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In the course I understand and agree why ride hight should be adjusted with the spring perch but what confuses me is that the instructions that came with my Driftworks Cs2 coilovers by HSD for my Nissan s13 says I should adjust them with the lower mount. Are these made differently than other coilovers then? Should I follow the manufacturers recommendations or adjust with the springs?
These are the coilovers i got: https://www.hsdcoilovers.com/cs2-coilovers/
Here is the mounting instructions from the manufacturer: https://www.hsdcoilovers.com/faqs/
Yes, they are of a different design, and the adjustment proceedure is different - as per the instructions, take up the 'play' in the spring and lock the seat (not happy with using a drift, though - maybe(!) striking the spanner with a soft mallet?), not forgetting to check regularly as, especially when they're new, even the best springs do settle slightly in use. Then adjust the ride height as desired.
The procedure for correctly adjusting the ride height that we go through in the wheel alignment course applies to your coilovers too. I disagree with what Gord has said here, the ride height adjustments for your situation should be made at the spring perch as well.
The reason you see bad advice on this from some manufacturers is simply due to a misunderstanding of all the implications involved. You'll see this advice being given from lower-end (no offence intended to you or the manufacturer of these coilovers) suspension providers. If you go with any high-end supplier (think KW, Ohlins etc) you will see the advice being to adjust the height at the spring perch. The reasons for this are consistent with what we teach in the course.
In summary, your thinking and understanding is correct! 👊
Uh, for a 'conventional' damper with only a spring seat adjustment screw and the damper body being fixed relative to the mounting point(s), I would agree with you, Tim, but the dual thread type is different. You 'could' just change the preload on the spring, but that would be ignoring one of the biggest advantages of the dual screw design - being able to use the full extension of the spring, and avoiding the problems that can result from pre-load at the end of the suspension travel and/or the need for different length springs of the same rate. It's like fitting a vernier cam' sprocket and then using offset keys.
I posted a breakdown on the advantages, and disadvantages, of both designs a while back, if either of you are interested in looking for it.
Failing that, look at section 3 of this - https://www.tein.com/products/flex_z.html - TEIN advert, as it's the same design. It also calls dampers 'shock absorbers' [GRRR] - the SPRINGS are the 'shock absorbers', damnit!
Hey Gord, thanks for that and I see the point you're making 🤓. We teach people to make all their adjustments at the spring perch for the simple reason of not having problems with the tyres contacting the inner guard and chassis at full compression to avoid tyre damage. It's true there are some finer points involved with the effect of altering preload when it comes to the transient interface of the tyre re-contacting the road when the car comes back to all four wheels after 3-wheeling. In my opinion, this is a minor effect in the context of people modifying OEM style cars for some moderate track use which is the vast majority of our community.
Our preference is to use the lower mount adjustment to tune the position of the wheel&tyre at full compression to ensure no contact, set the RH at the spring perch, then use a but of iteration between the two (if needed and possible) to get the suspension travel (bump to droop ratio) in a sensible window. I think this approach is particularly important when you have most people fitting larger and wider wheels and tyres which makes inner guard contact more dangerous and more likely. 💪