Very thrilled for the kind words from him and his team, and figured it was NSX related so we'd drop a link in here. Enjoy 
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TJ Trying out the SakeBomb Ohlins on his NSX Barn Find Build
- Thread starter SakeBomb Garage
- Start date
So to be sure,. Adjustment is done from adjusting the preload? What's the point of a preload then? If you lower it by an inch and a half, doesn't that effect the preload? My s2000 and M3 ohlins get adjusted with the lower perch.
Lowing can be done with free length or preload or both. Pre-load does not change the spring rate... it only changes your bump stop contact point where the bump stop prevents the wheel from hitting the fender. To say it in another way, pre-load allows you to dictate how much of the total stroke is given to compression or droop. Free length changes, change the ride height of the car without changing the ratio of compression to droop... IE your wheel may keep moving and slam into your fender if not adjusted correctly.
So yes and no. Also the NSX has clearance issues with the front control arm... and to protect the inner fender we pre-set free length, and suggest adjusting ride height with preload to make sure there are no issues. However, for advanced setups and for customers with modified tire and wheel setups, you *can* adjust free length *if* you know what you are doing. So the dummy proof way is using preload only, and you won't end up doing something that could damage your car. If you know what you're doing and are able to check the bump stop contact points and set it for aftermarket wheels, and can check your control arm clearances, then you could use free length, or free length + preload to adjust your height. The safe way is just using preload and not touching our pre-set specs for free length though
Hope this helps
Pm'ed you.
"Spring perch" (upper) and (lower) "damper body perch" are a little more accurate and better terminology for the two adjustments that affect ride height.
A spring's "free length" is the length of the uncompressed, static spring.
A spring's "preload" is statically compressing the spring at the spring perch at full-droop.
Adding "preload" reduces the suspensions rebound/droop travel, which affects grip, comfort, and compliance.
Coilovers with helper springs will rarely be able to actually compress the main spring with "preload", so calling the spring perch "preload" is not really applicable here (although you are technically "preloading" the helper spring but it still has no affect).
Adding "Preload" CAN change the static spring rate. For example, if a front corner of the NSX has a static corner weight of 500lbs, and you are running a 500lb spring, and preload it 1-inch, the static spring rate will equal the corner weight, and you will have zero droop/rebound travel. If you then compress and preload it further, say 1/2" more, you've added another 250lbs to total 750lb of spring preload on a corner with 500lbs of static weight. This means that it will now take over 250lbs of force for the suspension to move, which effectively changes the initial, static spring rate to 750lbs for the first inch of travel before acting like a 500lb spring.
Compression travel should be set where the bump stops prevent tire-chassis contact. This can be set with the bump stop length, adding packers to make the bump stop longer/taller, or changing the height on the lower damper body perch if the coilover is equipped with that adjustment.
It's great to hear that the lower body perch height is pre-set so the tire does not contact the chassis on these coilovers, and I would agree on the advice to only change ride heights on the upper perch unless you know what you are doing and are trying to achieve something specific.
0.02
A spring's "free length" is the length of the uncompressed, static spring.
A spring's "preload" is statically compressing the spring at the spring perch at full-droop.
Adding "preload" reduces the suspensions rebound/droop travel, which affects grip, comfort, and compliance.
Coilovers with helper springs will rarely be able to actually compress the main spring with "preload", so calling the spring perch "preload" is not really applicable here (although you are technically "preloading" the helper spring but it still has no affect).
Adding "Preload" CAN change the static spring rate. For example, if a front corner of the NSX has a static corner weight of 500lbs, and you are running a 500lb spring, and preload it 1-inch, the static spring rate will equal the corner weight, and you will have zero droop/rebound travel. If you then compress and preload it further, say 1/2" more, you've added another 250lbs to total 750lb of spring preload on a corner with 500lbs of static weight. This means that it will now take over 250lbs of force for the suspension to move, which effectively changes the initial, static spring rate to 750lbs for the first inch of travel before acting like a 500lb spring.
Compression travel should be set where the bump stops prevent tire-chassis contact. This can be set with the bump stop length, adding packers to make the bump stop longer/taller, or changing the height on the lower damper body perch if the coilover is equipped with that adjustment.
It's great to hear that the lower body perch height is pre-set so the tire does not contact the chassis on these coilovers, and I would agree on the advice to only change ride heights on the upper perch unless you know what you are doing and are trying to achieve something specific.
0.02
No, The car can be lowered on these coilovers, but using preload not free length. As we go up in spring rate, we need less vertical travel to absorb the same bump... so we can afford to give up some compression stroke to lower the car. Again, this is for factory wheels, and fender clearance to stay safe.... if you have anything different, you can have a shop custom set up the suspension if they know what they're doing and adjust free length accordingly - they just need to check all clearances. We normally do this by removing the spring, setting free length with the wheel fully compressed, and bump stop engaged, with your desired wheel and tire package. If you're doing this at home, and don't understand the process of setting up coilovers just stick with our standard pre-set and you'll be fine.
Only a couple things I'd add to clarify... that preload does not change the main spring rate, only the point at which the spring becomes a spring. So if we have a 500lb corner, and preload 100lbs worth, the car looks like it weighs 400lbs from the perspective of the spring... counteracting 100lbs of force means the car will raise up and give more compression stroke before hitting the bump stop (taking this stroke from droop). Helpers allow you to go into *negative* preload numbers on the main spring essentially.
Thanks for the in-depth reply!! I wish more people had this level of understanding when it comes to suspension
Many years ago when I was hunting for my suspension, I emailed Ohlins and they pointed me to SBG.
I had SBG Ohlins for many years and enjoyed them very much.
It was a pleasant surprise to see them on TJ's build because most folks use other brands.
When I saw the video, I had flashbacks of mine when they were new and the gold illuminated the garage upon opening the box for the first time.
I have the grand touring setup, which means it's paired with the softer springs. The car has been to some track days and they performed fantastically for my level of talent. Usually, my car is on the highway or on the mountain roads. I am impressed how well it soaks up the road's imperfections especially at highway speeds.
I personally recommend pairing them with stock sway bars for more comfort.
I adjusted mine as recommended. No issues. I figured the experts know more than me.
I had SBG Ohlins for many years and enjoyed them very much.
It was a pleasant surprise to see them on TJ's build because most folks use other brands.
When I saw the video, I had flashbacks of mine when they were new and the gold illuminated the garage upon opening the box for the first time.
I have the grand touring setup, which means it's paired with the softer springs. The car has been to some track days and they performed fantastically for my level of talent. Usually, my car is on the highway or on the mountain roads. I am impressed how well it soaks up the road's imperfections especially at highway speeds.
I personally recommend pairing them with stock sway bars for more comfort.
I adjusted mine as recommended. No issues. I figured the experts know more than me.
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