For a race car with coilovers. I hear lots of people are using the stock rear sway bar? But which one? Regular GT? Perf pack? Other?
Thanks
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Stock 350R rear sway to my knowledge. Quick maths with a 600/800 spring setup you have ~ over 70% front RC (lots of understeer) A large rear bar will tune that out, depending on how big it is you might get around 10% more rear RC (adding oversteer). You need to decide on what springs you will be running first since they are the main provider of roll resistance, then get your damping figured out, lastly tune with sway bars.
Thanks for the reply!
RC? (Sorry i'm french canadian)
So keep in mind my car is an ecoboost (ligher). I had 600f and 750R spring rates. I felt like the car had very little weight transfer, I just got 500F and 650R, you think it's going too low? I have not tried the setup yet. I generally prefer a softer car to be able to go over speed bumps etc and try to tune out the roll with sway bars. I dont have 4 way adjust shocks yet.
RC= roll couple:
Roll couple percentage is a simplified method of describing lateral load transfer distribution front to rear, and subsequently handling balance. It is the effective wheel rate, in roll, of each axle of the vehicle as a ratio of the vehicle's total roll rate. It is commonly adjusted through the use of anti-roll bars, but can also be changed through the use of different springs.
I'm guessing here because I don't know the distance between the springs for the ecoboost but its front track width is 152cm and the rear is 165cm so your 500/650 is about 70% front (without taking ARB into consideration) So you'd need to drop the front springs to 400, or some combination of 401-499lbs with a larger rear ARB.
Thanks for the reply!
RC? (Sorry i'm french canadian)
So keep in mind my car is an ecoboost (ligher). I had 600f and 750R spring rates. I felt like the car had very little weight transfer, I just got 500F and 650R, you think it's going too low? I have not tried the setup yet. I generally prefer a softer car to be able to go over speed bumps etc and try to tune out the roll with sway bars. I dont have 4 way adjust shocks yet.
Or just go 500F 900R and call it a day :? I assume your rear springs are in the divorced rear spring location.
than R650 is plenty should be good enough that's like 1300 on the divorsed spring location. For road racing 650/1200 is plenty.I have a coilover setup on the rear also
With the OE shock/ coilover MR that is 2.4hz front and 2.1hz rear, giving a LOT to pitch and front roll stiffness (more understeer)Or just go 500F 900R and call it a day :? I assume your rear springs are in the divorced rear spring location.
I learn from Kenny Brown he is suggesting 650/1200 for track focused builds for the S550 because when you have more spring rate in the front the Mustang turns faster and this is more important than setting the front mid corner which you can do with trail braking anyway.With the OE shock/ coilover MR that is 2.4hz front and 2.1hz rear, giving a LOT to pitch and front roll stiffness (more understeer)
I would run 400 front 750-800 rear unless he has lots of aero.
While I am no expert, simple statements like "higher front spring rate makes car turn better" is not meaningful in this conversation. If you add roll stiffness to one end of the car, you are reducing total available mechanical grip. If you have predominately aerodynamic grip then you need to run higher spring rates because of the added weight in down force. Where you sacrifice mechanical grip as the more aero you can use effectively the faster your lap time will be.I learn from Kenny Brown he is suggesting 650/1200 for track focused builds for the S550 because when you have more spring rate in the front the Mustang turns faster and this is more important than setting the front mid corner which you can do with trail braking anyway.
While I am no expert, simple statements like "higher front spring rate makes car turn better" is not meaningful in this conversation. If you add roll stiffness to one end of the car, you are reducing total available mechanical grip. If you have predominately aerodynamic grip then you need to run higher spring rates because of the added weight in down force. Where you sacrifice mechanical grip as the more aero you can use effectively the faster your lap time will be.
Does JUST adding front spring make the car turn better? No it does not, if anything it transfers more weight away from the front of the car under acceleration and causes understeer. If you do not have a large amount of aerodynamic grip, you need to pay attention to the rest of the suspension setup (some options are restricted by class, division, or series). What your statement is relevant to here is drivers (myself included) like the feel of an over dampened roll mode and a lot of that is accomplished in the low speed compression settings on the shocks/ dampers. The lower your spring rate, the less rebound bias you are stuck running, and so you can run more compression, this gives the driver the supported feel at turn in.
What we should be focusing on is the roll couple as I mentioned prior. That number is made with just the spring force and does not take into account the ARB. This allows you to select the stiffness of your ARB's. The general rule of thumb is you want low speed oversteer (slight) and high speed understeer (slight). In all the US/OS balance of the car is a driver preference. From my own research and observation drivers start with 55-60% front roll couple and tweak from there. Everyone will always tell you to run as little ARB as you can get away with, as the stiffer it gets the less independent your suspension becomes, if you start lifting a tire you will be slower than the guy who keeps all 4 on the floor.
Oh an E peen measuring contest. I do not agree with anything you have said. That's fine.
It's you own right.
I'm just saying that the Mustang is under sprung from factory. I plan to go with Ohlins R&T this season with 500F and 800R in the OEM location. Plan to use the GT PP rear bar for time been but probably will change bushings to some aftermarket option. I discovered that when you add front bar (Steeda on the softest setting) and change alignment (F: -1.4 camber -0.1 toe out per side -0.2 toe out total, R: -1.4 camber +0.1 toe in per side 0.2 toe in total) the car balance moved from Understeer from the factory to Neutral on the OEM PP tires and to slide oversteer in the 275/35/19's I run on the track. But the flex on the rear bar cause the bushings to unglue themselfs. I guess with more spring this thing with the bushings will not happen but aftermarket solution could and should be considered however the OEM bushings are super cheap and easy to replace so it make sense to stuck with it. If when I add the Coilovers I have problem with car balance I would consider adding Steeda adjustable rear swaybar. But Kenny Brown (I did his Speed Therapy Academy) suggest that for the track the car don't need rear bar because every time he added adjustable rear bar to an S550 he just leave it in full soft anyway. With that in mind the reason why the GT350 and GT500 have bigger rear bars is for the added aero from the rear wing (you need more spring rate and bar to prevent load because of downforce) but also this have better bushings. I was surprised when my car balance changed that much because it didn't made sense based on all I had read regarding car setup. My BMW track friends also said that this didn't make sense to them but it's clear that is working. My lap times dropped 5 seconds season beginning to season end (2KM track) just by adding 275/35 stickier tires, Camber Plates, Strut Tower Brace and Front Sway bar and I'm within 1.7 seconds of the 2nd placed VLN driver. I have no doubt that adding more front spring will improve my times even more based on everything posted in this forum. Hope this helps.
With the OE shock/ coilover MR that is 2.4hz front and 2.1hz rear, giving a LOT to pitch and front roll stiffness (more understeer)
I would run 400 front 750-800 rear unless he has lots of aero.
Lots of aero? On the front or the rear?
Specifically the front. If you had a meaningful amount of front aero and 500lbs springs that lowers the front rude frequency. And you would have less pitch.
Aero balance is very pitch sensitive and is a large consideration to both spring rate and damping rate selection (s).