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UP vs MPP Coilover
- Thread starter tkhan006
- Start date
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- Tags
- coils suspension fix
jackmott
Member
Gauss Guzzler
Safety Score = 42
@Motion122
Hooke's Law describes linear spring forces: F = kx
where:
F = Weight of one corner of the car, say 450 kgf (1000 lbs) on a Model 3.
k = Spring rate at the wheel, say 3 kgf/mm
x = Vertical travel from full droop (loose spring) to ride height.
So in this example you would have a droop of x = F/k = 450/3 = 150mm (5.9") and you can see from the formula that the droop distance is defined entirely by the weight of the car vs the spring rate.
Now to circle back around to spring locations (coilover vs divorced): Say you have a divorced spring located halfway between the control arm pivot and the wheel centerline (the Model 3 spring is close to this location). That 2:1 leverage means the wheel moves twice as far as the spring so you'd need a 6 kgf/mm rate to get the same ride quality as above.
In this case your droop *at the spring* will be F/k = 450/6 = 75mm but the droop at the wheel will be twice that - 150mm just like above.
Hooke's Law describes linear spring forces: F = kx
where:
F = Weight of one corner of the car, say 450 kgf (1000 lbs) on a Model 3.
k = Spring rate at the wheel, say 3 kgf/mm
x = Vertical travel from full droop (loose spring) to ride height.
So in this example you would have a droop of x = F/k = 450/3 = 150mm (5.9") and you can see from the formula that the droop distance is defined entirely by the weight of the car vs the spring rate.
Now to circle back around to spring locations (coilover vs divorced): Say you have a divorced spring located halfway between the control arm pivot and the wheel centerline (the Model 3 spring is close to this location). That 2:1 leverage means the wheel moves twice as far as the spring so you'd need a 6 kgf/mm rate to get the same ride quality as above.
In this case your droop *at the spring* will be F/k = 450/6 = 75mm but the droop at the wheel will be twice that - 150mm just like above.
Sorry, you're still not really right. Wheel total travel is only defined by the shock length. The only thing hookes law is stating is where spring would become "loose".
Also, your 2:1 leverage ratio would have a 4:1 effect on spring rate (MR^2).
Also, your 2:1 leverage ratio would have a 4:1 effect on spring rate (MR^2).
Last edited:
thesmokingman
Active Member
Yes it’s 100 on all 4 corners and their sport. That you’d have to ask them but I’d imagine being modular and customizable is the appealing factor for each owner. I have a friend with a Y and he has their coils but they were able to a do a custom luxury max low version for him.
Gauss Guzzler
Safety Score = 42
Absolutely. The loose spring is all I was referring to because the context was the effect that springs have on "usable" droop. And specifically that the free length of the spring doesn't enter the equation - only the rate.
You're correct that there is a trigonometry term in there that I didn't mention, but that's because it divides out. In my divorced spring example the wheel actually travels in an arc, but so does the spring. And the arc length at the wheel is twice as long as the one at the spring so whether or not you include the trig you still end up with the same 2:1 ratio.
And MR^2 is an inertia term, we're talking about static forces here. The torque equation (T = Fd) would be a better fit if that helps to visualize the force/distance ratios.
jackmott
Member
MPP has a similar part that is lighter and lets you keep the aero cover, but doesn't eliminate as much spring perch hardware, or allow for as easy adjustment, I think
thesmokingman
Active Member
Look into shock covers/boots. They're made for use in sand dunes etc but I use them to keep my coils clean.
This is completely different set that they don't sell. And it costs 15K$
There are 2 sets done there - another one was supposed to be mine, a year ago. This is not done in cooperation with Ohlins - it's custom mounts, valving, springs with stock motorsport TTX dampers. To the best of my knowledge, UP is dealing with Ohlins stuff through Atomic for a first time. I never seen UP stating that they use or cooperate with Ohlins...
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