986 Forum - for Porsche Boxster & Cayman Owners

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-   -   Roll? (http://986forum.com/forums/boxster-racing-forum/75246-roll.html)

mgfranz 05-10-2019 09:20 PM

Roll?
 
Nice pic of a tight left, abut 35-40 mph... But what I see is a lot of roll and unloading of the rear. Should I be looking at coils & struts or sway bars to correct? Right now all parts are stock. Probably a combination of both, but the unloading of the rear has me thinking sway bar.

http://i65.tinypic.com/n68jh2.jpg

Racer Boy 05-10-2019 11:13 PM

Truth be told, it doesn't look like much roll at all to me, especially for an autocross.

What is your car doing, understeering or oversteering? That is what you should be concerned about. If it's balanced, don't worry too much about how much your car is rolling in the turns, unless it is rolling so far that the car is unsettled.

Trying to tune your suspension by looking at a picture of your car probably isn't the best approach, in my humble opinion.

mgfranz 05-11-2019 08:02 AM

I was getting a little oversteer before I dropped the rear tire pressure to 29lbs, tightened it up nicely. Very well balanced at that point and my times dropped over 4 seconds!

And I will agree with you, looking at a pic isn't the best way to tune a suspension if it's working, it just looked like a lot of loading.

Racer Boy 05-12-2019 12:28 PM

http://986forum.com/forums/uploads02...1557692469.jpg

Here is a picture of me going through a 70 mph sweeper at Pacific Raceways, not the kind of turn you are likely to encounter at an autocross. Notice how much the car is leaning - maybe even more than your car in the picture you posted.

The car is really well balanced, so whatever lean there is doesn't really matter.

That said, I did put slightly stiffer sway bars on last week. They are ROW M030 sways, so they are a matched set. The reason I'm going with those is because I'm going to be using track tires now, and the loading will be a bit more than with the street tires, meaning it will lean even more. I don't want to chew up the edges of the tires, so hello stiffer sways.

mgfranz 05-12-2019 12:42 PM

Nice. I'm thinking of going to the 030 bars as well when I move to the track only tires. I will probably be going to a matched set of tires, probably a 225-235 sidewall, 200 compound.

SCCA_AX 05-13-2019 07:28 AM

You call that roll? I'll show you roll:
https://4.bp.blogspot.com/-00QIBEX9A...25281%2529.jpg

Or watch a well driven current gen Miata at full toot. Tons of body roll, yet the cars manage to be super fast at autocross.

Roll isn't necessarily a bad thing, means your car (and the driver) is generating grip. Inside tires aren't doing much of anything anyways, as long as you're not roasting the inside rear on corner exit.

Stiffer speeds rate of weight transfer, and creates less total roll which may keep a tire in better camber range, but it's not always better.

mgfranz 05-13-2019 03:35 PM

That's not roll, that's stiff! I like!

thstone 05-13-2019 04:54 PM

I agree, roll isn't your biggest problem. The first and foremost parameter to worry about is camber. The stock suspension (even M030) is hugely camber limited. Lack of camber is the primary reason the outer portion of the tire will wear (although roll contributes to running out of camber).

With the right suspension components and settings, its easy to get more than sufficient roll stiffness...

http://986forum.com/forums/uploads02...1557795215.jpg

mgfranz 05-13-2019 06:05 PM

Right now I'm set up for ROW settings, and I like them. (That's a great pic btw, your car is working!). I just want a tighter feel, more seat of the pants.
When I put a set H&R springs on my Audi, the change was immediate and I loved it, but I don't track that car, I just drive it. Maybe I'm getting overboard...

thstone 05-13-2019 08:33 PM

Quote:

Originally Posted by mgfranz (Post 594999)
Right now I'm set up for ROW settings, and I like them. (That's a great pic btw, your car is working!). I just want a tighter feel, more seat of the pants.
When I put a set H&R springs on my Audi, the change was immediate and I loved it, but I don't track that car, I just drive it. Maybe I'm getting overboard...

No, you're on the right track (haha!). If you have camber under control then reducing roll will help you to balance the car better and it will also help a bit with camber so its all upside. Carry on!

Robert986 08-06-2019 02:58 AM

I have the M030 bars, Bilstein B8, sticky tires, enhanced camber and... (drumroll) quite a lot of roll.. I´m looking into switching to öhlins r&t, that might fix it, however if I still get a lot of roll and want to stiffen up the roll bars, are there any "go to" combo between rear/front? I´m guessing a combo of GT3 & tarett-bars maybe? The car is really well balanced, just to "soft" given the great grip I have.

steved0x 08-06-2019 05:56 AM

This is me loaded up for turn 5 at Roebling Road Raceway, here the car is on M030 USA suspension with Koni FSD struts and Maxxis RC-1 tires.

Tire wear was pretty good at all tracks I go to, with Roebling being the hardest on the front left tire. Shortly after this I went to GT3 front bar and Tarett rear bar which helped some, and then I ran a set of PSS9, but what helped the most was getting lots of front Camber (was at -3 here) and working on not overdriving/sliding the front when going through the big sweepers at Roebling.

http://986forum.com/forums/uploads02...1565099425.jpg

On my Cayman I have the Ohlins Road and Track and Camber set to -3.25 in front and -3 in back, with only 4 dry days at 2 wet days, including 111 laps at Roebling, wear has been pretty good. I am really liking the R&T so far.

Racer Boy 08-06-2019 05:56 AM

Robert986, your next step should be stiffer springs.

mgfranz 08-06-2019 07:41 PM

Is there any significant difference between the M030 and the GT3 bar? Can we use the GT3 rear bar on the 986 as well? I know a large concern on my car is the tire I use, I currently use a Falken Zies series, and while they work well on the street, I know I am giving up at least a second or more on the track.

thstone 08-08-2019 12:56 PM

Quote:

Originally Posted by mgfranz (Post 600469)
Is there any significant difference between the M030 and the GT3 bar?

Here is a chart comparing a few of the stock, M030, and 996 GT-3 front and rear sway bars. Yes, the M030 and 996 GT-3 sway bars greatly differ. As the chart shows, the GT-3 front sway is 1.51 (or 51%) to 2.06 (100%) times as stiff as the Base M030 front sway bar (depending on which hole is used).

http://i1114.photobucket.com/albums/...ps3e2f2609.jpg

Quote:

Originally Posted by mgfranz (Post 600469)
Can we use the GT3 rear bar on the 986 as well?

No, not easily. The most common rear sway bar upgrades are the M030 or the Tarrett adjustable 986 sway bar.

Quote:

Originally Posted by mgfranz (Post 600469)
I know a large concern on my car is the tire I use, I currently use a Falken Zies series, and while they work well on the street, I know I am giving up at least a second or more on the track.

Yes and no. Yes, a more track oriented tire will provide much greater grip. But a higher performance tire won't significantly affect the chassis roll.


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