Beginner’s Guide / Tips for Buying a Street-Based Suspension

[xXDavidCXx]

Where did you find that info? Koni is telling me otherwise — just the rebound. TireRack also describes it this way: "The Special Active dampers also have a fixed compression setting, but instead of allowing the user to manually adjust the rebound, the internals of the Special Active dampers automatically adjust the rate and shape of the force curve (when plotted on a graph) on the fly, responding immediately to the frequency of the damper's movement."

So much conflicting information for a shock that is essentially just for daily driving.

The Actives have a set compression setting and it's lower than the koni sport shock. The extra valve blows off rebound forces.

The red line is the special active compression, yellow is the sport, both fixed.

 

[mrmatto]

OK, that jives with what Koni is telling me. Thanks. Would be interesting to have the OEM dampers as a comparison.

 

[tigeo]

Not sure if folks have seen this/I've posted it before elsewhere but an interesting look at the stock dampers after use with sport springs around 8:00 from my YouTube:

 

[tigeo]

I've posted this elsewhere but curious to get @Hammersticks opinion:

So I decided to nerd-out as I do and do some suspension measurements to figure my droop and bump travel. My setup is GSW w/4Mo + DSG, Bilstein B8s, Eurosport Street camber mounts, H&R Sport springs. Beyond those primary bits, I have H&R f./r. upgraded sway bars (27mm/25mm, respectively), 034 adjustable f. end links, Moog r. end links, Superpro aluminum LCAs, and the Tyrolsport f. deadset kit and 034 r. subrame inserts. What I did was measure the static level by doing wheel lip to fender lip both f. and r. and then jack up each until the wheels were off the ground and take the measurements again. Both were the same; 3.5" so 3.5" droop/extension travel. Next I was able to contact Bilstein and get the specs on each damper including total shaft travel/length and for the fronts the internal jaunce bumper length. I was able to find the r. jaunce bumper length by part no. Then I did some video testing to measure the actual bump travel up front using a speed bump. Data below:

So bottom line is, I don't have nearly as much travel up front as I thought I would have. Would be ideal to be at a 70/30% bump to droop ratio in my mind but I'd need to be able to pre-load the springs a bit to get that travel in that range and increase my ride height a bit - the B14/16 coilovers would allow me to do that. Going with the coilover that have adjustable bodies would remedy this more easily as you can set the bump/droop with preload independently of the ride height but of course you can put the tire through the fender with those too if you go too low. I noted I lost 0.25" of f. ride height after the LCAs/camber mounts/etc. so not sure there - maybe that changes the geo enough to do that? I can't see how else that would happen as the spring rate/strut length sets your ride height. I'd happily add 0.25 back to gain a little more bump travel up front. The fact that you ride on/into the jaunce bumper is news to me but based on the info from H&R below, makes total sense...really just addes progressiveness to the coil springs. Also makes me wonder if you can tune the springs a bit more (increase the rate) by just doing some upgraded jaunce bumpers? Finally...just how far can you compress a jaunce bumper? 100% of it's length is not possible. Based on he video work I did it looks to be ~30% of it's length compresses until you are fully "bottomed out" and feel a thud.

Here's the video. I just taped a measuring tape I made to the fender and zero'd it on the lip of the wheel. Looks to move 1" and I'm assuming that the wheel movement to strut shaft movement is 1:1 for this but that may not be accurate but the math on the numbers bilstein gave me works and 30% compression of the foamy makes sense:

https://youtube.com/shorts/8NDWFYTMBXw?feature=share


Post was more informational/to spur supension nerd talk so have at it!

Some good reading from H&R on this topic here:

https://www.hrsprings.com/technical/micro-cellular-jounce-bumper

Excerpt that seems to back my measurements/that my car sits on the foamy jaunce bumpers:

Also, Steve Dinan has some good info if your'e willing to spend the time on this podcast re suspension and jaunce bumpers:

 

[xXDavidCXx]

Not sure if folks have seen this/I've posted it before elsewhere but an interesting look at the stock dampers after use with sport springs around 8:00 from my YouTube:

BTW, all shocks are "gas struts" unless they have had the gas removed. I did that once on shocks on an S2000.

 

[tigeo]

BTW, all shocks are "gas struts" unless they have had the gas removed. I did that once on shocks on an S2000.

Sorry yes. Meant the monotube vs. dual and the impact that has w/r the gas bubble.

 

[daujin_mk7]

After six years of owning the car, it's time for much needed upgrades. I'm interested in getting thoughts on these upgrades for my DD (sees a lot of windy roads and road trips).

• ORT RS coilovers w/ Swift springs @ ORT's recommended spring rates
• H&R 24mm rear & 26mm front sway bar paired with Superpro end links
• Eurosport street camber kit + OEM strut mounts
• Superpro control arms (1 degree of camber) - I need to confirm this would fit with aluminum subframe
• Aluminum subframe A3/S3 (why not if the subframe has to be dropped)
• TyrolSport Deadset kit (front and rear)
• Powerflex street hybrid
• Pendulum mount (APR or RocEuro) - unsure about this one. been hearing mixed reviews. OEM + BFI's stage 2 dogbone mount has worked well for me.

Thoughts? Anything else I should consider while I'm adding all these upgrades? TYIA.

 

[scrllock]

Thoughts? Anything else I should consider while I'm adding all these upgrades? TYIA.

ALOY00018K arms fit the aluminum subframe. They do not give that much camber. maybe -0.3 to -0.5.
I would check to see if you can use that combo of strut mount, spring, and lower spring perch. Might be clunky if the spring diameter is off.
If you're not doing hard launches regularly I'd just stick with the stock dogbone arm.
Other than that looks good.

 

[tigeo]

ALOY00018K arms fit the aluminum subframe. They do not give that much camber. maybe -0.3 to -0.5.
I would check to see if you can use that combo of strut mount, spring, and lower spring perch. Might be clunky if the spring diameter is off.
If you're not doing hard launches regularly I'd just stick with the stock dogbone arm.
Other than that looks good.

The Eurosport mounts for stock-sized springs. Don't those coilovers come with their own camber mounts?

 

[scrllock]

The Eurosport mounts for stock-sized springs. Don't those coilovers come with their own camber mounts?

like most of the one-size-fits all coilovers, yeah.

 

[GTIfan99]

Since you mention comfort and no plans for track or ax, forget springs. Just get better tires, thicker sway bars and some form of front camber adjustment.

I think you're underestimating how much a decent set of shocks improves handling and ride over base suspension.

Agree with you if we're talking about DCC in good working order.

 

[odessa.filez]

I think you're underestimating how much a decent set of shocks improves handling and ride over base suspension.

Agree with you if we're talking about DCC in good working order.

yeah you're right on the dampers. My Koni yellows are better than stock. Was trying to make my comment simple and avoid picking a shock, but Koni pairs well with GTI stock springs on my car.

 

[odessa.filez]

I've posted this elsewhere but curious to get @Hammersticks opinion:

So I decided to nerd-out as I do and do some suspension measurements to figure my droop and bump travel. My setup is GSW w/4Mo + DSG, Bilstein B8s, Eurosport Street camber mounts, H&R Sport springs. Beyond those primary bits, I have H&R f./r. upgraded sway bars (27mm/25mm, respectively), 034 adjustable f. end links, Moog r. end links, Superpro aluminum LCAs, and the Tyrolsport f. deadset kit and 034 r. subrame inserts. What I did was measure the static level by doing wheel lip to fender lip both f. and r. and then jack up each until the wheels were off the ground and take the measurements again. Both were the same; 3.5" so 3.5" droop/extension travel. Next I was able to contact Bilstein and get the specs on each damper including total shaft travel/length and for the fronts the internal jaunce bumper length. I was able to find the r. jaunce bumper length by part no. Then I did some video testing to measure the actual bump travel up front using a speed bump. Data below:

View attachment 258989


So bottom line is, I don't have nearly as much travel up front as I thought I would have. Would be ideal to be at a 70/30% bump to droop ratio in my mind but I'd need to be able to pre-load the springs a bit to get that travel in that range and increase my ride height a bit - the B14/16 coilovers would allow me to do that. Going with the coilover that have adjustable bodies would remedy this more easily as you can set the bump/droop with preload independently of the ride height but of course you can put the tire through the fender with those too if you go too low. I noted I lost 0.25" of f. ride height after the LCAs/camber mounts/etc. so not sure there - maybe that changes the geo enough to do that? I can't see how else that would happen as the spring rate/strut length sets your ride height. I'd happily add 0.25 back to gain a little more bump travel up front. The fact that you ride on/into the jaunce bumper is news to me but based on the info from H&R below, makes total sense...really just addes progressiveness to the coil springs. Also makes me wonder if you can tune the springs a bit more (increase the rate) by just doing some upgraded jaunce bumpers? Finally...just how far can you compress a jaunce bumper? 100% of it's length is not possible. Based on he video work I did it looks to be ~30% of it's length compresses until you are fully "bottomed out" and feel a thud.

Here's the video. I just taped a measuring tape I made to the fender and zero'd it on the lip of the wheel. Looks to move 1" and I'm assuming that the wheel movement to strut shaft movement is 1:1 for this but that may not be accurate but the math on the numbers bilstein gave me works and 30% compression of the foamy makes sense:

https://youtube.com/shorts/8NDWFYTMBXw?feature=share


Post was more informational/to spur supension nerd talk so have at it!

Some good reading from H&R on this topic here:

https://www.hrsprings.com/technical/micro-cellular-jounce-bumper

Excerpt that seems to back my measurements/that my car sits on the foamy jaunce bumpers:

Also, Steve Dinan has some good info if your'e willing to spend the time on this podcast re suspension and jaunce bumpers:

Yeah bump stop / bump spring tuning is not talked about alot but is fertile ground for suspension tuning. I spent some time doing so on the rear suspension and it's a great solution having one spring rate for street and another spring rate for autocross.

I won't consider dampers with internal bump stops as it makes bump stop tuning more complex. That said, the guy Shaikh at Fat Cat motorsports has a youtube video on how to modify a Bilstein internal bump stop. IMO it's simpler on a Koni. But in your case, you might explore modifying or replacing your internal bump stop with a shorter firmer version to increase your bump travel.

You can also raise ride height with spring rubbers, but it will increase your spring rate in the process. If you only need it for track, that might be worth exploring.

 

[tigeo]

Yeah bump stop / bump spring tuning is not talked about alot but is fertile ground for suspension tuning. I spent some time doing so on the rear suspension and it's a great solution having one spring rate for street and another spring rate for autocross.

I won't consider dampers with internal bump stops as it makes bump stop tuning more complex. That said, the guy Shaikh at Fat Cat motorsports has a youtube video on how to modify a Bilstein internal bump stop. IMO it's simpler on a Koni. But in your case, you might explore modifying or replacing your internal bump stop with a shorter firmer version to increase your bump travel.

You can also raise ride height with spring rubbers, but it will increase your spring rate in the process. If you only need it for track, that might be worth exploring.

I've been looking at those rubber spring spacers but they all seem to be 1". Really need like 1/2. I'll see what I can try out.

 

[odessa.filez]

I've been looking at those rubber spring spacers but they all seem to be 1". Really need like 1/2. I'll see what I can try out.

scroll down and pick your size.
https://www.acrotechinc.com/automotive-applications/
Haven't dealt with Acrotech for a year or two but at that time, they were willing to pour any height and durometer you wish.