With the dramatically increasing engine power, I experienced lack of
grip during hard accelerations. The tyres was just spinning and on a
prepared 1/8mile strip and the rear axel started tramping.
I new wider wheels was part of the answer. The other part is the rear axel
suspension. The rear suspension of the classic
Morgan is by semi-eliptic leaf springs. The rear dampers was original
'Armstrong' lever type. These I converted to telescopic shock absorbers
in 2001.
The tramping problem seems to come from wind up of the the blader springs
during hard acceleration.
I decided to make a rear axel motion test setup. The two pictures below
shows some of the test results. Even the spring system is very stiff it
indicated some 5-7mm move backwards of the rear axel during
acceleration.
I hope the answer is 'anti-tramp' bars.
The 'anti-tramp' bars need, ideally, to form a
parallelogram, when viewed from the side, between the front spring eye
and the centre of the axle thus allowing the axle to rise and fall
without any spring wind-up but allowing sufficient axial rotation such
that the axle is not disturbed by body roll. Because the shackles are at
the rear it is normal to run these bars forward to the cross member
which supports the front spring eyes.
Not much space was available and I had to mover the catch tank and break
pipes. Lag of space also meant use of squared tubes for the bars.
The results of the efforts has been tested on a Raceway prepared with
TrackBite. The wider tyres gave much better grip and almost no tramping
was experienced during take off.
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