Teach Me Suspension

[Reda90]

Hello All,

I've read through a lot of the track threads and suspension threads; and I'm looking to have the information I've gathered that I think is correct verified, and have it here for other beginners (similar thread to "teach me race seats"). Thank you to anyone who reads/contributes.

So if I'm understanding correctly, suspension upgrades, as far as springs/coilovers can be broken down into 4 categories:

Lowering Springs - mainly for looks, slight confidence upgrade, detrimental for track use
Examples are Swift Springs, H & R, Eibach, etc

Adjustable Springs - am I correct in understanding this could be considered entry level suspension upgrade for track use?
Examples are MSS, HKS, Ohlins

Mid-tier/Street and Track Coilovers - a full coilover suspension replacement for the OEM suspension setup
Example would be Ohlins Road and Track
Would it be correct to say that these are for the person who either doesn't want to go to a full setup like MCS or JRZ but still wants a track oriented suspension setup?

Top-tier/Full Track Coilovers - these are the coilovers that are made for the track and are the best of the best, can be broken down further into 1 to 4 way adjustability
Examples are MCS and JRZ

Supporting Suspension mods
Camber Plates - for camber, not sure how that relates to track setup and tire degradation
Control Arms - I have no idea what these are for
Toe Links - used for toe in and out, not sure how that relates to track setup and tire degradation
Sway Bar End Links - I have no idea what these are for either
Sway Bars - chassis stiffness

Wheel Spacers - any use for these on the track??

Am I missing any parts? Anything glaringly wrong? Thanks again for input and time!!

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[Traxion]

Am I missing any parts? Anything glaringly wrong? Thanks again for input and time!!

I hope to see you start tracking the vehicle! It's extremely capable in stock form for beginners besides needing upgraded brake fluid and maybe pads. Don't feel like you need to do any suspension upgrades. I climbed the HPDE ladder in mostly stock form and the car itself won't hold most people back for quite a while. I jumped into all the upgrades when I was cleared for competition level. Anything I don't address is probably not important, what you said about it holds true enough, or I happened to forget.

Adjustable Springs - I would generally skip these and run OEM suspension until budget can allow for a mid-level coilover. The main benefit of HKS is it gets rid of the OEM spring perch in front which allows for larger wheels and tires to be mounted to the car. I personally wouldn't lower the car much beyond 1/4". If budget is a concern, it'd be better for hold out for some used good condition coilovers instead of spending $1000 on these. A lot of people think that lower is better, that's not necessarily true because suspension geometry comes into play.

Shocks (Coilovers) - I don't really get the point of a street coilover. Things that do dual duty are never going to be as good as a specialized one. Might as well save up for a decent entry level one like FA510/Ohlins ($2.5-3k) rather than get some random coilover for the sake of having a coilover. Yes these will get you the bulk of the performance needed and the next step are for people who desire to be on extreme end of the speed spectrum or simply want the best. MCS/JRZ/Penske ($5-10k) are the big boy ones as you mentioned and the more expensive you get, the more adjustability they tend to have. The adjustability comes in the form of compression and rebound which can help correct understeer and oversteer under certain conditions like turn in, corner exit, mid-corner throttle application, etc.

On the supra, the OEM rear shocks have the springs divorced from the shock. Certain brands of the above come in that same divorced setup, and others remove the OEM spring location and put it on the shock body itself and turn it into a true rear coilover.

The info you're missing is that the big boy shocks can be custom ordered and have their valving set to pair with certain spring rates. Valving is a little over my head but for example my shocks are supposed to be good for a spring rate range between 650-850lb. If I wanted to make my car feel everything and bump to a 1000lb spring, I'd need to have my shocks revalved to take that into consideration. Any good vendor (Shout out to JAXSPEED) who sells these should offer a consultation to talk about spring rate, valving, and your build as a whole so that the right suspension is ordered. The mid-level options tend to come with preset spring rates or maybe one other choice because the valving is what it is when you buy it. It's meant to be ready to go off the shelf and isn't a custom order. MCS and the like offer the ability to ship your shocks into them for servicing and being revalved for a cost.

Camber Plates - One of the best things to buy starting out! This is used to dial in the contact patch while driving on track. As the steering wheel is turned, the tires on the outside will lose camber. What this means is that at stock camber approx -1.8* to -2* it will put more of the contact patch on the shoulder of the tire and cause it to wear down to the cords there before other parts of the tire. The goal is to have a flat contact patch while cornering which increases grip and evens out tire wear across the whole tread.

Control Arms - I'm going to be general and blanket this as everything connected to the wheel hub. Aftermarket arms are used to adjust the positioning of the wheel hub and/or upgrade the bushings that are attached to them. For example camber can be adjusted at the top (via camber plates) or at the bottom with adjustable lower control arms. All these arms are used to dial in the alignment settings. For example when I only had camber plates, one side of the vehicle could reach -4.2* and the other side could only reach -3.8*. Caster also wasn't adjustable so I was stuck with an unbalanced cross caster and had 7.7* and 8.8* on each side. By adding caster arms and adjustable lower control arms, I was able to get -4.4* on each side and 9* caster on both sides. This will help my car to be pointy, meaning it will go exactly where I point it when turning.

Most all bushings on the OEM arms are rubber. That means that they inherently have some flex to them so while the car is under load, the alignment specs won't hold as true as metal bushings. The car will stay more compliant and also thus more responsive. Rubber makes for a better daily driver as it doesn't transmit road conditions as much.

Toe Links - Add in traction link to this as well. Pretty much same reasoning as above. Factory toe links use eccentric bolts, that means they have limited adjustment range and if they spin from coming loose, the toe flops around more. You want toe stay as close to static while traveling through compression ranges for stability reasons and tire wear reasons. Most rear tires are corded due to toe. A less squirmy back end under accel and braking makes for better confidence and easier to put down power.

Sway Bar End Links - After adjusting all those other bits, the sway bar needs to have no preload on it, aftermarket end links can be lengthened to allow for this and also help with clearance on other arms. It is extremely common for the front sway bar to hit the tie rod pinch bolt when under compression+turning. Maxing out the length of sway bar end links will resolve this since nobody wants a bent tie rod.

Sway Bars - I like the term anti-roll bar since it explains what it does a little better. I wouldn't necessarily call this chassis stiffness but more of an adjustment for how quickly weight will transition from one side to another. I'm making up numbers here but if you are in a chicane and have thrown the front 1000lbs of the car to the left and then need to throw it back to the right, an anti-roll bar will smooth out how exaggerated that weight transition is. I like to adjust this based on how corner turn-in feels. Too stiff means the car won't want to transition the weight and it'll keep going in the direction it was originally (understeer). Too soft and it'll feel like you're having to wrangle the car through turns because there's too much load on the outside.

Wheel Spacers - Can be used to help clear suspension springs, suspension components, fenders, etc. It also can be used to dial in how the front of the car feels. It increases front track width which adjusts front grip.

AERODYNAMICS - Note that adding aero will affect most all the above. For example it's suggested to get stiffer shocks/springs to offset downforce provided by splitter, wing, diffuser, etc. Certain alignments specs will be better with aero. Aero may induce understeer/oversteer in new places and that can be worked through by adjusting all the rest of the above.

 

[noogie]

There’s also suspension frequency and learning how to read shock dynos.

https://www.supramkv.com/threads/suspension-frequencies.20423/

basically you’ll go down a never ending black hole. At the end of the day, you need something that just feels good to you. Ask 10 different drivers and you’ll get 10 different preferences. Having confidence in the car is what makes you go fast.

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