MCA Suspension "Traction Mod"

[mrk1]

I'm really excited to try these. I've never been sold on the garden variety adjustable control arms.

[jamal]

Lowering the car will also reduce anti-squat. Seems like if the car were reasonably low adding this part might be a little much. But I guess it would also depend on power and spring rate.

Originally Posted by wootwoot

You sure? There are control arms from different manufacturers that have two sets of holes where they attach to the chassis. One set for factory height, one for a 15mm drop. How would changing the pick up point be any different than that? Also, one user already mentioned he had to raise his rear after install...

This lowers the front mounting point of the trailing arm. Nothing to do with the rear LCA where the shock mounts, definitely no change in ride height.

[wootwoot]

Ohhhhh. My bad. Carry on.

[wparsons]

Originally Posted by wootwoot

You sure? There are control arms from different manufacturers that have two sets of holes where they attach to the chassis. One set for factory height, one for a 15mm drop. How would changing the pick up point be any different than that? Also, one user already mentioned he had to raise his rear after install...

Without changing the spring length/preload, the only way you can raise or lower the rear is to change the upper or lower shock mounting point. Lowering LCA's do so by putting the lower shock mounting point further from the upper point.

What LCA are you talking about that has a different mount point to the chassis to change ride height?

I imagine the person that raised the rear back up did so to change the handling bias, not because this mod lowered the rear more.

[jamal]

Originally Posted by wparsons

What LCA are you talking about that has a different mount point to the chassis to change ride height?

There are a number of rear lcas out there that have a lowered shock mounting point in relation to the ends. Not a terrible idea for a really low car.

Like these:

[wparsons]

Originally Posted by jamal

There are a number of rear lcas out there that have a lowered shock mounting point in relation to the ends. Not a terrible idea for a really low car.

Read my post that you quoted... I acknowledged that there are LCA's that lower the car, but it's by changing the lower pickup point for the shock. The post I quoted specifically claimed different options where it mounts to the chassis that would alter the ride height.

[Gunman]

Lowering the lower shock/strut mount isn't to lower the car, but put the damper back in it's designed operating range.

[strat61caster]

Originally Posted by Gunman

Lowering the lower shock/strut mount isn't to lower the car, but put the damper back in it's designed operating range.

If you don't raise the spring perch to compensate then the car will be lowered with the lca. That's what happened in wootwoot's example. Not sure why wparsons is arguing with it, looks like a reasonable typo...

po-tay-toe
po-tah-toe

[wparsons]

Originally Posted by strat61caster

If you don't raise the spring perch to compensate then the car will be lowered with the lca. That's what happened in wootwoot's example. Not sure why wparsons is arguing with it, looks like a reasonable typo...

po-tay-toe
po-tah-toe

I don't think it was a typo, especially since he asked why changing the mounting point with this mod wouldn't also change ride height. I think he thought that the LCA actually had different mounting options to the chassis, not the shock mounting points.

[bigbcraig]

Originally Posted by wparsons

I find it tough to believe that reducing rear anti squat wouldn't make lift off oversteer more drastic. Reducing anti squat lets the suspension compress more under throttle, backing off the throttle is going to let it rebound. That weight transfer will induce oversteer

For posterity - this isn't how antis or weight transfer work.

It is true that antisquat reduces body movement under throttle, but it does so by putting some of the torque into binding up the suspension (putting force into the trailing arm and subframe rather than letting the spring/damper absorb the weight transfer). Basically antis are the same as roll centers, but drawn in the side view instead of front view.

Nonetheless, weight will transfer given an acceleration.

By having the spring/damper take the weight, it actually slows down the transfer (both applying and releasing the throttle) and will thus calm lift-off over the same way it lets the driver apply the throttle earlier.


...

Keep in mind... Like roll centers and almost everything else suspension wise, one cant say "antis are bad," it's just another lever to pull in finding your desired suspension balance.

[86•BRZ]

Have any of you Northern Hemisphere chaps tried this yet?
I am keen to hear your thoughts..

[Somerandom18]

320 USD for a pair of brackets? Rather spend 50 on the whiteline positive traction kit.

NE Ohio represent.

[Gforce]

Originally Posted by 86•BRZ

Have any of you Northern Hemisphere chaps tried this yet?
I am keen to hear your thoughts..

Yes, fitted them about a month ago to my DD. They perform exactly as advertized.

My car is at stock ride height, so the effect on anti dive will be at the maximum.

I run Bilstein HD (B6) dampers. I have the 20 mm Whiteline front bar. I fit 2017 rear springs. I fit the Whiteline rear subframe bushing inserts and transmission mount insert.

I run the Edelbrock eForce supercharger on 91 octane Shell V Power, all we can get around here.

With winter tires there is no longer any wheel hop. We shall see if this also is the case when the summer tires go on.

The transition from grip to powerslide is no longer of the tank slapper variety. I have not yet tested the effect of an abrupt lift off, I tend not to drive that way. I expect the tuck in to be much more controlled but we shall see.

I highly recommend this modification. Subaru should redesign the trailing arm pickup point to drop it the same amount.

I predict the benefit will be slightly less for a lowered car since lowering the car already reduces the effect of the anti squat geometry. The benefit is most for stock ride height.

[Gforce]

Originally Posted by Somerandom18

320 USD for a pair of brackets? Rather spend 50 on the whiteline positive traction kit.

NE Ohio represent.

Should be closer to US$270. The cost is the small production run compared to the development testing they had to do. The brackets are hefty gauge steel, powder coated complete with chassis bolts and nylok nuts. Also, they are engineered with a precision slot so as to allow installation in the existing chassis bracket without offsetting the trailing arm. Clever piece of kit.

The Whiteline bushing inserts are a no brainer, every BRZ/86 should have at least a set of rear subframe bushing inserts. The subframe moves around a lot especially if you fit better tires.

http://www.ft86speedfactory.com/whit...l#.WN7RN9TOef0

If you are really looking for stability at the rear Whiteline also makes track rated bushing replacements, as do other makers. These are different in function from the MCA brackets.