Confused

If you adjust the upper spring perch ( compression of the spring ) alone what should I expect to be the end result ? I don’t think I have wrapped my mind around this concept totally and does the bottom move in the same direction in relation to the intended goal

In simple terms, as the mass of the vehicle is resting on the spring via the upper spring seat (perch), moving the position of the seat in relation to the vehicle will lift it on the suspension.

In more complex terms, it will also lift the ride height, centre of mass, and all the chassis mounting points of the suspension and so also affect the vehicle's geometry.

It will not change the spring rate.

So in simple terms (compression )of the spring using the spring perch is raising ride height and lowering of the spring ( decompression or extension ) of the spring is lowering the car ? So I have already attained ride height using the lower mount how do I solve this issue, return the ride height using the lower mount and adjust via upper perch ?

I seem to be missing something, if you are able to get the ride height you wish, what is the "issue"?

Move the lower and upper spring seats the same amount - if you want to move the upper spring seat 1", move the lower seat by 1".

If you mean the mounting points for a coil-over, same basic principle applies EXCEPT if the mounting points aren't in line, you may affect the wheel rate slightly, as the wheel-spring movement ratio (leverage) will change slightly.

Oh thank you for clearing up the movement ratio I was unclear about that. I similarly attained ride height firstly by adjusting the lower mount which now I understand is the wrong. So my question at this point is do I return the set up to the original setting using the lower mount and readjust using the 1:1 ratio outlined ?

The question may be redundant but I just want to be sure I have the correct concept thank you . In lowering the car the bottom spring perch and the lower mount moves away from each other or does it move in the same direction and vice versa ?

I really think we may be talking about different things -there seems to be some confusion in the difference between the spring seat, and the mounting points of the coil-over?

Anyway, it's 7am here and I'm off to bed, but will pick this up tomorrow.

For sure it’s the spring seat I’m adjusting not the mounting points , the mounting points are the same and fixed I do not have camber plates. So that should clear it up ? We are talking about the same thing

Ah, I thought so, but... There is at least one design, for a strut, that has a second threaded adjustment, but didn't think you meant that. The Tien FlexZ, for example - https://www.tein.com/products/flex_z.html

Yes, move the top and bottom seats by the same amount. If the top seat is moved 50mm away from the top mount, move to bottom one 50mm towards the bottom mount - you're just moving the spring up or down the damper and keeping the compressed lengths of the coil-over and spring the same.

Ok bro I have finally understood fully thank you for your patience . what can I expect to feel in terms of ride? I have found the ride to be stiff and very accurate is that the intention ? I found that when I adjusted the lower mount alone the ride had gotten softer and less accurate with more body roll am I in the right direction ?

OK...

The primary reason for fitting coil-overs is it makes it much easier to tailor the spring to the requrements of the vehicle - they are available in off-the shelf lengths and spring rates - for firm, soft, or whatever ride. Similarly, the more reputable coil-overs will provide, at least adjustment in compression and extension to further aid adjusting the ride and compliance.

So, most setups for cars from the aftermarket will assum the purchaser is looking for a firmer, 'sportier' ride and that 'stiffer' but more easily controlled drive is what you've got. You can try adjusting the damper settings to see if that makes an improvement.

As I said earlier, adjusting the ride height will affect the suspension geometry, which will affect the ride, and that may be what you're feeling with the change you made.

I haven't checked out the videos yet, but I would expect this to be adressed in them, as it is quite an important factor.

Hi, bit of a bump but thought i'd rather post in an existing thread rather than starting a new one.

I believe I'm understanding it correctly in regards to setting ride height. Please correct me if I'm wrong. My understanding is that you set the spring perch to the point where it becomes captive. Then remove the spring and bump stop, refit the top mount and refit the damper unit to the car, refit the wheel and then adjust the lower collar to shorten or lengthen the unit, you then refit the wheel and use a jack to bring to to full bump (2/3 of the damper travel I believe?) and ensure the tyre doesn't catch the body work. This is your minimum height, you then refit the bump stop and spring the unit and refit to the car, you then use the spring perch to increase or decrease ride height depending on your requirements?

I really don't follow you.

Before getting into it again, can you confirm the specific design of the coil-over you are using - is it like the TEIN example above with an upper threaded area where the spring seat is adjusted, and a lower (or continuation) threaded section that is then screwed into a lower mount OR is there just an upper threadeded section with the lower mount part of the body?

Hi,

Sorry I'm crap at describing stuff. It's the same design as the tein example above.

For those teins, ride height and... damper location are separate adjustments. However, they're still related.

Mostly your description is correct. However, the bumpstop is king. It's what prevents damage. The upper adjustment controls how much available compression there is before you hit the bumpstop. The lower controls the ride height. If you lower the car, you might end up with too much compression travel, and hit the wheel well before the bumpstop prevents it. You'd lower the upper adjustment, and raise the bottom adjustment to keep the same ride height, but allow the bumpstop to do it's job.

So you can't just treat them as 2 separate unrelated adjustments. If you follow your steps(keep the bumpstop on if you're measuring this) you should be able to test your way into the minimum ride height. Basically riding on the bumpstop, 1mm away from contacting the wheel well with the vehicle on the ground. This leaves basically 0 compression travel, and is a bad idea. But it's your true minimum. From there, change the lower adjustment to give yourself some travel, then adjust the top so the bumpstop once again prevents colliding with whatever limits your travel.

If you simply target 1/3rd rebound 2/3rds compression, you'll need to adjust your ride height(lower adjustment) so that the bumpstop prevents collision. But you could go lower if there is enough available travel deviating from 1/3rd rebound 2/3rd compression.

I will have to disagree, as per the other adjustment question in this sub-forum, just take up the freeplay with the damper at full extension (one of the big advantages of this type of design is it removes the hassle with 'helper' springs and the like to maintain captivity) - this ensures that the spring is captive - then use the lower adjustment to set ride height.

The travel is going to be down to the spring length - the difference between barely captive or fully compressed - and as a general principle the longer the spring the greater the travel - you need to have a good idea of what you want when ordering the spring(s).

As Robbie said, you REALLY want to avoid coil bind (reflects poor spring length selection, no excuses! If the rate is correct, use a longer one), the damper striking the bottom of it's travel, under compression and, as mentioned, there is also the risk of tyre to chassis/body contact.

There are at least four different types of 'bump stops', two of which are internal and beyond your scope. However, there are options left to you - if your vehicle doesn't have a chassis mounted 'stop that bears against the suspension to limit travel, you may be able to fit one and there are many types and rates available on-line - some race clases run very soft 'main' springs and ride on the chassis stops, effectively making them the springs, to maximise the earo'. Another common option you could consider is the type that slips over the damper shaft and this is sometimes also used as a tuning aid as they are available in different lengths and stiffnesses - I'm less keen on this, but it works well.