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Old 09-19-2014, 01:44 PM   #1
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Are you running the 14mm MSM rear bar on track? Sometimes it seems like it may be a little too stiff for me. When my rear end breaks loose it is rather sudden and I have spun or gone off a couple of times. I am a low level intermediate driver so it may be nothing more than a lack of skills. Don't get me wrong...I love this suspension, just looking to get the most out of my car with my abilities. I have 700/400 clubsports with the dual springs SA on a 2450# 2002 fully loaded car w/o me in it. I guess I could just install my 12mm and see, but wanted some feedback from the experts

Thanks!
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Old 09-19-2014, 02:24 PM   #2
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Been running a 14mm rear bar since way before the BGK existed. It's definitely the right bar for track use, IMO.
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Old 09-19-2014, 03:11 PM   #3
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There are so many variables to consider with your setup. Spring rates, bars, ride height, alignment, corner weights, aero, driving style...
I used to ask questions like this. Maybe I still do in private. Lol
But the only way to figure out what is going to work for you is to test things. Don't be afraid to try different things. I used to be afraid to make big changes in fear that it would be so far off that it could waste a session. However it's the only way to really learn what different changes will feel like.
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Old 09-19-2014, 04:04 PM   #4
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Shaikh over at Fat Cat Motorsports has this Front Roll Couple calculate available (see the link bellow). It's a quick and simple way to see what changes springs, sway bar sizes, etc effect your FRC. He also has some good youtube videos.

FCM_MSDS_1_8NB.xls
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Old 09-19-2014, 05:11 PM   #5
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14mm works great. I am running 700/450 xidas.

probably just need some practice with this stuff. catching the rear isn't always that easy depending on the situation. Lots of other factors as Eric mentioned.
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Old 09-19-2014, 05:13 PM   #6
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Low-level intermediate? Spinning?

I'd recommend that you set the shocks to a middle position, run a consistent hot tire pressure and go get maximum seat time. I think that spending a bunch of time messing with the suspension before you really know how to rotate the car will be counterproductive. Once you're going fast enough that you're comfortable with throttle steering and trail braking, then you can start the suspension fine tuning.

In other words, work on the driver first.

I'm running the OEM non-MSM Miata rear bar on mine and would like more bar because it can be hard to unstick the rear sometimes. I suspect you will grow into the formula you have and start liking it more. It's a well-proven setup.
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Old 09-19-2014, 05:42 PM   #7
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Ride height (too low) or shock settings are probably causing the abrupt oversteer with that setup. If it was just in general loose I'd be pointing more towards alignment being a problem, or having too much rake if the alignment was good.
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Old 09-19-2014, 05:49 PM   #8
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I was running a middle setting (4) front and rear. I have more recently moved up to (5) front and rear and like that better. Seems to stick better. I use a pyrometer to set tire pressures. I think I do need more seat time. I've spent a lot of time and money over the last couple of years prepping the car. I can now afford to spend the extra money driving. When I first started (with this car) I had all season radials on it and discovered I could steer the car in some turns with the gas pedal. I am more afraid to do this now with stickier tires and higher speeds. I have never been good at deciding what my suspension needs. I raced Motocross and other offroad motorcycle racing for about 30 years and never was good at knowing how to set things up other than following what others did! That's why I followed Emilio's recipe.
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Old 09-19-2014, 05:52 PM   #9
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I have the rake and the street and track alignment recommended on 949's site
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Old 09-19-2014, 06:54 PM   #10
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My car is very similar, ~2530 lbs empty, 700/400 Big Grip kit. I've never had the rear feel overly loose as you are describing. When I was on Rivals or RS3's I ran the shocks at 8 front & rear. I have some aero now, a CoT wing planting the back and a front lip, but before aero the car was neutral and balanced. I've certainly spun it a couple of times, but it was always clear to me what I had just done to cause the spin. It's never had a sudden-breakaway type feeling like you are describing.

Can you describe the conditions under which you are feeling the car be loose? Knowing how you're loading the suspension with the car can help us figure out what to change.
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Old 09-19-2014, 07:19 PM   #11
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I never said it was "overly" loose, just that when it does let go, it is the rear that goes. I thought a well balanced car would slide all four wheels at once. It has happened on a wet track when I thought the car had taken a set in a turn, it has happened in the dry, when exiting a corner that I late apexed for the next turn leading on to a straight. Sometimes I feel it letting loose and I catch it.

I think Hornetball is right I need to get more seat time
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Old 09-19-2014, 08:41 PM   #12
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Quote:
Originally Posted by tomiboy View Post
I thought a well balanced car would slide all four wheels at once.
This is a myth.

No matter how well "balanced" a car is, at the absolute limit of grip either the front tires or rear tires will lose grip first. The more "balanced" a car feels, generally it means there is more ultimate grip but in the end, one end of the car will always break away first.

A car that is set up really well but at the absolute maximum tends to under steer is "safe" and "easy to drive". A car that is set up really well but at the absolute maximum tends to over steer is...fast.

That's taking a very basic few of things. Most cars exhibit differences in the "absolute maximum" behavior between turn-in, mid corner, and corner exit behaviors. You might have a car that overseers on turn-in, is well balanced through mid corner and under steers at corner exit.

Generally, sway bars have the largest affect on mid corner or "steady state" behavior. If you find that the car always seems to oversteer, if you're constantly fighting the back end of the car through the whole corner, then too much rear bar may be likely. If you find that it "snap" over steers on corner entry or exit then it's more likely that it could be shock settings, alignment, or tire pressure related.

OR, it could be that your still learning the car and aren't comfortable driving a "loose" fast setup. There's nothing wrong with that and most drivers usually don't like a loose car. If you truly feel the car is too loose and unpredictable all the time, then it might be worthwhile looking into setup changes that will tend to make the car under steer more.

Best of luck. Whatever you don't don't stuff the car into a wall driving a car you're not comfortable with because you set it up based on Internet "wisdom".
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Old 09-19-2014, 10:43 PM   #13
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Quote:
Originally Posted by tomiboy View Post
I never said it was "overly" loose, just that when it does let go, it is the rear that goes. I thought a well balanced car would slide all four wheels at once. It has happened on a wet track when I thought the car had taken a set in a turn, it has happened in the dry, when exiting a corner that I late apexed for the next turn leading on to a straight. Sometimes I feel it letting loose and I catch it.

I think Hornetball is right I need to get more seat time
if you are oversteering during track out, then you may need more rear camber or stop pinching your turns after the apex. A lot of people tend to pinch track out. Also, late apex, before a straight on a slow corner...you maybe taking it too fast.

At intermediate levels (truly intermediate), you should be comfortable enough adjusting tire pressures and have a general/basic idea of what to do with compression/rebound. More importantly, know what your alignment is doing for you. You should experiment with these things lightly so you get a feel for their effect on the car.

Suspension setup will change drastically based on grip conditions, so keep that in mind if you have mixed conditions during your day/weekend.
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Old 09-19-2014, 11:08 PM   #14
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It's not your rear sway bar. Sounds like it maybe bottoming out in the rear. Make sure you have enough clearance between the bump stops and the shock body. If not adjust ride height or trim the bump stops.

I find the rear bar affects turn in and mid corner the most. By track out it's less of an issue. I ran a 15mm rear bar before dropping down to a 14mm. Track out was pretty much the same with each.
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Old 09-19-2014, 11:37 PM   #15
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We need videos so we can properly critique you
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Old 09-20-2014, 09:41 AM   #16
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What is your exact pinch weld height with driver in the car?
Hot pressures?
How many clicks from full clockwise on the dampers?

Is the sudden over steer in response to bump or driver input? If driver input, lift throttle brake or steering?
Corner entry, mid turn or exit?
Only one direction or both left and right?
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Old 09-20-2014, 10:10 AM   #17
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It's been awhile since I had it aligned, but I had the guy follow your street/track alignment.

I usually end up at 30 PSI hot with RS3s

In the wet I am on the softest setting. On a dry track I go clockwise 5 clicks from full soft front and rear

It is not from hitting a bump. Probably induced by me backing out of the throttle or too much steering input

Right turns, but my track is clockwise so there are more rights.

I'm not sure there is really an issue from reading the previous posts. This is not a regular occurrence. Actually it has only happened 3-4 times, but it shakes my confidence. I'm beginning to believe I am just making some small errors that lead to it letting go. My thought was it should go into a 4 wheel drift if set up properly, and I'd have more time to reel it in. I'm now realizing that may not be reality
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Old 09-20-2014, 11:52 AM   #18
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consider playing with shock settings. its rare that I end up with a square setup.
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Old 09-20-2014, 12:19 PM   #19
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I have a friend that has the same set up as I and I believe he is much stiffer in front than rear with his shock settings. Is that typical?
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Old 09-21-2014, 08:06 AM   #20
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Quote:
Originally Posted by tomiboy View Post
I have a friend that has the same set up as I and I believe he is much stiffer in front than rear with his shock settings. Is that typical?
I am usually about 3-5 clicks stiffer (in the front). depends on tires, conditions, etc. though.
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