Damper/shock absorber forces

[NoHachi]

Quote:With 8kg/mm/6kg/mm springs I've calculated bounce frequency of 2.49hz front and 2.56hz rear.

Hmz, that weird, I get 2.67Hz/2.42Hz in two wheel bump, or 2.75Hz/2.62Hz in roll. And those numbers are already compensated for the added weight of the CA18DET and turbo stuff added to the front of mine..so for a stock AE86 the rates would be even higher? I also didn't detract the sprung weight from the cornerweights, so that would make the freqs even higher.

What front lever ratio are you using? I did some measurements (also not very accurate) and ended up at 0.99 when I included the influence of KPI (measured at~8degrees). Also what are you using as cornerweights? That might explain some of the differences.

Quote:I'm not into mega stiff suspension so I'm sure some people would disagree with the above but I think comfort and grip are as important as handling.

Amen. Comfort is completely secondary to me. But optimise for grip and suddenly you get some comfort back too. How about that

Quote:I'm using a guestimate of 500mm for CoG but haven't done any research as to how accurate it is. As I'm only using for making comparisons, not outright results so it doesn't make a big difference.

Shame, I would like to do some roll rate calcs..guess I'll have to hoist the whole thing on its side one day and measure CoG location. Hope that works on 86's only ever tried it once with a tiny formula car.

Quote:Anyway I think less than 2Hz would be a good start

I'm at 2.2/2.1 Hz and its a world of difference (used to be a 2.8/2.7). The car now actually grips the road instead of skipping over it. However, I think I'm at the outer limit of what is possible on a 86 without massive wheelgaps. And I already run the car quite high compared to the popular JDM tight yo stance.
As I have the car now (5.8kg/mm-4.46kg/mm, shortstroked), the total stroke at the front is 90mm (@1G acceration max) while I measured the AE86 to have about 98mm available between full droop and tire/fender contact.

[Ozone]

Ueno - thanks for your observations. I've not driven my 86 much since it landed in the UK so I'm still getting a feel for it.
Have you measured the total stroke of the Greddys? So far I just measured rebound stroke on the front at recommend setting - 22mm!
Nohachi - remember I said I want to make sure I had no errors before posting spreadsheets? Well I had not accounted for the unsprung mass so that is why my frequencies are a little on the low side. I used 920kg kerb mass with 58.7% on the front (can't remember how I worked that out) and also added driver + passenger mass (75kg each) 50% along wheelbase. So total mass used is 615kg front and 455kg rear. If I use an unsprung mass of 50kg front and 65kg rear (rough guess) the rates come out as 2.59hz front and 2.6hz rear.
The lever ratios I've used are 0.98 front (experience, not calculated but 0.99 may be closer), 1.0 rear ride and 0.69 rear roll.
I also include a small rate due to suspension bushes - 2.5N/mm front and 3N/mm rear, based on a little experience.

[NoHachi]

Quote: I used 920kg kerb mass with 58.7% on the front (can't remember how I worked that out) and also added driver + passenger mass (75kg each)

F!@#$ forgot to add passenger mass (also quite a bit more then 75kg). That might just bring the freqs down to 2Hz with a codriver. Excellent!

Your mass number seems on the optimistic side for a normal hachi...920kg is realistic for a full out stripped and kitted racer though. The only corner weights I found for an AE86 are these from club4AGs forums. F/R weight distribution is pretty close to 50%. I added the pic..might be usefull?
How did you get the 0.69 rear roll leverage ratio number?

[SekiguchiUeno]

I found the letter with damper forces i had, measured by KW. Thanks to Reinhard

Old stock springs taken from old corolla:
F 19N/mm
R 20N/mm

Old, used KONI lowering springs
F 20N/mm
R 20N/mm

Older used Koni oil dampers
REAR:
Comp: 51N
Rebound open: 125N
Rebound Half open: 160N
Rebound 3/4 close: 260N
FRONT
Comp: 20-50? not measured,only comparing to the bilsteins with hand. Rebound open: 80-100? same as above
Rebound: 3/4 close: 160N

2year Amateur rally driven Bilsteins B6, stock settings.
REAR:
Compression: 100N
Rebound: 220N
FRONT:
Compression: 72N
Rebound: 140N

Stock abused shocks
REAR only:
Compression: 35N
Rebound: 120N

[Ozone]

Interesting information.
At what speed are these damping forces measured?