CSG Spec Tein Flex A Owners Thread

[Var]

Originally Posted by timurrrr

Isn't that the whole point of RC kits? To have near-stock control arm angles while still reducing the ride height.

If you have a damper length designed for lowering with stock arms and then use it with an RC kit, you get double the lowering. You need to actually make the damper longer to work with an RC kit to get the optimal control arm angles.

Are you talking about just a roll center kit or a drop spindle kit? Those are 2 completely different things. A roll center kit does not lower the car. It only compensates for control arm angle at a given ride height. It's basically just a taller ball joint. A drop spindle kit places the spindles higher up on the upright, which moves the wheel mounting point upward, thus lowering the car without affecting geometry.

If you are talking about a drop spindle kit, the dampers designed for factory arms, at least in my case with the CSG FLA, were tall enough to get the control arms parallel. This is with the bodies fully extended but leaving enough threads in the lower mount for safety. With the shock bodies fully extended, and with control arms at or close to optimum geometry, the car sits very low. If you purchased a taller lower mount to raise the car up an inch for example, your parallel control arms would no longer be parallel. They would now be facing down on the outsides.

This is effectively the same thing that happens to 4x4 vehicles when they are lifted without correcting geometry

[CSG Mike]

Originally Posted by timurrrr

Well, HBS only works as good as the damper travel range is set up. Assuming the Wisefab front kit also has a drop knuckle, one would need to compensate for that drop with the lower bracket in order for the HBS to prevent digging the tire inches into the fender liner.

I certainly do bottom out the HBSes regularly, just by driving on a highway. As far as I understand how HBSs work, the difference from regular bump stop is just that when a HBS bottoms out it doesn't bounce back (it absorbs the energy through viscosity and converts into heat) as a rubber bump stop (which releases the potential energy back to the car body). See

.

Basically it's like dropping a sandbag on a hard floor vs basketball. It's not some magic pill to prevent a damper from bottoming out though.
Please correct me if I'm misunderstanding how HBS works, preferably with references to TEIN public technical info.

The HBS engages on compression only, and only at a high enough piston speed, at a designated part of the stroke range (at the upper end of shock travel).

In particular, this allows for rally cars to run very long, low rate springs, to have huge droop travel, without bottoming out when landing from jumps!

This video better visualizes exactly what the HBS does.

[churchx]

Roll center kits .. isn't it more about front suspension, KCA435 that is, which is from updated ball-joints/tie-rod ends for more lowered cars?
For rear i recall mostly LCAs with relocated shock mount points to retain shock travel even with more lowering .. not so much about angle of LCA itself? (as otherwise one would need to move rather LCA inner pivoting point at subframe to keep angle, no?), and of course diff risers to also retain axle angles/reduce wear on CV joints?

[timurrrr]

Originally Posted by Var

CSG FLA, were tall enough to get the control arms parallel. This is with the bodies fully extended but leaving enough threads in the lower mount for safety. With the shock bodies fully extended, and with control arms at or close to optimum geometry, the car sits very low.

Got it, looks like this particular kit lowers the car much more than you wanted.

[timurrrr]

Originally Posted by CSG Mike

The HBS engages on compression only, and only at a high enough piston speed, at a designated part of the stroke range (at the upper end of shock travel).

In particular, this allows for rally cars to run very long, low rate springs, to have huge droop travel, without bottoming out when landing from jumps!

Got it, that aligns with my understanding of how the system works.

Originally Posted by CSG Mike

This video better visualizes exactly what the HBS does.

The video is great indeed. Looks like dropping a sand bag, just a little more viscous than that
I presume with a regular bump stop on the same rig the weight would bounce back up, and that's what you call "bottoming out".

What I call "bottoming out" is "the damper is compressed to the point it can't compress anymore, or to the point it resists further compression at a rate much higher than the spring rate".
In other words, when suspension no longer "works": impacts from bumps are transmitted to the chassis, and the tire has reduced traction.

Having that said, for a HBS to prevent the tire from interfering with stuff around it, the damper body length should still be adjusted correctly. When it comes to RC / drop spindle kits that lower the car compared to stock suspension, that means the damper body should be proportionally extended relative to settings used with stock suspension.

[Var]

Originally Posted by timurrrr

Got it, looks like this particular kit lowers the car much more than you wanted.

Correct, as I wanted exactly zero lowering

[timurrrr]

Originally Posted by Var

in my case with the CSG FLA, were tall enough to get the control arms parallel ... the car sits very low.

Looks like the only solution is to remove the Wisefab kit. With this kit you basically just replaced "geometry is not optimal" problem with another "geometry is not optimal" problem, while replacing all the bushings and paying at lot of money. For that amount of money I'd expect the only acceptable outcome to be "geometry is better than with stock arms".

It appears that the CSG FLAs are not really part of the problem here after all.

Curious what RC kits are recommended by CSG to to achieve better suspension geometry at the same ride heights as one gets by just installing CSG FLAs with recommended settings on stock arms.

[Var]

Originally Posted by timurrrr

Curious what RC kits are recommended by CSG to to achieve better suspension geometry at the same ride heights as one gets by just installing CSG FLAs with recommended settings on stock arms.

The cheapest option is the Whiteline roll center kit. It adjusts both FLCA for roll center and the tie rods for bump steer. Relatively inexpensive at just over $200. These are not adjustable parts and just give you a static compensation by lowering control arm and tie rod ends at the knuckle

The "correct" way to do it is the SPL FLCA and the SPL Bump Steer kit, for around $1600 in parts alone. These are adjustable with shims to your desired angle. That control arm has much more adjustability than just roll center compensation though. There are always more risks involved in having parts that are adjustable beyond our means and understanding. But the parts themselves are legit af

[Var]

Originally Posted by timurrrr

Looks like the only solution is to remove the Wisefab kit. With this kit you basically just replaced "geometry is not optimal" problem with another "geometry is not optimal" problem, while replacing all the bushings and paying at lot of money. For that amount of money I'd expect the only acceptable outcome to be "geometry is better than with stock arms".

Yup. Or the other solution is that I compromise and just deal with the lower ride height, and install the SPL Front suspension parts to lower the front without messing up the geometry

It appears that the CSG FLAs are not really part of the problem here after all.

No, not at all

[CSG Mike]

Originally Posted by churchx

Roll center kits .. isn't it more about front suspension, KCA435 that is, which is from updated ball-joints/tie-rod ends for more lowered cars?
For rear i recall mostly LCAs with relocated shock mount points to retain shock travel even with more lowering .. not so much about angle of LCA itself? (as otherwise one would need to move rather LCA inner pivoting point at subframe to keep angle, no?), and of course diff risers to also retain axle angles/reduce wear on CV joints?

It's both for shock travel and for LCA angle.

Some kits are adjustable, others are not. Kits like the Whiteline and SPL are adjustable with shims, and in theory, is weaker than a drop knuckle which has much more strength in the area. Drop knuckles are not adjustable, but most of them are set to a reasonable height expected of a car that's lowered.

[CSG Mike]

Originally Posted by timurrrr

Looks like the only solution is to remove the Wisefab kit. With this kit you basically just replaced "geometry is not optimal" problem with another "geometry is not optimal" problem, while replacing all the bushings and paying at lot of money. For that amount of money I'd expect the only acceptable outcome to be "geometry is better than with stock arms".

It appears that the CSG FLAs are not really part of the problem here after all.

Curious what RC kits are recommended by CSG to to achieve better suspension geometry at the same ride heights as one gets by just installing CSG FLAs with recommended settings on stock arms.

The most elegant solution, IMO, is to just use a custom shock sleeve to run the CSG FLA at the normal recommended height, using the sleeve to extend the damper total length to fit the wisefab without extensive preload.

The wisefab drops the rear 45mm at the knuckle, which means via motion ratio, it's about a 32mm drop at the damper. Quite conveniently, the CSG FLA's recommended drop is 1.4" ~~35.56mm, so the Wisefab kit + CSG FLA + extended sleeve = virtually stock geometry instead of the compromised geometry of a 1.4in drop.

Quite literally, it's almost perfect.

[Var]

Originally Posted by CSG Mike

The most elegant solution, IMO, is to just use a custom shock sleeve to run the CSG FLA at the normal recommended height, using the sleeve to extend the damper total length to fit the wisefab without extensive preload.

The wisefab drops the rear 45mm at the knuckle, which means via motion ratio, it's about a 32mm drop at the damper. Quite conveniently, the CSG FLA's recommended drop is 1.4" ~~35.56mm, so the Wisefab kit + CSG FLA + extended sleeve = virtually stock geometry instead of the compromised geometry of a 1.4in drop.

Quite literally, it's almost perfect.

This doesn't make any sense. Raising the car with an extended sleeve, or even if you just had a long enough shock body that you didn't need an extended sleeve, would compromise the geometry. It would just be in the opposite angle than what would happen if you lowered it.

This is a horrible solution unless you want your customer's cars to have bad suspension geometry

[CSG Mike]

Originally Posted by Var

This doesn't make any sense. Raising the car with an extended sleeve, or even if you just had a long enough shock body that you didn't need an extended sleeve, would compromise the geometry. It would just be in the opposite angle than what would happen if you lowered it.

This is a horrible solution unless you want your customer's cars to have bad suspension geometry

Net 1.4" drop with RC for it, or net 1.4" drop without RC for it.

Pretty cut and dry here; most folks do the net 1.4" without RC for budgetary reasons, and live with the compromise.

Creative solutions like a drop knuckle or extended top perch is precisely how longer dampers like Penskes or Ohlins are run.

You have a setup on your car that I wish my budget (and classing) allowed for on mine.

[Var]

Originally Posted by CSG Mike

Net 1.4" drop with RC for it, or net 1.4" drop without RC for it.

Pretty cut and dry here; most folks do the net 1.4" without RC for budgetary reasons, and live with the compromise.

Creative solutions like a drop knuckle or extended top perch is precisely how longer dampers like Penskes or Ohlins are run.

You have a setup on your car that I wish my budget (and classing) allowed for on mine.

LOL..no it's not. Not even close.

If you had a BONE STOCK stock car with a 45mm drop knuckle kit, the car would still have factory geometry. If you tried to raise it any further from where it is, or lower it any further from where it is, you have compromised geometry.

But at least in the case of lowering, you're not sweeping past the optimum angle on compression. Your control arm will always be operating under that angle save for weird cases of excessive droop, which is not an issue generally and would be on the unloaded side anyway.

However, if you raise your car, as the suspension compresses, the control arms (on the knuckle side) will travel from below the pickup point on the subframe, to neutral, to above. This transition will cause unpredictable behavior because of nonlinear and not even unidirectional changes in roll resistance and camber curves