mdb4879

I'm just going to copy this from a local forum I posted in. This was my first autocross in this car:

In case you didn't notice (it was pretty hard to miss), my car was REALLY tail happy today. It's the first I've gotten to drive this car hard at all, but I must admit I was pretty surprised it was this prone to oversteer. I started the day with 32psi front and rear in the tires, full stiff on the shocks (Koni Yellows, only rebound adjustable), and a quarter tank of gas. It didn't take much for the rear end to walk out and when it did there was no coming back. It even almost felt like it wanted to come out during steady state cornering. This was with cold tires as well, so the front to rear tire grip ratio was about as close as it could get.

By the end of the day I was at 34psi front/28psi rear, 3/4 tank of gas (I figured the extra weight would help and I was sucking up air around sweepers at a 1/4 tank), full stiff front shocks and 1/2 a turn from full soft rear shocks. It felt pretty good around sweeper (almost no understeer unless you tried to make it push), transitionally it was a bit too tail happy for my taste, but it was manageable if you stayed steady through the slaloms. But if you trailbraked it'd easily spin around. The problem was if I came in too hot and was still braking when I turned in or I locked up the brakes it'd swing out and since I was already going too fast I couldn't bring it back with throttle. All I could do was let it spin.

To sum up the handling characteristics, at apex and corner exit the car feels great. The tiny bit of understeer I have is neglible due to the nature of FWD cars and I may even be mistaking slip angle for understeer. Just a light lift off throttle if you're going off line will let hhe rear hang out a hair and pull you back in and you can then use the throttle to feather it around the turn. The front grip is unbelievable on corner exit, it puts down power like crazy and I don't really notice the inside tire even trying to spin. Through the slaloms it's a bit too tail happy for my taste, but it's manageable with smoother inputs. With that it doesn't come out, but I have to be careful because I know once it comes out there's almost no bringing it back. The worst is corner entry after a straight. If I'm still on the brakes or if I lock them the rear kicks right out and spins the car around. The only safe way to enter is to completely let off the brakes before turning in.

So anyways, I need to tune this out somehow. I have some ideas, but I'd like some other input as well. The rear tires at 28psi was about as low as they could go before it looked like they'd start loosing grip. The front has a fair bit more camber than the rear, so at 34psi they are far from optimal grip. I would like to do my best to gain grip in the rear before losing it in the front. I'd like to maintain not having a front sway bar to maximize side to side independence since I have no LSD. I'd also like to keep the rear sway bar I have simply because if it's cost and I may have a hard time selling it without the rear subframe brace (which would be handy for any sway bar I run). So here's my current setup:

1992 Honda Civic VX Hatch
B18C1 GSR swap, no LSD
No A/C, no P/S (evaporator core removed as well)
No radio or speakers
No rear interior
Lithium battery relocated to behind the passenger seat
Carbon fiber tailgate
Full exhaust, including the axle back
3/4 tank of gas (about 8 gallons)
Guesstimated weight is around 2000lbs, plus or minus some. I'm going to try to have it weighed tomorrow at the cotton gin by my house and check the weight distribution.

Koni Yellow shocks with Ground Control sleeves and extended top hats. 450f/500r springs
No front sway bar
Cheap eBay rear LCAs (not a fan of them, but now I'm thinking having three holes to mount my end links to may be nice from an adjustability standpoint)
ASR 24mm 2-point adjustable rear sway bar with adjustable end links set full soft in the middle hole of the LCA
205/50/15 half tread BFG Rivals on 17lbs 15x8 +20 Rotas
No shock tower bracing or any other chassis bracing
Front ride height is 5" to the ground from the rocker (not pinch weld)
Rear height is about 5.5" to the ground from the rocker
Camber is natural from stock UCAs front and rear. Not sure of the actual numbers, but the front has quite a bit more than the rear.
Front toe is zero. Rear toe is 1/8" in as I measured it before I left (this could certainly be a problem, but idk how much of one it was. It will definitely be zero before the next event)

A few other notes that probably don't have much to do with it's handling characteristics:

Hawk HPS front brake pads on stock calipers and rotors
Stock rear drums and shoes
Stainless brake lines
ATE Super Blue brake fluid

Here's what I think may help:

Swap springs to 500f/450r
Zero rear toe
Lower the rear (gain some static camber and take some weight off the front, but I already know if I go much lower the rear will rub the front of the bumper)
More rear static camber via camber links
Raise the front (I'd rather not because I think that'll take away from potential front grip)
Move the end links closer to the center of the car on the rear LCA's (less leverage, but then the end links will be angled in relation to the bar so that isn't ideal)
Add weight to the rear
Remove weight from the front (about all I have left to remove is the bumper reinforcement)
My rear bar might have some preload when the car is lowered, so I need to see if I can eliminate that if so.

Another thing to consider is I tend to be an aggressive driver. I'm working to smooth things out, but it may also be noted that I realized last year that my aggressiveness could aid in preventing a car from being tail happy because I use the throttle a lot mid turn which transfers weight to the rear and plants it down. But that seems to work better in a more moderate setup than what I have now.

Any other ideas or thoughts on what may be the most effective are greatly appreciated. Thanks for the help.

EGUK

I had oversteer issues with my EG on Koni/GC 10k on front 12k rear, 24mm sway front, 22mm sway rear.

I went down to 8k in the rear and it helped alot but high speed turn in still felt unpredictable.

I ended up with 12k front 10k rear and no rear sway at all.

My hatch is pretty light which was not helping (830kg) and staggered wheel/tyre combo 225 on front 195 rear.

Happy with it now.

Agent_Smith

First question I had was what's your alignment settings & it's very vague based on total toe of 1/8" in for the rear and "zero" front. Your rear end could be tracking left or right if your only measuring total toe too. Get some real numbers to go off of. If you only have -1 or -1.5 rear camber that could be the entire source of your issue too.

Having a real alignment with actual numbers will really help give more actual data to the source of your problem.

To me it sounds like a driving style issue, you talk about entering a corner too hot then being upset that the rear end is coming around while your braking in a turn. Braking in a turn generally equates to oversteer (losing it). Do you have any in car videos?

Matt_EH3

What is your brake setup?

mdb4879

Unfortunately I lost my phone mount, so I don't have any videos. When I say coming in too hot, I don't mean way too fast. I'm use to being able to brake hard and ease off as I turn in, but not completely (leaving some load on the front tires helping turn in). If I do that in this car, though, the rear walks right out. It's not a gradual thing either, when it comes out, it comes out fast. I've driven a friend's Integra before (nowhere near this level of prep, but well balanced) and could slam the brakes mid sweeper for a pin cone and let the rear walk out as I slowed down then hit the gas at the pin and pull the car back around without issue. It's a bit different as the weight distribution is different, but you get the idea. At the beginning of the day yesterday it came right around on me mid slalom with next to no warning. Another thing to note is our venue was sealed last year. Now that it's cured it has a decent amount of grip, but the drop off is much sharper than on normal pavement.

I don't have any actual camber numbers because I refuse to go get a professional alignment when I will more than likely have to change it to tune the car. So I plan to buy a camber/caster gauge to tune with, and when I get it about where I like it I'll have it permanently set with things like thrust angle sorted out. For now, I figured knowing I was on stock arms should give a rough idea what my camber should look like from knowing my ride height.

I'm not even close to optimum front grip, and the rear is really wild. Today I've been taking some local advice as well and have swapped the springs front to rear (500f/450r) while letting the ride height change naturally. The front came up about to between 5.25 and 5.5" and the rear is sitting 0.25" lower than the front. I checked the toe on the rear at ride height and with the rear lifted an inch and noticed it toes in an 1/8" in when the rear lifts. So I toed out the rear from 1/16" in (the car lowered in the rear so it toed out some) to 1/16" out. Hopefully this will straighten the rear tires as weight lifts off the rear. After a quick 40mph "slalom" the car feels more balanced. Being on cold tires I got a slight push from the front as I transitioned holding steady speed. I think this will give me a better baseline for Saturday.

mdb4879

My brakes are Hawk HPS front pads on stock VX calipers and rotors, stock rear drums and shoes, stainless braided lines, and ATE Super Blue fluid.

Matt_EH3

Hmm, for the hard braking corners/trailbraking, with the colder start of season temperatures I was suspecting the rear could be locking up before the front, but with your setup, it seems that this is unlikely the cause.

I am surprised that you felt less oversteer with more toe out. Changing the setup from toe in to toe out will usually add oversteer, not the opposite. Then again, too much toe in will make the car feel very strange at the back (not sure how to describe it better than "strange" here; this is based on personal feeling/experience).

When you go back, don't hesitate to lower the shock rebound setting a little more if needed. I don't know in which area you are, but with colder temps, you need to run everything a little softer than during the summer time.

I don't know how much experience you have, but if you don't already know this, in a fwd vehicle, when in doubt, just get on the throttle. If you have the amount of front grip you say you have, just transfer that weight to the rear and let the fronts do their job.

10cjennings

iTrader: (1)

Make sure your rear bar doesn't have any preload or bind and figure out where your alignment is at. This doesn't sound like a setup that should be extremely loose.

Going from toe in to 0 toe in the back should loosen up the back end, not settle it down.

From there, test and tune. Maybe try a front bar, or swapping springs. You're going to want to get an LSD asap. The difference is significant, and you'll have to adjust the car around it. But check that nothing is out of the ordinary with the rear bar and alignment first.

mdb4879

I've only got one full season under my belt, so I'm technically not very experienced. But I picked it up very quick and do really well for my experience level. I can usually hop into someone's car who's been autocrossing for several years and beat them by anywhere from just barely to 1.5 seconds on a 50 second course depending on their skill level. I had a six time national champ drive my Speed3 with me last year and he beat me by 0.7 seconds because I pushed hard on one corner. But that let me know on the days I knew I couldn't get any more out of the car, it was pretty close to it's limit. Had I made a good run I would've been right on top of his time. I have a comparison video if anyone cares to indulge.

I'm from North Alabama, so it was decently warm yesterday. I'm very familiar with FWD, but the rear would come out so fast I couldn't do anything about it 80% of the time. As I said before, the worst was going into a slalom after a 65mph straight. I was still trying to slow down, so stomping on the gas would've just driven me straight through the cones.

The toe wasn't the only thing to change, so that was a poor comparison on my part. I was actually told to toe the rear in even more to 3/16", but decided to try toe out because of what I observed when jacking up the rear of the car. I swapped spring from 450f/500r to 500f/450r, raised the front about a 1/4" and lowered the rear a 1/4" (which should have put more weight over the back and less over the front, in addition to less static camber up front and more in the rear). Then I changed the toe from 1/16" in to 1/16" out. So I couldn't say what the toe change did on it's own. Plus I was on different pavement, and on the street, so it's hard to really simulate my driving of yesterday. I'll definitely play with toe in for the rear, though.

I've been doing my best to set up the car like an STS car. The setup is different, but it's pretty similar. The weight is about the same, but the distribution is different. I have no LSD, but I'm making more power. I'm sure an LSD would help and it would probably allow me to stiffen the front more without loosing the ability to put down power at corner exit. But for now I don't have an LSD, so I'm trying to maintain as much front grip as possible. If I can't do any better to settle the rear, I guess I'll have to try a small front bar.

I've also been informed that I was in fact three-wheeling the car. Which doesn't come as a surprise as I see tons of FWD cars do this. But I'm wondering if I were able to keep all four tires on the ground if it'd improve overall corner grip.

N2RCN4FUN1

I have a 1991 ef only for track use, i run front shock 1/4 from full soft and rear 1/4 from full firm, run like a 700 rear spring, 650 front with 32mm asr rear sway and have ground control and yellows, i would start by changing the way your shocks are set, do one thing at a time

10cjennings

iTrader: (1)

A good rule of thumb is to change one thing at a time.

Keep testing, but figure out where you're at first. If you don't have the $ to buy adjustible UCA's or pay for an alignment. See if you can get a free/cheap alignment check from any typical tire place.

Putting theory aside, Every fast fwd autox car I've ever seen picks up a rear tire sometimes.

mdb4879

What wall thickness bar are you running? The thinnest wall they offer is softer than the 24mm bar if I'm not mistaken, correct?

I can afford an alignment, I just can't afford to get an alignment every week until I get it set how I like. I think I'm good on front camber, there looks to be plenty, even if I don't have an exact number for you. But if I need more down the road I think I'll opt for new stock arms, slot the holes, then weld a washer when I get it set how I like. I'll more than likely have to play with rear camber first, so rear camber links are on the list.

At the track I was trying to do one thing at a time. But the behavior was so extreme that I figured I should take multiple steps in the week before the next event since they take too much time to do between runs. Then I can play with alignment and tire pressure and shocks at the track.

Also, I'm curious, the Koni Yellows are only rebound adjustable, just to confirm, correct? I understand how compression and rebound control the spring, but how does rebound adjustment alone affect how a car handles if it isn't underdamped? Meaning if the spring rebound is already under control, how does more rebound affect the car?

N2RCN4FUN1

I run the thinnest wall asr has, with using soft rear springs and soft set shocks your forward bit has to be poor because of the weight transfer when you get on the throttle. The problem might be your car is to tight up front and the balance is off, but without seeing it or driving it is just a guess

mdb4879

It seemed like softening the rear shocks helped a bit the other day. If anything I would think having the front stiff would induce understeer. I was running 450f/500r on Sunday. I didn't swap the springs around until yesterday. And with no front bar and the 24mm rear bar, my rear suspension frequency should be much higher than the front.

I did some experimenting today and I found that on a couple roads that have a sharp 90° turn with a stop at the end of them, if I go in at about 80% and brake for the stop sign (60%-70% brake I would guess) my inside rear does lock up, but it's still on the ground being dragged. I'm not sure how much weight is actually on the tire mid corner, so it may not be much, but does this sound like I have too much rear brake bias? I don't see how I could with stock rear drums and shoes. The fronts lock up first under straight line braking.

Jujutsuka

Don't be surprised your FF is oversteering actually.
keep in mind that your car has most likely a 60/40 weight ratio.
So when you are braking weight is being shifted off rear towards the front. So your rear end has no weight pushing down on the tires for friction. I would try wider tires. And maybe small increment of stiffer spring/shock in the front. And maybe decrease diameter of the sway bar in the rear and then throw a tiny diameter sway in the front. Also if you are noticing this in higher speed corners try functional down-force wings. Then I also saw where you weren't doing your alignment. You need to try running negative camber. Increase negative camber in small increments to see if you can smudge out your oversteer. I would zero out your toe front and rear. Toe can cause huge problems in handling if not needed.

If you need to take it to a dealership to get it alignment. Just tell them what you want your camber to be. I used to make friends with the techs at honda dearlership and nissan dealership.
I would give them a sheet of paper of what I wanted my alignment settings to be. And they would do it. I would sometimes walk back there to look.

mdb4879

I'm not surprised that it's coming out, I'm surprised at how it comes out. It takes less than half a second to pull a complete 180. I drove a Mazdaspeed3 last year, and it's rear end came out on me regularly (63/37 weight split), but it was completely controllable. I've been setting my front toe to zero (didn't bother with any toe out since it already turns in so well). I hadn't checked my rear toe until after the event, but it sounds like the 1/8" toe in I had would've helped better than zero toe. I do more than likely need more negative rear camber. The spring change should help with that some, but camber links are on the list. Along with a camber/caster gauge so I can get some actual numbers on that as well. If I can't get the car close to how I like this weekend then I'll find a stock front bar to try.

Agent_Smith

I still think your main problem is alignment.

My guess is you need more negative camber in the rear.

Am I the only one thinking total toe could be off? That's the one thing I don't like about toe plates on the rear axle, if you have zero toe, both wheels could still be angled sightly left or slightly right & undetectable by the naked eye, this hugely effects cornering & causes this oversteer reaction your describing.

I went a full year without a REAL alignment under the same mentatlity of I'm still dialing in the car, playing with settings, why pay for each alignment when with a simple degree guage & toe plates I could do it myself. For some changes & trackside fixes DIY is great, but having a solid foundation & numbers to start with is key in my book. Never again will I worry about total toe being off, laser alignments for me unless trackside changes are a must. It's not worth the headache.

Adjustable toe arms will also help greatly if you are doing rear diy or trackside alignments frequently.

CW-ITR

iTrader: (11)

Base on your description, we have a similar driving style. Since this style is serving you well, don't change it. But, change these two simple things:
Put 225 wide tires on the front and play around with the rear tire pressure with mostly increasing it. GL

Oh! and remember follow this as well:

joel n

I run the same chassie, 95 civic CX. Stock D15B7 95WHP. Springs are around 400lbs skunk2 sport shocks. stock front integra sway-bar and 19MM suspention technics rear bar, i have a exhaust spring between the bushings so i can adjust load on the bar (mounts out at the shock bolt). Integra RS brakes all-round, HP+ pads, 2200LBS with me in the car, and i run 1/2-1/4 tank of fuel at autocrosses. 5 inchs front, 4.5 inchs rear hight, at jack points. -2.8 camber front and -2.2 rear, toe out 1/16 per side front and rear. all poly bushings. I do run R-comps. R888s, NT-01s or V710s. Whatever is getting low from our racecar. I have a really hard time getting mine to oversteer. I trail brake and use mid corner throttle lifting to help it step out. I ran 550 front 600 rear springs and old V710s for a few events. stepped out much better but our lot was off camber and very dirty, switched back because of the dirty, broken asphalt lots. If i had your HP i would have stuck with the higher rates. I dont have the power to pull the car along. 86LB-TQ doesn't get you very far sideways. lol

personally i would move your battery to the trunk, switch your rates front to rear, and lower the rear ride hight. Also set your toe to 0 front and rear. Then adjust once you see how it acts. I would swap springs first. And atleast equal the ride hight. Also make sure your bushings are free and good. Our poly bushing were dry and binding up. Cause weird handling problems. Lubed everything up and stopped.

A friend of mine here runs a 89 CRX, sleave coilovers, 400ish rates, stock honda bars, but a 176WHP LS-VTEC, open diff. 13 inch wheels, used R-comp. (R888s) we gave him a award one year because he spun at every event he ran. We all tried to help him, I drove his car once, Never spun or even wiggled, He told me after the run, he would have spun atleast 4 times with the speed we had. I was 3 seconds faster then him. First time i drove his car. He learned alot from the throttle i used, and last year i dont know if he spun once, beat me at 1 event and made some very good improvements, But he said he was lifting at the wrong places in every corner or slalom. You said you drove a mazda 3 before, is there anyone in your area, you trust to run your car and get another opinion? Someone who knows the chassie?

We changed alot on our Del Sol racecar last winter and removed way to much rear weight. Ran tires that cause the car to be to higher in the rear then the front, and paid the price. Car is super lose in right turns at high speed. Scary when your going 175KPH. First time it happened i caught it and got it straight and just went off the outside, Just grass. Next weekend they put a wall were i went. It was very nice of them lol. I just firgured since we gained 40HP i was going that much faster, it was causing the car to slide. Put another guy in the car that knows setup really well, and he helped make the car massively better in just 1 weekend. Gave us a few ideas for the winter, and i think it will help us alot. I find it very usefull to get him in my car every so often to get a little input.

mdb4879

Does thrust angle really have that much of an effect on handling? I just figured the rear of the car would sit to one side or the other so the rear wheels were parallel to the fronts and that would be it. I guess a professional alignment is on my list now as well. I found another potential problem that I'll have to fix before I do, though. My left trailing arm bushing is cracking and the right is cracking and partially torn. I've heard they cause weird handling issues, but I've never experienced them first hand where I could say "yep, that's the trailing arm bushings." I agree that I may not have enough rear camber, but I won't know for sure until I see just how much I actually have and get some adjustable links to change it.

I did finally get a few number to play with, but they probably aren't as important as my alignment values. I weighed the car today and it's 2240lbs with me in it. 1420lbs over the front and 800 over the rear. Some variance in there since the scale reads in 20lbs increments. This was with 5/8 tank of gas. Going by this and assuming 65lbs of unsprung weight per corner my suspension frequencies are as follows:

450f/500r setup - front is 1.78Hz, rear is 2.83Hz
500f/450r setup - front is 1.87Hz, rear is 2.68Hz

Considering I have no front bar and the size of my rear bar, the frequency split is probably much larger under cornering load. But now I have some values so I can say what a difference "x" change in frequency can make.

My battery is behind my passenger seat. I placed it there because it offers a lower center of gravity and a more central load in the chassis. Plus my battery only weighs 2lbs, so I would probably gain more weight in wiring putting in in the very back.

Back on thrust angle, I can see where that may be causing me issues. It seems like the majority of the time I spun I was turning to the left (loading the right suspension). If my thrust angle was such that the track was narrower on the right than the left from the center, then that'd make that side more prone to oversteer. Add in the partially torn trailing arm bushing and I could have a world of trouble.

I would like to be able to run 225's on the front, but right now I don't need any more front grip until I get the rear sorted out. Adding pressure to the rear tires would also worsen my problem. I'm not getting rollover on the rear, so any additional pressure would create less of a contact patch.

Matt_EH3

...wait, you have a torn RTA bushing? Look into this first and fix it before you do anything else. This could very well be your problem.

mdb4879

Already on it. Quick question about them, though. I was going to either do OEM Honda or Moog replacements, but I noticed Doorman has a "quick press fit" replacement that looks like an ES bushing except it's rubber. Has anyone tried them? Only reason I'm considering it is because the center of it, which bolts to the chassis, presses in separate from the bushing. So it could be greased on a regular basis and not have to worry about binding I think. Then again, if it's loose enough for that then there may be room for side to side play on the rod, which wouldn't be good. Any thoughts? Or just stick with tried and true OEM Honda or Moog?

Agent_Smith

If your getting serious about tracking this car, just get spherical rear trailing arm bushings, you won't regret the purchase, it's worth the coin. Handling is much more predictable and the precision of the rear end is exceptional.

If you want to cheap out, moog or honda or hard race will work fine for a while then they will wear out or weather out & crack again. At least in Arizona oem RTA bushings just don't last. I replace them on my daily driver GSR every 2 years because they crack & turn to crap.

mdb4879

I'm not sure if I can run sphericals in the trailing arms. The rules are kind of vague about it. It reads to me like I couldn't, but I know people do for camber links. So maybe it's provisional on what the arms is used for?

I took the car to Birmingham yesterday and it feels much better. Here are the changes I made:

Swapped springs to 500f/450r
Raised the front 1/4" and lowered the rear 1/4"
Set rear toe to 1/16" out
Removed swaybar preload. Not sure if it was there before, but it was after the spring change and would help explain the tailhappy rear end.

By the end of the day my tire pressures were 30psi front and 28psi rear. It still feels like I could lower the front pressure more and gain some front grip without worry of the tail end coming around. It was hard to tell how it would behave in a slalom, though, because the only slalom we had at full speed was descending so I couldn't get too crazy with it. A sudden lift in a sweeper or a tap to the brake would get the rear end out, but it was very predictable and controlled. The car seems to like staying in check, though. Part of it may be I can't turn it fast enough when it does come out. The amount of tail out I could get from lift throttle would normally be manageable, but with the stock manual steering rack I can't turn back fast enough when I get back on the gas and the front would snap over and pull me off line. Not really a handling issue, just something to note. My driving changed a bit and I was smoother and more fluid with my inputs which helped keep the car in check. I can still make a few changes to gain more overall grip (such as drop the front tire pressure even more, gain some camber up front possibly, if I get too tail happy again I can toe in the rear and add camber). So far the car feels ten times better and it made for a pleasant day yesterday.

Here's a video of my best run. There's a few tenths to drop all over the course, but since I was making changes to the car between every run I'm pretty satisfied with my time. I should have a pretty good hold of it after the next couple of events.

Stinkycheezmonky

Yep. Stop all the analysis until you do this. You're now making adjustments to compensate for a real problem. Surprised it took that long for someone to suggest it.