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Old 04-14-2017, 10:35 AM   #11
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Originally Posted by Biggins View Post
Thanks for the suggestions. I'll play around with settings more tomorrow at the test day.

The car is mostly good everywhere except mid-corner to corner exit when I get the oversteer. It is very good on corner entry. In transitions, the car is good and easily manageable but not particularly stable, but I thought it was slightly better the season I had a little wider tires (235 vs. 225).

I hate to say this and it could be ignorance, but I really cannot tell a ton of difference in the OTS Konis when I do 1/2 turn increments. Most people run a little less up front (1.5 turns from soft vs. my 1.75) and a little more in the back (1 turn from soft vs. my 0.5). I've tried that and did not notice a difference, but I'm not convinced the OTS Konis make a huge difference vs. stock shocks on this car which is why I still am hoping to save enough for MCS.

I am running the smallest aftermarket front bar (19mm) on the soft setting, so I'll try the hard setting this weekend for a few runs. The TRD bar I want is 20.6mm and Sam's is 22mm hollow, but most people opt for the Whiteline 20mm on hard setting. The TRD rear bar is 17.5mm vs. OEM 14mm, but I'm not looking to change that until I can afford the MCS and really do some testing/tinkering.

For the less rear toe-in, just so I'm not screwing up the positives/negatives, do you mean go closer to 0 toe from the 0.17 on each side?

Another note is that the only time I ran data with Craig, I was always way faster on corner entry, he was faster on corner exit, but we still would run the exact same times (within 0.1). It could just be my driving style?
Adjusting by feel is all kinds of error prone. It will get you to what feels fast and comfortable, but that's not necessarily fast. The looser the RX-8 was, the faster it was. But I was faster in it when it was a little tighter than it should have been. That wasn't good for JV.

Data. Even video of runs compared frame by frame can help if you have notes about what was different about settings and driving.

Be careful when looking at bar specs. Rate matters more than thickness or outer diameter. A "smaller" hollow bar with a greater wall thickness may have a higher rate than a bigger bar. It's not always easy to get that info.
OH NOES!!!!!1 MY CAR HAS T3H UND3R5T33R5555!!!!!!1oneone!!!!11

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Old 04-14-2017, 11:54 AM   #12
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Originally Posted by bren View Post
Oh, and don't get a z06, your driving style won't work very well - ask me how I know.
I've only ever driven a regular C6. It seemed fine, but it wasn't for me.

Originally Posted by John V View Post
One of the things we always ask in the morning at the Evo schools is "How many of you think your car understeers?" We ask the same question at the end of the day and get a lot fewer people raising their hand. I agree with Bren's assessment, you might be standing the car on its nose and snapping the throttle open which can cause oversteer. Or it could be as simple as you're not unwinding the wheel. Do you have any video?

Positive toe on the alignment sheet is toe-in. Negative is toe-out. So you have about 1/8" of total rear toe-in, which doesn't sound excessive to me, but I like to run as close to zero toe in the rear as I can get away with. Now, more rear toe-out will make the car looser on corner exit and in transitions but theoretically the car will slalom faster like that. I like to be able to hammer on the car through slaloms and not have it come around on me. If I can't do that, I'll make shock changes until I can.

Look up some shock dyno curves for your shocks and see what the rebound curves look like at full stiff versus full soft. I don't remember how single-adjustable Koni curves look.
I'd have to dig for some video. Craig and I would run video, but I haven't for a couple years. I do find myself making more steering corrections in sweepers than I should. Maybe I should get a GoPro and pay closer attention.

I would love to have a little more slalom stability, but I'm just afraid it would be rough in the sweeping turns. I'm glad I have this test tomorrow to play with things. I know that the re-valved Konis that some have been running seem to be much better than the OTS, but I have not driven one with those quite yet.

I'll play around this weekend a bit more, but I think a quick change to the stiff setting and going closer to 0 toe will be my first move besides working on the driving.

Originally Posted by clyde View Post
Be careful when looking at bar specs. Rate matters more than thickness or outer diameter. A "smaller" hollow bar with a greater wall thickness may have a higher rate than a bigger bar. It's not always easy to get that info.
The FT86 forums actually have a really good dataset of bar stiffness levels. I'm not sure how scientific, but it seems accurate. No one who is competitive runs a bar larger than Sam's in Street, but a few brands' 20-22mm bars seem to be the sweet spot (with/without the rear TRD bar).

Thanks again! I'll report back if I notice anything else.
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Old 04-18-2017, 09:30 AM   #13
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I had a lot of time to play with some settings and get some seat time on a couple decent but not great courses at Saturdayís BMW test-n-tune. Iím not sure Iíd call my testing process scientific, but I think I learned a few things. It was super dusty and pollen was flying everywhere.

The big takeaways:
1. I seem to be taking sweeping turns too wide. Once I started cutting the wheel more on entry and staying tighter, I dropped 0.5-0.7 seconds.
2. I played with shock settings. I went down ĺ turn in the front from stiff vs. my usual Ĺ turn from stiff with the Ĺ turn from soft in the rear and it produced my best times consistently by 0.2-0.4 seconds. I tried even less rebound in the front, but the car got a little wonky. I also tried more rebound in the rear, but that did not solve anything and made things worse. I plan to play with shock settings a little more at future events, though Iíll start ĺ turn from stiff front and Ĺ turn from soft rear.
3. The car was still not fully confidence inspiring in slaloms. This could be from the nearly corded 192 run Bridgestone tires from 2015, but my quickest runs needed a tap of the brake on slalom entry to stabilize and point the car in the right directionÖ others didnít need that. Iíll be on newer tires at the next events, but I think Iíll have to go with a bigger front bar soon enough.
4. I worked hard on rolling steadily onto the throttle mid-corner to exit instead of just mashing the gas, and itís something I need to remember to keep improving. This might be part of my problem.

Thanks again for all the suggestions, Iím going to keep working on set-up this year to get it to work with how I drive.
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