Suspension tuning - dampers, spring rates, etc.

[Dave-ROR]

A couple of links I've had saved over the years on damper setup/tuning plus some other misc info. Nothing beats your own seat time and experience but there's some good info in some of these to help you get there a little faster.

Basic damper tuning suggestions by Ford/Sachs
Penske's Adjustable Damper manual/tuning guide - MUST READ IMO
Reading Shock Dynos (at least some material copied from Penske's guide, I haven't read it but some pictures at least are the same)
Far North Racing - General Shock Info
Far North Racing - Shock Buyers Guide
Far North Racing - Setting Shock Forces
Far North Racing - Reading Shock Dynos
Far North Racing - Shock Tuning Payoffs

@Xian can add more now

[Xian]

Dang! The site's been up for less than 48 hours and I've already been called out.

I'll plan to pull together some general information Wednesday (my work from home day). Figure we can start off with some general setup ideas and generic "off the shelf" setups as well as talk about different ways to achieve the balance you're looking for.

[aw614]

Still on my OTS Bilstein sport/stock itr spring + skunk 2 front camber kit combo. Happy with it, but I think it could be a touch stiffer.

Really need to take it out to an autox or FIRM event with the LSD, but new motor that was installed isn't currently idling so that will have to wait so I can make another base line on it, before making another change.

Maybe I should let Dave-ror drive it at one of the Brooksville fast autocross events lol.

[coolhandluke]

Dang! The site's been up for less than 48 hours and I've already been called out.

I'll plan to pull together some general information Wednesday (my work from home day). Figure we can start off with some general setup ideas and generic "off the shelf" setups as well as talk about different ways to achieve the balance you're looking for.

Awesome, I look forward to reading!

[Xian]

Dang! The site's been up for less than 48 hours and I've already been called out.

I'll plan to pull together some general information Wednesday (my work from home day). Figure we can start off with some general setup ideas and generic "off the shelf" setups as well as talk about different ways to achieve the balance you're looking for.

Awesome, I look forward to reading!

Sooooo... I'm slow.

I don't really know where to start... front stiff vs rear stiff? Springs vs bars? It seems like we've beaten it all up on the old forums, HT, or the Sandbox. Here's some general stuff to maybe get the conversation going:

Koni Sport "Yellows" - awesome OTS solution for most applications. Not a load of compression, decent rebound, and can handle rates up toe ~500#. It's a solid street shock that you can also use on track or for autox. Be careful with bump travel if you're lowering the car much at all. Consider getting extended upper mounts or their "Race" shocks if you want to go low.

Koni Race - this is a version of the Yellows that has more rebound damping and shortened bodies/shafts. You'll end up with more suspension travel at low ride heights with these than the regular Yellows. They're also valved to handle rates up to around 1000-1200. Probably a little stiff for street use but liveable if your roads aren't horrible.

Bilstein - After having a set of these, I'm a fan. They're rebuildable and revalveable. Plenty of paths to upgrade them but you'll need to get friendly with someone who can do the work.

Whitener Race Suspension - David Whitener is a well known fast guy in National Autox circles who started making his own shocks from Bilstein parts. If you're ok have non-adjustable shocks, these are the ones to get. The curves are remarkably similar to those that you'll find on any of the high end monotubes from Moton but at a fraction of the price.

I don't know a ton about the mid-range stuff (Feal, Fortune, PIC, D2, etc.). What I've been told is that many of these shocks are made with the same internal components and then valved to their specs... dunno if this is accurate or out of date. I'm sure others can (and will) chime in with personal experiences.

MCS/JRZ/AST/Moton - aka Pimp Shocks. All these are going to be pretty similar if I'm honest. The "J" from JRZ went to Moton that was bought by AST right after "J" started MCS. As a result they're all sorta inter-related. I prefer MCS because they're heavily involved in autox/wheel to wheel and are located in ATL (I'm in FL). Any other the others should be good to work with as they can all do the same stuff WRT revalving and rebuilding. MCS has always taken care of me and I've seen them perform "free" fixes on failed components when they really didn't have to. The way they stand behind their product is what keeps bringing me back to them.

Shock adjustments - keep in mind that nothing on the car works in a vacuum; meaning, if you change something at one end of the car, it won't just effect that end of the car... it'll impact the whole thing. Generally speaking, adding rebound to one end of the car will make it looser/easier to rotate by transferring load more quickly. Adding compression aids in grip by helping to keep the tire tracking the surface until you have too much and then it decreases grip. If folks have questions, post them up and we can discuss. High end Monotubes/Pimp Shocks will have a much larger range than the entry level twin tube stuff from Koni mentioned above.

Bars - FWD cars typically like a large rear bar. It transfers weight laterally and, in the process of turning the car, the load transfers diagonally as well. Going to an extreme of too much bar can actually cause a pushy/loose situation where the car has a push right at turn in that transitions to being too loose. The ASR stuff is my go to for a rear bar though you can fab your own with Speedway Engineering parts. Look for Andy Hollis' posts on the topic (believe he has them on FB under his OneLap CRX page) or post here and I can dig up other links. If you dig out any of the rate calculators for sway bars, make sure that you're not looking at single wheel "bump" and that the answer is the correct doubled amount that you get in roll.

Springs - Dedicated track cars can live better with a "stiff rear" bias that would make an autox or street car almost undriveable or unbearable. Remember that, as you increase rear spring rate, the suspension moves less so your rear bar contributes less to total roll stiffness. As a result, if you just up the spring rate, you've made the rear bar correspondingly less effective. For anything less than a dedicated wheel to wheel car, I prefer a front stiff setup. Front rates in the 650-1100 range (depending on application and street tires vs R-comps) and rear rates in 500-650 range (again, depending on the details). This gives you a turn-in that won't kill you and some compliance over bumps/curbs while, when coupled with a big bar, the balance that you want to get the car turned.

[aw614]

I've been considering David Whitener's setup as an eventual upgrade, especially after I listened to the slip angle podcast he was on talking about them.

Still need to wait and drive with the LSD and new motor for about a year before making any changes. No rush heh.

[RTW DC2R]

Courtesy of Kaz Tech and DSport

Tuning Chart https://drive.google.com/open?id=0B3IOs ... zJzdzlpYWs
Damping Calculations https://drive.google.com/open?id=0B3IOs ... GhLMjRBY0U
Damper Basics https://drive.google.com/open?id=0B3IOs ... HRNNGdyWnc
Damper Guide https://drive.google.com/open?id=0B3IOs ... URXV1BXMmM
Damper Basics Equations https://drive.google.com/open?id=0B3IOs ... k9zYy16Z1k
After Calculations Vehicle Tuning https://drive.google.com/open?id=0B3IOs ... DdFdENqb3c

[coolhandluke]

...front stiff vs rear stiff? Springs vs bars? It seems like we've beaten it all up on the old forums, HT, or the Sandbox. Here's some general stuff to maybe get the conversation going....

Springs - Dedicated track cars can live better with a "stiff rear" bias that would make an autox or street car almost undriveable or unbearable. Remember that, as you increase rear spring rate, the suspension moves less so your rear bar contributes less to total roll stiffness. As a result, if you just up the spring rate, you've made the rear bar correspondingly less effective. For anything less than a dedicated wheel to wheel car, I prefer a front stiff setup. Front rates in the 650-1100 range (depending on application and street tires vs R-comps) and rear rates in 500-650 range (again, depending on the details). This gives you a turn-in that won't kill you and some compliance over bumps/curbs while, when coupled with a big bar, the balance that you want to get the car turned.

Christian, I feel this section is worth diving into, since most in here (including myself) have dual-duty street/track cars. The front bias vs. rear spring bias seems like an intriguing conversation, particular as it relates to your point:

...keep in mind that nothing on the car works in a vacuum; meaning, if you change something at one end of the car, it won't just effect that end of the car... it'll impact the whole thing...

My experience:
98-1040:
Eibach R2's 650lb F/750lb R
23mm JDM RSB
24mm USDM FSB
Tires: NT01 / RE71R's (Rcomp/Street)

97#151:
Eibach R2's 450lb F / 400lb R
26mm Mugen RSB
24mm USDM FSB
Tires: NT01 / RS4's (Rcomp/Street)

Two setups, both of which I tweaked (over time) into a favorable track and road experience.

[Xian]

Anyone reading along should keep in mind that everything I post is IMO, YMMV, my $0.02, etc. I've got a decent amount of experience playing with different set-ups, alignments, chassis, etc but there are plenty of folks waaaaay more knowledgeable out there.

Ultimately all you're trying to do with springs and bars is tune total roll stiffness so the chassis is relatively flat and responsive to inputs. As ride height goes down, spring rate needs to go up to keep the car from bottoming everywhere. This leads to the discussion about shock stroke and bumpstops. You can get pretty much any bumpstop rate/length you could possible need from RESuspension.com (look in their COT, foam section). Minimum ride height on all the DW cars will be determined by removing the spring, disconnecting the front bar, and running that corner through the full suspension stroke (leave a zip tie on the shock shaft). When the front UCA hits the chassis, that's the absolute limit to travel regardless of anything else you can do to the suspension short of cutting on the unibody. You want your bumpstop to be long enough that the shock body hits it and slows down/stops upward movement just before or at the point the UCA hits. Bumpstop rate will be dependent upon spring rate and bumpstop length. The bumpstop rate is additive to the spring rate and you want something that will be a smooth transition vs. a hard bumpstop that abruptly stops the suspension stroke and upsets the tire/car (you'd get a sudden push as things bottom out).

As far as the spring rate portion of things, if you're running it on the street, you're probably not going to want to go much above 500-600# unless you've got good dampers. The Eibach stuff that Ryan mentioned is supposed to be a really good but still relatively inexpensive option. Add to that the fact that Mark Krumme works there and it's a really good option that gives you some adjustability. If you've got higher end dampers, going to rates up to 750-850 is doable for most folks (except the rust belt and NE where the roads really suck). Key pieces to keeping the ride bearable at high rates is to make sure the car isn't pounding the bumpstops everywhere and that you don't have crappy shocks with too much high speed compression.

Rear rate choice is where things get a little more interesting. You don't really need to worry about bumpstop height back there aside from making sure you're not getting into them. There's enough travel that it shouldn't be a huge deal to remove or shorten the rear bumpstops (unless you've got a funky offset and the tire is hitting the fender). Softer rates with bigger bars seems to translate into a car that feels a little more progressive at the limit. This is largely (IMO) due to the big bar still needing to compress the soft springs as it transfers load. You end up with car that has great mid-corner balance but isn't trying to kill you on corner entry or with cold tires. Bonus points are also awarded because the lower rates don't suck on the street (think about ride/spring frequency here... I'm not a fan of tuning via frequency but the theory is sound when you apply it to ride quality). Dedicated track/race cars make the rear stiff thing work because you need a car that will always be on the loose side of neutral even when/if the front tires start to go away... this sorta setup also encourages earlier throttle application with little to no downside beyond the car being a handful to anyone who's not super experienced.

Another great tuning tool is rear camber. If you find the car is a little too tight for you on track, use some washers to shim out the rear UCA and reduce camber. Dropping a half degree of camber from the rear makes a huge difference to how the car drives with the only downside being slightly uneven wear at the rear of the car. The converse is also true... if the car is overly loose, adding rear camber can help to tighten up mid-corner.

Lastly, I'll touch on rake. Most folks run a higher rear ride height with anywhere between 0.5-1" of rake. Advantage to rake is that it encourages rear load transfer earlier in the corner (looser) similar to running more rear bar. Disadvantage is that the roll also pulls some load off the inside front which, if you're running a gear type diff and especially a stock diff, can cause inside wheelspin. If I had another Honda, I'd try playing with "reverse rake" in an effort to keep load on the inside front and then tune it with more bar or with shock.

[Underrated99si]

Great info lots to think about.

Anybody want to take a stab at helping me on my set up.

01 itr
FRONT
Pci front bronze bushing kit
Pci UCA"s
Zeal s6 coilovers 12k
Oem strut bar
Usdm ITR fsb /hard race endlinks
15x7 +40 205/50/15 nt01
2.25-5 (forgot) degrees camber
Corner balanced

REAR
Mugen 26mm rear seat bar
Zeel s6 10k
Pci rear toe links
Pci camber kit
Pci trailing arm spherical kit (when I update coilovers)
Kirk racing roll bar
15x7 +40with nto1's 205/50/15
1.75 degrees camber
Corner balanced

I love my set up accept

-dive after long strait aways under hard breaking
- more understeer than i would like in hairpin corners (streets of willow)
- more roll than would like in some tight corners

Car turns in good and is verry predictable and rotates when pushed hard or a quick lift but nothing scary. I wouild like a tad more rotation but nothing oh shit sucking seat crazy and stiffen up the roll a bit. Car is a hpde dedicated car so no worries about street comfort.

*** thinking of bumping to 14k f 12k r rates or 16kf 14k r and mabe pull out some camber out back.

Or

14,16k up front and go a tad stiffer rates out back & play with camber to get right amount of rotation.

Any help to fine tune would be appreciated.