Sway-bars, under-steer and over-steer

CMR 30mm rear Swaybar GTR
Well, I got some new parts over the last few weeks, so I've now updated my build story. I also did a small write up on Sway-bars for the GTR, and added it to the "how-to" guides on the right. I also managed to pick up a great new steering wheel!
Momo Champion Wheel


I feel as though I should mention that in the downloads section, we've got the 340 mb Holy Bible of how to assemble the Nissan Skyline, it's the one made by Nissan themselves, and used by the service technicians.

Leave some comments and let the authors know what you think of their stories!

Click "Read more" to see the updated portion of the build story:

New Year? New Parts!... January 10, 2011
After being prompted by several forum members to look into how sway-bars work a little more, I found out that its not advisable to change one sway-bar and not the other, unless you want to modify the over/under-steer characteristics.

So, Naturally most cars come from the factory setup to have a little bit of under-steer, thats because in a high speed turn, even an inexperienced driver can handle under-steer, but not everyone would be able to handle an over-steer situation, cause over-steer would send the tail out and spin the car.

Well, so too is the Nissan Skyline GTR setup to come with a little under-steer from the factory, and I haven't made this problem any better by fitting the 9" wide rims in front and the 9.5" in rear, more traction from the rear + it's a rear-wheel biased AWD system, its a recipe for a huge amount of under-steer! Which I noticed pretty quickly at the track, it made the car pretty safe to handle since I'm still a novice track-day goer.

so, by using bigger/smaller sway-bars in the front and rear, one can modify the over/under-steer. For example; If your car is under-steering, and you wanted to help balance it out you would fit a stiffer rear sway-bar, the stiffer rear end will cause the tail to slide out more, effectively correcting under-steer. 

So, when my car gets fitted with a stiffer front sway-bar, it would make it under-steer even worse! Not, what I needed at all, so I sent an email over to Adam in Japan and told him to find me a big after-market rear sway-bar, and a set of bushing kits for the end-links (mine are rather worn). He didn't fail me! CMR 30mm Rear Sway-bar with bushings and brackets, and a kit of pineapple bushes for the links.
CMR 30mm Rear Sway-bar GTR and pineapple link bushings
So to put the whole thing in perspective, I measured the OEM sway-bars, and compared them to my after-market ones, heres what I found:

  • OEM Front: 21 mm (Apparently hollow?)
  • OEM Rear: 26 mm (Solid as far as I can tell)
  • Cusco Front: 24 mm (Solid)
  • CMR Rear: 30 mm (Solid)
So my front would see an increase of 3 mm, while the rear would see 4 mm, I think this is enough of a difference now between front and rear stiffness that my under-steer problem will be much better.

Got a Handle on things... January 24, 2011
I've been putting of the interior of my car for a little, while working on performance stuff, so when I saw this pop up on the forum for sale section, I jumped on it.
Momo Champion Steering Wheel 352mm
Momo Champion Steering wheel, 352 mm, with suede on the top third, really happy with how it feels. I've already ordered up a steering boss adapter from Adam, should be here by the end of the week I'm told.

Comments

  1. Josh, excellent job on refinishing that bar.

    Remember the day I went back to Ebisu Circuit with new front and rear sway bars wtih upgraded bushings. Car felt so much better, really could hit the corners with a lot more speed. At one point I was bouncing off the apex on two wheels hahahahaha

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  2. The sway bar is the first step to correcting some understeer. The R32 GT-R though, does have a huge sway bar in the rear, compared to most cars. Not many you will find with a larger diameter rear bar than front bar.

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  3. It's brutal eh? what do you figure would be the next step to helping with the under-steer issue?

    Or, if anybody else out there knows a thing or 2 about track setups, what would you think might help understeering?

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  4. Josh,

    I know a thing or two about setting up a car. I know my way around car setup, or I can ask people that know more than me.

    The first thing I would do with your setup, is go back to a proper square setup. Staggered sucks for a GT-R.

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  5. just jumped on it, seeing about how much it would cost to get 2 SSR's for the front to match the rears,

    question though, Right now my rears are a +41 offset rim, that I mount to a +20 spacer, for an effective offset of +21 with the 18x 9.5 it doesn't rub with 265's RE01R's... and I want it to be the same for the front... but do I go for +22 (they only make +22) fronts in 18x9.5 and ditch the front spacers? or would that be no good? better to just order up a +41 and stick with spacers on all 4s?

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  6. Go with the +22. I am not a huge fan of spacers. Extra failure points. Minimize failure points, and your life will be easier. Roll the fenders if it rubs. I don't think it will. We have stuffed some pretty wide rubber under stock R32 fenders. Steve Mitchell had some 18 x 10.5 with 285's all around on his R32.

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  7. so, +22, even though I'll still be running spacers for the rear wheels? you don't think it'll look weird front to back being different concavity?
    lol

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  8. Oh well. Eventually get some more +22.

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