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Author understeer
FlaFFy_91
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17th Oct 11 at 14:39   View Garage View User's Profile U2U Member Reply With Quote

Understeer in cars.

This isnt a help me my cars understerring thread

Its a general chat about understeer and what you think is the best way to get rid of it in a car

Lets take a fwd civic for example. The handling on them are realy good as standard. Lowered, tyres and some arbs and its going to be a winner. But when you put too much power into them they understeer more

I know you can go into things like damper rates and spring rates but i dont realy know alot about them

more damper means less understeer or the otherway round and more spring rate means less understeer or again is it the other way around?

And does a stiffer front end (stiffer or thicker arb) mean less understeer too?

Basicly if theres and track boffins out there who can go into a daft amount of detail feel free

Jake
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17th Oct 11 at 14:45   View User's Profile U2U Member Reply With Quote

flexible front end reduces understeer i reckon
Neo
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17th Oct 11 at 14:47   View User's Profile U2U Member Reply With Quote

Soften front springs and remove ARB if it has one
Graham88
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17th Oct 11 at 14:47   View User's Profile U2U Member Reply With Quote

Stiffer front end makes the understeer worse. I was just bouncing around some corners at Silverstone trying to put the power down, slacked off the dampers on the coilovers to competely soft, drove like a different car, but did make it bumpier at high speed

All I know about it really is that stiffer on the front isn't good, which is why alot of people take front ARB's out on some cars. But spring rates etc is out of my knowledge
antnee
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17th Oct 11 at 15:17   View User's Profile U2U Member Reply With Quote

Generally, the rear will be set harder than the front on a FWD car.

Its all about balance, you can't just say a stiffer front is better. For a really good handling car on semi slicks, it can be a lot stiffer all round over the standard setup.

When people take front ARB's off, I think its probably cos the rear isn't stiff enough.
FlaFFy_91
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17th Oct 11 at 16:54   View Garage View User's Profile U2U Member Reply With Quote

so basicly a stifferfront end is more understeer realy?

i do get what you mean antee every car is different and you do have to balance between front and rear but in generalities a front end that is softer is better

i would of thought a softer front end but with a higher spring rate to keep the wheels down onto the track would be better?

what about rear and 4 wheel drive cars, same sort of deal?
antnee
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17th Oct 11 at 16:59   View User's Profile U2U Member Reply With Quote

But softer than what? Standard?

If the front is too stiff it will understeer.
AK
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17th Oct 11 at 17:16   View User's Profile U2U Member Reply With Quote

Understeer....

Tyre pressures too high (tyres too hot?)
Susp too firm.... (springs or do firm dampning)
too firm from ARB

A stiffer front end is good IF you have tyres and geometry to cope with it! i.e you'll just get understeer if you are running 0 camber and softsidewalled tyres. The tyres will flex and roll over

Add as much CASTOR as you can to give more camber where you need it (on corners). Healty amounts of static camber will help too.

Springs and dampers. The spring is what holds the cars weight... the damper just controls its transfer. If its too soft the car will just wallow/bounce on the spring (assuming 1 way adjustment for compression/rebound). If its too firm the tyres will take more of the load. The tyres can only take so much, esp when your asking them to turn and accelerate.

[Edited on 17-10-2011 by AK]
AK
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17th Oct 11 at 17:19   View User's Profile U2U Member Reply With Quote

adding a rear ARB will also help turn in (reduce understeer) but increase rear twitchyness.

quote:
would of thought a softer front end but with a higher spring rate to keep the wheels down onto the track would be better?



a higher spring rate would make it a stiffer front end. If you soften off the dampning on a stiffer spring the car will just skip about. You need decent amounts of dampning to allow the car to lean onto the tyres gradually, but you also need quick enough rebound to keep the tyre in contact with the ground on bumps. Its always a bit of a compromise on 1way adjustable dampers..... even 2way!

You dont need high spring rates to push the wheels back down. Gravity helps out even the softest sprung suspension. On 1way adjustable suspension if you increase it the rebound gets slower (wheels hang in the air longer). 2 way you can adjust compression and rebound - so the car car lean slowly into high speed corners for stability but have slightly quicker rebound to help keep wheels on the ground. 3way you have hi speed rebound and lo speed - (kerbs etc = high speed).

[Edited on 17-10-2011 by AK]
Nick-S
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17th Oct 11 at 19:05   View User's Profile U2U Member Reply With Quote

Always though 3 way was hi and low speed compression and rebound. Ie, low speed sqwat, dive and role. Hi speed, bumps and kerbs and rebound?
sand-eel
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17th Oct 11 at 19:10   View User's Profile U2U Member Reply With Quote

Also if you have thicker ARBs, there is no need for majorly negative camber anymore as the car obviously won't roll as much.
Nick-S
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17th Oct 11 at 19:12   View User's Profile U2U Member Reply With Quote

Also am not convinced about removal of FARB. Surely that will make it unstable at high speeds.
sand-eel
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17th Oct 11 at 19:14   View User's Profile U2U Member Reply With Quote

It does...yes, its a stupid thing to do.
Alex_Rally
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17th Oct 11 at 19:16   View User's Profile U2U Member Reply With Quote

would a welded in roll cage stiffen everything up ??
Eck
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17th Oct 11 at 19:17   View Garage View User's Profile U2U Member Reply With Quote

If you're speaking strictly of a FWD (as per example), I've found it's not really understeery unless I'm being a proper tool. The back is really stiff (more so than the front) so I'm guessing by the above that this helps!
sand-eel
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17th Oct 11 at 19:17   View User's Profile U2U Member Reply With Quote

It stiffens the shell up, meaning the suspension does its job better.
sand-eel
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17th Oct 11 at 19:19   View User's Profile U2U Member Reply With Quote

Ideally a FWD should have higher poundage springs than the front.
Eg corsa with redtop conversion - 250-275lb/mm front 500-600 lb/mm back.
Alex_Rally
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17th Oct 11 at 19:19   View User's Profile U2U Member Reply With Quote

quote:
Originally posted by sand-eel
It stiffens the shell up, meaning the suspension does its job better.


i hoped so , cos mines about 95% in there now lol , twat of a job lol
sand-eel
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17th Oct 11 at 19:20   View User's Profile U2U Member Reply With Quote

quote:
Originally posted by sand-eel
Ideally a FWD should have higher poundage springs than the front.
Eg corsa with redtop conversion - 250-275lb/mm front 500-600 lb/mm back.


^^^ oh this would be very good on a track not so good on shit uk roads.
Mieran
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17th Oct 11 at 20:38   View User's Profile U2U Member Reply With Quote

quote:
Originally posted by Nick-S
Also am not convinced about removal of FARB. Surely that will make it unstable at high speeds.


I wouldn't take a front anti roll bar off unless its a shit design like the Nova/Corsa/Tigra ones which are designed to make the car understeer!
0775kieran
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17th Oct 11 at 21:58   View User's Profile U2U Member Reply With Quote

When i have taken the front arb off it has made for a better turn in and less understeer, but has made it unstable at higher speeds, if its a road car just leave it on.
AK
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18th Oct 11 at 04:18   View User's Profile U2U Member Reply With Quote

quote:
Originally posted by Nick-S
Always though 3 way was hi and low speed compression and rebound. Ie, low speed sqwat, dive and role. Hi speed, bumps and kerbs and rebound?


that would either be 2 or 4 way then

Front ARB (on corsa)

If wet trackday, remove it. Test it on round-abouts - constant raduis with a bit of power. I always found you'd get more power down without the ARB.

Rear ARB:

Our GTR (not fwd) is very RWD biased and has been struggling for rear traction this year. We've gone from an adjustable thick blade ARB, to a thinner one and now nothing!

[Edited on 18-10-2011 by AK]
Mike GSi
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18th Oct 11 at 09:21   View User's Profile U2U Member Reply With Quote

When i removed my FARB on my Let corsa with coilovers it was much better on smooth tight long bends, but on a gradual shit country road bend at anything over 70mph you could feel on the steering wheel the slow rebound time.

As said. For track conditions no FARB, for a daily driver on uk roads FARB is a must imho.
Rob B
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18th Oct 11 at 09:30   View User's Profile U2U Member Reply With Quote

quote:
Originally posted by sand-eel
Ideally a FWD should have higher poundage springs than the front.
Eg corsa with redtop conversion - 250-275lb/mm front 500-600 lb/mm back.


Entirely depends on the motion ratio front to rear?

AK
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18th Oct 11 at 10:29   View User's Profile U2U Member Reply With Quote

quote:
Originally posted by Mike GSi
When i removed my FARB on my Let corsa with coilovers it was much better on smooth tight long bends, but on a gradual shit country road bend at anything over 70mph you could feel on the steering wheel the slow rebound time.

As said. For track conditions no FARB, for a daily driver on uk roads FARB is a must imho.


Not arguing or anything.... BUT removing an ARB will promote FASTER rebound, i.e your car will have have less tendancy to 'pickup' a wheel at the corner under hard cornering. Without the ARB the car will lean on the springs more.

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