Interesting how the suspension of the trans era SFs have different rates of suspension stiffness.
Have had many apart. My 1st. thought was it was the color of the spring denoted the spring rate.
Probably not the case. Lesney was likely just using left over colored plastic sprues, etc. to concoct the many different muddy hues found besides white.
Now I think it has more to do with how much room the plastic spring has freedom to travel inside the casting,
and where the spring's rivets are located.
If the car's interior doesn't hinder the movement of the spring, the softer it can be. And I don't mean interference in the wheel well area.
Case in point; the Cadillac Sayer's & Scoville #54 Ambulance Superfast spring seems mighty taught. Well the front suspension is doubled up in front.
Still has the interior of the regular wheel version - and the RW's interior IS the suspension.
Little tabs stick out to suspend the front wheels, and the rear has no travel due to the "business end's" low loading deck.
So the SF Cad has two layers of suspension.
Having taken many cars apart, I can say it is more likely where the spring is "riveted". I think
this is the answer.
If the rivets are closer toward the centre, the softer the spring action.
Springs attached closer to the wheels would make for that nice stiff Western European area ride.
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2nd. case in point - anyone can see for themselves...the #69 Rolls, and it's older brother, the #24 Silver Shadow.
Nearly identical in many ways. Same wheel base; even share parts. Only real difference is it's heavier given it's metal roof.
So here's the kicker....and anyone with these cars can see for themselves without dismantling.
Look inside the holes for the trunk lid hinges.
On the #69, the spring rivet is much further inboard, giving the spring more ease of travel.
#24, the rivet is much close to the wheel.
Bingo! The proof is in the "boot" of the Rolls!
Also notice the chassis' of the two castings.
#69 has a relief cast down into the base for the spring. Less chance of the spring interfering with the int.
No such luxury option was engineered for #24.
We don't know how much thought was really put into the suspension of each model,
but we can now see proof...examples of some suspension tuning Lesney did take time to tune the ride. Pretty darn cool if you ax me!
Let's see who can come up with a more nerdier topic!