Ohlins DFV Coilover Kit
09-21-2016, 02:57 PM
#161
My car has about "1 finger gap". 12.5" is the approx measurement from fender arch to wheel centre. But...those are both notoriously inaccurate. The most accurate and scientific measurment is "lowered so it looks good AF".
09-21-2016, 06:21 PM
#163
Yes, adding preload will raise the car up.
I actually set the bottom bracket 12mm lower than ohlins rec.
They said 27mm. Mine is at 15.
The bottom bracket has room to go maybe? 7mm? shorter?
If you dial in 10mm more preload...you'll need to lower the bottom bracket 10mm or more. So if there's only 7mm left on the bottom bracket....the car would end up 0.2" taller than mine.
I actually set the bottom bracket 12mm lower than ohlins rec.
They said 27mm. Mine is at 15.
The bottom bracket has room to go maybe? 7mm? shorter?
If you dial in 10mm more preload...you'll need to lower the bottom bracket 10mm or more. So if there's only 7mm left on the bottom bracket....the car would end up 0.2" taller than mine.
09-21-2016, 07:00 PM
#164
What's the trick to preloading on the bench I got to about 189mm but need to get to 186mm for the 12 mm preload in the rear and it was then hard to turn it any further
Also hard to get the lower lock ring loose on the bench too , should that be done on the car?
Also hard to get the lower lock ring loose on the bench too , should that be done on the car?
09-21-2016, 07:13 PM
#165
You can undo the lower bracket while on the car.
Use the wrenches to turn the spring up. If you can't hold it...load it into the car. Then turn the upper most perch 2 more full turns to get your necessary 3mm.
Use the wrenches to turn the spring up. If you can't hold it...load it into the car. Then turn the upper most perch 2 more full turns to get your necessary 3mm.
09-21-2016, 08:07 PM
#167
BTW, wheel rates are used to calculate roll stiffness. Or...resistance to deviation from rest for a system.
At rest, the car weighs (insert sprung weight here) at the shock tower. The same as the sprung weight at the spindle.
Deviation from rest would take some amount of force at the wheel...which would create a reaction in the spring.
A rate of roll would happen until the motion was equalized.
Also....
When you corner weight a car, you're combining sprung weight and unsprung weight. Wheels, brakes, spindles, control arms, and half the damper are not sprung.
You can only use the SPRUNG corner weight for wheel rate calculations. Not total corner weight.
Here are helpful diagrams and equations.
https://www.slideshare.net/mobile/gu...ension-lecture
At rest, the car weighs (insert sprung weight here) at the shock tower. The same as the sprung weight at the spindle.
Deviation from rest would take some amount of force at the wheel...which would create a reaction in the spring.
A rate of roll would happen until the motion was equalized.
Also....
When you corner weight a car, you're combining sprung weight and unsprung weight. Wheels, brakes, spindles, control arms, and half the damper are not sprung.
You can only use the SPRUNG corner weight for wheel rate calculations. Not total corner weight.
Here are helpful diagrams and equations.
https://www.slideshare.net/mobile/gu...ension-lecture
09-22-2016, 07:06 AM
#169
Originally Posted by Apex1.0' timestamp='1474482584' post='24067020
Absolutely set them on a bench to start, couldn't agree more. On the car, the bushings (if indexed properly) would be pulling the control arm up back to ride height position. However the weight of the brakes, hub, etc would be pulling the arm back down. Because of the limited travel, my guess is it would not take much force to fully extend the shock.
But this is guess work, I will actually install them this week end and let you know how it works out. FYI, I went with 6mm of rear preload.
Ah gotcha.
Well...once they're in the car, and you know your initial preload...if youd like to then adjust the preload...you don't need to extend the shock.
Just remember than 1 turn of the spring perch is 1.5mm vertical.
So...if you have 6mm to start, and you want 3mm more, just turn the most upper spring perch 2 turns CCW.
Come to think of it, that method replaces my first thought of "remove to reset". I forgot Öhlins specs a 1.5mm to 1 turn ratio
BTW, how much clear travel did 6mm REAR preload give you? Hopefully 0.8" total?
I say hopefully, because if 6mm gives 0.8", then it proves my theory that 12mm gives 1.0"
09-22-2016, 08:03 AM
#170
Curse them for using 8.178KG/mm springs.
I did all my math based on 8KG/mm flat lol.
meh. close enough. my 8KG (447LB) numbers are 97.8% the same as the 8.18KG (457LB) actuals.
I predicted 12mm preload for 1" clear travel. 11.76mm is close to 12mm.
0.24mm is the thickness of like...2 sheets of standard printer paper.
My life is ruined.
I did all my math based on 8KG/mm flat lol.
meh. close enough. my 8KG (447LB) numbers are 97.8% the same as the 8.18KG (457LB) actuals.
I predicted 12mm preload for 1" clear travel. 11.76mm is close to 12mm.
0.24mm is the thickness of like...2 sheets of standard printer paper.
My life is ruined.