between spring and axle.
Phil

[moggiegeek]

Thanks Phil, I must have misled you.
There is no Panhard Rod. The transverse element I describe is a proprietry aftermarket top mounting bar for telescopic shock absorbers at the rear which runs under the boot floor and is located there by four vertical bolts. I'm pretty sure the crashing about at the rear when going over bumps is some shock load being transmitted to the boot floor and the boot acts as a sound box.
I was thinking about putting some rubber cushioning between the bar and the boot floor and of locating the bolts on rubber washers above and below the floor.
Its not really the ride height its the stiffness of the springs at the rear.

[IslipMinor]

Hi,

We have a similar arrangement to you, using Koni dampers all round, with a similar transverse mounting beam at the rear. The front dampers are set to 'full hard' (+ some re-valving by Koni 20 years ago to increase the front damping only) and 'full soft' on the rear. The ride is 'firm' but never harsh, and definitely no sound box effect from the boot! The cross-beam is bolted directly to underside of the boot floor.

Which springs do you have? The early 7-leaf or the later 5-leaf? We have the early 7-leaf, but with the bottom, shortest leaf removed, turned upside down and put back on to the top of the remaining 6 leaves. The effect is to slight soften the rear, and also lower it about 1.5/2" - the bump stop is cut down around 1.5", and apart from the occasional pothole, it very rarely bottoms out.

Spax can be a bit harsh, so I would try half-hard on the front and full soft on the rear and work from there.