Williampreza's Kamaitachi: NA BRZ The "Easy" Way

[Vital]

Originally Posted by Williampreza

Alignment is done. Specs ended up -1.5 camber all around, zero toe. This ain’t quite what I wanted, but was within the limits of the hardware and my budget for labor. I should have moved the lower strut bolts up to the top hole when I installed the camber bolts. Hindsight...

Anyway, cornering is a bit tail happy for my tastes, and low speed steering is still a bit labor intensive. I’m gonna drive it a while and see if I feel differently in a few weeks.

Hmm thats odd, i am running pretty much similar specs and i havent noticed it being tail happy at all. I too have SPC camber bolts up front except in the lower hole and control arms in the rear with RCE Yellows. I honestly love how the car drives and feels on entering and exiting corners.

[Williampreza]

Originally Posted by Vital

Hmm thats odd, i am running pretty much similar specs and i havent noticed it being tail happy at all. I too have SPC camber bolts up front except in the lower hole and control arms in the rear with RCE Yellows. I honestly love how the car drives and feels on entering and exiting corners.

I’m certain it’s subjective at this point. But I have a solid baseline that I can work from now. Thanks for the tips!

[Vital]

Originally Posted by Williampreza

I’m certain it’s subjective at this point. But I have a solid baseline that I can work from now. Thanks for the tips!

Would you mind posting a pic of your car with the RSR springs installed? Im just curious to see how it looks as those were one of the springs i had considered getting as well. There are not too many people running the Down springs mostly its the Superdowns.

[Williampreza]

BEFORE


AFTER

[Vital]

Nice and subtle. Looks clean

[PadSprouts]

Bit of a noob here. I am also researching camber options for a new suspension setup. Why is it that more front negative camber is preferred when the engineers designed less negative camber in the front?

[Vital]

Originally Posted by PadSprouts

Bit of a noob here. I am also researching camber options for a new suspension setup. Why is it that more front negative camber is preferred when the engineers designed less negative camber in the front?

Having more front camber is nice because it will allow to maximize grip around corners. Stock alignment specs are very conservative and are geared toward DD and not really any kind of performance driving.

[BlueWhelan]

Originally Posted by PadSprouts

Bit of a noob here. I am also researching camber options for a new suspension setup. Why is it that more front negative camber is preferred when the engineers designed less negative camber in the front?

OEM specs are usually geared more towards the low tire wear and overall safety side of the spectrum. Most cars will have more camber in the rear than the front, which can result in safety understeer from the factory. Having less camber can also help even out the tire wear over the course of a tires life.


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[PadSprouts]

Originally Posted by BlueWhelan

OEM specs are usually geared more towards the low tire wear and overall safety side of the spectrum. Most cars will have more camber in the rear than the front, which can result in safety understeer from the factory. Having less camber can also help even out the tire wear over the course of a tires life.


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That makes sense. I do like using it as my DD; would I have any noticable performance increase if I kept it kinda conservative and upped the front to 1deg or 1.5deg?

[BlueWhelan]

Originally Posted by PadSprouts

That makes sense. I do like using it as my DD; would I have any noticable performance increase if I kept it kinda conservative and upped the front to 1deg or 1.5deg?

In short, yes. That amount of - camber in the front will have a negligible effect on overall tire wear, but it will make a substantial difference for overall tire grip and performance. You will dig it.


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[Williampreza]

Some quick notes on lowering springs and current alignment setup. These are mostly for my own reference/journaling.

The car feels under-damped. Lots of bouncing on dips and crests. The unloaded side tends to feel hiked up and there's a bit of wallowing around long curves. Need stiffer dampers or could it be the stock bumpstops?

The back end has an unnerving tendency to jump to oversteer, specifically when the rear gets unloaded in mid-turn, such as a corner going over a hill. It seems to catch itself quickly. A rear toe problem? It's almost time for tires, so an alignment adjustment might be in order too.

Finally, I'm trying to pin down why the car feels less grippy now. It could be that the tires are worn. They're almost to the wear bars, and I've not been particularly easy on them. Could also be the alignment?

[BlueWhelan]

Originally Posted by Williampreza

Some quick notes on lowering springs and current alignment setup. These are mostly for my own reference/journaling.

The car feels under-damped. Lots of bouncing on dips and crests. The unloaded side tends to feel hiked up and there's a bit of wallowing around long curves. Need stiffer dampers or could it be the stock bumpstops?

The back end has an unnerving tendency to jump to oversteer, specifically when the rear gets unloaded in mid-turn, such as a corner going over a hill. It seems to catch itself quickly. A rear toe problem? It's almost time for tires, so an alignment adjustment might be in order too.

Finally, I'm trying to pin down why the car feels less grippy now. It could be that the tires are worn. They're almost to the wear bars, and I've not been particularly easy on them. Could also be the alignment?

Hard to say over an internet discussion. If you increased the spring rates and kept the same tires, the car would feel like it has a bit less grip. Generally, you change the springs to cater to your tire choice, not the other way around. Apples to apples, upping the spring rate without upping the grip level will make the car feel skittish.

It could be amplified by the car being a bit underdamped, but given your spring choice, I’m not sure...aren’t the “downs” pretty soft?

Speaking of springs, are the spring rates quoted by the manufacturer actually the spring rates you are getting? Consistency in spring rates is a hard thing to accomplish in the world of aftermarket springs.

That said, the bump stops could absolutely be adding to your issue. Now that you’re lowered, you are on the bumps tops constantly, which through a corner can upset the car pretty noticeably over inconsistent surfaces...

As mentioned earlier, a bit of toe-in could help settle down the rear.


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[Vital]

Try getting better tires first and see if that helps. Also, when you installed the springs did you re-use the OEM bumpstops? or did you trim them a bit?

[Williampreza]

Originally Posted by Vital

Try getting better tires first and see if that helps. Also, when you installed the springs did you re-use the OEM bumpstops? or did you trim them a bit?

I reused them. I can use some modeling clay and a drive to see if there's interference (theoretically). When I installed the springs, I considered trimming, but there was no clear consensus on whether to trim or not and how much to trim for springs this conservative. I figured pulling things apart again to trim was the lesser of two evils. The other being a bumpstop cut too short.