Handling issues

[EMWHYR0HEN]

This past weekend I took the car out to the Streets of Willow for the first time since all my major engine/suspension/chassis changes. Over all it went well and I was able to lay down some decent lap times. Late braking, and going fast on the straights and fast corners helped lower my times but I just couldn't get the car hold a slow to medium speed turn, which is about 70% of the track!

 

Initial turn in is okay. I can get it pointed where I want after braking. It's after I turn in where the car starts to understeer, and pushes outward. I tried giving some throttle mid corner to try and induce oversteer and it doesn't seem to help much. All that does is push the car along further, or slide the rear out too much. The car is very predictable where you can pretty much catch any under/oversteer as it happens.

 

I didn't have a pyrometer at the time only played with tire pressures.

 

Here is my current set up:

 

Front

TTT camber plates

Bilstien struts

350 lb spring

Sectioned housings

1 inch bump spacers

adjustable LCA w/rod end

23mm sway bar w/poly hardware

255/40/17 Falken Azenis rt-615

 

 

Rear

stock insulator

Old Koni Reds single adjust

325 lb spring

Sectioned housings

Adjustable LCA w/ outer rod ends

no sway bar

1-way diff with light preload

275/40/17 Falken Azenis RT-615

 

Alignment:

 

Front

Camber -3

Caster +5.5

Toe 1/16th out

 

Rear

Camber -2.5

Toe 1/16 in or zero (don't remember)

 

Ive never experienced this kind of problem so i'm kind of stuck on where to start.

I think ill be adding droop limiters just from looking at some pictures, and maybe a little more neg. camber to the front from looking at tire wear. I have a rear sway bay that I removed when I had a welded diff installed and was thinking it might help out but im not sure.

 

I’ll have some pics up shortly.

[JMortensen]

Get a pyrometer and reinstall the bar. You can pull one end link at the track between sessions to see the difference with and without the bar. Without tire temps all we can give is relatively vague suggestions.

 

EDIT--I do see that you have different struts front and rear. I can't imagine that being a good thing, especially since the Konis aren't really the "race" version.

Edited November 9, 2010 by JMortensen

[EMWHYR0HEN]

Any suggestions on a pyrometer? The konis i'm running are valved much heavier than the Bilstien's so it shouldn't be an issue.

 

I'm going to be switching back to 325 lb front and 350 lb rear. I switched it in the first place thinking I could bump up my front spring rates since It was much tighter than before. Also, installing the rear bar again in hopes of unloading the front outer tires and adding more to the rear outer tires.

 

I'm really interested in adding some droop limiters and curious on how some are doing this. I'm thinking some kind of thin tow strap that attaches the lower housing and to the camber plate or strut tower?

[johnc]

You're running a staggered tire setup and you're wondering why you have a push? It sounds like the car is behaving exactly as it should based on your wheel and tire selection.

[JMortensen]

Pretty simple test there... switch them and see if it's loose.

[260DET]

More front camber should help, the S30's I know run four to five degrees negative with semi slicks. Stock S30 front struts flex too which does not help. Car sounds like its pretty good otherwise so look at your driving technique too, with no rear ARB it will always tend to push but the advantage is significantly better rear grip.

 

As far as driving technique goes, have a look at this video at 0:54 and 1:56 where my Z always want to push. See the quick nudge I give the steering wheel to get it to turn in and hold the line there? It works better the second time.

 

Edited November 10, 2010 by 260DET

[EMWHYR0HEN]

Static

Heavy braking into right hander

same turn mid turn

same turn exit

Slow 180 degree right hander

Edited November 10, 2010 by EMWHYR0HEN

[EMWHYR0HEN]

I don't think my problem is as simple as changing my tires but, in addition to the rear ARB I will be widening my front track with a bit on the LCA and wheel spacers.

 

I'm a little hesitant to add a rear ARB because the car is already a lot to handle when exiting a turn. I can only imagine things getting tougher.

[JMortensen]

I'm really interested in adding some droop limiters and curious on how some are doing this. I'm thinking some kind of thin tow strap that attaches the lower housing and to the camber plate or strut tower?

I put up some pictures here: http://forums.hybridz.org/index.php/topic/89478-making-droop-limiters/. You can use straps but then it's hard to adjust the slack in them. I used turnbuckles for that reason.

 

Might redo the fronts. The rears are going to work fine as shown.

[johnc]

I don't think my problem is as simple as changing my tires but, in addition to the rear ARB I will be widening my front track with a bit on the LCA and wheel spacers.

 

I'm a little hesitant to add a rear ARB because the car is already a lot to handle when exiting a turn. I can only imagine things getting tougher.

 

Widening the front track will reduce lateral load transfer at the front and will probably help. I'm still saying the main issue is the tires, especially after you say you're unwilling to add rear bar. Increasing front tire width will not reduce traction on the back of the car. It will increase traction in front.

[tube80z]

Initial turn in is okay. I can get it pointed where I want after braking. It's after I turn in where the car starts to understeer, and pushes outward. I tried giving some throttle mid corner to try and induce oversteer and it doesn't seem to help much. All that does is push the car along further, or slide the rear out too much. The car is very predictable where you can pretty much catch any under/oversteer as it happens.

 

I didn't have a pyrometer at the time only played with tire pressures.

 

Here is my current set up:

 

Front

TTT camber plates

Bilstien struts

350 lb spring

Sectioned housings

1 inch bump spacers

adjustable LCA w/rod end

23mm sway bar w/poly hardware

255/40/17 Falken Azenis rt-615

 

 

Rear

stock insulator

Old Koni Reds single adjust

325 lb spring

Sectioned housings

Adjustable LCA w/ outer rod ends

no sway bar

1-way diff with light preload

275/40/17 Falken Azenis RT-615

 

Alignment:

 

Front

Camber -3

Caster +5.5

Toe 1/16th out

 

Rear

Camber -2.5

Toe 1/16 in or zero (don't remember)

 

Ive never experienced this kind of problem so i'm kind of stuck on where to start.

I think ill be adding droop limiters just from looking at some pictures, and maybe a little more neg. camber to the front from looking at tire wear. I have a rear sway bay that I removed when I had a welded diff installed and was thinking it might help out but im not sure.

 

Heavy braking into right hander

 

Looking at your pic it appears you don't have enough camber on the loaded side. If you don't have a pyrometer you can also look at air pressure rise. The end that is being worked the hardest will show a larger increase in pressure. Did you track this at all?

 

Your setup doesn't mention coilovers but if you have those I'd try raising the rear of the car (start with two to four turns). This should raise the rear RC up, which should shift balance towards the rear. You could also try lower the front but make sure you don't go too far or the turn-in will get lazy.

 

Hope this helps,

 

Cary

[260DET]

As a general comment more rear toe in should help in corners, up to 10mm. In the pics the car looks just a little bit soft on the outside front which will tend to put more load on that wheel and lift the inside rear, neither of which is good.

 

My philosophy is always to firstly try those remedies that will improve the overall grip level before trying those that merely shift existing grip to one end of the car or the other.

[BLOZ UP]

The staggered tire setups were created by lawyers for OEMs, they increase understeer and make the car more predictable. They also have great marketers that pass it off as the "performance" look.

[JMortensen]

The staggered tire setups were created by lawyers for OEMs, they increase understeer and make the car more predictable. They also have great marketers that pass it off as the "performance" look.

Do you have any support for that statement at all? I think I can find a lot of arguments that staggered tires work better, especially on cars that have a rear weight bias. Porsche, Ferrari, Lamborghini come to mind in the street car realm, ALMS, F1, sprint cars, and just about every other kind of road racing uses them too.

Edited November 10, 2010 by JMortensen

[Sideways]

I know I dont pop my head in much on these things, I usually leave it to the more experienced- but im feeling zelous today. Im inclined to agree completely with john, your set up has everything going for it that induces understeer, softer rear springs, no rear sway, a good stagger, a slight toe in out back, etc. Changing any one of or any combination of these will (well, should) help. Youve set yourself up to have a lot more traction out back then up front. Unless youre really missing your line to the next corner or just REALLY cant stand this feeling, its probably not a bad thing, especially if youve got a good bit of power. It should really let you be able to squirt out of the corner a LOT faster than a looser set up will allow, and hey- Slow in fast out right?

 

Edit: Quick question for you, your tires are close to what i plan to run for my car- Did you have any issues with the fenders(or flares themselves) rubbing with this set up? Im assuming you cut the fenders as well when you installed those flares?

Edited November 11, 2010 by Sideways

[BLOZ UP]

Do you have any support for that statement at all? I think I can find a lot of arguments that staggered tires work better, especially on cars that have a rear weight bias. Porsche, Ferrari, Lamborghini come to mind in the street car realm, ALMS, F1, sprint cars, and just about every other kind of road racing uses them too.

 

I'm talking about street cars, but I have no experience with any high powered MR cars. The 350Z, RX8, and other "cheap" sports cars. Ask anyone who actually races their 350Z, sizing up the fronts to match the rear make the car neutral. On an MR I could see it being more neutral with more in the rear, but in general OEMS make their cars understeer by design for the lowest common denominator. I don't think Lamborghinis fall in that category, their LCDs usually have better sense than most.

[Sideways]

I'm talking about street cars, but I have no experience with any high powered MR cars. The 350Z, RX8, and other "cheap" sports cars. Ask anyone who actually races their 350Z, sizing up the fronts to match the rear make the car neutral. On an MR I could see it being more neutral with more in the rear, but in general OEMS make their cars understeer by design for the lowest common denominator. I don't think Lamborghinis fall in that category, their LCDs usually have better sense than most.

 

 

I dont think the argument was about it adding neutrality, I think the issue was the light you painted the staggered set up in. Im only assuming he had the same impression as I did, but you made it appear as though it wasnt favorable and was just a "performance look".

[EMWHYR0HEN]

I put up some pictures here: http://forums.hybridz.org/index.php/topic/89478-making-droop-limiters/. You can use straps but then it's hard to adjust the slack in them. I used turnbuckles for that reason.

 

Might redo the fronts. The rears are going to work fine as shown.

 

Thanks for the link Jon. This will help in the near future.

 

I'm still saying the main issue is the tires, especially after you say you're unwilling to add rear bar.

 

I didn't see it that way. That makes sense. However, I'm not totally disatisfied with the understeer enough to change out my wheel and tire combo just yet. I think I still have plenty of options to try and come up with a compromised solution.

 

 

Looking at your pic it appears you don't have enough camber on the loaded side. If you don't have a pyrometer you can also look at air pressure rise. The end that is being worked the hardest will show a larger increase in pressure. Did you track this at all?

 

Your setup doesn't mention coilovers but if you have those I'd try raising the rear of the car (start with two to four turns). This should raise the rear RC up, which should shift balance towards the rear. You could also try lower the front but make sure you don't go too far or the turn-in will get lazy.

 

Hope this helps,

 

Cary

 

Thanks for the input. I did observe tire pressure under two heavy sessions. The track is a right hand dominant so left side tire pressures were obviously higher. After tires pressures recorded The car came in hot with an increase as follows ; LF +8 RF +5 LR +4 RR +3 PSI.

 

I do have adjustable ride height. I will be playing with this as well.

 

 

Youve set yourself up to have a lot more traction out back then up front. Unless youre really missing your line to the next corner or just REALLY cant stand this feeling, its probably not a bad thing, especially if youve got a good bit of power. It should really let you be able to squirt out of the corner a LOT faster than a looser set up will allow, and hey- Slow in fast out right?

 

Edit: Quick question for you, your tires are close to what i plan to run for my car- Did you have any issues with the fenders(or flares themselves) rubbing with this set up? Im assuming you cut the fenders as well when you installed those flares?

 

After adding more power I was shooting to add lots more rear grip. I think I may have just ignored slow speed turns up until now. I agree It's not a BAD thing especially on a high speed course like WSIR (which feels pretty good there BTW). I'm not looking for a drastic change. Only some tuning in regards to understeer.

 

As to your question about the wheel setup- Yes your going to have to cut A LOT of metal if you want your tires to clear everything and especially if your going to run a lowered stance and + caster angles. Also, If your going to be doing track events get 4 rear wheels. They fit fine up front plus you wont be having understeer issues like I am!

Edited November 11, 2010 by EMWHYR0HEN

[JMortensen]

I'm talking about street cars, but I have no experience with any high powered MR cars. The 350Z, RX8, and other "cheap" sports cars. Ask anyone who actually races their 350Z, sizing up the fronts to match the rear make the car neutral. On an MR I could see it being more neutral with more in the rear, but in general OEMS make their cars understeer by design for the lowest common denominator. I don't think Lamborghinis fall in that category, their LCDs usually have better sense than most.

Vette, M3, M5, S2000, Supra, CTS-V, Camaro all have staggered tires.

[ZR8ED]

All else being unchanged, when I first completed my v6 swap, the first time I tracked it, the car instantly and dramatically understeered. Previously the car had a very neutral feel (as described by myself and very experienced racers who drove the car helping me with the suspension setup.) I had a staggard tire setup (225/50/16 and 265/45/16). I then went to even more dramatic staggard setup. (235/45/17 and 315/35/17) Adjusting the suspension again, I managed to get back to a neutral feel. With excellent exit throttle application control. (in short I could easily put the power down, yet add oversteer on demand if I wanted)

Nothing wrong with staggard setups, it just takes different planning. The lightweight setback position of the v6 made standard "known" suspension setups for the S30 inappropriate, and took a bit of pure trial and error.

I am not a suspension guru in the least, so I can't commment on your specific settings other than the Fore/aft settings for my car had a larger delta than I started with.

 

Good luck!