Scrub Radius

"Roadster Man" (roadsterman) 04/23/2015 at 21:55 • Filed to: None

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A picture of my car for your trouble:

Any Oppo guys have any good articles or resources on “Scrub Radius” and how it affects handling and braking? I bought another set of wheels (pictured) and I’m not particularly happy with how they handle.

I know scrub radius generally affects parking lot handling, but I know it can also affect high-speed handling, how the car behaves under braking, etc. I have found some scattered information on the Miata forums but not enough to give me a good understanding of the physics at work here. I know there are some engineers who are willing to break this down for me.... Or copy-paste the link that I can’t seem to find. Thanks in advance homeboys.

jkm7680 > Roadster Man 04/23/2015 at 21:57

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Raise ride height a bit.

Roadster Man > jkm7680 04/23/2015 at 22:21

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No can do. Shocks & Springs my friend, no coil-overs.

jkm7680 > Roadster Man 04/23/2015 at 22:29

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Just messing with ya, haha.

Boxer_4 > Roadster Man 04/23/2015 at 22:36

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I’m not sure how much this helps, but H&R seems to have a decent explanation.

What are the specs (specifically width of both wheel and tire and wheel offset) of both your new wheels/tires and your old wheels/tires (assuming you liked your old setup better)?

desertdog5051 > Roadster Man 04/23/2015 at 22:59

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Nice pic. Hat tip to you.

The last time I thought about scrub radius was when I was cleaning the floor and wished my arm was longer. :)

dr861 > Roadster Man 04/23/2015 at 23:28

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Nicely done good sir. This is one mean miata.

e36Jeff now drives a ZHP > Roadster Man 04/23/2015 at 23:50

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I dont know how good your understanding of mechanicals are(im hoping ok-good), but the wiki article on it is pretty explanatory and has pictures. http://en.wikipedia.org/wiki/Scrub_rad…

It is probably a good pre-read to the H&R article someone else already posted though. it more goes into what it is, not what it does.

alwaysmiata > Roadster Man 04/24/2015 at 08:29

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This might help. The whole series is pretty good

http://www.motoiq.com/MagazineArticl…

TTercel > Roadster Man 04/24/2015 at 09:59

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Check this out, it is a full guide to suspension tuning.

http://www.motoiq.com/MagazineArticl…

Roadster Man > TTercel 04/24/2015 at 10:13

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Awesome! I was hoping that MotoIQ would have a good article but I couldn’t find one myself. Thank you!

Roadster Man > alwaysmiata 04/24/2015 at 10:13

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Yes. Exactly what I was looking for. I go on MotoIQ all the time, I dunno how I missed this.

TTercel > Roadster Man 04/24/2015 at 10:17

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No problem It’s a pretty intensive read, so take your time to absorb it all. I tried reading someo fo it but ended up tl;dr after some pages haha. Once I get coilovers for my gen 2 Integra maybe I will have to give it a read.

Roadster Man > Boxer_4 04/24/2015 at 10:18

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That H&R link was pretty helpful. Thanks!

I used to have 15x9 et36 on 225/45 Hankook RS3 tires. Those rubbed on the inside against my springs at full lock. It bugged me a ton and rubber that wide on a Miata really wants to follow the road. I was constantly fighting the car, but I had so much grip.

So I found a set of 15x8 et0 with brand spanking new Nitto NT-05 205/50 tires. I got the wheel/tire combo for the price of the new tires alone, so I’m not heartbroken about this result. I know I want to stick with 15x8 and 205 rubber now, but I want to step back from such an aggressive offset because I don’t like how these drive. I want these articles so I can figure out exactly why I don’t like how it drives now.

Roadster Man > desertdog5051 04/24/2015 at 10:20

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Thank you! iPhone 5S if you were wondering, no instagram filters either...

Roadster Man > dr861 04/24/2015 at 10:21

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Thanks man. What you can’t see is the missing 1/4 of the front lip on the driver’s side courtesy of a dump truck dropping a rock in front of me.

Roadster Man > e36Jeff now drives a ZHP 04/24/2015 at 10:22

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Haha, yeah “ok-good” is about where I’d put myself. I’m no engineer though. The Wiki was a helpful primer to the H&R and MotoIQ articles. Thanks!

alwaysmiata > Roadster Man 04/24/2015 at 10:43

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No problem. Are those NT05s on your car? If so, how do you like them? The only car I have driven with them was an LS1 F-body so I am curious how they would be on my Miata.

dr861 > Roadster Man 04/24/2015 at 12:11

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Damn, that sucks!