Wheel spacers on front (only) of E30 track car??

[TrackE30*]

No response from this post on the wheel and tire forum so will try on the track forum... I recently replaced my front big brake kit with a BIGGER brake kit due to frequent rotor over-heating and cracking. I've had to install 10.5mm spacers (with hubs) on the front so the spokes of my 17" wheels clear the new Wilwood Superlite radial mount calipers. The 235-40-17 tires protrude slightly from the front fenders but the vertical clearance and stiff suspension should prevent tire/fender contact. I'm concerned using 10.5mm spacers on back could cause tire/fender contact due to less vertical clearance. Does anyone have experience running spacers on front but not the rear, especially on an aggressively-driven E30 325is track car, and have comments regarding the impact to handling (or lack of impact)?

Thanks!
Kent

[snakebit8]

Now Mind you my experience is with E36s but I have only ever run spacers in the front and not the rear. Has never been an issue with me or the many people that run that way. 15 years racing it front only and no issues yet.

[aeronaut]

It does change the car dynamics very slightly. Very slightly. Scrub radius, wheel rate, and track are (very slightly) changed, and probably other stuff I don't understand about suspension (and there's a lot).
Nothing's going to suddenly explode, and nothings going to dramatically change. Try it, you'll get used to it in one session if you notice it at all, and never look back.

That said, hopefully an experienced E30 guy will post and state fact. lol.

[satakal]

dude, just do it. Adding 3/4" of track width to the front is fine. "front grip is the best grip"
Its not a big deal. Do it.

[revzillia]

I Scca club race a E30
No issues on my end I’ve run spacers on front only / rear only
On paper the wider the stance better turning but something that small will be hard to measure

[TrackE30*]

Many thanks for the helpful replies!!

[mrf]

Wider front track will make the car understeer more.

Wider rear track will make the car oversteer more.

This sounded counter-intuitive to me at first, until I tried it.

[badmonkey]

Wider front track will make the car understeer more.

Wider rear track will make the car oversteer more.

This sounded counter-intuitive to me at first, until I tried it.

orly?

[mrf]

orly?

Yep.

Post # 10 explains it well here.
https://www.s2ki.com/forums/s2000-un...experts-60381/

After only installing 15mm rear wheel spacers on my otherwise stock S2000, made the stock VSA interfere a lot earlier because I needed less steering angle to initiate the same amount of yaw.

[aeronaut]

I didn't read the whole thread, but what I did read and scan didn't show definitively that increasing front track width increases understeer. It's much more complicated than that. Of course.

[mrf]

That's the problem with the internet. Every opinion gets equal consideration so quantity wins over quality. If 9 out of 10 posts in a thread say one thing, people like you will believe that instead of what may be actually correct. Some posts are worth more than others. In this case, Post # 10 in the previously mentioned thread is correct.

Put it another way, as anyone ever understeered on a tricycle?

But forget theory, try it for yourself as I have and collect some empirical data.

Anyway, my goal isn't to convince the rest of the world of what's correct. I just want to know it for myself. Figured I would do my part and at least attempt to set the record straight. I really don't care if any of you pay attention.

Cheers.

[aeronaut]

That's the problem with the internet. Every opinion gets equal consideration so quantity wins over quality. If 9 out of 10 posts in a thread say one thing, people like you will believe that instead of what may be actually correct. Some posts are worth more than others. In this case, Post # 10 in the previously mentioned thread is correct.

Put it another way, as anyone ever understeered on a tricycle?

But forget theory, try it for yourself as I have and collect some empirical data.

Anyway, my goal isn't to convince the rest of the world of what's correct. I just want to know it for myself. Figured I would do my part and at least attempt to set the record straight. I really don't care if any of you pay attention.

Cheers.

As the kids say, chillax dude.
The referenced post #10 in no way shows that adding track decreases relative traction on that axle in all cases for all cars. The author even agrees that it increases absolute traction on that axle. These changes are so minor (increasing track a few percent), that weight bias, spring rates, suspension type, suspension geometry etc will all play a role, if not the dominant role. The point is, one doesn't change ONLY the track width when a change is made. Does it do what you say, for your car, in your case? I believe your assessment.
And the oft quoted tricycle analogy is a poor one. It is an extreme example where weight transfer and high CG causes instability long before any "understeer" or "Oversteer" characteristics might be seen. Can/does a tricycle understeer on ice? I'd bet yes.

[mrf]

As the kids say, chillax dude.
The referenced post #10 in no way shows that adding track decreases relative traction on that axle in all cases for all cars. The author even agrees that it increases absolute traction on that axle. These changes are so minor (increasing track a few percent), that weight bias, spring rates, suspension type, suspension geometry etc will all play a role, if not the dominant role. The point is, one doesn't change ONLY the track width when a change is made. Does it do what you say, for your car, in your case? I believe your assessment.
And the oft quoted tricycle analogy is a poor one. It is an extreme example where weight transfer and high CG causes instability long before any "understeer" or "Oversteer" characteristics might be seen. Can/does a tricycle understeer on ice? I'd bet yes.

Do you also read a tire test report where they used the same car to test various models and shrug it away because those tires were only better/worse on 'that particular car'? lol

The principles of weight transfer are the same across all 2 axle cars. Their magnitudes might differ but the trend of the effect is consistent. Load up your favorite car into a suspension dynamics simulator and play with track width. Feel free to prove me wrong.

Also, regarding "The author even agrees that it increases absolute traction on that axle", yes but he goes on to say traction at the opposite axle is increased even more.

So you are dismissing my tricycle analogy as being extreme, yet you responded with an even more extreme example by comparing vehicle dynamics on asphalt to ice? lol

Fine, forget the tricycle analogy. Look into the Morgan 3-wheeler which has a front track that is significantly wider than the rear. It redefines the definition of 'rabid understeer'.

Also, regarding "one doesn't change ONLY the track width" many people do, self included. It is an excellent tool to fine tune that last bit of handling balance. Regardless, this wasn't meant to be about the end-all means to magically transform the handling balance. I was merely suggesting that increasing track width adds grip to the other axle more. How much more? Well, that depends on the car and other factors such as "weight bias, spring rates, suspension type, suspension geometry etc ".

[aeronaut]

No, you do not only change track width when adding spacers. You also change (at least) scrub radius and wheel rate.