The Parabolic springs are manufactured by Paul Heystee of Heystee Suspensions in Netherlands
We imported a shipment of 5 sets of these 4" lift parabolic springs for 4 x 40 series, 2 x pre 1979 and 2 x post 1980 (different shackle pin diameters) and 1 x set for 43 series, to South Africa.
Upon fitting the springs we found that the shackle angles were all wrong, on the rear it was the wrong side of vertical, and on the front only slightly forward of vertical.
We communicated this to Paul Heystee and he assured us that the length of the springs are "correct" [bollocks ! ! !] and that the springs would "settle" with time and use.
The bottom line is, We have 5 sets and all the 40's the shackle angle is crap, and to return them from South Africa to Netherlands just isnt an option, so it is the considered opinion here that these springs are too short for the 40's.
Jonathan Tee (Teebag) is presently going through the same loop with these springs on his 40 rebuild.
As we all know the importance of shackle angle on a leaf sprung truck relative to articulation and comfort, and I at least wanted to achieve a decent shackle angle, for this reason I decided to take advantage of the fact that my chassis was stripped to at least use the springs and evaluate if the hype about parabolic springs holds any truth, so I moved the shackle mounts on my truck.
I moved the front shackle mount back by 45mm and the rear shackle mount was moved 35mm forward. The reason for moving the rear less that the front, was to cater for load carrying capacity, as our trucks will mostly be used for the purpose of overlanding through Africa, where we carry large amounts of fuel, water and provisions for long periods.
What I can confirm is, since I moved the shackle mounts, the difference in ride quality now is significantly smoother and softer that it was before the shacklle mountings were moved.
When my truck arrived in South Africa from Aussie it was fitted with OME leaf springs, and admittedly the shackle angle with these springs was also less than perfect, and IMO the original OME leaf packs were also too short.
This is the resultant shackle angles.
Front after moving:-
And the Rear after moving:-
The truck arrived with OME leaf packs - notice the crappy front shackle angle
These were the shackle angles after fitting the Heystee parabolic springs but before moving;-
It's usually me, tho, not someone else.
