Track: front and rear

[adey]

I just transferred tires from a pair of my steelies to my pair of alloy rims that have a +5 offset and are 7" wide... this increases my track by a good margin, and got me thinking about the effects of having a wider front/rear track than rear/front.

I've noticed that most cars have a wider front track than rear, and I've heard that this increases stability some how -- just as a tricycle would ideally have two wheels in front and one in the rear... which is why all the 3-wheeled cars (yes, they have them) always have 2 wheels up front and one in the rear.

What would happen if you had a wider track out back, though? From my basic junior-high physics classes, it looks like wide rear track and narrow front track would cause understeer, and vice versa. Is this true? or would it not make a difference?

BTW I had to put the rims out back even though I wanted them in front -- I'm afraid they would rub in front (they stick out of the fender well quite a bit) but they were also scratching my calipers (!!! )... so I didn't have much choice.
(I wanted them in the front for brake-cooling purposes, 'though having them in the back should help with a "smoother" loss of traction...i.e. 205s on a 6" wheel vs. 205s on a 7" wheel.)

[adey]

bump --

This is a topic I've heard close to nothing on... and am interested!
I know weekends are usually slow on these boards, so here's a bump for Monday. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>

[Chokudori]

Whether you get understeering/oversteering will just depend on how balanced your car is and how much horse power it has.
Let's say your car has 300+ hp. Your car would most likely oversteer coming out from a turn because your rear tire will loose traction and tend to slide out. This is why many high hp rear wheel drive cars have wider rear tires.
But you could also adjust this oversteer by raising/lowering the front/rear of your car. If you raise the front, you will get more understeering because there is less weight going on to the front. Meaning less traction to the front tires.

If everything was neutral, and you added a wider front tire. Then yes, you will get oversteering.

[mrdirty]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Chokudori @ Oct. 07 2002,2:31)</td></tr><tr><td id="QUOTE">1)Whether you get understeering/oversteering will just depend on how balanced your car is and how much horse power it has. ....

2)But you could also adjust this oversteer by raising/lowering the front/rear of your car. If you raise the front, you will get more understeering because there is less weight going on to the front. Meaning less traction to the front tires...</td></tr></table><span id='postcolor'>
1) Not true, the key to maintaining traction is even pressure on the contact patch and has a lot to do w/ the height of your mass center. A wider stance reduces body roll by decreasing the total difference in pressure from one tire's contact patch to another; caused by a larger moment arm from tire patch to the mass center -vs- moment arm from mass center to ground. And don't forget how much a good set of tires will do for your skidpad rating.

2)Not always the case, especially w/ mcpherson struts. Often lowering the stance can raise your roll center which has as much to do w/ body roll as mass center.

Increasing rear track will cause an increase in understeer which u could learn to control w/ throttle oversteer. If u had wider track up front then you wouldn't be able to correct for the oversteer w/ power....that's a no good.

don't take this as a shot, I'm just elaborating a bit.

[adey]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (mrdirty @ Oct. 07 2002,12:47)</td></tr><tr><td id="QUOTE">Increasing rear track will cause an increase in understeer which u could learn to control w/ throttle oversteer. If u had wider track up front then you wouldn't be able to correct for the oversteer w/ power....that's a no good.</td></tr></table><span id='postcolor'>
Thanks for the... uh.. description of what wider tires do, chokudori, despite my not asking for that info. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'> I was (am) asking about TRACK, not width of an individual tire. Anyway.

mrdirty, you mention correcting understeer with throttle-induced oversteer. I'm curious as to whether or not poor line following- induced understeer is also correctable with throttle. I mean, despite my rear shocks being set stiffer than the fronts (which naturally induces oversteer) I sometimes understeer into a corner due to either entering too fast or turning too late or a combination of both (poor 'line'.) I take it this (these) can also be remedied by throttle oversteer?

Or can't they? Why? Why not?

[Chokudori]

adey-
Oops, I didn't realize that you were talking about the track. Should have realized it when you said your rims were 7" wide.
I am not able to give you a sure answer for this, but I would assume that it would understeer because you have less body roll in the front of the car, meaning less traction to the outer front tire.

mrdirty-
&nbsp; Interesting how you could flat out say "not true" to my opinion... especially when I wasn't being technically specific.

[mrdirty]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Chokudori @ Oct. 07 2002,6:15)</td></tr><tr><td id="QUOTE">mrdirty-
Interesting how you could flat out say "not true" to my opinion... especially when I wasn't being technically specific.</td></tr></table><span id='postcolor'>
"will JUST depend on" is pretty specific in my book, like I said, I'm not trashing u, just elaborating; exactly as my post says...

[mrdirty]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (adey @ Oct. 07 2002,3:03)</td></tr><tr><td id="QUOTE">...poor line following- induced understeer is also correctable with throttle...</td></tr></table><span id='postcolor'>
hitting the throttle in response to missing the line &nbsp;is a bandaid on the problem. I think job one for u is to work on entry....
however, if u do enter the turn late for instance jamming (for just an instant) the brakes to load the front and hitting the throttle will bring the tail around and then u can ease off the throttle and get back control, u will lose momentum though.

[MrMigs]

Its kind of funky. Sometimes, when I would enter a corner understeering, I would press on the brakes and the front would grab again. Other times, I would mash the gas to try breaking out the rear. But sometimes unexpected shit happens.

One time at the mountains, I started understeering, so I hit the brakes only to find that it locked up the front tires and caused me to veer off the road. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/nervous.gif" border="0" valign="absmiddle" alt=':nervous:'>

I guess it would have worked if I was a little bit gentler on the pedal... but oh well...

And mashing the gas doesnt always work either, unless you have a pretty fast car or crappy rear tire grip. Sometimes, all it will do is push you off the road faster than before. So i guess ideally, you should gently, ("gently" being the important part) press on the brakes to get the front back...

... or you could try some e-brake action or something... haha.. I've never tried this, but if you do, let me know how it goes <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/tounge.gif" border="0" valign="absmiddle" alt=':p'>

[HippoSleek]

Oh damb - the next mod for all the mad doriftas will be to install a J30 subframe in the 240 (it is narrower). &nbsp;That way they can hold the dori longer. &nbsp; <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/dozingoff.gif" border="0" valign="absmiddle" alt=':zzz:'>

Others - generally, the same technique is used to correct understeer as oversteer. &nbsp;Stay on or lightly breathe off the gas and steer into the skid. &nbsp;Seems counterintuitive, but by doing so, you have scrubbed speed and need to allow the tires to regain their grip. &nbsp;Once this happens, you can resume turn in. &nbsp;Note - this is NOT a radical lock-to-lock steering event. &nbsp;It is subtle.

Using your brakes is a really, really bad idea. &nbsp;If you are understeering, you are already outside the friction circle for your front wheels. &nbsp;Asking the tires to do more isn't going to help at all!

[Chokudori]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (mrdirty @ Oct. 07 2002,8:46)</td></tr><tr><td id="QUOTE"></span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Chokudori @ Oct. 07 2002,6:15)</td></tr><tr><td id="QUOTE">mrdirty-
Interesting how you could flat out say "not true" to my opinion... especially when I wasn't being technically specific.</td></tr></table><span id='postcolor'>
"will JUST depend on" is pretty specific in my book, like I said, I'm not trashing u, just elaborating; exactly as my post says...</td></tr></table><span id='postcolor'>
Yes, it would just depend on how balanced your car is. There are many things that contribute to how well your car may be balanced. You could adjust your camber, toe angle, caster, weight... etc, to achieve your total balance.

You could nit pick all you want. But I personally think that all these nit picking (not just you) on minor technicality really doesn't help on forums.