diceman":1tzfsoq6 said:Nice project, I have been looking into a similar Koni race setup but using some old Tein HA strut cases.
I assume you have read http://wilhelmraceworks.com/koni-shock-dynos
The shock dynos and calculation sheets (adjusted for ST185 corner weights) suggest that 8611 race series will be a pretty good match to the GT4 from around 4KG/mm up to around 12KG/mm (from memory). What I really like in comparison to the majority of "adjustable shocks" is that the low speed damping shifts in line with the high speed damping, most BC/Tein etc all seem to lose all semblance of low speed damping as soon as you open the bypass valve needle.
I would be interested in why you chose such stiff rear spring rate in comparison to the front?
celicast184":1h9vksh5 said:Koni's are great Combo 'd with ground control kit. Only thing that turns me away from them is that they are not ride height adjustable without sacrificing shock stroke and preload on the springs. This worries me because as a daily/weekend worrier, there will be lots of stress on the shocks. Especially when the spring basically just floats around if the springs are lowered to get the desired ride height.
MWP":2v5rpu9n said:I got the fronts finished this arvo
Top adjuster is for rebound, bottom adjuster is for compression.
Will hopefully get the rears finished tomorrow.
diceman":we35rx89 said:My Tein Ha are regular configuration (not inverted) unfortunately. The main benefit is that they already have threaded cases and are larger diameter.
IMHO the combination of Eibach springs and Koni single adjustable inserts was about as good as it got with the TRD 4-way adjustable and TRD springs also pretty good on the ST205.
I have spent many an hour trying to match/select spring rate and damping rate and run through a load of calculators which all seemed to suggest that for my purposes (mainly fast road) 5kg/mm and 4-4.5KG/mm front rear respectively were about right if I didn't want to lower it too much. With the current 40-50mm of lowering the car would probably need springs rate of around 8-10KG fornt and 7-8 KG rear which initially seemed more suited to billiard table smooth tracks!
This was until I read this article... http://wrcbehindthestages.blogspot.co.u ... gs-co.html
From this I am inclined to keep to the softer rates and maybe run a little more damping as an initial setting.
Would you be prepared to share any damping rates for your selected spring rate from TTE? I believe at the time they were using Bilstein?
TRDTurko":jnbpjz7s said:that is not the Ground Control kit, where is that from?
I was also curious why your rear spring rate is so high.
I have spent many an hour trying to match/select spring rate and damping rate and run through a load of calculators which all seemed to suggest that for my purposes (mainly fast road) 5kg/mm and 4-4.5KG/mm front rear respectively were about right if I didn't want to lower it too much. With the current 40-50mm of lowering the car would probably need springs rate of around 8-10KG fornt and 7-8 KG rear which initially seemed more suited to billiard table smooth tracks!
This was until I read this article... http://wrcbehindthestages.blogspot.co.u ... gs-co.html
From this I am inclined to keep to the softer rates and maybe run a little more damping as an initial setting.
Wow, 5-4kg springs are soft! Great for comfort, but you cant get a decent low'ish ride height with that rate.
The 185 and 205 WRC cars achieved it by having greatly increased bump travel with raised towers, and top mounted stut tops.
Running that soft, as you mentioned, you also need lots of compression damping, which introduces heat and cavitation problems.
I doubt the 8611 series would be up to the task.
I dont know how you get the idea that the 8611's are ok with 4Kg springs?
Using that spreadsheet shows that even with my 8kg springs the rebound damping will be a bit too high when set on the minimum level.
diceman":19yrp3ib said:5/4 may be soft for race use but is much more suited to fast road use here in the UK. Having run 4.3/3.9 KG/mm before with circa 25mm drop on my TRD equipped ST205 this is a pretty good compromise. I don't want a large amount of drop as the travel is pretty small to start with for road use. The 5/4 is actually harder than the late TTE spec tarmac spec setup (albeit with v.high quality Ohlins dampers).
I've done a fair bit of research in Bilstein damping rates for some known spring rates and they appear to opt for a higher damping rate than that calculator indicates. Even my TRD Dirt/Rally fixed struts with the matching TRD springs have damping rates far higher than that calculator would suggest as ideal. Don't get me started on the BC/Tein excessive damping if plumbed into that calculator and compared to dyno plots - I have no idea how they reached the valving selection or why but it seems flawed.
I don't confess to being an expert by any means and am just starting in suspension calcs but the data I have accumulated suggests the Wilhelm calculator provides quite different ideal damping rates than those developed by the big companies. I suspect the difference is if you are coming at the task purely as a race car on billiard table smooth race tracks where the only item you really need to control is the spring and to hell with body motion but I speculate.
diceman":18bz9glf said:I did read your original posts and even watched the videos .
Your roads appear far better than ours! I would say those roads have undulations and the odd bit of surface break up. Ours seem to have major grooves from traffic, roads that have dropped in short parts due to partial subsidence of the road sub-layer and large amounts of camber to assist rain run-off (centre whiteline as high point). I've never had the opportunity to drive hard in a firmly sprung GT4 over these roads but much firmer than I am aiming for I would expect would result in large vehicle body movement and wheels leaving contact with the road too much. It would probably be fine on 60mph plus roads. Again I hope to be educated/experience this soon in a friends car.
Sorry for any confusion; I said "drop" not "droop". By this I mean the suspension lowered the static ride height by xx mm over standard springs.
I have figures for standard and calculated droop somewhere but I seem to remember that my current (BAD and not my choosing) AVO springs provide around 115mm of droop! this leaves around 40mm of suspension travel until the wheel/tyre has come into contact with the wheel arch and the shortened bump stop is solid and compressed. Given that we only start off with around 140-150mm of suspension travel we need around 50mm of droop according to the 1/3 and 2/3 guide suggested (which I have also read before) and aligns with a circa 8kg/mm spring at the front (without any helper or preload) and would give around 100mm of bump travel but only if you run at standard ride height otherwise you will be reducing the available bump travel. At this point you have 2 options as far as I can ascertain: -
1) run the stiffer springs at circa 8-10KG/mm and lower the vehicle a fair bit (say 40-50mm) in the knowledge that the stiffer spring will require less suspension travel.
2) run the softer spring at circa 5kg/mm and don't lower the vehicle as much (say 15-25). Also don't suffer as much from bump steer in this region.
I'd guess there is merit in both approaches depending on application.
From your writings it sounds like you have read similar sources as myself when endeavouring to select/fine tune spring/damping rates. These seem to be loose guides and far from precise. My concerns have been that all full suspension kits (spring & shock) I have reviewed so far have been way off the numbers from the guides I have read, why I have yet to establish. In particular the commonly reported "Rebound damping needs to match the spring. Ideal compression damping is determined by vehicle weight" seems massively simplistic and bears little resemblence to the shock dynos I have reviewed.
Hence - I keep saying damping rates = compression & rebound as I am not convinced as yet to the accuracy of the sweeping statements that are banded about.
Please don't take my posts as argumentative, far from it. I am merely trying to ascertain the truthes. If we can calculate that Tein/BC/Bilstein/KYB/TRD are all doing differently to the ideal damping calculation (some are miles out) then to me it suggests that the calculation is flawed or there are different requirements.
I'm very interested in to why you feel the Koni 8611 will not be upto the job with respect to the heat and cavitation, again this isn't argumentative but hopefully your experience or findings may save me from making the wrong choice.
No problem - I had feared the same for myself.MWP":14fgprdp said:Normally i would write longer replies, but im a bit short of time at the moment
BTW, sorry if i do come across as being argumentative... i know i do have a bad habit of replying that way, i don't do it on purpose. I enjoy discussions like this.
diceman":14fgprdp said:I did read your original posts and even watched the videos .
Your roads appear far better than ours! I would say those roads have undulations and the odd bit of surface break up. Ours seem to have major grooves from traffic, roads that have dropped in short parts due to partial subsidence of the road sub-layer and large amounts of camber to assist rain run-off (centre whiteline as high point). I've never had the opportunity to drive hard in a firmly sprung GT4 over these roads but much firmer than I am aiming for I would expect would result in large vehicle body movement and wheels leaving contact with the road too much. It would probably be fine on 60mph plus roads. Again I hope to be educated/experience this soon in a friends car.
I'll have a look.Our roads are terrible! They truly are.
Before your comments, i had considered 8kg to be fairly soft. Most guys here buying Tein, BC, etc coilovers go for above 10kg. The ride must be terrible!
Watch some more of that Corsican rally footage too, you can see that the ~8kg springs they are running aren't really that stiff.
Sorry for any confusion; I said "drop" not "droop". By this I mean the suspension lowered the static ride height by xx mm over standard springs.
I've just measured mine at 320mm and 305mm respectively. I will be aiming for pretty much the minimum ride height legislated in Oz. Mine is too low.Oh! Oops, my mistake.
Our state government has legislated minimum ride heights for all cars. They measure it by "eyebrow" height which is the distance from the center of the wheel, to the lip of the guard arch.
After thinking about it for a while is actually a great way to measure suspension height as wheel size doesn't effect the measurement.
The minimum ride height they state for a ST185 is a front eyebrow height of 345mm, and a rear of 330mm.
I have figures for standard and calculated droop somewhere but I seem to remember that my current (BAD and not my choosing) AVO springs provide around 115mm of droop! this leaves around 40mm of suspension travel until the wheel/tyre has come into contact with the wheel arch and the shortened bump stop is solid and compressed. Given that we only start off with around 140-150mm of suspension travel we need around 50mm of droop according to the 1/3 and 2/3 guide suggested (which I have also read before) and aligns with a circa 8kg/mm spring at the front (without any helper or preload) and would give around 100mm of bump travel but only if you run at standard ride height otherwise you will be reducing the available bump travel. At this point you have 2 options as far as I can ascertain: -
1) run the stiffer springs at circa 8-10KG/mm and lower the vehicle a fair bit (say 40-50mm) in the knowledge that the stiffer spring will require less suspension travel.
2) run the softer spring at circa 5kg/mm and don't lower the vehicle as much (say 15-25). Also don't suffer as much from bump steer in this region.
I'd guess there is merit in both approaches depending on application.
Yeah, it really comes down to personal choice.
Though if you intend to run light springs and a decent level of compression damping, that overheating/cavitation problem might come into play.
From your writings it sounds like you have read similar sources as myself when endeavouring to select/fine tune spring/damping rates. These seem to be loose guides and far from precise. My concerns have been that all full suspension kits (spring & shock) I have reviewed so far have been way off the numbers from the guides I have read, why I have yet to establish. In particular the commonly reported "Rebound damping needs to match the spring. Ideal compression damping is determined by vehicle weight" seems massively simplistic and bears little resemblence to the shock dynos I have reviewed.
Hence - I keep saying damping rates = compression & rebound as I am not convinced as yet to the accuracy of the sweeping statements that are banded about.
Please don't take my posts as argumentative, far from it. I am merely trying to ascertain the truthes. If we can calculate that Tein/BC/Bilstein/KYB/TRD are all doing differently to the ideal damping calculation (some are miles out) then to me it suggests that the calculation is flawed or there are different requirements.
True but it is rare to find a shock with adjustment that shifts the damping curve evenly like the Konis, The Bilstein will probably be closer than most so called adjustable shocks over more of the velocity range.The ideal damping rates can only be achieved by trial and error from feel and lap times.
You can do the math and theorise all day, but they will never be correct.
It's one of the reasons why i do like the Koni Racing inserts over Bilstein. They have easy adjustment, a wide adjust range and decent accuracy and repeatability. Where as Bilstein's would need to come off for a re-shimming every time.
I'm very interested in to why you feel the Koni 8611 will not be upto the job with respect to the heat and cavitation, again this isn't argumentative but hopefully your experience or findings may save me from making the wrong choice.
The more a damper restricts oil flow, and the more they move, the more heat they generate.
So hence why i do worry a bit about running a soft spring (=lots of movement), and lots of compression damping (=lots of restriction).
The 8611's have to be housed in another tube, which means they dont get the best cooling effect from air passing over the housing tubing.
Rally dampers are built to dissipate a lot of heat via special strut tubes and the external canisters.
The 8611's also aren't pressurised (i dont think so anyway, you have any info on this?), which means they cavitate easier than pressurised dampers.
Also when they start getting hot they will be prone to more cavitation.
[/quote]It may not be a problem at all... its just all this adds up to something which could be a problem.
I guess the only real way to tell is to put a temp sensor on the inside of the strut tube somehow and monitor temperature.
flyingdutchman":1n1dygil said:Any progress on this build?
CMS-GT4":2l2psdin said:A fwd guy had some threaded tubes made for his 8611s on his 5th gen.