How to screw up your cars handling and ride - step by step!

[MALAJSTD]

Originally Posted by Gent

LOL. I left that out on purpose. My tires are an exercise in cheap. They are surprisingly good: "Achilles ATR Sport 2". I had to look them up, as I had never heard of them; however, at $80 a tire I figured they were worth the experiment. So far, so good.

I can already hear the comments coming about buying Flex-A's and cheap tires.

Hahaha, no I get it.
I get most tires at cost, so I'm afforded that luxury. But wheels were a different story. I bought the Konig Hypergrams because of cost/weight ratio, and was going to wrap them in Firestone INDY500 to save initial $$. Until...

[MALAJSTD]

Originally Posted by Gforce

Toyota issued a set of lowering springs and uprated roll bars early on. All reports are these are a good addition, or the many equivalents from other makers. Toyota bought theirs in from Eibach, one of the biggest and best aftermarket makers.

Lowering the same by that much will improve handling but reduce suspension travel which may not be what you want if you experience rough roads. But, you give up the factory suspension which is now very good indeed.

No free lunch, just a set of trade offs. One modification at a time is a good practice. You stop when you think the car is perfect for you, or you run out of money....

I'm a little turned off of the TRD away bar set, as they are non-adjustable.
Although having drivin a couple FR-S with them installed I must say it is well sorted. I'd just feel comfortable if I had the ability to adjust stiffness.

I guess it helps I can get all TRD stuff dirt cheap... but I still have reservations.

[Gforce]

If I may suggest you select the front bar with the rate you like and fit an adjustable rear bar. The changes you are likely to want to make are probably best made to rear roll rate.

Additional front grip is easily achieved by fitting camber adjustment. Either crash bolts or camber plates depending on how much negative front camber suits you.

In my experience this chassis is limited by rear grip. Most aftermarket setups add front roll stiffness either by higher rate springs or roll bar.

I did the opposite by fitting softer 2017 rear springs to achieve more relative front grip. The 20 mm front bar also pushed roll stiffness forwards. . My car has a Supercharger and benefits from less roll stiffness at the rear. Increasing roll stiffness also reduces grip delivered by the inside tire in favour of increasing grip of the outside tire. The Torsen differential is not quite the same as a clutch type LSD and only works well if both drive wheels have solid road grip.

[Racecomp Engineering]

Originally Posted by MALAJSTD

Thanks for the advice.
I mean compared to stock, as I truly love this car and it's handling character. I dare not do anything to mess it up.

It'll be much better than stock with the new tires and alignment.


- Andrew

[JMon85]

Originally Posted by Racecomp Engineering

7. Tire choice

Running sticky tires on soft OEM springs is a problem too, but you will still gain grip from the tire. It'll just feel sloppy and move around a lot.

Interesting .. This right here explains one issue I ran into after I put on new tires.. hopefully the bushing kits I ordered can somewhat sort this issue umong others.

[Gforce]

Stickier tires increase the maximum possible loading on the chassis bushings. The sloppy feeling also comes from the rear dampers being too soft for the stock rear springs. Bilstein B6 help a lot there. The front struts are ok from the factory so fitting Bilstein B6 to the front isn't really essential. I did this in two steps just to see what the effect of rear Bilsteins only would be. If budget is tight just do the rears first. The BRZ handles well with this set up.

A 20 mm front bar helps tighten up the front end as you turn in although since Whiteline also supplied me with poly bushes and beefy drop links to go with that bar it may be that most of the effect comes from those better components.

Finally, MCA traction brackets are amazing. The reduction in anti squat jacking forces which otherwise move the rear suspension around as you corner is impressive. Also, wheel hop is eliminated by fitting these brackets. They give the geometry this car should have from the factory. Bonus, they drop the trailing arm connection point level with the rear subframe bushings so ground clearance is not affected. Good in winter. About a 2 inch drop in the front mounting point for the trailing arms is a lot to achieve and it works extremely well.

[PWBRZ]

Originally Posted by JMon85

Interesting .. This right here explains one issue I ran into after I put on new tires.. hopefully the bushing kits I ordered can somewhat sort this issue umong others.

I noticed this as well and ended up doing the following:
front non-adjustable swaybar -- BSF45 (20mm) [stock is 18mm]
rear adjustable swaybar -- BSR53Z (16mm) [stock is 14mm]
rear swaybar mount support brackets -- KBR38
rear subframe inserts -- KDT921 and KDT922
positive shift kit, transmission insert -- KDT926
steering rack bushings -- KSR210
trailing arm front bushings -- W63414
rear differential inserts -- KDT925
toe control arm inner bushings -- SPF3099K
rear lower control arm inner bushings -- SPF3106K
camber bolts -- SPC81305

Also, the alignment helped as well - stock settings had slightly positive camber up front. The NVH increase is there but not terrible and not a big deal for me. The car has less body roll and feels more precise, with much less understeer. At the track it is fairly neutral, with just the slightest understeer tendency at the limit. I also now notice during track time that the changes highlight the stock springs and especially dampers -- it could use a bit more of each. But that's only really a concern at the track; for street and backroad driving it's fine.

[Gforce]

Do you still notice an odd side to side sway from the rear axle under hard cornering in a fairly tight bend?

I did until I fit the MCA traction brackets. That cured that completely.

I recommend a set of Bilstein or Sachs struts and dampers. The stock dampers are too soft, especially at the rear. .

[boredom.is.me]

Originally Posted by Gforce

Do you still notice an odd side to side sway from the rear axle under hard cornering in a fairly tight bend?

I did until I fit the MCA traction brackets. That cured that completely.

I recommend a set of Bilstein or Sachs struts and dampers. The stock dampers are too soft, especially at the rear. .

I never felt that sway with my RE760's or PSS. I do feel it on the A/S 3+ even though I went from 235/255 to 225/245. It almost feels like my toe just randomly decides to change.

[JMon85]

Originally Posted by boredom.is.me

I never felt that sway with my RE760's or PSS. I do feel it on the A/S 3+ even though I went from 235/255 to 225/245. It almost feels like my toe just randomly decides to change.

Same here MPS a/s 3 225/45 i hate it

[Gforce]

Originally Posted by boredom.is.me

I never felt that sway with my RE760's or PSS. I do feel it on the A/S 3+ even though I went from 235/255 to 225/245. It almost feels like my toe just randomly decides to change.

I think you are on to something here.

The MCA brackets drop the trailing arm pickup point by 53 mm (2 in). This reduces the static angle of the trailing arm from 3 in slope to 1 in, equivalent to a two inch spring drop with no camber changes.

Dropping the trailing arm pickup point pushes the bottom pivot point of the rear hub backwards which should increase static toe in a toe in direction. Factory rear toe setting is around zero. Suspension compression initially toes the rear out. Dropping the angle of the trailing arm at static ride height will likely eliminate or substantially reduce this initial toe out movement. If so then these brackets will eliminate that odd swaying feel to the rear axle as the cornering load increases. That's been my experience

I'll try this again tomorrow on one of our very entertaining off ramps.

[Racecomp Engineering]

Bump.

One other thing I'm not sure is emphasized here is that there are a couple things you can do to these cars that seriously change the handling/driving feel WITHOUT lowering the car, if that's your thing.

- Andrew

[Jajanken86]

Originally Posted by Racecomp Engineering

Bump.

One other thing I'm not sure is emphasized here is that there are a couple things you can do to these cars that seriously change the handling/driving feel WITHOUT lowering the car, if that's your thing.

- Andrew

Examples? What I can quickly think of is sway bars, bushings, mounts, tower brace,...what else is there?

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[N234]

Originally Posted by Jajanken86

Examples? What I can quickly think of is sway bars, bushings, mounts, tower brace,...what else is there?

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Sticker tires, Wider tires, Less offset, lighter wheels, etc.

Coilovers that don't lower your car!

A little front camber, a lot of front camber, other alignment related...

Driving practice, driving courses. This is by far the most effective.

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