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-   -   Rear camber - impact (https://www.ft86club.com/forums/showthread.php?t=148519)

ACT86 01-21-2022 04:58 AM

Rear camber - impact
 
Hey all,

Had a quick question which I couldn’t find a definitive answer to. Seems everyone recommends more camber front than rear, and generally use adjustable rear LCAs to reduce rear camber when needed.

I am lowered about 40mm on coilovers (ST), with 18x8.5s and 255/35 tyres. Camber is about -1.4 (maxed) front and -2.6 rear. The car feels great and has a nice balance (more front than rear grip when pushing).

My question is what would the benefit of reducing the camber in the rear be (other than tyre wear)? Is it really worth buying adjustable LCA? Does it make it more predictable on the limit?

Car does a lot of windy mountain drives, but won’t be tracked.

Thanks in advance for your advice.

https://uploads.tapatalk-cdn.com/202...209072ddfc.jpg

Purist 01-21-2022 05:44 AM

Your launches will be slow and lacking in grip.

Your grip will be poor in the wet.

Sent from my SM-G973F using Tapatalk

ACT86 01-21-2022 05:51 AM

Quote:

Originally Posted by Purist (Post 3498468)
Your launches will be slow and lacking in grip.

Your grip will be poor in the wet.

Sent from my SM-G973F using Tapatalk


Thanks mate, really appreciate that.

Ok, launches seem fine (way more grip than stock with the extra width) but I’m stock power.

Feels pretty good in the wet so far (we’ve had way more heavy rain that usual this summer). May be largely down to the newer tyres, but I’m comfortable with its wet weather performance as is, so that’s good.

So basically no unpredictable / snappy handling on limit due to excessive camber on the rear (vs front). Haven’t felt this as yet when pushing, but just wanted to make sure I wasn’t missing something.

Purist 01-21-2022 06:04 AM

Quote:

Originally Posted by ACT86 (Post 3498469)
Thanks mate, really appreciate that.

Ok, launches seem fine (way more grip than stock with the extra width) but I’m stock power.

Feels pretty good in the wet so far (we’ve had way more heavy rain that usual this summer). May be largely down to the newer tyres, but I’m comfortable with its wet weather performance as is, so that’s good.

So basically no unpredictable / snappy handling on limit due to excessive camber on the rear (vs front). Haven’t felt this as yet when pushing, but just wanted to make sure I wasn’t missing something.

Handling is fine but grip... My daughter's 2001 Corolla has more grip in the wet than my BRZ.

My theory is that in the wet, the reduced contact patch means you can't generate enough lateral force to deflect the tyre enough to take advantage of the camber.

But who cares, they're an underpowered car so less grip= more fun :)

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EndlessAzure 01-21-2022 06:27 AM

@ACT86 The reason that the general advice for camber on FRS/BRZ/86 platform calls more front than rear camber is due to its general driving character and suspension layout
  1. Overall, the car tends to understeer at the limit (it has less front grip than rear grip)
  2. Front MacPherson strut suspension tends to lose camber under load
  3. Rear Multilink suspension tends to gain camber under load
To aid front grip and get proper tire contact, you increase front camber. To help rotate the car and get proper tire contact for the rear, reduce rear camber. For most track alignments, the camber distribution tends to come out to somewhere around -3F and -2.5R.

That being said, most manufacturers of modern cars tend to have a bias toward more rear camber for safety reasons. It helps keep the car from entering an oversteer condition, which the average driver is less likely to recover from (especially in FWD cars). If you ever take a look at the OEM alignment specification for the FRS/BRZ/86, you will find the car to be set-up from the factory with more rear than front camber for likely this reason.

ACT86 01-21-2022 06:31 AM

Rear camber - impact
 
Quote:

Originally Posted by EndlessAzure (Post 3498472)
@ACT86 The reason that the general advice for camber on FRS/BRZ/86 platform calls more front than rear camber is due to its general driving character and suspension layout
  1. Overall, the car tends to understeer at the limit (it has less front grip than rear grip)
  2. Front MacPherson strut suspension tends to lose camber under load
  3. Rear Multilink suspension tends to gain camber under load
To aid front grip and get proper tire contact, you increase front camber. To help rotate the car and get proper tire contact for the rear, reduce rear camber. For most track alignments, the camber distribution tends to come out to somewhere around -3F and -2.5R.

That being said, most manufacturers of modern cars tend to have a bias toward more rear camber for safety reasons. It helps keep the car from entering an oversteer condition, which the average driver is less likely to recover from (especially in FWD cars). In fact, if you ever take a look at the OEM alignment specification for the FRS/BRZ/86, you will find the car to be set-up from the factory with more rear than front camber.


Excellent response. Thanks mate. So basically if I’m happy with my front grip as is, I’m not going to be introducing any snappy or unexpected handling traits by keeping a bit more rear camber.

Also makes sense as our FWD hot hatch (which has endless front grip in any situation) comes with near -2deg front camber from factory and has quite a playful rear (lift off oversteer) [emoji1360]

ZDan 01-21-2022 06:55 AM

You don't need LCAs. People overly fixate on "more front than rear" but -2.6 degrees rear camber isn't going to hurt "launch" much if at all, and is no prob at all for "wet grip" (tons of wet/inundated track days with my car at -2.7 rear camber, -3.2 front

An ideal setup for handling will have more front camber than rear, but that doesn't mean you should reduce your rear camber just because you don't have enough front.

LCAs are way overprescribed, IMO you don't need them. Might get offset front top mounts for front camber but not necessary for street...

ACT86 01-21-2022 06:58 AM

Quote:

Originally Posted by ZDan (Post 3498476)
You don't need LCAs. People overly fixate on "more front than rear" but -2.6 degrees rear camber isn't going to hurt "launch" much if at all, and is no prob at all for "wet grip" (tons of wet/inundated track days with my car at -2.7 rear camber, -3.2 front

An ideal setup for handling will have more front camber than rear, but that doesn't mean you should reduce your rear camber just because you don't have enough front.

LCAs are way overprescribed, IMO you don't need them. Might get offset front top mounts for front camber but not necessary for street...


Excellent, thanks mate [emoji1360]

strat61caster 01-21-2022 12:21 PM

If you’re happy leave it alone.

ZDan 01-21-2022 12:52 PM

Quote:

Originally Posted by Purist (Post 3498471)
Handling is fine but grip... My daughter's 2001 Corolla has more grip in the wet than my BRZ.

What tires are you on? I would put money on FT86 with good street (Conti ECS) or track (A052) tires vs. your daughter's Corolla for wet grip...

Quote:

My theory is that in the wet, the reduced contact patch means you can't generate enough lateral force to deflect the tyre enough to take advantage of the camber.
In the wet, you don't need as much camber as in the dry, but the camber isn't really hurting wet grip either. Assuming you have some inner groove tread depth remaining. To an extent the heavily cambered tire will act a bit like a narrower tire for theoretically better hydroplaning resistance.

My car with -3.2F/-2.7R camber, on newish RE71Rs (225 and 245) or A052s (245s and 235s) is kind of a revelation in pouring rain/standing water conditions at the track.

Wet grip doesn't seem to me to be sensitive to having a lot of camber, hence I just keep same setup wet vs. dry.

marco_mc22 01-21-2022 02:45 PM

I think anti squat and rear damper setup would hurt more your performance in the wet rather than rear camber. 2.6 is still too much on paper but as someone said before….do not fix something that is already working for your application/purpose.

TommyW 01-21-2022 03:16 PM

These cars don't like a lot of neg rear camber so don't bother upgrading anything the get more.
Around -3 front and -2 to -2.5 ish in the rear is a good overall setup You can mess with your sway bars a bit also.

norcalpb 01-21-2022 05:35 PM

It sounds fine, I would just periodically check your rear tires for excessive inner wear.

Going aftermarket RLCA can have its own issues too: I have the whiteline rear arms and I’m getting slippage in the eccentric bolts. My shop is recommending they weld on a metal stopper for the lock washers. Wtf

The better designed control arms use a threaded rod for camber adjustment and are not susceptible to slippage, but they typically come with spherical bearings (often times with no dust boots) which may not be ideal for a street car that sees a lot of miles.

strat61caster 01-21-2022 07:08 PM

mo uga dugas

Looking at the whiteline docs the 50 ft-lbs torque spec seems real low, the rear factory toe arm specs 76 ft-lbs on that eccentric bolt which is good for the lifetime of the car in most cases.

I broke one of those fancy threaded adjusters, aluminum suspension parts + daily driving doesn't last, much happier with the whiteline, one year of usage zero slippage :iono:

Edit; yeah they spec a lower torque then factory at 59 ft-lbs, I'd bump that up to 76 at minimum.


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