For most this AX season i've been battling understeer on entry & oversteer on exit, with plenty of body roll.

Front: Bilstein shocks 22mm torsion bars & stock ARB set 3rd stiffest
Rear: Koni set at 50% stiff, 175lbs springs no ARB
Weight 2000, front to rear roughly 45%-55%, ride height front 5" rear 5.5"

Thus i've had to back off earlier & earlier into turns. Turn way early & hold off the gas till way past the apex. Quite frustrating.

I've heard stiffening the front ARB will reduce body roll, as would stiffer torsion bars or even stffer shocks. But wouldn't they all increase understeer?

So i lay it open to you'all to help with speccing a more neutral, less roll ride.

Soften up the rebound of the rear shocks.

Yes slow in and fast out is quicker. Someday I'm gong to learn that.....

I am always guilty of going into a corner with my hair on fire only to realize 1/2 way through that the car is pushing and I ain't going to make the exit clean.

Several questions: What brand, size and age of tires? What air pressure front and rear (cold and hot)? What is the temp spread across the tires (inside edge, middle and outer edge)? What are the front alignment settings, what are the rear alignment settings? What are the corner weights at each wheel with you in the driver's seat with safety equipment on? Do you have a limited slip? Finally, does the car do this both left and right turns? The answers to all of these will determine the best advice and a serious autocrosser needs to have this info so minor adjustments can be made depending on the day, track, weather, etc. If you can fill in the blanks here I can query some serious auto-x drivers as I have not done too much lately, been vintage racing which requires some differences.

http://www.wtrscca.org/tech.htm
I like this page. Usually have a copy in my possesion when things are going screwy with handling.

Thanks John, filled in the blanks as best i could without my note book.

Tyres are mismatch front to rear (not great i know) 225/50/16
Front: Yoko a000 something treadwear 80
Rear: Yoko A034 Hard compound Treadwear 60

Air pressure, adjusted hot pressures based of tyre temp & sidewall chalk marks.
Front: Cold 34 Hot 35
Rear: Cold 36 hot 37

No tyre pyrometer or IR readings. Hand check gave cold on front & warm on rear. Even temp spread across surface.

Alignment
Front, Toe 0, Camber -1, Caster 5.50
Rear, Toe -0.1, Camber -1.5

Corner weights, with 165lb driver. Had trouble getting any better than a 60-80lb cross axle bablance. Ended up choosing rear to be closer.
Front Left 480 Right 420
Rear Left 560 Right 540

No limited slip.

Understeer is consistent in both left & right turns. Could be simply old crappy tyres.
Oversteer has been most promenant in medium speed (circa 40mph) left handers.

QUOTE (Rough_Rider @ Oct 26 2005, 01:35 PM)

For most this AX season i've been battling understeer on entry & oversteer on exit, with plenty of body roll... Thus i've had to back off earlier & earlier into turns. Turn way early & hold off the gas till way past the apex. Quite frustrating.

Trev,
Try this: As you aproach turn-in, brake later/harder to transfer weight to the front tires just before you turn in. This might eliminate the understeer on entry. Next, roll into the throttle earlier in the turn than you have been doing to move weight back to the rear to reduce oversteer on exit. Try to get these weight-transfers done just BEFORE you would otherwise expect to feel the under/over conditions. Using more throttle to reduce oversteer sounds counter-intuitive but it works if you do it smoothly and don't give it too much.
When one end of the car doesn't stick it is unweighted. Use the brakes to weight the front and the gas to weight the rear. I wouldn't make any suspension adjustments at this point. I can get much more 'adjustment' out of these techniques than I can from my swaybar settings.

-Ben M.

Well, what stock front sway bar has adjustments? Seems to me you might have an aftermarket bar insted.

Moving on from that, corner entry push is more often than not the result of just going in too hot. Slow in, fast out. With that much spring and bar in front, you might very well be too stiff on the front suspension, and you're washing out on entry. Then, you slow down more, give it _more_ wheel, and (with almost 6 degrees of caster, you're gaining a lot of negative camber there) getting a jump in grip in the front which overloads the rear.

However, it sounds like something's not quite right. I'd first start looking for bad bushings and links. The missmatched tires also could be contributing to your problem. If you're running Yokohama A008's then they're at least 5 years old most likley and they're probably about as grippy as a slab of granite. That could also be contributing to your entry understeer.

Keep in mind that Koni's only allow for rebound adjustment. Bump is fixed.

This is all assuming the slow-in, fast-out, and SMOOOTH is not working for you...

-Josh2

You guys make it sound so damn easy!
However whenI do remember to apply throttle when the rear is loose the car does regain grip and I am just amazed at the whole process.

Getting the whole thing to become instinctual is difficult.

I also plan on running the fun runs on street tires so I can get better at catching the car as it slides and squirms and wiggles. Did this at my last drivers school and was much better the next day when it got "for real"

This question was answered in a copy of Sportscar...last winter, IIRC. Multiple National Champs (solo) were asked. In what order should one attack a car/driver combo to improve lap times?The consensus:

Driver
Tires
alignment
suspension

They're not lying.

QUOTE (Joe Ricard @ Oct 26 2005, 01:43 PM)

I am always guilty of going into a corner with my hair on fire only to realize 1/2 way through that the car is pushing and I ain't going to make the exit clean.

QUOTE (Joe Ricard @ Oct 26 2005, 02:55 PM)

You guys make it sound so damn easy! However whenI do remember to apply throttle when the rear is loose the car does regain grip and I am just amazed at the whole process.

Yep, you can't play 'catch-up'. Make those weight-transfer adjustments with throttle/brake BEFORE you feel loose/push. This will take learning to recognize when it's going to happen rather than waiting until you feel it happening.
You mention correcting the oversteer on exit - good. Try what I said about braking harder just before turn-in to load up the front tires. It works so good that when I first started working on doing it I went from pushing at turn-in to being very loose at turn-in. I'm still working on the balancing act.

-Ben M.

QUOTE (J P Stein @ Oct 26 2005, 03:13 PM)

QUOTE (Joe Ricard @ Oct 26 2005, 01:43 PM) I am always guilty of going into a corner with my hair on fire only to realize 1/2 way through that the car is pushing and I ain't going to make the exit clean.

like this squeezing the throttle to wide open coming out of a corner. speed is about 55 or so. Ass end is firmly planted probably just about lifting passenger front tire.

Yeah, nice pic, but where is the flaming hair

Wow this one slipped by quickly! Here's my thoughts

Tyres are mismatch front to rear (not great i know) 225/50/16
Front: Yoko a000 something treadwear 80
Rear: Yoko A034 Hard compound Treadwear 60

- Match the tires or put the softer ones on the end that has the push.


Air pressure, adjusted hot pressures based of tyre temp & sidewall chalk marks.
Front: Cold 34 Hot 35
Rear: Cold 36 hot 37

- When Julia raced with Yoko A008s we used 26# cold front and rear and had no push.

No tyre pyrometer or IR readings. Hand check gave cold on front & warm on rear. Even temp spread across surface.

- See if you can borrow a meter or Pyro as your hand is not sensitive enough.

Alignment
Front, Toe 0, Camber -1, Caster 5.50
Rear, Toe -0.1, Camber -1.5

- I'd go with camber -1.5 in the front, maybe more. we used -1.5 with our Yoko A008s.

Corner weights, with 165lb driver. Had trouble getting any better than a 60-80lb cross axle bablance. Ended up choosing rear to be closer.
Front Left 480 Right 420
Rear Left 560 Right 540

- That's close enough, it is good you know as most people have no idea.

No limited slip.

Understeer is consistent in both left & right turns. Could be simply old crappy tyres.
Oversteer has been most promenant in medium speed (circa 40mph) left handers.

Try soaking the tires to soften them. Grassroots Motorsorts mag did a test and proved it works!

This is a good thread to air opinions about 914s, AX, track and generally going around corners quickly....a great combo.

As you guys may have noticed, I'm a firm believer in tires as the basis of all this. Race cars are often designed around what ever tire is allowed....or redesigned around them as they become available. The latter would be us'n.

Them 2 Subbie guys were on street tires as they decided to switch to another class where street tires are required. STX or sumthin'. They both hated their cars thus shod....even the one guy's wife was disgusted. Neither had the good Falkens, but were headed that way... if Falken ever make their sizes.

I've pretty much run the gamut of AX tires....street(a little bit), R spec, diferent brands, different compounds, now to slicks and one more compound to try. I learned some stuff along the way
and the progression has not been smooth learning curve.
One thing I believe to be true consistently. Given equal cars, drivers, & tires, the guy that sets his car up best for his tires will win.

BTW,IMO, If you're AXing your car on good R spec tires you will learn nothing by going back to street tires...except how bad they are in comparison. The car will behave much differently unless they are *very* good street tires...Pilot Sports or sumthin' and you'll be going slower.

QUOTE (J P Stein @ Oct 27 2005, 05:06 PM)

This is a good thread to air opinions about 914s, AX, track and generally going around corners quickly....a great combo. As you guys may have noticed, I'm a firm believer in tires as the basis of all this. Race cars are often designed around what ever tire is allowed....or redesigned around them as they become available. The latter would be us'n. Them 2 Subbie guys were on street tires as they decided to switch to another class where street tires are required. STX or sumthin'. They both hated their cars thus shod....even the one guy's wife was disgusted. Neither had the good Falkens, but were headed that way... if Falken ever make their sizes. I've pretty much run the gamut of AX tires....street(a little bit), R spec, diferent brands, different compounds, now to slicks and one more compound to try. I learned some stuff along the way and the progression has not been smooth learning curve. One thing I believe to be true consistently. Given equal cars, drivers, & tires, the guy that sets his car up best for his tires will win. BTW,IMO, If you're AXing your car on good R spec tires you will learn nothing by going back to street tires...except how bad they are in comparison. The car will behave much differently unless they are *very* good street tires...Pilot Sports or sumthin' and you'll be going slower.

Well Said!

When I bought my car, it came with an extra set or rims with Yoko Advants. I drove the shit out of those tires without sway bars or any other suspension enhancement. I slowly added some suspension components and tuned the car to actually use the entire range of performance from the tires. To me, tires are the very first improvement you should make to your car if you want to perform at the AX. Not a bigger engine, not crazy suspension, not harnesses or seats! You don't have to go crazy with tires either, I run a set of Falkins Azenias and have no issues...I like them because they have a stiff sidewall and predictable handling. I can actually feel the flex of the sidewall in my street tires when going around a turn...I hate that feeling.

-Britain

Let's face it, Britian, Azenias (SP?) are thinly disguised R spec tires, they just made some tread blocks on em'.....not that there's anything wrong with that

QUOTE (J P Stein @ Oct 27 2005, 04:38 PM)

Let's face it, Britian, Azenias (SP?) are thinly disguised R spec tires, they just made some tread blocks on em'.....not that there's anything wrong with that

I beg to differ there JP...

I've driven the Azenis tires. Heck, I've even tested them durring a test 'n tune autox. They are NOT R tires. They may have a stiff sidewall like R tires, and that's why they are so wonderfully responsive. But the tread compound is most definitely, -street-. It has no tollerance at all to temperature buildup. And they will actually start to go off before you're even across the finish lights at a regular autox. The cars best suited to the axenis are small, light weight cars. Anything heavier than around 2200-2300 lbs really need something like the BFG...

-Josh2

QUOTE (jhadler @ Oct 27 2005, 05:45 PM)

I beg to differ there JP...

No need to beg, this is a discussion, not an arguement.

I will admit that I don't much about the Azenis....but now I know how to speel it I skipped that step
on the way to AX supremacy

Top 5 guys at Topeka were running Falkens in STU.
STIs & Beemers...porkers....maybe another model tire? The SCCA website, Finals Solo results, is a gud place to shop for tires.... can't think of a better place, in fact

Those Suby guys that I spoke of know their shit......they didn't specify Azenis.....that was my assumption.

710 Kuhmos have little heat build up resistance. Bring your own garden sprayer cause nobody in your class will loan you one It seems to work.

I copied your picture and lightened it up so I could see the bottom of the rocker panel which is a good reference as to how the car is sitting. I showed it to a couple of other auto-xers and they agree with me. It appears it is nose high coming out of the corner you are in which means less weight on the front wheels which means more chance of of understeer which is what you are fighting. I'd say raise the ass end up some (an inch ?) as the front is already pretty low, possibly too low and the A-arm geometry has been affected. The other option is to go to stiffer rear springs so it doesn't squat quite as much and also keeps the inside front wheel planted.

John:
He says up front he's fighting understeer on turn in and mid corner, but oversteer on exit.....golly, I have similar problems .

There are a bunch of ways to work this, suspensionwise...few of which, IMO, include raising the car up. It is possible he's running out of suspension travel and bottoming out on the bump stops.....which will yeild some....ah.. interesting effects and in that case one would raise the car in front for a quick fix. It takes some serious jackin' & wrenchin'
to check this.

BTW, Trevor, what'cha got for brakes?

You know now that i think about it i've had better turn in with a set of newer street tyres than i've had on any the slicks i've tried. Mind all the slicks or R's i've used we're part worns & old.

Exit oversteer is partially due to whacky suspension settings & a big part the driver getting on the gas early. I left foot brake so gas is justa twitch away.

Lesson learned, old tyres just plain suck :-) Next year after figuring out wheel sizes i'll be plumbing for some 710's

Suspension wise i'm not bottoming out, 5" on front & 5.5" on rear. Using a old mtb trick of zipties on front damper rods. I still have 1/4" to 1/2" front travel remaining.
A arms are pointing down at rest & all teh bump steer mods have been applied. Bushing on the other hand may be shot to hell which would be bad for geometry.


Brakes are a tad upgraded, could even say overkill. 19mm master cylinder, brake brace, brake bias in rear line, ate dot4, braided lines, 951 4pots & carrera rotors front, 85 Carrera rotors & calipers rear.

QUOTE (john rogers @ Oct 27 2005, 07:34 PM)

I copied your picture and lightened it up so I could see the bottom of the rocker panel which is a good reference as to how the car is sitting. I showed it to a couple of other auto-xers and they agree with me. It appears it is nose high coming out of the corner you are in which means less weight on the front wheels which means more chance of of understeer which is what you are fighting. I'd say raise the ass end up some (an inch ?) as the front is already pretty low, possibly too low and the A-arm geometry has been affected. The other option is to go to stiffer rear springs so it doesn't squat quite as much and also keeps the inside front wheel planted.

John, you talkin to me? Just guessing. Ya that's on the list. Car squats even more now with Hoosiers because I am loading up the suspension so much more.

Car in picture had stock 17mm torsion bars and 150 lb coil overs. no rear sway. big front welt sway. Koni's all around

So I know I shouldn't have done this but I replaced the stock torsion bars with 21mm's A-arms are now level when measured at the seam of the arm. I am going to order some stiffer rear springs as soon as I figure out which one's to get.

So what is the spring rate of 17mm and then 21mm torsion bars?????? Looking at jumping up to 200 or 250 rear springs any manufacture more that likely linear rate.

I don't know what the exact spring rates are--you have to take into account the "lever arm" that the torsion bars work through, and pretty shortly you start talking about "wheel rates" instead of "spring rates"... However!

Torsion bar stiffness goes up with the fourth power of the diameter. So a 21mm torsion bar is about 2.3 times as stiff (or as much effective spring rate) as a 17mm one!!!

From what other people have said in other threads on this site, you should consider 200#/in or 250#/in springs in the back to match those massive torsion bars.

--DD

Hi Joe, I was as a matter of fact. I use 300# rear springs on the race car and it was just enought to keep the inside front wheel down. It originally had 250# and they were a little too soft. Raising the rear slightly will shift a small amount of weight forward on the exit as the rear will be squatting less and should help with the understeer. The lower pressures in front will help also. Remember the rear tires will pick up some heat (not evenly thought) when sitting in line for the next run due to the engine heat being generated right next to them while the front tires are cooling off some! This makes things even more complicated when watching the tire temps and pressures.

Hey Joe,

John's suggestion of 300# is probably a bit high for an autoxer, I'd suggest 200#. That's what I was running, and the car was really quite nice to dance with around the cones. 21mm t-bars, 22mm sway war, 200# coils. All on 225/45-15 hoosiers on 8" rims. Sound familiar?

-Josh2

Here is something elso to ponder. I noticed in the picture that the Targa top is off. When you are driving are you getting some breeze in the face when the top is off and the windows are down? If so the rear window is acting like a huge air brake and pulling down on the rear of the car. If you are doing 40 or 50 MPH like in the picture, there is a fair amount of drag there, helping to increase the understeer. Silly you say, why do many 914 racers cut the top off completely? Or most leave the top on or do as I do, raise the rear edge about 1 1/2 inches so the trapped air can get out.

Reading your post and talking with Hassan just a minute ago. We agree top on is better even in the sweltering summer heat as there is some shade.

Hmm what did you use to keep the rear clamped down. Everyonce in awhile I've been know to get a little backwards. Hate to have the roof fly off.

Ande here is the shameless request for stiffer springs for cheap.

Joe,

Cheap springs are only as far away as your local roundy round shop... Them roundy round boys use the same size springs that the sports car guys do (coil overs) and you can get 'em WAAAAY cheaper. Like $50 a pair instead of the $250 ground control coils...

-Josh2

QUOTE (Rough_Rider @ Oct 26 2005, 01:35 PM)

For most this AX season i've been battling understeer on entry & oversteer on exit, with plenty of body roll. Front: Bilstein shocks 22mm torsion bars & stock ARB set 3rd stiffest Rear: Koni set at 50% stiff, 175lbs springs no ARB Weight 2000, front to rear roughly 45%-55%, ride height front 5" rear 5.5" Thus i've had to back off earlier & earlier into turns. Turn way early & hold off the gas till way past the apex. Quite frustrating. I've heard stiffening the front ARB will reduce body roll, as would stiffer torsion bars or even stffer shocks. But wouldn't they all increase understeer? So i lay it open to you'all to help with speccing a more neutral, less roll ride.

The only suspension work I can see that needs work before next weekend is up front. Other things need work, but they involve spending money & gathering parts.

You're understeering is caused by your front end being too stiff.
about all you can do is back off the AR bar to full soft.....that won't getcha far, but should help a little bit.

Your front to rear spring rates are way out of balance.
With 22mm T bars, you would need 350-400 rear springs.
I have 21s & 300s and that isn't enuff in back to cure my push in the tight stuff. I will prolly go softer in front this winter.
The 300s mostly cured my inside rear wheel lift, so that's as far as I'm going. I could loan you some stiffer springs if you have adjustable rear perches. If not, add them to your list.

To the best of my knowledge, Koni doesn't offer custom revalving for their shox.....Bilstein does.....there's a clue here. I have an extra set of revalved Bilstein inserts if you wanna give them a try. Shox are for turn in & AR bars are for steady state cornering.


Your exit oversteer is caused by crap tires & a heavy foot.
We'll get ya out on the skid pad at the driver training deal
a week from sunday & see if we can learn ya drop throttle oversteer.....a useful little bit to drive around mid turn understeer.

Top off is worth a half second minimum off my times......I hab no idea why..... this was also true when I had a back window.

Cheers JP,
Came to the same conclusion on the front ARB.
Rear koni's have the coilover conversion. So ID2.5" by 10" springs fit perfect. Koni will do a rebuild of their dampers but its spendy & takes time. The local roudy round guys use a bilstein specialist in PDX, he's willing to work with us to dial in my fronts. Although might take you up your already re-valved inserts.

Am looking a for a friendly site nearby who'll let me test & tune, will let you know what i find.


C ya on the 6th.

Btw, top off thing. (A) i prefer things with tops off..... ( some BMW engineers concluded weight high up raises CoG, duh!!. thus the carbon roof on the CSL. IMHO its a personnal thing, For me i prefer it on but will be working to make it lighter.

Revalved & rebuilt....65 bucks ea plus parts from Bilstein west.
Lotso places "revalve" Bils. They select the valving and send the shox to their expert Bill West for the actual work.....and take a cut.

I have 225s & 275s spring sets on the shelf 2.5 X 10.

I'm a little late getting in on this one

Yes, tires, all the way.

I ran streets, Falken's, Yok's A032's, Hoosier AS04's, and now 710's.

I like the 710's the best. They love heat and double as a track tire. Are supposed to last longer, too. ( $$$ )

Simply put, there are some turns you just can't drive fast in. You will *always* understeer in them. Back off and set up for the exit instead of fighting your way through them while losing time.

Get fresh tires and report back.

A great driver told me he had some old sticky tires I could have .
Sais they prolly would make sparks...


KT

Trekkor is right about some AX corners, all you can do is get grit your teeth and get thru them. The nicest thing about our last AX course was that you could attack almost every corner......that is a rarity and a hoot.
Kudos to Gary Chapman.

So, Trek, you've decided good tires are a gud plan......Soon it will have been your idea all along.

QUOTE

Soon it will have been your idea all along.

Uh, yeah!

It is mine, which is mine and it is mine...


KT

BTW, Trevor, I have 4ea 225 X 15, R3SO3 Hoosiers that I'll sell ya for 50 bucks. There's a season left in them.

Hi Trev,

JP has it right regarding your rear spring rates...you're way too soft in spring rates for the T-bars you have in front.

On our 914 we ran the following at Auto-X's:

Front...

22mm T-bars
27mm Smart Racing ARB
Bilstein struts

Rear...

375 lbs Eibach 2.5 x 10 inch springs
Stock ARB connected
Bilstein shocks

We had a 901 with an 80% LSD. We ran an open diff the year before and ran the rear ARB disconnected on really tight courses.

With this setup you can use the front bar to adjust out most things, including going from Auto-x's to the track (Laguna Seca, Sears Point, Thunderhill, Buttonwillow).

With this setup with a 23mm weltmeister bar up front we could make auto-x crossing work but couldn't get the tail happiness out of the car at the big tracks. The heavier bar from Smart took care of that.

Also, with the bigger bar, we can move up in rear spring rates depending upon the track...for instance, we were faster with the 375's on the longer tracks and over 1 second a lap faster at Laguna Seca with 450's in the rear.

My $9.14 is to either soften the front or go bigger on spring rate in the rear.

Bill P.