Advice on curing WRX understeer

[gary]

It's getting to be about time to buy some parts to dial back the massive understeer the WRX is experiencing in stock form (I run STX). I had an alignment done recently, and they were able to squeeze 1.3 degrees negative camber out of the front, but still I chewed up a large amount of the outsides of my front tires at the last event.

I'm thinking about camber plates up front to help with grip and tire wear. How much camber should I be aiming for up front? 3 degrees? I don't drive this car a whole lot, so I'm not terribly concerned about tire wear on the street.

I know nothing about parts for these cars. How does this look:
http://www.pltek.net/catalog/product_info.php?products_id=247

Then I'm thinking a big fat rear sway bar to loosen up the rear (I've still got 2 degrees negative camber in the rear). Something like this:
http://www.cobbtuning.com/wrx/suspension-i.html

Anyone have better parts in mind? Better ideas? More bang for the buck?

Any help much appreciated.

-Gary

[LoCore]

What are the rest of your alignment settings? Specifically, toe setting for front and back.

[SubaDrew]

My secret... a rear sway bar (22mm or 24mm). I have the Cusco 3- way adjustable one (as seen here http://gruppe-s.com/Subaru/subsus.htm ) You'd need the one for 02+ wrx.

And some cheapo camber bolts in the rear will enable you to zero out your rear camber (while having your front maxed (at like 1.3 degrees).

The sway bar difference was HUGE and you might be able to find a used one on nasioc.com or something for like $100. I actually got mine from Flatirons subaru (good deal too i think around $130 new). Might be worth it to install some heavier duty endlinks at the same time.

Check out AWDPirates.net gary. That's where pretty much all us local Suby (and Evo) racers hang out and everyone is willing to help.

Oh. And for these last two races, I've had 0 camber and 0 toe all around (stupid dealer taking my alignment out). I should have some large camber for the next race though =)

-Drew

[Captain_Solo]

2-3 degrees of camber up front would be good. A good rule of thumb is to have one more degree of camber up front than you have in back. That rear swaybar will help a lot too...do you have adjustable struts? If so, softening the front and/or stiffening the back will get rid of understeer too-but if you overdo it, high speed transitions will be tricky.

Do one thing at a time and as you get accustomed to the car's new behavior go from there.

The camber plates and rear swaybar are a good start. I'd go ahead and set the alignment and then add the rear swaybar and start with the softest setting...

Good luck.

[gary]

Thanks for all the help.

I'm pretty sure I've got zero toe all the way around. I'm thinking that I might add 1/8" total toe out up front. That sound like a good thing to do? I don't do huge amounts of street driving.

I'd like to dial out the negative camber in the rear, but with the huge, tall tires I've got (245-45-17's), that's not an option right now. I'm thinking I might roll my fenders. Just eyeballing it looks like things might fit in there if they were rolled. Also hoping the rear sway bar will help with the rubbing.

No, I don't have adjustable struts (or anything else) right now. The car came all stock except for the goofy body kit and the "go fast" SPT stickers. Those are an amazing performance boost, you all need to get some.

-Gary

[gary]

Parts are on the way! Next event I'm sure to cut the gap between Dylan and myself from 3 seconds to 2.8 seconds!

[SubaDrew]

ooooo. what parts did you get?


If you want to rool the fenders, I'll help. Not that I've done it before, but chances are I'll have to do it in the fairly near future.

Yeah, I'm trying to cut my avg time to dylan down to .5 sec. Most the races he gets me by 1.5. Grrrr. Looks like roger is signed up for the next race too so it should be a good one.

[gary]

From the nice folks at Oakas:

Perrin adjustable rear sway bar
Noltec adjustable strut tower plates

Hopefully when I turn the wheel next time something will happen besides squawking tire noise. I've had a couple of people suggest that slow in fast out is also particularly important with big heavy cars with no torque like ours.

Hey, did you use first gear on Easter? My transmission does not play nice shifting to first at speeds above 2 mph, but there were a couple of places where I felt I really needed it. It felt lilke it took about 4 seconds to get from the final turn to the finish, for example. Sigh.

-Gary

[mdahl]

Gary, where did you notice your understeer the most?
These cars have differering tendencies depending on what part of the track you're on.
By the end of last summer, I was able to cure any nagging traits in mine, and now I can rotate as requested.

...Then, I change cars.
I would have to say that the alignment and the BIGGEST sways bars you can fit were the best at tuning the spin though.. I'm foggy on the details, but I think I had my rex sitting at -2.2 fr 1/16 toe out, -1.2 r 0toe.
At the time, all I could were progress bars, both front and rear are 22mm.

btw, when upgrading the bar in the rear, upgrade the mounts and endlinks, or you'll snap them.


---ROGER COMING TO A RACE???----time will tell.. he'll probably be stuck with baby-nallath

[gary]

I'd say I noticed the understeer most at corner entry, though that could be attributed largely to driver error I suppose (coming in too hot). But really it seems pretty prevalent in all parts of the turn. For some reason it seemed much worse at the Easter event than at the last winter event (no changes in setup). Just a different course I guess.

This car would rock if I could get it to shed about 700 lbs. :)

-Gary

[mdahl]

well, lift power oversteer is accentuated with a larger rear bar,
power ON oversteer is with a larger front bar.

what kind or tires are you running, and at what psi?

-and, what size bars did you buy?

[gary]

I'm currently sporting 245-45-17 Falken RT-615's. Nice grip, but certainly doesn't help with the low-torque situation. I may go down to 235-40 after I chew up the outside edge of these beasts (which shouldn't take long at the rate I'm going). I've been running 35psi up front and 40-45 in the rear.

I only bought the rear bar, for fear of Wrath Of Wife. It's a 22mm bar, but some places list it as being adjustable from 22-24mm. I guess we're just talking about increasing stiffness, so when they say it adjusts to 24mm, it's "kind of as if" you had a 24mm bar. Or something.

-Gary

[mdahl]

Gary, I thiink you're running to high.
I ran 615's last year and experienced optimum grip at 32fr, 29r. At higher psi, the tires felt less stable, damn near greasy. Also, they need to be as cold as possible, so bring your big water can.

Yes, I have adjustable bars also. I believe that they are listed at 22 stock, but go up in stiffness.
I have my front set at full stiff approx 23mm, and rear set at middle, approx 23mm.

[gary]

Good to know. My high pressures in the rear were a (mostly vain) attempt to reduce grip. I'm hoping to bring that down to a more normal realm with some of these other adjustments.

-Gary

[26STX]

I haven't noticed the 615's being as slippery when hot as the 215's were. Even after many laps on the track without a cool down they did OK.

I don't know about the pressures. I ran high pressures at the last event (like 45 all the way around) and it felt decent. I haven't tried anything as low as what MD is recommending, but I would be willing to try. This is something I really need to experiment with myself because I always get different advice. It probably depends on driving style too. We need a good test and tune day.

FWIW, I have upgraded sways and endlinks all the way around (hotchkis competition package) on an 02 WRX.

[Captain_Solo]

Hey, did you use first gear on Easter? My transmission does not play nice shifting to first at speeds above 2 mph, but there were a couple of places where I felt I really needed it. It felt lilke it took about 4 seconds to get from the final turn to the finish, for example. Sigh.

-Gary

Yep. I had to downshift there, I didn't need to anywhere else. If I was not comfortable with heel and toe I wouldn't have done it though...As I recall, subies are kind of tricky to downshift into first, you almost HAVE to double clutch to do it without making harmful noises...

BTW, 1/8" toe out seems like a lot, but i've never messed with toe all that much...you definitely want zero toe out back on that car though... I'd leave the rear camber at around 2 and bump the front to around three. Try not to to take grip away from the car to get it to handle better...

[mdahl]

Trust me, I thought I was crazy to experience the grip at such a low pressure. I ran it by the motorsports forum on nabisco, and quite a few people agreed with me regarding this paticular tire on the rex.

I used to be the only dude that would pump up his tires leaving an event.
(supposedly it's bad for the diff to run anything other 4psi difference between front and rear on rex's.) I know on lift throttle at low speeds, I'll hear the diff making louder mechanical noises if I run anything other than 4.

Autocross? screw it, I'll take down poles with my mirrors if I can gain a second.
http://eskimo.org/mackenzie/web/killerwrx.jpg

[mdahl]

After the first few times, you can get a rex to pop into first at speed just fine. But it's not straight up from second.. it's more like hard over tio the left and up, like german reverse.

I'm sure it's abuse that helps it along.

[Captain_Solo]

Dude, that pic just made my day!

I like the one running...

[26STX]

I'm not trying to doubt ya, I just wish I could try it in a test and tune instead of competition. The sidewalls are stiff on the 615's, so I can easily imagine the tires working at a lower pressure.

[mdahl]

..you need a large secluded parkinglot.. I have a few up by my house.

..Sent via email to RogerN last week regarding porsche suspension..
fixed the rub,
tested at the parking lot, 30/33 is too much pressure.
I scared some stoners getting baked when I came drifting into the highschool parkinglot sideways at WOT. They jetted about 1.5 seconds after THAT.

she steps out too easy on lift at speed, but like I said, I think I need to drop the psi down to 28/30 or LESS,
which is not really mentioned on pelican.....

I'm sure there was fire on lift too.. Also, if you come come in really hot, and slow lightly, start and at MID commit to the turn, put it into first, she will rotate like a wrx -meaning, on her nose, 180--.. (maybe I'm getting too used to the cones at the ridgeline turnaround)

[Captain_Solo]

Are you checking how much they're rolling over? I'm beginning to think that up to the point that the tire isn't rolling over at all, more pressure =more grip...also, it's very hard to judge how well a tire is performing by feel...YMMV

[gary]

After the first few times, you can get a rex to pop into first at speed just fine. But it's not straight up from second.. it's more like hard over tio the left and up, like german reverse.

I'm sure it's abuse that helps it along.

Yeah, that could be, I'm working on abusing all parts of the car on the same theory. Mine is having trouble in non-racing situations, too. It sometimes makes ugly grinding noises when I go from neutral to first too quickly while standing still. German reverse style left-and-up actually seems to make it worse. Go figure.

This is why I got rid of the STi. I can abuse this one without feeling bad. :)

[mdahl]

Porsche transmissions seem to work best with the theory of "smooth and deliberate" I have found this works well for the WRX also.
The STI tranny mount made that even more apparent.

I've ground first at streetlights too.. It seems to happen every few months if I'm not paying attention. I think it's a different symptom.

I've only driven one other rex in anger, and that was Rogers.. his will shift into first at speed also, with a nudge to the left.
Jenn Higbee won't let me touch her's... :(

[26STX]

I have thrown my 02 into first many times, even at speed. I'm not proud of it, just bragging a bit. :rolleyes:

I got a good picture of high schoolies puffing out when all of a sudden a porsche comes flying through the parking lot sideways, tires screeching and engine screaming. Funny stuff, especially today.

[MrViggy]

Interesting. I don't seem to have any issues getting into 1st at any speeds below 15 or so... No grinding, but it does take a little force to get it in there (i.e. not as easy as 1st->2nd).

I've downshifted into 1st at a few events (wasn't at the Easter event, sorry). At Mt. Elbert I found it did shave a few tenths off; at Coors Field (the usual 180), I found that it really didn't make much of a difference in time, since I had to upshift almost immediately out of the turn. What I made up for in the downshift, I lost in the upshift... Of course, that could have just been me (most likely, it was!).

Viggy

[mdahl]

I hit first a couple of times on last weeks course..
the finish was a killer, I watch the in-car, and I'm amazed I didn't blast about 2 cones right by the lights.
last run (http://eskimo.org/blog/041606e.wmv)

[26STX]

Like viggy, mine doesn't complain either. I am running redline fluid in the tranny and rear diff. Maybe that helps?

[mdahl]

I have the stock fluid.

[MrViggy]

I'm running stock fluid as well. How diffucult is it to change the trans fluid?

Vig.

[SubaDrew]

pretty easy to change trans and diff fluid (probably best to do them both at the same time). I used a sport drink bottle with squirt top to fill the diff. takes 1 or 1.5 pints if I remember correctly. I think the trans takes 4 or so. I filled the trans through the dipstick (small mouth funnel) in the engine bay (behind the intercooler). On the 04's, the trans bolt is a t70 torx, I think yours might be different. The diff should be a 1/2 inch square. I just used a 1/2in ratchet and that worked great.

I shifted to first a minimum of 3 times (max 5) on the easter race. I'm crazy like that. But I can do it pretty darn smoothly without and noises or real jerks. Just takes practice. Enter the turn, rev high on throttle, brake, while braking.. shift to first (while revs are coming down). I do the same on the streets while stopping for stop lights (at less speed of course). The hard part if shifting back to 2nd without disrupting the car/line.

Part of my excess shifting may have been because I had no front brakes on that race. But I may have done the same with normal brakes, only faster... :rolleyes: