My 300 has always understeered but it is becoming worse now. Replaced tyres already, running 245/35xZR18. My next thought is to stiffen the front suspension with harder/adjustable shocks (Koni?) or to add a front strut brace. Anyone got any thoughts on this as to the best way forward.

 

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"Polished on drive"

"Dirty at 156mph"

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Z first and anything else is secondary and live life a quarter mile at a time!

John Newcomb (NukeEm)

www.geocities.com/jn300zxtt

Have you got anti-roll bars (sway bars as they're called in the US)? If you get the Suspension Techniques (oft sold as Stillen) ones you can adjust a bit of this in/out.

I've done nothing to the suspension yet so I don't think I have any if they are an aftermarket addon.

Worth considering, call MJP or Johnny.

where do they fit? what do they do? how much are they approximately?

 

------------------

"Polished on drive"

"Dirty at 156mph"

---------------

Z first and anything else is secondary and live life a quarter mile at a time!

John Newcomb (NukeEm)

www.geocities.com/jn300zxtt

Hi,

 

I would get a 4 wheel track done first and make sure all is as it should be..

 

My ZED never washed out at the front!!!

 

Then check shock and spring condition, and bushes.

 

Leigh

 

 

They are bent steel rods that fit between the two sides of the suspension, one front, one back and replace the two bits of limp edam that Nissan use. So not only are they more solid, but they have adjustable ends so you can vary the leverage to suit your requirements. Seem to remember mine cost about £250 if you buy front/rear together. Call Mike.

John

You sure its understeer? Mine just doesnt and I am not brave enough to try to reach the kind of speeds it might happen on a dry public road!

I think your geometry might need a check. Also a strut brace will do nothing unless you're on the track a lot or rallying! Then you need extra rigidity. Otherwise its even more weight to lug around even if it does look good. Then you need a rear one too!

 

I think increased anti roll/sway bar stiffness and harder shocks might actually increase understeer not reduce it. You have 245s on front. Thats a major rubber patch! Maybe too high a pressure?

It just shouldnt happen

Willie

There are the fellas :-

http://www.stillen.com/sportscars_detail.asp?cat=5&subcat=143&id=12853&page=1

 

What tyres are you running on the fronts john ?

I find it very hard to get my Z to understeer. Only one corner in particular can I do it on. About 60-65mph hard left hander, if I have the window open, I can hear all sorts of drivers' side front tyre torture going on but other than that, it never ever understeers.

It may be something else.

 

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I only use the brakes so I can accelerate all over again.

John,

 

First question is how are the tyres wearing? Are they wearing evenly across the tread pattern or what??? This will give you an initial clue as to how well the car is aligned

 

Also, check the rear tyre wear too. This sounds daft at first. I have seen a large number of zeds that have been running serious rear toe-in - mine was at 24mm and went through a set of rears in 1000 miles The proper toe-in should be between 0 and 4mm. Rear toe in gives understeer - see where I'm going with this? If you feel across the tread blocks, they should wear evenly - too much toe-in and they'll have a ridge down the inside rear (looking at the top of the tyre) of each of the tread blocks.

 

Stiffening the front suspension will cause even greater understeer so don't go there...

 

I presume you are running non stock wheels? What tyre pressures are you using? BTW, by checking the wear across the tyre you can determine if you running too high/low pressure...

 

HTH

 

CheerZ,

 

Andy

OK loads of questions to answer. I am little way along with this so bear with me. I take the car on trackdays 2/3 times a year and drive it hard on the country raods.

 

Leigh - a full steering geometry was done a month ago and found front camber in high neg camber, since had that corrected using plates to move the upper link arm out by 6mm and is now back within tolerance. All springs are level and have a 10mm sag on them but are sagging evenly so pretty much like a little lowering has happened naturally. Shocks and bushes are all in visibly good condition.

 

AndyP - I have now ordered from Mike/MJP a front strut brace and also the front/rear sway bars from Stillen too. Good ideas thanks.

 

Willie - yes it is understeer. Pushing the car hard into a corner it slides towards the outside of the corner rather than digging in and turning into the corner. Running the tyres as per Pirelli advice, 33psi front and 36 psi rear.

 

GavinL - was 225/40xZR18 Pirelli Pzeros but now is 245/35xZR18 Toyo Proxes T1-S and much improved but still not tight enough.

 

Dunk - I don't get it normally but on track or pushing hard on sharp corners the front slides a tad too much to be nice, following a porsche carrera 4 it turned a corner at the same speed as me and he ran tight to the corner and I went a metre or so wider, slowing me up, not good.

 

OK I think I will fit the sway bars & strut brace and with the new tyres see how it is at Donnington in August. Then maybe harder front springs and adjustable shocks if still not good enough.

 

 

------------------

"Polished on drive"

"Dirty at 156mph"

---------------

Z first and anything else is secondary and live life a quarter mile at a time!

John Newcomb (NukeEm)

www.geocities.com/jn300zxtt

change your sprins or uprate them. this car has never been an understeering car from the original design. which would say that perhaps that you have some part of your suspensiont hat is old worn and on its way out.

 

i had mine at kemble airstrip and no matter how hard i tried it never understeered. And of all the other zeds at that meet that day 3 of them went into the hedge backwards none forwards :S

Dont forget, if you stiffen up the front, it will understeer on wet roads, I would be inclined to sort the springs out first and just for a laugh, try standard wheels and tyres, see how they compare, go on, amuse me hehe

Id do the springs before adding more bits to it etc. Sagging springs, (be it all the same sag or different) are sagging springs after all, and are probably behaving differently to what new standard or non standard springs would.

Replace all the springs or just the fronts?Standard springs or what?

 

------------------

"Polished on drive"

"Dirty at 156mph"

---------------

Z first and anything else is secondary and live life a quarter mile at a time!

John Newcomb (NukeEm)

www.geocities.com/jn300zxtt

It would probably be better to just replace all the springs at once, because springs of different ages will have different amounts of 'creep' (fatigue) in the metal. You'd have to see what other people think of lowered or standard springs though.

Depends if you are happy with how low it is at the moment. What springs do you have on at the moment? standard or lowered?

Have you ever been happy with the handling? has the understeer problem developed? if its always been there, then I would try a different set of springs -assuming it is the springs- but its always better to eliminate things which are older (sagging, fatigued etc) with new items, then start adding things. Cos if you add stuff and it *is* the springs, you are only masking the problem.