20mm Spacers didn't work for me
 

So normally, I wouldn't even slightly mod my new 2018 BRZ, but so many of you have added spacers to get a flush look, I thought the very slight increase in understeer wouldn't be a problem. So yesterday, I received a set of 20mm spacers from ft86speedfactory -- their own brand -- and put them on the rear wheels. So many have said that 20 in front and 25 in back would be perfect. Their spacers are really well built, hub centric, and just good looking. The only other functional mod I made on the car was replacing the OEM Primacies with 225 PS4S.

After taking the car on a test drive, the handling was an absolute disaster. Severe understeer and more difficult cornering. As for looks, to my eyes the poke was about 5mm too much on the rears, which really surprised me. I know the 225's are slightly wider than the stock 215's, so perhaps that is one of the issues. I think the understeer was multiplied by the extra sticky tires I had. I know that also putting spacers on the front will reduce some of the understeer, but I hate the look of poke in the front and if 20's were too big in the rear, then I'm not sure there is a good solution. If I'm only going 10-15's, it just isn't worth the effort in my book. I did have the advantage of taking a test drive just before and then one right after and perhaps that amplified the difference. I owned Porsches for 27 years so I am very sensitive to handling and suspension.

I guess I don't understand why this isn't more of an issue here. But I've learned a lesson that the Subaru/Toyota engineers knew what they were doing when "balancing" this car. No more mods for me except for accessories and perhaps an audio upgrade.

So I'll take them off today and put them up for sale at half price or so plus shipping. They are the nicest spacers I've ever purchased. Years ago, I did use some spacers on a couple of cars but I guess they were not as sensitive as this one....

I don't think spacers would realistically make that much of a difference on their own. Check your tire pressures. Are you running 225 all around?

I had the same notion, and I was extremely surprised. Yes, I checked the tire pressures and am running 225's square. Again, after driving Porsches for so many years, perhaps I'm just more sensitive to the change. If I hadn't driven the car before the change, it would probably seem acceptable as it changes the nature of the car as it feels heavier. But I have driven the car and I just prefer the "light and fun" feel of the car. If this heavier feel was the way the car came from the factory, I would have purchased an MX-5 or Cayman.

Is your alignment stock? Then imho it's not that spacers caused understeer, rather stickier tires made stock understeer bias more pronounced. I'd get camberbolts for more camber in front + good alignment and call it done.
As for heavier feel .. yes - car now due stickier tires is less playful/less willing to loose grip and needs to be pushed. So it's upto you what you choose, what you prefer. There are some that want that and disliked lack of grip of primacies. To each his own.
Adding spacers in front too will make also steering heavier (due change in scrub radius).
To summarize, imho biggest changes you got comes from tires, not spacers.

Have you had an alignment done with the spacers installed? If your toe was off before, the spacers would exacerbate the issue.

Must have been one hell of a test drive if you were getting "severe understeer".

Did you put the tires and spacers on at the same time? Stickier tires would make the biggest difference in how the car feels. The stock tires like to slide a lot, and are pretty stiff, which makes it feel like it has extremely sharp handling. Stickier rubber may make it feel like it handles worse, but actually allows you to corner faster due to the extra grip.

Also, how hard were you pushing it that you experienced severe understeer? To me, severe is when you turn your steering wheel, but keep plowing straight ahead. I feel like you're probably just feeling a bit more body roll now that the tires are sticking to the ground significantly more than the primacys were.

I changed the tires about a month ago, so it's not the tires that make the difference. My use of the word "severe" is probably an overstatement. I really wasn't expecting to feel very much difference and when I could immediately notice the understeer, it was a surprise. Over the years, I've tracked a number of cars, so I am very sensitive to changes in handling. And I could feel the understeer at low speeds, i.e., slightly more effort to turn corners, etc. I don't push my cars anymore and purchased this one as a little fun car.

Sorry about the use of the word "severe", I guess I was just disappointed in the results. Also, I was expecting the rear to look more "flush", and to my eyes, the 20's actually poked a little. I dislike poke a lot more than not being flush. I know this isn't the experience for most of you who like 25's in back, but each of us to our own.....

The alignment is stock as the car is only a month old. I changed the tires as soon as I got the car, so it's not the tires that made the difference. I did notice the heavier feel when I changed the tires, but that is what I wanted. Those tires made the car seem more controlled. Again, spacers should not make this much of a difference, hence the surprise.

I'm planning to purchase spacers in the future and I know that I will do an alignment the same day they're installed. Might help?

20mm Spacers didn't work for me
 

Exactly. The change in scrub radius does not affect camber or understated/oversteer (not with stock caster anyway), the wheel will feel a bit heavier, that's it. The stock understeer gets exacerbated with stickier tires.


Ehhh. No. Understeer is a condition that occurs when the front tires reach their transverse LIMIT before the rears. If you're not losing grip or squirming at least 1 tire you simply cannot have oversteer or understeer. It's impossible to gauge a car's tendency to rotate at low speeds. If you stay with the linear portion of the friction curve of all 4 tires, the car cannot understeer, no matter how badly it's set up.

Slightly more effort to turn is due to the scrub radius, and has nothing to do with the balance of the car.

I put 20mm all around on my 17 brz performance package. Didn't notice a change in steering or handling. And if anything the rear could stand to move a little more further out for flushness. https://uploads.tapatalk-cdn.com/201...fdd8377958.jpghttps://uploads.tapatalk-cdn.com/201...48e9050439.jpg

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Point taken. The car still felt heavier and less controlled to me. If I wanted to keep the spacers, what would you recommend? Add 20's in front? Alignment? Camber bolts?

20mm Spacers didn't work for me
 

Camber bolts help balance the understeer out for sure, and for $10 it's a no brainer. An alignment with less toe-in helps too. Another way to make it feel lighter is with stiffer sway bars, they help a lot in the transitions and making it feel tighter and more controlled.