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1G Front and Rear Sway Bars = More Understeer?

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ChessmoDSM

Proven Member
466
200
Apr 22, 2017
Burlington, Vermont
92 1G AWD, 17x8 wheels with Nitto 235/45/17 tires, FEAL Coilovers, rear upper control arms from 3SX Performance, car is for street, hillclimb and occasional auto-x, so trying for a really good handling setup that takes corners nicely..

I am currently running an ST Sway Bar in the rear and I also have one for the front(not mounted yet) but after doing some reading I am seeing that having both is not recommended and can actually have adverse affects(e.g more understeer) than just having the rear in an AWD setup..(e.g rear sway bars work well with the stock front bar, it gets your AWD car turning closer to neutral, adding both produces understeer again)

Is anybody out there running a front and rear sway bar on a 1G DSM that can refute this or is it true what I am reading, is there anyway to use both and offset the understeer a different way? I have the FEAL adjustable coilovers, can I make the front softer than the rear or would I need to change the spring rates themselves?(ex: 7k/7k are the spring rates now, but FEAL would modify if needed)

All opinions and advise appreciated..

Thanks!!
 
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Depends on how big the rear bar is. I was planning on going with Whitelines biggest rear bar and their front bar, which was bigger than stock but it wasn't the biggest they offered at th time - can't remember the sizes now.

Other things you can do to counter understeer - rear toe eliminator kit, poly bushings or even solid bushings in all suspension connections, and the big one... Evo 8 rear diff swap:
http://www.dsmtuners.com/threads/how-to-install-evo-lsd-into-1g-dsm-gvr4.516126/

The rear diff swap should help reduce the need for huge swaybars, giving you more tuning ability at different tracks.

Now go post a DSM Profile so all your mods are tied to it.
 
The stiffer you make the front sway bar, the more the car will understeer, in theory.
In my experience I had RM rear sway bar, and stock front. Things got better but it still understeered. Car is heavily road raced and autoxed. This year I'm switching to ST rear bar, 25mm, and still staying with the stock front.
It's difficult to make the 1g awd platform oversteer on demand without doing the things mentioned above by Ludachris. Bottom line is, unless you have all of the above done, get the biggest rear bar, and skip the front. Spend the cash elsewhere
 
You can change spring rates as well. Feal told me, when I got them over a year ago, when they valve the coilovers you can go +/- 2k in spring rate without needing to re-valve the strut. Stiffer in the rear will help. The biggest change for understeer under POWER was the rear diff upgrade as stated above. It changed my car completely. I wound up with the rear softer than the front while adjusting at the last AutoX. I can rotate the rear with the throttle now. But yes, technically if you make the front more resistant to rolling than the rear you will have more understeer. I have the front and rear RM bars for my 2g
 
There are three types of spring rates on a car. corner springs effect wheel rate, roll, and heave. Sway bars effect roll rate. heave springs (only used on racecars with a lot of aerodynamics really) effect heave. The corvette is an example of a street car that technically has a heave spring. sway bars and heave springs are generally considered tuning devices since you'll practically never see a car that doesn't have corner springs. The usual process is: set your corner springs to set your desired wheel rate, then use the other two to achieve your desired roll/heave characteristics. A typical road car set up for wheel rates would be around 1.5 hz. This is a function of the mass of the sprung weight (the chassis) on the axle, the mass of the unsprung weight (the wheel/other stuff that doesn't move) and the spring rate. Based on your track width and motion ratios this will determine the roll rate your corner springs contribute. Once you know this, you'll see how much swaybar you need to keep your tires in their desired camber range. This will also show you how much swaybar you need front versus rear to keep your roll rate balance. My autocross car has a roll rate front to rear that is almost identical. If I remember correctly, the rear is 3% more than the front. With my weight distribution this works out to about 130% more rear roll rate than front.

If none of that made sense to you, then you should probably just do what people before you have had success with. Put the largest rear swaybar you can on and use the stock front swaybar. What are you trying to achieve? What are you expecting to find? Adding a bigger front swaybar will make your car roll less overall, and the load transfer will occur more on the front than the rear, meaning your front outside tire will become overloaded before your other tires. This causes understeer. If you stiffen your rear swaybar, the rear outside tire will take a larger percentage of the weight transfer. My 1g awd is fairly neutral under power, but understeers still on corner entry a touch. I have the ST rear bar and the stock front bar. Your corner springs are fairly stiff, and if you go stiff with your swaybars too you might find that you pick up tires instead of having them follow the road. In the end you'll be losing grip and cornering slower. Depends on how flat the track surface you race on is. Bigger swaybar = less independent suspension.
 
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