Oversteer issues with Tein Flex A

[D_Thissen]

Originally Posted by brzsubie

Checked already and everything was good

Define 'good'. What were the F/R psi's?

[Clipdat]

How can you "datalog" a coilover system's performance?

Originally Posted by CSG Mike

Get me a datalog from your car, and I can determine what is actually happening.

If you are able, replicate the event with the pedal dance active, on a skidpad or similar safe location, and get a datalog.

[Gunman]

Originally Posted by Clipdat

How can you "datalog" a coilover system's performance?

Shock pots, load sensors, etc.

[Icecreamtruk]

A simple log of G-forces, throttle pedal position, brake pedal position and steering angle will tell you exactly what is going on. Additional data like speed along with an overlay of the track map helps even more. Most laptimer apps do this by default, so its basically a "export as CSV" and send it, really simple stuff.

[CSG Mike]

Originally Posted by Clipdat

How can you "datalog" a coilover system's performance?

Great question. With just wheel speeds, accelerometer data, and GPS data, I can extrapolate (quite precisely), what is going on in the car.

I do data analysis for race teams

An AIM Solo DL does all of the above and more, which is I recommend it so frequently; it's a bargain for $700.

[JazzleSAURUS]

I think you may need a chance to step back and ensure everything is right.

Check the torque spec on all alignment related hardware.
Set tire PSI to 35psi at all 4 corners, (this is entirely just to rule the tires out so you can get some of the underpinnings right.)
Look over the coilover install instructions from Tein. Are your lower mounts set correctly? I had a set come to me where the height appeared to of been set by using the preload, (slammed,) and the lower mounts were up as high as they could go. Spinning the coilover back down into the mount to Tein's specs and checking preload resolved a very harsh feeling everywhere, (this was on Flex Z's, felt like bumpstops on tiny bumps...it most likely was.)

What tires are you running? What's their condition? If you're asking too much of junky all seasons, or have 'tired' old tires, you could be down on grip which is making the tc light flicker at you and upsetting concentration and the car as well.

I think the folks suggesting some actual data are correct, that there's a bit of proving everything is okay, but you should do all you can to rule out a mechanical issue, and incorrect installation is a common issue with coilovers, be it noise or handling/compliance issues.

[samson123]

im not sure if you chose to get oem alignment but if you did that could be the problem. when you change the ride height of the car, the rest of the geometry changes aswell. you will need to get parts like adjustable toe arms/balljoints along with a custom alignment to go along with all the stuff you changed. for the bouncy feel, you might be able to solve that by adding more preload on the spring. the spring rates on the flex a is only 6k f and r so it might not be stiff enough to stop the bounciness.

[FirstWinter]

Originally Posted by samson123

im not sure if you chose to get oem alignment but if you did that could be the problem. when you change the ride height of the car, the rest of the geometry changes aswell. you will need to get parts like adjustable toe arms/balljoints along with a custom alignment to go along with all the stuff you changed. for the bouncy feel, you might be able to solve that by adding more preload on the spring. the spring rates on the flex a is only 6k f and r so it might not be stiff enough to stop the bounciness.

You don't need adjustable toe arms. You'll be fine with the stock ones unless you're going crazy with your camber/toe. Is it nice & makes it easier for your alignment guy? Sure.

[strat61caster]

I agree there's no way to know if it's oversteering or not, but imho it's not really relevant.

Focus on the actual problem which is the driver sensation:

Originally Posted by brzsubie

When I'm about at the apex of a turn the car feels almost bouncy and the rear starts to slide a little and traction control comes on.

Ride heights, bump stops, spring rates, damping, wheel weight, tire size, tire compound, tire wear, tire pressure could all be causing the issue or help in alleviating it.

Regardless of actual handling balance of the car or if traction control is on or off, the car doesn't feel good and I think anyone would agree the OP is describing a problem worth solving.

Alignment is good provided everything is tight, the printout looks like it's from a good local alignment shop that should have checked all that, but that doesn't rule out potential problems though.

There's also the possibility that as the OP has grown comfortable with the car they're driving it more aggressively and you're simply asking the car to do more than it's capable of doing given the tires it has and the road quality. Adding gas while turning = back end slides out, even at moderate speeds. The joy of decent torque available at ~3k rpm.

Originally Posted by samson123

im not sure if you chose to get oem alignment but if you did that could be the problem. when you change the ride height of the car, the rest of the geometry changes aswell. you will need to get parts like adjustable toe arms/balljoints along with a custom alignment to go along with all the stuff you changed. for the bouncy feel, you might be able to solve that by adding more preload on the spring. the spring rates on the flex a is only 6k f and r so it might not be stiff enough to stop the bounciness.

OP got an alignment and posted it in the very first post. He needs no further parts to achieve a good street alignment and the numbers look good.

Bounciness has to do with damping, not spring rates or preload. You can make any spring on any car feel not bouncy with the right damper tuning. You can also make it feel like a pogo stick on each corner with a bad damper.

In OP's case I suspect a ride height that is too low is causing excessive bump stop usage which means the effective spring rate is too stiff for the damper, softening the damper just makes it bouncier.

[sIowbrz]

i see that your adjusting from *FULL SOFT* arnt you suppose to adjust it from *FULL STIFF* seems from the post you have the rear stiffer than front... and also what kinda tires you have on?

[JazzleSAURUS]

Originally Posted by strat61caster

In OP's case I suspect a ride height that is too low is causing excessive bump stop usage which means the effective spring rate is too stiff for the damper, softening the damper just makes it bouncier.

Agreed.

With coils that adjust height from the bottom, using preload to adjust ride height is a common symptom. "But I'm not that low!" Because preload non-existent and the strut body is barely in the mount at all.

It's either a ride height issue, or a setup issue I bet. (Wrong end of the coilover is being played with...)

[EffaressNOOB]

Originally Posted by PandaBRZ

Chiming in here. I drove @brzsubie's car and there is oversteer but the more pressing matter is that the dampers aren't critically damped and making the car unpredictable during hard driving. To my feel, the car is neutral but the car is unsettled easily. We dialed the front to 12 from full soft and the rears 15 from full soft. These settings felt compliant enough for the backroad we were driving on but the dampers feel underdamped on rebound. Compression felt fine.

What would help is if someone with Flex As and track experience chimed in with their settings to get us started with dialing in the shocks.

Thanks.

You have to adjust from full stiff. I’ve noticed that you can click 28 times towards soft. Tein recommends not going passed 16 clicks from full stiff. Sooooo, for instance.... if you clicked 12 times from your definition of full soft, you’re actually now on full soft using Tein’s recommendations.


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[norcalpb]

Have you considered you live in the Bay where the roads are FUBAR?

[NoHaveMSG]

How is the spring preload on each coilover? One with more/less then the rest maybe?