MCA Suspension "Traction Mod"

[86•BRZ]

Originally Posted by Somerandom18

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

NE Ohio represent.

Honestly, Just LOL. NE Ohio would not be happy about this representation.


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[Somerandom18]

Originally Posted by 86•BRZ

Honestly, Just LOL. NE Ohio would not be happy about this representation.


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You're a funny guy. I was looking for someone to explain why these are worth a damn over just the inserts. The fellow above you got it. You... Not so much.

NE Ohio represent.

[86•BRZ]

Originally Posted by Somerandom18

You're a funny guy. I was looking for someone to explain why these are worth a damn over just the inserts. The fellow above you got it. You... Not so much.

NE Ohio represent.

Because they're a completely different product aimed to do completely different things so you can't write them off on price. Sure, if you're just looking to +1 your mod list then get inserts.


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[Gforce]

These brackets lower the pivot point of the trailing arms reducing anti squat. Inserts only reduce bushing flex.

The cost of these parts reflects the amount of testing required to get the desired geometry correct. The actual brackets would be fairly cheap to make if you didn't have to do any engineering.

MCA are to be commended for selling these for so little.

[Gforce]

Originally Posted by 86•BRZ

Because they're a completely different product aimed to do completely different things so you can't write them off on price. Sure, if you're just looking to +1 your mod list then get inserts.


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And many thanks to our OZ friends for putting us on to these really effective brackets.

[Gforce]

Originally Posted by mrk1

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

These are totally different to adjustable control arms. I highly recommend these especially for stock ride height cars.

[Gforce]

Originally Posted by 86•BRZ

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

On my stock ride height 2013 BRZ these work extremely well for road use. Since lowering the suspension also reduces anti squat I expect the benefits will be proportionally less the lower the car is to begin with.

The reduction in twitchiness at the rear axle is noteworthy. I also fitted 2017 spec rear springs leaving the Bilstein B6 the same and the front springs stock, adding only a Whiteline 20 mm front bar. The Whiteline rear subframe bushing inserts and transmission mount insert are no brainer mods every BRZ should have.

Since I have an eForce Supercharger the increased rear axle grip delivered by these brackets is a big help when exiting a corner, the power can go down earlier and harder without the rear axle stepping out.

Ride is improved without compromising grip.

Most remarkable is the improved feel from the drivers seat. The reduction of longitudinal jacking force improves the feel of the actual contact patch for the driver, which also assists in getting more power down earlier.

[driggity]

Originally Posted by Gforce

On my stock ride height 2013 BRZ these work extremely well for road use. Since lowering the suspension also reduces anti squat I expect the benefits will be proportionally less the lower the car is to begin with.

The reduction in twitchiness at the rear axle is noteworthy. I also fitted 2017 spec rear springs leaving the Bilstein B6 the same and the front springs stock, adding only a Whiteline 20 mm front bar. The Whiteline rear subframe bushing inserts and transmission mount insert are no brainer mods every BRZ should have.

Since I have an eForce Supercharger the increased rear axle grip delivered by these brackets is a big help when exiting a corner, the power can go down earlier and harder without the rear axle stepping out.

Ride is improved without compromising grip.

Most remarkable is the improved feel from the drivers seat. The reduction of longitudinal jacking force improves the feel of the actual contact patch for the driver, which also assists in getting more power down earlier.

Thanks for the updates. Is there much of a difference in stability when hitting mid corner bumps? My biggest complaint with the stock suspension is the rear end getting unsettled during aggressive cornering on rough roads.

[Gforce]

Originally Posted by driggity

Thanks for the updates. Is there much of a difference in stability when hitting mid corner bumps? My biggest complaint with the stock suspension is the rear end getting unsettled during aggressive cornering on rough roads.

Definitely. There are two motions you are feeling. The first is movement of the rear subframe in its bushings which is particularly bad on these cars. The rear suspension and subframe come right out of the Subaru Impreza and are not up to the job of handling the higher g forces developed by the BRZ. Better tires make this particularly bad. This is why the subframe bushing inserts (Whiteline makes a good set) are a no brainer. I suspect Subaru and Toyota deliberately did nothing about this because it does make the car feel more exciting and alive for less experienced drivers. The more experience you have the less you can enjoy this puppy dog effect.

The BRZ can be made into a much more sophisticated driver's car quite easily with a couple of mods. Softer rear springs (or stiffer fronts if you prefer) make a big difference. Moving the roll stiffness forwards a bit by fitting a bigger front bar relative to the rear bar also helps. Subaru did this initially to differentiate the BRZ from the 86 but used spring rates to do so rather than roll bar rates. Then the 86 was changed to be more like the BRZ by fitting the same springs to all versions. . In 2017 Subaru changed both the BRZ and the 86 to move roll stiffness to the front axle with stiffer front springs and softer the rear springs to improve the ride (they upped the rear roll bar from 14 mm to 15 mm at the same time to fine tune the roll stiffness allocation front to rear) and roadholding over bumps. It works.

Once you fit those subframe inserts then you still feel the jacking effect of the steeply angled trailing arms. The inside arm drops down into a higher anti squat angle in fast corners while the outside arm rises to a shallow anti squat angle. A mid corner bump abruptly alters these jacking forces across the axle which is quite disconcerting.

One of the big benefits of MCA brackets is the reduction of rear anti squat jacking forces. The rear axle tends to stay put even if the corner gets bumpy.

These effects are most noticable in slower speed tighter bends or at high speed with abrupt bumps.

The MCA brackets settle the rear axle significantly. Easier to drive faster.

[Gforce]

MCA traction brackets drop the front suspension pick up point for the trailing arms by 53mm. This leads to a 25mm drop from that point to the trailing arm pivot point at the LCA.

So anti squat angle is reduced by that difference, 2/3.

I suspect that some of the benefit of this mod lies in the reduction of toe change as well as reduction of anti squat effects.

[86•BRZ]

Originally Posted by Gforce

MCA traction brackets drop the front suspension pick up point for the trailing arms by 53mm. This leads to a 25mm drop from that point to the trailing arm pivot point at the LCA.

So anti squat angle is reduced by that difference, 2/3.

I suspect that some of the benefit of this mod lies in the reduction of toe change as well as reduction of anti squat effects.

There is no toe change. Static or dynamicly measured through the range apparently.


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[Gforce]

Originally Posted by 86•BRZ

There is no toe change. Static or dynamicly measured through the range apparently.


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Interesting. MCA says fitting their brackets does not require an alignment. My mechanic agreed and did not do one.

On the other hand the pivot point on the subframe for the toe link is further outboard than the LCA and upper A arm inner pivot points. There must be some toe change with compression from this difference. One would think.

Then there's the effective length of the tracking arm pushing the bottom pivot of the hub back as the suspension compresses. That would tend to toe in the hub.

This pretty knowledgable site confirms this:

http://www.motoiq.com/MagazineArticl...cion-FR-S.aspx

Interesting is the point that anti squat may need to be reduced if more power is added. This would be needed to assist in maintaining contact patch adhesion under acceleration. MCA suggests you may need to increase the rear damper rate if you add their traction aids. This would be consistent with the effects of reducing anti squat.

It looks to me just from eyeballing the pivot points of the various multi link ends that the rear suspension must toe in and gain camber under compression. Lowering the trailing arm pick up point would start the toe in gain at an earlier point in the compression arcs without changing the camber gain curve. Possibly, the increase in the effective static length of the trailing arm after the MCA brackets are installed would eliminate any tendency of the rear hubs to toe out under rebound of the suspension. If so, the rear axle would feel more planted throughout any cornering maneuver.

Logically, after fitting the MCA traction brackets you would usefully increase rear damper rates, perhaps increase rear roll bar rate a tad and set static camber at a higher initial negative amount than stock.

Just went for a spirited drive. All traces of that curious vague feeling that the rear axle is moving around between the body and the tires is gone. The only change made that could account for that is these MCA traction aids. Every BRZ/Toyota 86 intended for fast street driving would benefit from installing a set of these. In fact, this is the cheapest most effective mod you could make and should be done first before you decide what else needs improving.

[Panman]

Originally Posted by Somerandom18

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

NE Ohio represent.

As an FYI, I have both, they are in no way similar in function or intent.

[Gforce]

I have both. I confirm they are totally different in design and effect.

The MCA kit would be a better choice for the first mod. I thought the odd swaying feeling from the back axle was due to the rear subframe moving around in its bushings and it is but that isn't the full story. By all means install these bushing inserts as they are cheap and very effective.

Something else is going on that feels like the rear suspension geometry is changing under high cornering loads. It's a hard thing to describe in words but definitely not pleasant when driving on the limit. Well, not pleasant anytime but most objectionable at the limit.

The MCA brackets eliminate this feeling and allow the driver to feel more directly what the rear contact patches are doing. Powersliding the car with these brackets installed becomes much easier to control. For example. Sensing the limits of rear contact patch grip is made much easier.