uxon

What is the impact of the rear camber on handling in a fast road car? What is the best be rear camber value in GD chassis?
My car is a WRX wagon, I have swapped struts and front LCAs from STI. In the front I have about 1-1.1 degree of camber and more than 4 degrees of caster (which I think is OK for a road car), while on the rear due to stock LCAs I have only 0.2 degree of camber. Does it have any negative impact on handling? Is it worth to invest in adjustable camber bolts to increase rear camber?

BrownPantsRacing

iTrader: (6)

I have always run more camber on the rear than the front on my Imprezas. Mine is currently -1.5 on the front and -2.0 on the rear. Absolutely no tyre wear and handling and feel are greatly improved.

2pot

iTrader: (3)

.....really?

BrownPantsRacing

iTrader: (6)

Here we go again! lol.

Yes, on both my last 2 modified subarus over the last 12 years or so I have run more camber on the rear than the front as above. I significantly sharpens up handling on the car and makes for very flat cornering.

uxon

I am not an expert but isn't bigger camber at rear than at front a bit pointless? In my opinion we need more camber in the front because:
- front wheels are turning (and we use mcpherson);
- there is more mass transfer in the front;
Wouldn't too much negative camber in the rear decrease rear end grip and induce premature oversteer?

2pot, what would you suggest? For front = -1.0, rear=? For Front= 1.5, recommended rear=?

BrownPantsRacing

iTrader: (6)

It actually reduces premature oversteer at the rear with more camber as when cornering and the car is leaning over there is technically more tyre in contact with the road than if it were neutral camber and the inside of the tyre were lifting. I tried lots of setups on my cars over the years and this was the one that worked best for me and made the car feel most planted and confident.

Each to their own I guess. When I used to race mini's & MG's I used to run stupid front camber and less so on the rear, but always found my setup above works better for a Subaru. Personal preferences.

2pot

iTrader: (3)

That's the key: use the set-up gives you the most confidence.

Front and rear strut suspension - I'd suggest minimising the rear negative camber. While increasing the front negative camber - 30mins to 1deg further negative at the front. If the inside tyre edge starts to wear, drive faster or reduce negative camber. I wouldn't use camber plates on a road car.

Excessive negative camber will have deleterious affects on braking, acceleration, will cause tramlining and the car will wander as it follows the camber of the road surface.

bonesetter

iTrader: (9)

LOL - well done for stepping into the fire

Any answer except the most Trumpist was going to be wrong for some

BrownPantsRacing

iTrader: (6)

uxon

Is it like ongoing conflict between BPR and 2pot? Or just in the subject of rear camber :P
Anyway, thanks gents for your opinions.
Under load - with increasing suspension compression, does camber increase?

BrownPantsRacing

iTrader: (6)

NO no, not at all. I have no conflict with anyone on Snet and have never directly discussed suspension with 2pot. I think the comment was made because 2pot is quite vocal on suspension and very pro struts and springs over coilovers and rather vocal on ride height settings etc as he actually sells struts and springs. lol.

That is not in any way meant negatively against 2pot, he's a very nice chap and has always given great content to the forum. All advice from personal experience is good advice!

uxon

You guys both seems to have massive hands on experience with modifying scoobies' suspension, so I appreciate your opinions
Just got a little confused after 'Here we go again! lol.', 'LOL - well done for stepping into the fire ', etc.
BTW, @bonesetter could you explain what you exactly mean by 'most Trumpist' adjective?

bonesetter

iTrader: (9)

I've ran more rear than front and that works well. I have also ran less rear and that also works well

When I bought my current hatch the balance was fine and it handled 'very well' I was quite impressed. So much so I went along to my local Hunter alignment shop and had it measured to 'see where it was'
-1°33' rear
-0°38' front

That was January. Fast forward to summer, thicker bars, sticky summer rubber (AD08R's) and I decided to go more neg front camber to make the most out of what I had
now run one and 3/4 neg front

The whole Impreza suspension thing is over discussed and has been over complicated (by hey, I suppose that's what we do on forums). There's a few simple don'ts (eg over-lower, use crappy Tein springs etc) and most of the rest is personal preference and tweaking a quite forgiving chassis

So camber can go either way, many go equal and just as many go more rear and more front...

Here's an example of personal preference

2pot

iTrader: (3)

Front, under braking, dynamic camber goes more negative. Front, under cornering, goes less negative into positive dynamic camber.
Add front positive caster = reduces the amount of static front negative camber required/decreases the loss in negative dynamic camber.

Reducing ride height will lower the centre of gravity increasing grip. But, reducing the ride height means loss of bump travel and affects the roll centre - a roll centre kit will reduce the loss of negative dynamic camber during cornering (can compensate down to approx 365mm front ride height). Increasing positive rake reduces understeer (Prodrive P1 and RB320).
Rear strut towers move outward under cornering reducing negative camber.

2pot

iTrader: (3)

Again, a front strut, rear strut vehicle, unlike the hatch.
Peter also maxed out the front camber to 1deg 20mins, on that particular vehicle.
Had he got Whiteline kca335 front top mounts, he could have gained further negative camber and positive caster. He might also have introduced a spacer into the lower control arms, to further increase positive caster.

2pot

iTrader: (3)

bonesetter

iTrader: (9)

I was talking about my hatch

That magazine article was about Peter Cambridge spending some time with an enthusiast, not ultimate race

Tons of of castor and camber etc is not where most want to go

2pot

iTrader: (3)

I'm talking about strut/strut, as per the OP's stated car and his requirements.
Front - neg 1deg 30mins to neg 2deg with caster pos 5deg to 7deg: a mild fast road set-up.

TECHNOPUG

iTrader: (1)

I asked Peter the same question last week when we were aligning my car and he said that there wasn't much benefit to rear neg camber on a road Impreza (Newage). Obviously on track it comes down more to personal preference as to how the car handles, as said previously.

bonesetter

iTrader: (9)

That's interesting, coming from PC too

I get even tyre wear at minus one and half degrees...

What alignment settings did you both go with?

uxon

And what about rear camber?
BTW the geaometry settings that I previously quoted were not from my last alingment. I have found another printout which is fresher (values from memory):
left right
Front camber 1,25 1,25
Front caster 4,1 3,85
Rear camber 0,2 0,57

AFAIK you cannot align rear camber on struts (unless you have camber bolts). Do you think that I could even camber on the rear by centering rear subframe? If the answer is yes, I should be getting 0,35-0,4 negative camber at the rear. I am thinking about mounting lock bolts, so this operation could also help on my rear end alignment. I wonder if I should also mount camber bolts all at once

MrRtm

I had my tracking done a few weeks back at a place in Fleetwood recommended by scooby spares, I've ended up with 1.41/1.48 0.01 toe l/r on the front and 3.09/3.17 - 0.23 on the rear, apparently they don't have the ability to do Castor and the back wasn't really adjustable, my steering has felt weird ever since and they said there is some play on the left ball joint It felt fine before, now it doesn't,

Looks like some camber bolts, possibly a new joint or wishbone or whatever the issue is and another realignment is in my immediate future :-(

It's in for an mot in 3 weeks or so though so I'm gonna get it through and ask them to check the joint, when I've replaced anything that's needed I'll get the bolts fitted and take it for yet another alignment, hopefully with somewhere that has a more capable machine somewhere in the lancs area

TECHNOPUG

iTrader: (1)

~0.05 Rear Toe both
Total 0.11

0.01 Thrust Angle

~-1.15 Front Camber both
0.02 Front Toe Both

~4.10 Front Caster both

Peter was pleased with how balanced we could get the front end. I think it helped that I had new lower control arm bushes, ball joints and drop-links fitted. When I had a previously alignment, it tore up the inner tyre walls, as although the static settings were fine, the dynamic settings caused the toe to deflect considerably, due I'm certain to worn bushes on the front.

It's only a Wagon Daily Driver so I didn't want anything too extreme. PCA Springs with Koni inserts and KCA335s to achieve that increased caster. Drives really, really nicely now. Steering as a good weigh to it and understeer all but eliminated at public road speeds,

2pot

iTrader: (3)

You lose approx 35mins of negative camber, front and rear, by using saloon struts on a wagon.

With a pry bar, there is 20mins of adjustment in the rear strut mounting holes.

I'd just try to equalise the rear camber you currently have.

bonesetter

iTrader: (9)

^^ great advice

Your tech just needs to know this, as looking at the data sheet it says rear camber cannot be adjusted - slack off the clevis bolts and muscle it (they 'drop' when on a decent alignment ramp

uxon

My tech told me there is probably no adjustment, but for sure there is no way to get to the bolts in rear struts without removing wheels (probably with an impact gun), so he refused to even try adjust them.

BrownPantsRacing

iTrader: (6)

Sounds like you need a new mechanic.

The top 3 strut mounting bolts are accessible in the boot by simply removing the side lining cover. To be honest the bolt slop in the 3 holes will not give you adjustment worth worrying about so I wouldn't even both with these.

But, the rear strut is held on with 2 lower bolts, one of which as standard is already a camber adjustment bolt. They can be undone (on a ramp) without even taking the wheel off or in minutes from the outside with the wheel off. It's a really easy job to do.

bonesetter

iTrader: (9)

Top srtut mounts #fail