Alternative to lowering

[Gforce]

Originally Posted by guybo

I can see how the MCA suspension mod can maybe lower the rear end a little, but what do you do about lowering the front end?

I wouldn't go with lowering springs because 1) this car doesn't need higher spring rates 2) shorter springs means less suspension travel which negates anything good about a lower CG 3) blown dampers. But I could see moving the pickup down to lower the car and maintaining the stock suspension travel being a good thing if you can lower the front too.

MCA traction aids have no effect on ride height. That is why they were thought of in the first place. Fitting these brackets is the only way to reduce anti squat without lowering the car.

The body end of the trailing arm is lowered. The spring perch remains at the same height.

What changed is the arc of travel of the trailing arm. It begins more horizontal which reduces anti squat leverage. That's all it does.

Your reasoning is why I fit these devices and also softer rate rear springs from the 2017 model. The 2017 factory car handles better than previous model years for this reason: more front roll resistance and less rear roll resistance. This pattern has been consistent at the factory beginning with the initial differences between the FRS and BRZ in 2013. In fact I'd be willing to bet that all the really good aftermarket spring sets up the front spring rate more than the rear % wise. Certainly fitting a stiffer front bar always improves the handling balance. Every tuner producing a better BRZ chassis goes this route.

[ApexEight]

This is consistent with what I've read elsewhere. Stiff front, soft rear, with big bar up front and little bar out back. It's a proven path for setting up the handling of a front engine, RWD car. Makes sense in theory as well.

I'm still wondering about optimal camber front to rear. I'm thinking with front crash bolts and camber bolts you could get -2+ degrees of camber up front with stock suspension or moderate lowering springs (~1" drop) and a big front bar and then something like SPC rear LCAs and less camber, maybe around -1.5 degrees out back plus the MCA traction mod sounds like a super solid, somewhat affordable setup.

Edit: Also, do these control arms achieve the same effect as the traction mod? Although they mount at the stock location, it has some drop integrated into the arm. Idk, just thinking out loud! http://www.stance-usa.com/main/produ...ith-60mm-drop/

[OND]

Dont know if you are a shill or trying to justify your $350 bracket purchase by making bold claims, but I smell so much BS in this thread.

Do you guys even track your cars to suggest BRZ needs more roll stiffness in the front? Steady state cornering behavior of the BRZ is already mild understeer, which gets more recognizable with higher grip tires.

2017 cars have softer rear springs but stiffer rear swaybars.

Nothing you change with the camber and suspension links will provide the same reduction in lateral load transfer as a 1" lowering would provide.

[Gforce]

Ask our Australian friends who do track this MCA mod successfully. That's how I found out about these brackets. Some hard numbers are posted here:

http://www.ft86club.com/forums/showthread.php?t=112859

You can make of this what you will. The described improvements are real.

Modified LCA do not usually change the anti squat because they do not change the body mounting point.

They could do so if the hub end were made sufficiently high relative to the body end but they generally make these only to accommodate a lower spring mount.

[wparsons]

Originally Posted by ApexEight

This is consistent with what I've read elsewhere. Stiff front, soft rear, with big bar up front and little bar out back. It's a proven path for setting up the handling of a front engine, RWD car. Makes sense in theory as well.

There's a lot more to it than that... you have to consider motion ratios to get wheel rates, and frequencies. Once you factor in wheel rate on a stock FRS or BRZ, the rear is effectively softer than the front even with stiffer spring rates out back.

Originally Posted by ApexEight

Edit: Also, do these control arms achieve the same effect as the traction mod? Although they mount at the stock location, it has some drop integrated into the arm. Idk, just thinking out loud! http://www.stance-usa.com/main/produ...ith-60mm-drop/

Not even slightly. The MCS mod lowers the front pivot of the trailing arm, not the overall ride height. Those arms just lower the shock mounting point to lower the car.

[Gforce]

MCA brackets also eliminate wheel hop. I fit my summer tires today and did a controlled wheelspin standing start, no wheel hop at all and also a nice chirp when into second.

Powerslides are now also very smooth and controllable, no tank slapper return to straight ahead.

[ApexEight]

Originally Posted by wparsons

There's a lot more to it than that... you have to consider motion ratios to get wheel rates, and frequencies. Once you factor in wheel rate on a stock FRS or BRZ, the rear is effectively softer than the front even with stiffer spring rates out back.



Not even slightly. The MCS mod lowers the front pivot of the trailing arm, not the overall ride height. Those arms just lower the shock mounting point to lower the car.

My bad, I need to read up more on wheel rates and motion ratios. Not trying to spread any misinformation.

Yeah I figured those RLCAs were different than the traction mod. Thanks for the clarification.

[Gforce]

The mention of motion ratios reminds me to also mention the "jacking" forces induced by the angled of the suspension arms at any given point in their ranges of motion. This is how anti squat and anti dive forces are created. Roll stiffness is also affected by suspension arm angles, in this case it is described in relation to roll centres. Lowering springs change the effective range of motion and thereby also the initial roll and jacking forces. The biggest effect of lowering springs comes from the reduction in ride height effects on suspension arm angles. The effect on weight transfer torque of a 12-25 mm drop are minimal in reality.

MCA brackets create in effect a softer spring rate in relation to spring compression because more of the weight transfer torque is carried directly by the springs. MCA suggests increasing the rear damper rate if the transient effects of their brackets create faster roll rates than desired, just for example.

There is a lesson here: making your own suspension modifications is tricky. Bottom line is only the actual driving experience will allow you to find the correct set up for your driving style and environment, be it aggressive or track oriented or occasional canyon runs.

Consider how you like the car to behave and where you will be driving it. Then find the parts suppliers who have been there and done that and buy their stuff. The price of those parts should include the cost to the maker of some heavy duty road testing. I know Bilstein for example won't build after market shocks until there is an aftermarket and then they build a specific shock for a specific application. Even their adjustable kits are designed for your car specifically.

MCA did the same and extensively tested their brackets to ensure the stated results set achieved. Whether you want those results is the only question to ask yourself.

[wparsons]

Originally Posted by Gforce

MCA brackets also eliminate wheel hop. I fit my summer tires today and did a controlled wheelspin standing start, no wheel hop at all and also a nice chirp when into second.

Powerslides are now also very smooth and controllable, no tank slapper return to straight ahead.

That's a direct result of the reduced anti-squat. It lets the rear suspension work more under acceleration forces.

[Gforce]

Originally Posted by wparsons

That's a direct result of the reduced anti-squat. It lets the rear suspension work more under acceleration forces.

That's what our Ozzie friends are saying in their introductory thread. That's why I bought a set.

Everyone who makes their BRZ faster ends up moving roll resistance to the front axle. These MCA brackets are the only mod that addresses the unfortunate legacy (har har) which resulted from fitting the Impreza rear subframe assembly into the BRZ virtually unchanged.