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djsteviec

Hankook RS4 on FWD

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7 minutes ago, Wittenauer Racing said:

How does the car do in terms of body roll? Does the Toe go all weird if you lift the front end of the car? Diff type?

 

Also which pits were you using? Looks like there's one set coming out of turn 14 and another off the long straight leaving 10?

 

 

 

Body roll is quite controlled as we put stiffer springs on allaround for this year.  Though, no idea what toe does if lifted.  Its an Helical LSD with nearing 300k kms on it (read: its dead and basically an open diff).  Using the main pit (NOT the one at the end of the long straight).

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19 minutes ago, thewheelerZ said:

@wvumtnbkr More camber, as in less negative camber is what I assume you mean right?  Yes, Im surprised to at the temp difference between sides. Yes, clockwise so more rights than lefts.  Maybe the puddle didnt actually hit the right tires? (though rear tires dont really tell that story...).  I need to do some more research to see what is acceptable for tire temps.  But certainly we will be trying to lower the pressure on front tires.  Maybe try 35 lbs and go from there.

 

@mender Yeah, -1.75 on the front is what i was thinking would be worth a try.  However, the rear beam axle laughs at your suggestion for the rears!

And I would avenge myself by cutting the beam partway through in the middle and allowing it to sag until I get the camber I want, then weld things back up again. :)

 

Make the cut square and weld so you don't change the toe (unless you want to).

Edited by mender
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10 minutes ago, thewheelerZ said:

 

Body roll is quite controlled as we put stiffer springs on allaround for this year.  Though, no idea what toe does if lifted.  Its an Helical LSD with nearing 300k kms on it (read: its dead and basically an open diff).  Using the main pit (NOT the one at the end of the long straight).

 

Post someone up at a couple tight corners and have them watch the body roll/dynamic camber. No real need to measure precisely, just get a feel for how the car looks going around the corner.

 

Not saying this is what you have going, but it's what we're working on with the Minis right now. Basically we're eating the inside 1/3 of the front tire... We're finding that in hard corners under throttle, the inside front is getting real light and goes into droop. As it goes into droop it toes out. Combine that with the body roll and the 2ish degrees of camber we run, it sort of drags the inside edge of the tire across the pavement. The clutch type LSD made a big improvement as we aren't spinning it nearly so much now, but it's still something we're fighting.

 

If it is what's happening on your car, it's not nearly as pronounced as what we see. I wonder if you're only partially contacting the right front coming around 14 under throttle right before coming in and building more heat on the inside edge that way. I'm sure pressure will improve it, maybe camber changes too. 

 

For us we're playing with geometry next. Seems like the more we chase it, the faster we can run/more grip we make but the problem keeps coming back as we roll harder....

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Which is why you can't just go by tire temps to set camber. We had the same problem with inside edge wear and had to use tread wear as a main indicator of required camber to even things out.

 

Once your tread wear looks reasonable, do another tire temp test and record those as your new targets.

Edited by mender
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3 hours ago, Wittenauer Racing said:

 

Post someone up at a couple tight corners and have them watch the body roll/dynamic camber. No real need to measure precisely, just get a feel for how the car looks going around the corner.

 

Not saying this is what you have going, but it's what we're working on with the Minis right now. Basically we're eating the inside 1/3 of the front tire... We're finding that in hard corners under throttle, the inside front is getting real light and goes into droop. As it goes into droop it toes out. Combine that with the body roll and the 2ish degrees of camber we run, it sort of drags the inside edge of the tire across the pavement. The clutch type LSD made a big improvement as we aren't spinning it nearly so much now, but it's still something we're fighting.

 

If it is what's happening on your car, it's not nearly as pronounced as what we see. I wonder if you're only partially contacting the right front coming around 14 under throttle right before coming in and building more heat on the inside edge that way. I'm sure pressure will improve it, maybe camber changes too. 

 

For us we're playing with geometry next. Seems like the more we chase it, the faster we can run/more grip we make but the problem keeps coming back as we roll harder....

You are talking about bumpsteer, right?  Why not just fix the bumpsteer?  Usually it can be fixed by raising or lowering the rack or the outer tie rod connection.

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10 minutes ago, wvumtnbkr said:

You are talking about bumpsteer, right?  Why not just fix the bumpsteer?  Usually it can be fixed by raising or lowering the rack or the outer tie rod connection.

 

Yes, bumpsteer. As silly as it sounds, it took us awhile to diagnose it as a car issue and not just the yahoo behind the wheel :)  

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I swear it feels like the car is trying to turn right when I turn left....  but only once the suspension really gets loaded up....

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48 minutes ago, wvumtnbkr said:

I swear it feels like the car is trying to turn right when I turn left....  but only once the suspension really gets loaded up....

 

It's weird for us as the car toes out (inside wheel turns into the turn) as it droops, but the "springs" are progressive, so we get more droop than compression in most corners. Outside tire doesn't change angle much but the inside does... 

 

Does help explain why the car is a bit "darty" on landing sometimes over Grattan's hump/jump on the backstretch and I'm sure it would be less than fun over some of the bumps at Nelsons...

 

@djsteviec Sorry for the sort-of thread jack, but hopefully it's helpful info still.

Edited by Wittenauer Racing

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3 hours ago, Wittenauer Racing said:

 

It's weird for us as the car toes out (inside wheel turns into the turn) as it droops, but the "springs" are progressive, so we get more droop than compression in most corners. Outside tire doesn't change angle much but the inside does... 

 

Does help explain why the car is a bit "darty" on landing sometimes over Grattan's hump/jump on the backstretch and I'm sure it would be less than fun over some of the bumps at Nelsons...

 

@djsteviec Sorry for the sort-of thread jack, but hopefully it's helpful info still.

No prob. All good. And helpful info.

 

@mender, what about putting washers on the bottom of the bolts or studs that mount the backing plate to the axle? Then you can get negative camber.

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3 hours ago, djsteviec said:

No prob. All good. And helpful info.

 

@mender, what about putting washers on the bottom of the bolts or studs that mount the backing plate to the axle? Then you can get negative camber.

That works on axles that have a bolt-on spindle (1st gen Scirocco for one). I couldn't see that on the Maxima images that I found but if so, yes, shims work well!

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