Trying to do the right thing with damper setup - and potentially failing

So, as many others, I had previously been settting up my dampers using the lower mount adjustment for ride height, and then using the spring perch for spring pre-load. According to the HPA guide, this is wrong, so fair enough I though i'd try the HPA method.

Dampers are Meister R GT1's - which are single adjustment (coupled bump and rebound), however unusally they were supplied with progressive springs (I never even noticed to be honest). So today I stripped one of the front dampers down (Macpherson strut), identified the contact point (without bump stop installed), and used this as my maximum bump travel.

At this point, I then measured droop, and the resulting total damper stroke is 97mm. Ergo, going by the rule of 1/3 droop and 2/3 bump, ride height should be set at (max droop - 33), or thereabouts. Now this obviously means that the 'arch gap', if we were to use that measurement, would be approx. 66mm.. which is quite a lot!

The bump stops are probably around 40-50mm long, and look non-linear (stepped cone style), so it's obviously not going to take much bump now before the bump stop is part of the spring package.. previously the arch liner was the bump stop!!

So, from a front damper perspective, these are my concerns and observations:

- Ride height is now super high compared to previous

- Potentially have a working bump stop now

- Risk of tyre damage reduced/eliminated

- Effective spring rate affected, both by adjusting the spring perch (pre-load) and the bump stop

- Approx. 5mm of pre-load on the main spring, which whilst progressive the now effective spring-rate is unknown (damper manufacturer recommends 2mm pre-load, although I suspect that's with a linear spring not progressive)

- CoG is obviously raised at this new ride height

Now, this brings me onto my second point of discussion.. the rear dampers.. These are of a divorced spring setup (not a true coil 'over' as such). The dampers don't appear to have any bump stops on them, and I am unsure what the first lack of compliance will be - either tyre hitting something or the spring going coil-bound (unlikely as it's a barrel style spring).

My real concern though is the lack of damper travel, for the following reasons:

- Relative to the new front ride height, the rear is probably at least 20-30mm too low

- There's currently only around 10mm of droop on the rear

- There's maybe 10mm adjustment left in the bottom mount to extend droop

So I am not sure I am going to be able to achieve a reasonable rake angle if I go 'by the (HPA) book' on basic damper setup, not with these dampers, at least.

- If I maximise the rear damper length (still with some droop), and lower the front to give me a reasonable rake angle, I may be riding on the front bump stops

To further compound this entree into damper setup, I have also recently added a rear wing and built a front splitter, to try and venture into a bit of aero. The splitter had approx 100mm of static ground clearance before the ride height change, but is much higher now and most likely not remotely effective. I wonder if I am pissing in the wind by even remotely considering using progressive springs for an aero car, as I feel it needs much tighter control.

Too many variables.. appreciate all your thoughts.

Can you get the specs on the progressive springs you have? (I would expect it to be a curve showing rate vs. compressed distance). With that you would have a good idea of the load and rate at any given spring position. If you can't get that from the supplier, then you could rig up a way to measure that. I have used a hydraulic press, corner weighting scale pad, and a height gauge (or calipers or even a ruler), to make my own measurements.

Do you have a desired suspension position (lower arm angle) to give you the best bump steer and or camber gain in roll that you want? Depending on the geometry of your hub / spindle, and tire/wheel size; I would think that would dictate your desired ride height.

Set your spring perches to achieve this design ride height. Get the corner weights correct, and go testing.

These are good questions David, and not many I have answers too right now. Interesting regarding bump steer - I just installed new front hubs/knuckles which have a roll centre and bump steer correction (photo attached), however the question is obviously what ride height is this kit designed for. The race cars that run this setup are definitely a lot lower than what mine would be at the 33/66 rule.