Today I had the rear wheels off and had a look at the Konis.. stamped on the bottom is this reference number
80 2830 SPORTS
Also had a look at the springs.. they are seriously stiff, even with all that audio equipment in, I can still put three people in the back and the wheels don't rub.. with the car jacked up on a ramp.. the springs have 5 coils wrapped tight at the base and four unwrapped working their way up to the chassis.
Hi EF MAX,
that’s good info!
Rear:
The 80-2830 SPORTS yellow rear Konis are part of the regular set that is recommended for lowerings of 40 mm maximum. Below that, A2s MUST be fitted with # 80-2830SPD3. So our “research“ was successful because the needed SPD3 version comes with a shortened piston rod and the beforementioned “rebound“- feature.
In your case at about minus 50 mm at the front and minus 65 mm at the rear the piston rod can hit the bottom valve potentially during full compression stage. That means your compression valves could now be broken and have to be replaced.
With the SPD3 version however, at lowerings below 40 mm, there’s no danger of wrecking the bottom valve. Also your springs will always be preloaded due to the rebound sleeve. That is very important for safe operation.
Front:
So we can presume your front shocks to be the counterpart of 80-2830 SPORTS, i.e. #8710-1404Sport. Corresponding to the rears you definitely need the shortened and rebounded 8710-1404SPD3 version.
It would be interesting to see the actual condition of the front springs. Has the paintwork been flaking? If there are no visible imperfections there already seems to be a problem with the front shocks having smashed bottom valves at least. This also would be the cause for the abnormal metal sound over speed bumps.
What to do:
In Germany for instance there are at least two KONI-specialised firms that can modify any yellow and red shocks to your specs. I myself have had modded my front rebounded yellows at POOHL-POWER this year. They can retro fit the in your case needed „rebound“ feature and can also add a shortened rod if needed. In addition they would check all internals for damages (of the bottom valve e.g.) and change the oil if desired or necessary. New gaskets are assembled preventing future leaking.
Lastly they can carry out a damper test finally to verify the shock performance before sending them back to the customer. I hope there is an equivalent Koni dealer out there in UK.
In your case I would take the opportunity to add more compression strength at both the front and the rear dampers. Normally too much compression strength is to be avoided for the very light A2 rear part, but in your special circumstance (110 kg of stereo) this would support the back springs properly.
So I would like to recommend modified bottom valves having:
- 75 kg force in total at the front instead of about stock 45 kg
- 55 kg force in total at the rear instead of about stock 35 kg
This recommendation does include new oil, meaning high viscosity oil, that also would improve speed bumps handling noticeably.
Cheers
P.S. As for “springs are seriously stiff“, I bet your back already sits onto the non-shortened yellow PU bump stops permanently. So there is virtually no residual spring travel left. With the modified (shortened and rebounded) Konis it will be feasible to shorten the stock bump stop rubbers by about 30 mm and thus gaining free valuable residual spring travel at the rear. I would buy new front and rear bump stop rubbers for the altering. Your springs seem to be of progressive type by the way.
