See my sig for all installed parts.

Now here's my problem. At about +3/4 of full lock my car will start to push bad no matter what speed I'm going at. It happened right after I lowered the car(with all mods listed below). I felt it when trying to park first and I can actually hear the front tires pushing against each other when parking. I just competed in an autox event this past weekend and same thing at speed. It's only on real tight turns.

To give a little more info off the top of my head... my tie rods are basically sitting level. Slightly(<5*) pointing down towards the spindle and when going over bumps there's no steering problems. I've tried various alignment setups and it's always the same feeling at the same spots(equal to either side).

How can I fix this problem? Would the baer bumpsteer kit help? A custom length steering centre link?

 

Mine has always done that in full lock position since I first installed the larger 16"iroc rims from the stock 15" RS rims. The wider tire has less give so the ackerman affect is less previlant at full lock because of more tire grip. Its just something you have to live with.

It should not be happening at any speed above 5mph. Obviously you don't have to go lock to lock while driving unless in a tight parking lot. if you are turning the wheel that tight above 5mph then you have a major understeer problem with the car not reacting. Should never have to turn the wheel that much unless making a very tight u-turn- even in AutoX- I know AutoX, I ran a 540 HP '68 Vette for years with NO POWER STEERING and never had to turn that tight on a course.

EDIT:If you are running max positive caster, then that will cause more bumpsteer if the car is leaning hard. That will give tracking problems related to ackerman. Stiffen the spring rate.

 

with 850# springs, i doubt he needs more spring. i think dean hit it, with the tire thing. with the spring setup you have, your car is going push... but you knew that, as we already talked on IM

 

Yea, I'm gonna check out everything over winter and blueprint my suspension/chassis even to see if I can make it 'perfect'. As we talked about dewey and as one could guess from the rates I'm using even it's gonna push. Didn't think it would turn out to push this much at low speed. It isn't too bad at higher speeds 70-120km/hr but I have yet to push it beyond that. I've had the back end get light on banked +180* off ramps at ~80km/hr but it was slightly downhill also. Anyway with these rates the car is really easy to drive to the limit and catch when you go beyond. But yea, the rear definately needs some stiffening. Oh but I've yet to put the car on scales so who knows what kinda crossweights I'm driving around with.

 

yes i have some work to do over the winter also. i need to cure my understeer woe's too with the new springs it pushes much more than before. as it is now, i have the rear shocks set almost as stiff as they go, and the fronts on full soft, in an attempt to keep it from pushing at low speeds. mine acts a little diffrent at speed, i seem to understeer into the corners, oversteer at the apex, and then understeer again coming out, kind of a strange way to have to drive. i have talked with chickenman and gotten some ideas from him. and i will likely be getting new springs, and possibly at least a new front sway bar, maybe rear also. i think to cure it, i am going to go with stiff rear springs, small rear sway bar, slighly stiffer front that i have now, and a little less sway bar up there. but not entirly descided on that yet. i really need to put this combo on some race rubber, and see what it does.

 

Can you post your setup here for me again Dewey. I keep forgetting. Just spring rates, sway bars and what shocks with which settings you're using(also tires too).

Do you plan on getting your car on scales at all(if you aren't using weight jacks and are buying new springs again it'd be a good idea before ya do to help figure out some good rate combos)?

As for race compounds... yea I cant wait to get on em too. Probably need to buy a 5pt harness at the same time just to keep myself in my seat by then. These stock seats really dont provide ANY lateral support.

 

check sig.

yeah, i have harnesses in mine, i only run 4points (stock seats don't exactly lend themselfs to the anti-sub belt) keeps me from being tossed about pretty good.

 

Regaplanet....PM me if you wish. I'll give you some of my Autocross setups...

You're far enough away that I don't think we'll be running against eaach other soon

 

PM sent, thx for the help fellow canuck.

Who knows tho... after I beat everyone in the east here I may come out west for you ;p

 

Rega, I watch your videos on your link- the autoX ones. With things a wet as they are, you are still getting massive chassis movement over the front end. The cars pushing then spinning. Kind of what I call the rocking horse pivot. I see you have KYBS. The best thing you can do is get some better shocks first to control that movement. Your *** end is coming pretty high in the air- even for the slipppery wet comditions- on dry it has to be worst. You are diving on the frontend first, pushing and not turning because of the weight transfer, and then unloading the rear to eventually come around. It also looks to be a lack of rear brakes as part of the problem. Do you have rear drums or discs?

http://www3.sympatico.ca/ptcook/MOV01875.MPG

 

All part of my slow suspension tuning issues AGood2.8

I know the car is nowhere near setup properly right now(It's cold and Im lazy lately). And yes everything you do point out is the culprit. I have rear drums, KYB's and the rear is set too high to begin with. I'm glad you pointed it all out tho. Reminded me of it all and now I'm feeling more confident that my whole steering problem is just insignificantly minimal to original thoughts and it just due to poor setup at the moment. Another issue is the different make/size of tires I'm running front and rear. Tires in the front are Yoko A509's(215/60/15) which have a good rep of being great in the wet. Rears are BFG Radial T/A's(245/65/15). Now before you say more Tires were free, thats why the mismatch and oddball sizing and blah blah blah. Same sorta story actually goes for the shocks/struts. I only had enough cash at the time to put some KYB's on and didn't want to go replacing the springs/spindles etc and just leave the orignal shocks/struts on. Rest is just my laziness. I was actually just driving to an apppointment and its wet here to about the same degree and took a quick turn and my rear end started slightly coming around without me being on the gas or brakes at all. So yea, things are better overall but I've got some work to do.

What'd you think of the lateral movement side to side?
Also did you use scales to set your heights front to back or what have you done(I'm basically asking what can I do until I can get the car on scales to have better weight transfer)?

Also with budget in mind what would be best to replace first if I can't get all four corners done at once... shocks or struts?

Oh, and thx for the analysis of course. All input much appreciated.

 

Transitioning looked good as for balance of spring rate. You are correct in the steering department- I would leave it alone. It will correct itself with stiffer struts and shocks (that will limit movement)
What I saw in the video- I given the choice, I would definately replace the rear shocks first. keep your lca's a level as possible at compressed cornering height-(keeps the rear neutral steer, watch the video, you can judge rear tire/ fender level).

My car is a whole different setup- the V6 changes things dramatically. I actually have created a little more towards a push in my nose. This car steers too fast and can be twitchy if setup wrong, especially at high speeds. I actually run progressive rear springs to create more of a push entering and revert back to more neutral in and exiting a corner. The rear springs unloaded (entering) are more rated aprox #175, and are maxxed rate when squated beyond the progressive rate to aprox #225. This gives a more loose condition at low speed exits in tight corners (remember, I don't suffer from massive power oversteer). Helps the *** end around but keeps stable at very high speeds. And its controlled with very high rebound damper.

Edit: I can set this car so twitchy that it will jump lanes at a blinkof the eye. You accidently bump the wheel at speed and it will set you over 5 feet- It goes where it is turned. I reduced this with progressive springs and LCA angles. I like to have to "pull" the wheel into a corner, not hold it from going too far. The way it is set right now, I can drive it with a finger and thumb at all times.

Scales are really only used for weight jacks or coilovers. Especially if you are making springrate changes and need to reset rideheight and cornerweights-Ex making sure you don't have say 887 #'s chassis weight on the front left tire and 723 #'s on the front right- etc.

 

No B.S.- I can literally drive the car with this much grip on the wheel on any road at normal traffic speeds- no matter what ruts, etc are in the road any slight pulling side to side is not voilent enough to grab any tighter. Racing is a different story- I like to hang on at speed. If turning sharper than a 1/4 turn of the wheel, which is sharp enough for any corner (I have a quick ratio box) then of course I have to grab it to pull it around faster. Usually only in a parking lot- And only the tightest lock do I feel the Ackerman angles slip.

Note: I don't drive like this (west Hollywood style )- but I can with this car. It has 245/50-16's Goodyear F1 GS-D3's.

 

Makes sense to me. My LCA's are pretty bad in geometry right now.





Not the best pic to tell the angle but I just took it now quickly to give ya an idea.


Sounds exactly like how I'd like to get the car reacting for now. You're using custom valved Bilsteins right? Think I'd like to go with something adjustable for street, autox and road course adjustment. Have you had yours on all 3 and felt any need for adjustment?

Mind if I ask what your caster setting is?
As for you tires ummm yea... One of my top 3 choices. Think I may actually buy a set of R compound tires or try some Azenis or Advents(I think those are the two names?). They're supposed to be a really good street/autox tire.

Are you competing much these days with either your 2.8 or the vette? What classes do ya run in and how are ya doin against the competition if ya are?

 

I run Koni Yellows front and rear- No valving changes were made from normal street driving to AutoX. I always have the car set for maximum street performance, I never try to "soften" the ride.

I ran it in "esp" class here in So. Calif earlier this year to see what it would do. Had not run AutoX in about 8 Years (I use to literally dominate "bsp" in my '68 Vette{and all Vettes in all classes "most" days}for that matter} I use to be a driver on the GRA race team (Dick Guldstrand- Guldstrand Racing Association). It actually got boring- I would beat everyone in my class by 6+ secs.

When I ran Esp in the Camaro, I was the only V6 and the only guy on street tires- Took 5th of 11 cars with only 160 hp Just did it for fun to see what the car would do- I didn't bother doing coursework- they DSQ me. I embrassed several people though. Many said I would get eaten up in that class and I was out of my league being in a little V6. Tires did go away on me after about 5/8ths course each run.
Camber is about -.75 Caster is about -5.

Here's a pic of the Vette on course back in the early '90s I was auctually featured on a sports car program in Canada back then. A Camera crew came down to do an article on the "Monster Miata" (a V8 miata) and ended up doing 10 mins on us- I have the demo tape that aired. Thats the interviewer in the car with me, took him for a ride.

 

Thats some damn nice scenery!

Way to give it to all the V6 haters out there. Don't really need a whole lot of motor for autox around here. Not sure how big your courses get out there.

Thx for the alignment specs. That's not a whole lot of camber... then again I guess your car isn't using a whole lot of suspension travel either eh.

You wouldn't happen to have any of that demo tape in avi or mpg format would ya?

 

You bounce on the front of the car and it doesn't move- mostly tire flex only. (edit: I'm sure you've seen enough pics of it, Haven't you? I have posted enough pics of it around here.

The copy of what played on TV is only on VHS tape.


As for the AutoXtracks, in years past they always seemed to flipflop whether it was a HP track or a little car track (Narrower, favoring the popular honda CRX's at the time- They could go strait through things that I had to slow down and twist through). Now days they run at Calif Speedway parkinglot (not level ground) and it always seems to be the same basic track- Favors mostly big HP- Theres always a long slightly uphill straight after the first two turns. That killed me.

 

Seen many pics but always looking to see more

This past weekend it was an 86 CRX that won fastest time of the day but nobody else was in his class(CM) so.... he basically ended up being 21st overall with pax factored times. IT was a super tight track too. 66 seconds for 2 laps.

 

Here's a current rearend shot- There's a very lightweight Carbonfiber driveshaft up in there also that you can't see in the pic. You'll notice that the back axle is dropped out(not at ride height. I don't run the relocators on the bottom setting, but rather the middle- On this car with ride height, etc., My angles are best straight( favoring upward side just slightly at ride height) and then compressed upward for an inverted angle on the outside hard into a tight corner. That shortens the geometry of the arm on the outside tire and causes roll understeer under sway. Slightly turns the rear tire inward in a hard corner(rear wheel steer setting that can be used to your advantage- even only a 1/16" toe in will make a difference as opposed to a 1/16 toe out with the reverse setting. That can be a whole 1/8" difference in rear track through a corner- 1/8" in rear steering is quite noticable).

There's alot going on there that most won't pick up on- Notice the sway bar mounts- they are angled backwards. Why? to allow more freedom because the LCA's are shortened as much as possible for shorter wheelbase and greater affect of rear steer characteristic( the shorter the arm, the more geometry will change in movement)- again its all about geometry. Caution not to bind the tailshaft yoke, there must be adequate play still for movement.