flush with stock wheels. with Stud installation.

[dsgerbc]

Originally Posted by Draco-REX

Ok, I see what you're getting at. But I think the actual difference in this case is going to be so small that it won't matter. Given time I could come up with the numbers, but I think we're looking at less than a degree difference of the thrust forces against the bushings.

I'm not sure of the size of the effect, too many unknowns. I was hoping that by now people would have CAD files up for our suspension

[Laika]

Originally Posted by Evil86

How did you remove the original ones? Did you drive them out?

I don't know if someone can chime in with a more professional method but when I and a friend changed his WRX studs I just used a big hammer and drove them out. They weren't being used again but depending on the hammer you use, you don't have to actually damage them.

[RallySport Direct]

Wow I really like the way it looks. And I am not going to touch on the Scrub Radius issue, as this is something I have just started to study, so I will leave it to you guys.


Thanks,
Rick

[wheelhaus]

Do a quick google images search, if you can read geometric schematics it's instantly recognizable what spacers affect in reference to scrub radius. I'd link but I'm lazy right now. It's similar to caster and trail, but sideways. As far as it's effect within a suspension system under side load, compression, etc, I'm still learning, too...

If 10" wide wheels don't destroy the bearings, I highly doubt 15mm offset will. But, in either case, I wonder how bearing life will be affected. Something tells me we'll find out soon, considering all the huge wheels going on these cars already... Anyways, since you're swinging the entire wheel around a larger steering arc, you may get some strange feedback and tramlining, the forces will be different.

This car seems to have had more engineering efforts put into it's "feel" than an entire F1 team spends on developing a new chassis, lol... For that reason alone, I'd be suspect changing ANYTHING with the suspension system without proper research and testing. The bushing comment made above (I read the same study) is also why I'm holding off on any suspension mods for a while. You may "feel" a change and think it's good, but that doesn't mean it's actually for the better.

[RyleyMA61]

can we get some better pictures please? from the side, front and rear quarter shots etc. Thanks!

[uptown]

Will wheel spacers, if only installed on the rear hubs, effect performance negatively?

[White Shadow]

Some of you guys are so critical! These are 15mm spacers....that's pretty mild and certainly isn't considered extreme. Installing them isn't going to change the way the car feels or handles. If it does, then you must be the most sensitive driver in the world and driving the car at 10/10ths on a racetrack or something. Under normal driving conditions, 99.99% of drivers wouldn't even notice a tiny bit of a difference. Also, keep in mind that this is technically no different than someone installing aftermarket wheels with a more aggressive offset.

[Eau Rouge]

Originally Posted by dsgerbc

"Scrub radius", google it.

+1 on needing to be wary of changing your scrub radius and its effects on handling. Here's a link to some basic information that some might find educational: http://en.wikipedia.org/wiki/Scrub_radius

[Eau Rouge]

Originally Posted by uptown

Will wheel spacers, if only installed on the rear hubs, effect performance negatively?

Effects will be different than spacers on the front end where steering occurs, likely less dramatic, but there should still be some effect. Positive or negative depends on what you are trying to accomplish. At the very least, leverage against the spring/damper would increase so your effective wheel rate (vs. spring rate) would be lower, as would the suspension resonance frequency. Exactly how much change couldn't be determined without "crunching the numbers".

As I understand it, the rear wheel track width is actually 20mm narrower than the front track. If your objective is to get the tracks to be the same, a 10mm spacer on each side of the rear would about do it. Of course, what width spacers you should consider would depend on your actual objectives.

[glorydays]

Aww come on this thread needs better pics...

[ATL BRZ]

more pics?

[Eau Rouge]

Originally Posted by Draco-REX

"Scrub Radius" has become an evil term to decry low offsets and spacers. The thing is, it isn't all that bad. It will make the steering heavier and kill some of the feel, but that's about it.

/\
I just re-read this and had to laugh because:

1. "It isn't all that bad" clearly means it can't be good
2. "It will make the steering heavier and kill some of the feel", both of which indicate a negative outcome

Way to support your position on the effects of increasing scrub radius.

[Eau Rouge]

Originally Posted by White Shadow

Some of you guys are so critical! These are 15mm spacers....that's pretty mild and certainly isn't considered extreme. Installing them isn't going to change the way the car feels or handles. If it does, then you must be the most sensitive driver in the world and driving the car at 10/10ths on a racetrack or something. Under normal driving conditions, 99.99% of drivers wouldn't even notice a tiny bit of a difference. Also, keep in mind that this is technically no different than someone installing aftermarket wheels with a more aggressive offset.

Has anyone done the match to see what a 15mm addition to the effective length of the lower suspension arms actually does to other specifications such as effective spring rate at the wheel, suspension resonance frequency or corner jacking as the front wheels are turned? Okay, maybe it's just me but it does reduce the first two and increase the third one.

I do agree that most won't notice and, if you're just going for appearance, knock yourself out. If, however, you think you're wanting to "improve" your car's handling, it would be best to actually know the effects of any changes you may make. "Improve" can be subjective though so the overall goal for someone may not be exactly the same for the next person. I'm just saying there should be a bit of "caveat emptor". In this case, rather than buyer beware, it's probably more like modifier beware.

[Draco-REX]

Originally Posted by Eau Rouge

/\
I just re-read this and had to laugh because:

1. "It isn't all that bad" clearly means it can't be good
2. "It will make the steering heavier and kill some of the feel", both of which indicate a negative outcome

Way to support your position on the effects of increasing scrub radius.

Out of curiosity, why haven't you been on the threads with people running 35mm offset wheels then? Same thing, really.

I was pointing out that "Scrub radius BAD!" is an absolute and as such is incorrect. Increasing Track width is a good thing. And while there are some drawbacks, the amount of increase he's talking about isn't going to impact his performance negatively.

The issue is finding where theory meets reality. Worrying about a 15mm increase in scrub radius is splitting hairs. It's like the SAI discussion on the Subaru boards. Interesting in theory, but it doesn't pan out in the real world because the steering angle at any given speed is never great enough to impact the camber to the point where it matter for the speed the car is going.

In this discussion, 15mm of spacer (or 12mm of wheel offset) will not significantly impact the performance of the car. ALso, considering he's using the stock wheels and tires, it's pretty obvious he's not using the car in a competition where 100ths matter, and I'd still argue that 15mm of spacer is better than not in that form of competition. You only have to go to any AutoX to see modern positive-offset cars running negative-offset wheels.

So really, Scrub radius = Meh.