182/Cup very sensitive to tyre pressures

[Munson]

Recently, I had been noticing that my steering wheel was veeery slightly offset when driving in a staright line, and put it down the tracking. The wheels have never been within 2ft of a kerb, but I imagined a pothole or something might have knocked it out.

Also, I have recently been finding myself less confifent in the car. It hadnt been feeling very stable under braking, and it was understeering (especially with ESP off?) and generally feeling a little soggy.

So today I checked the pressures after not having done so for a few weeks. Now, the Renualt spec says 33/30, and mine were down at 31/29 or there abouts. Hardly very much at all. I pumped them up to 34/31 and the car just came alive. I can now feel every ripple through my arse cheeks again, the steering feel better weighted at the straight ahead and the wheel is now dead centre again. The whole car just feels planted again.

Id bever have thought that 1 or 2 psi from standard would have had such an effect on the cars feel. Is this normal or are the Exaltos and Cup chassis particularly sensitive to pressure variations? Oh and for all you psi junkies out there, give 34/31 a try

 

[Max172cup]

Placebo effect? Youve done something to the car so your mind thinks it must be better? Just a thought, but could be as you say, the car is sensitive to pressure changes.

 

[Westy]

I noticed this too on several occaisions. Ive just come back from holiday and my car felt unstable round bends and a bit heavier to steer. As soon as i pumped the tyres back up is behaves much better.

 

[Iain C]

mine hangs to the left!

its ok for about 20 min after u get the tracking done then it goes out again

 

[Tom]

No its very sensitive your correct.

Jon_r found the best pressures to use

 

[White16valver]

My valver and the exs old 19 1.4 energy are/were both very sensitive to tyre pressures.

Im running 33/32 at the moment but drop them to 31/30 in winter to make them a bit more progressive.

I do mine every week, if not twice a week to make sure theyre correct!

 

[dk]

Quote: Originally posted by Tom on 16 June 2005
No its very sensitive your correct.Jon_r found the best pressures to use

and they are please~?

 

[Munson]

Although outright grip levels are probably higher running on the low side, I defo prefer the sharper response, better weighting and feel, of higher pressures. I may even go for 35/31 and see how it drives.

 

[Munday]

Mine is doing the same under breaking, will check them tonight I think.

 

[Bealo]

Ill give it a try!!!!

 

[EK05YTO]

34f/31r

 

[chris-b]

lol,just had my tracking done today(£28.20) and now Im paranoid that my steering wheel is slightly off centre to the left! gonna check my pressures.

 

[Munson]

Mine was O/C to the right, so the gf was trying to convince me I was just steering against the camber. You know your own car better than anyone else though. It was defo off centre and it was defo trye pressures, even though both fronts were the same give or take 1psi

 

[chris-b]

mine are at 31 front and 30 back at the mo,gonna go spend another 20p now!

 

[Munson]

31/30 is too low (from my experience) The fronts need to be 33+ for increased feel and better weighting.

[Edited by Roy Munson on 6/16/2005 8:50:13 PM]

Mike, this is with the 182 Exalto tyres and Cup suspension. I dont know if the 172 will be as sensitive?

 

[y0z2a]

i swear that people who complain that the A539 is a crap tyre are running the pressures too high.

I think the tyre pressure makes such a difference on the cup that I tend to spend ages getting it right.

/y0z

 

[chris-b]

gonna go big em up now!Hope it doesnt feel too twitchy when I go back the long way

 

[Munson]

^^ couldnt agree more. Do you think Im running too high then Yoz? I dont do track work so Im unsure of outright grip levels, but 34/31 seems to work for me on the road.

 

[Munson]

Quote: Originally posted by Mike Rochips on 16 June 2005
gonna go big em up now!Hope it doesnt feel too twitchy when I go back the long way



Roy Munson is not responsibe for any cars that see the back side of a hedge as a result of trye pressure alteration

 

[chris-b]

Got GSD3s on now, I usually have em at 33 front 32 rear anyway.Right now Im goin to go pump em up,get some toothpaste,cerael and milk then have a blast!

 

[bogel]

when I got my 182 it was fine but after a while I thought something was wrong cause I was feeling every little stone on thre road and the steering was off.
Thought it was just me and the cup suspension.

Eventually I thought Id get it checked out. Turns out the tyres were up at 44psi and this was the way the garage had given it to me. Cause the pressure was so high it had knocked the allignment out, but everythins sorted now, took a couple of attempts to get the allignment spot on but runs great now!

 

[Munson]

Quote: Originally posted by bogel on 16 June 2005
when I got my 182 it was fine but after a while I thought something was wrong cause I was feeling every little stone on thre road and the steering was off.
Thought it was just me and the cup suspension.

Eventually I thought Id get it checked out. Turns out the tyres were up at 44psi and this was the way the garage had given it to me. Cause the pressure was so high it had knocked the allignment out, but everythins sorted now, took a couple of attempts to get the allignment spot on but runs great now!


44!? Strewth.

 

[chris-b]

My paranoia mmust be gettin really bad! Just been to the garage and as I was drivin on the road to it I noticed there was an astra(Mk3 I think)right up my ass,so I pulled into the forecourt he followed me.I then drove upto the air machine and proceeded to pump tyres up,I looked over to where he was parked and noticed he was just sat watchin me??? Anyhow I just thought he wanted to try his asian ass luck on me!Then as I left he followed me out! So I drove home(quickly) and he was still behind me.Should I be worried??? lol.

 

[Munson]

Was this on durka durka street, in durkustan?

Durka durka!

 

[Munson]

IN all seriousness it sounds a bit dodgy. Did he see where you parked up/live?

 

[Boroboy182]

tried a 34/32 combo on the way to work today,thought it made a little difference for the better.fronts were on about 30 anyway so needed the air.

 

[chris-b]

I turned onto my road and down my drive,so I think he wil have seen where I live.I park my company car in front of the clio anyway so not too worried!

 

[docter fox]

you couldnt loose an astra in a 172?

 

[edgerfs]

I spent my 20p after your post and went for 34/31, didnt have that much time to test but seemed to be less torque steer!!

 

[hillclimber]

Im finding my 182 cup is very tyre pressure sensitive too.

Went on a speed hillclimb school day yesterday with mine and found that with standard road pressures the driving experience was lacking in excitement, the car was very prone to understeer.

Dropped them down to 28f 26r and the car felt more alive and a lot more planted and balanced through the corners clipping all the apexes with the back wheel up everywhere so im told!

Put them back up now for road driving though, settled on 31f 29r as I felt the steering to be too light for my liking and lacking in feel when at 34f

Simon

 

[iwb1]

Increasing tyre pressure adds spring rate. Depending on how firm the suspension is to start with 1 psi will have a greater or lesser effect. As renaultsport cars have fairly stiff suspension (for a roadcar) to start with small changes in tyre pressure can make a big differance. Dont forget pressure builds in the tyre as it gets warm and the harder you work the tyre the more that pressure will increase. Optimum pressure will give the flatest contact patch as the car corners. Be careful you dont crown the tyre.