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Tyre Pressures - Understeer etc
G.Man - 30/1/07 at 06:44 PM

my car has quite a bit of understeer, so I lowered the pressures to about 18psi front and rear and this helped slightly, but its still not great..

Anyone suggest some tyre pressures to use or what geometry to change?


oliwb - 30/1/07 at 07:02 PM

Try upping the rear tyre pressure a bit - or even better fit either softer springs in the front or more sensibly harder springs in the rear. Should help out a lot.....Oli.


chockymonster - 30/1/07 at 07:16 PM

When did you last check the geometry?
It may need a bit of adjusting back to marc's suggested settings


TimC - 30/1/07 at 07:34 PM

18 is still borderline high. Try 16.


roadrunner - 30/1/07 at 07:44 PM

MK say that 17psi is best.


skydivepaul - 30/1/07 at 08:20 PM

I used to run 16.5 psi all round

seemed to work ok


G.Man - 30/1/07 at 08:54 PM

cool i will lower them a bit at the front..

Doubt it would need much adjustment, hasnt done enuff miles to be far off marc's factory setting... inc corner weights..

The springs seem okay at the rear, may want softer at front, will see how it is when the new water pump is fitted and I can drive it a bit more..


PAUL FISHER - 30/1/07 at 09:21 PM

I found fitting slightly softer front springs reduce my understeer,also reducing the front ride height can also help,not sure what tyres your running but if they are semi slicks ,R888 or AO48's etc,you tend to still get a lot of understeer especially this time of year until the tyres come up to optimum temperature,usually takes best part of a lap on circuit to achive this,but on the road this weather they could never get up to temperature.So it may be difficult to actually no if you have made any real improvement on your settings until you get chance to do some fine weather track setup .


G.Man - 31/1/07 at 05:05 AM

Hi Paul

R888's and yes I had got them warmed up..

I was considering dropping the front slightly to improve weight transfer as I only noticed this driving hard with a passenger. My car was setup 50:50 with just me onboard so maybe that was part of the issue as well.


JAG - 31/1/07 at 08:41 AM

No one has mentioned changing the damper settings - if you can.

If you have adjustable damping then less damping at the front will reduce the tendancy to understeer.


alanr - 31/1/07 at 08:51 AM

I run my MNR with 888's at 15psi (cold) and works very fine for me

A


G.Man - 31/1/07 at 08:54 AM

15 psi, wow thats good to know...

Yes, softer at the front will help with damper settings as well... I can do that no problem


TimC - 31/1/07 at 09:13 AM

Keep us informed of your findings.


G.Man - 31/1/07 at 11:03 AM

quote:
Originally posted by chris mason
failing that just get it sideways a you go into the corner, the understeer will soon disappear then

Chris


Strangely, thats exactly what I have been doing, mucho fun! A scandinavian flick is much easier with a responsive front end tho, and I know the MNR front end is usually very responsive, hence my request for more info...

My findings will of course be published!


Pezza - 31/1/07 at 11:20 AM

yup I ran 15 all round on my old pre-lit with a crossflow up front.


marc n - 1/2/07 at 07:28 AM

hi mark
check front front and rear ride height, suspect it may need the rear raising slightly and front lowering with an extra body in there, if i remember right you also have a huge fuel tank, then try softening the front dampers slightly and hardening th rears,

best regards

marc


G.Man - 1/2/07 at 07:51 AM

Hi Marc

yes huge fuel tank, but almost empty, I think a lot of it will be down to the extra body onboard, biggest problem at the moment is being able o drive it without someone demanding a ride

Wont be able to do anything this weekend as busy, but next weekend should see it sorted with new Master cyls, tyre pressures and time to experiment with damper settings...

Am I right in assuming that to raise ride height I just increase pre-load on both rear shocks the same number of turns?

Made some mods to transmission tunnel to facilitate better handbrake adjustment, and we are gonna map it on road next weekend as well...

Should be fun


procomp - 1/2/07 at 08:07 AM

Hi if you alter/turn both rear platforms by same amount it should not alter the corner weight left/right or diag by enough to worry about having to re corner weight can be done with the final setup when happy with the handeling.

cheers matt


G.Man - 1/2/07 at 08:20 AM

Thanks Matt

Thought that was the case, same as my older rc cars then...

Only ever changed bikes before, lol