Author Topic: Guide to Reducing Understeer  (Read 45490 times)

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Offline MrCrusher

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Re: Guide to Reducing Understeer
« Reply #15 on: May 26, 2008, 00:49:27 AM »
Hi all.

I know this is an old topic yet it will probably be still relevant to most Vx owners today.

When I had a Pug 405 MI16-(160bhp, XU9J4 engine running at 183bhp- no mods or TC), I used to run wider tyres on the front than what I had on the back. If I remember right, it had 195,50,15's on as standard.

I know the MI16 was known for its cornering prowess and grip, it was very difficult to get the car to understeer and almost impossible to get it to oversteer. If it went though, you knew you'd really overcooked it. Either that, or it was some s**te on the road- usually diesel.

Torque steer was the main problem- if you give it the beans, it would whip the steering wheel out of your hands if you weren't ready for it.

Anyway, on standard wheels, I used 205 or sometime 215,50,15's on the front just for the added grip. Did the wider tyre thing years before on my old Cavvy SRI although with the Cavvy, it didn't handle all that well until I dropped it 40mm at the front and 30mm at the back.

Seemed to help me. Less torque steer and you could cane it through the corners, gripped like a Pit Bull.

Just had to look out for increased tyre shoulder wear.
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Offline MrCrusher

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Re: Guide to Reducing Understeer
« Reply #16 on: May 26, 2008, 01:02:15 AM »
Hi all again. It would not let me edit my last post so this is in addition too.

I've not had to do the wider front than back tyre thing with my CRX Del Sol SiR. Although I run it on 215,40,17's, it cornered like a Go-Kart on standards anyway. Didn't even have to fit a camber kit to stop shoulder wear.

Honda can "do" proper suspension.

Turning circle now 3 miles though.
You've gotta grab life by the haunches and hump it into submission!!

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Kyleport

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Re: Guide to Reducing Understeer
« Reply #17 on: September 18, 2008, 19:37:21 PM »
I used to run my Calibra on 225/40/17s and it handled brilliantly on the corners.  The problem I had was tramlining in a straight line. 

My car was lowered 60mm aswell so I used to experience finacial problems buying tyres every 2 months as the inside of tyre used to wear at a fast rate due to me not bothering to install a camber kit !!

Manfred

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Re: Guide to Reducing Understeer
« Reply #18 on: September 22, 2008, 16:10:49 PM »
> you apply throttle and the car will pull itself straight

Yes, but you don't ever lift off the throttle in a bend unless there's a damn good reason.

When you're at the limit and the rear breaks away, you can steer into the skid and floor it to catch it... but you're still going in the general direction of the tree and not losing enough speed.

For the V6 at least, 60kg in the trunk did wonders.

Manfred

Offline [email protected]

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Re: Guide to Reducing Understeer
« Reply #19 on: September 22, 2008, 16:56:15 PM »
When I had a Pug 405 MI16-(160bhp, XU9J4 engine running at 183bhp- no mods or TC), I used to run wider tyres on the front than what I had on the back. If I remember right, it had 195,50,15's on as standard.

Anyway, on standard wheels, I used 205 or sometime 215,50,15's on the front just for the added grip. Did the wider tyre thing years before on my old Cavvy SRI although with the Cavvy, it didn't handle all that well until I dropped it 40mm at the front and 30mm at the back.

Seemed to help me. Less torque steer and you could cane it through the corners, gripped like a Pit Bull.

The tendency of fwd cars to understeer is obviously caused by the front wheels being asked to provide grip for steering and traction for drive, especially if you accelerate round a corner.  The result is less grip for cornering, so the front drifts wide.  Obviously by using wider tyres (and lower profile tyres) you increase the grip (at least in the dry), so you reduce the tendency to drift, at the expense of heavier steering and higher tyre wear.

I suppose that by using a narrower tyre on the rear, at the limit, the rear wheel has less grip than the front, so it tends to drift (oversteer), which might help to compensate slightly for understeer at the front.  In practice it is quite difficult to get the back end to let go before the front in a fwd car - unless you are braking, or lifting off the throttle and transferring weight forward (which you shouldn't be doing in a bend anyway).

Offline 9564thoro

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Re: Guide to Reducing Understeer
« Reply #20 on: August 12, 2010, 00:08:19 AM »

I've driven many cars fast and slow on race tracks and roads!!! This car is still the one that shocks me the most on standard suspension. Pottering about it leans alot, going round a corner fast it understeers, push it in a bit harsher and it gives you very controlable oversteer, when you feel the back go and mess your pants!!!....some how...it still stays under control!!!!!! Stunning car :o
[/quote]

I don't know whether you're talking about track driving or what, but, being fairly new to the car, I can agree with the first two statements, but my question is, once you've established you get understeer, to push harder than that to then find out about oversteer seems like lunacy?? personally, the point where you get massive understeer, is about the limit of how fast you can corner!

Offline DanSE4

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Re: Guide to Reducing Understeer
« Reply #21 on: August 12, 2010, 00:25:25 AM »
Thread started in 2006, last posted on in 2008.

Move on guys! :)
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Offline se5let

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Re: Guide to Reducing Understeer
« Reply #22 on: February 20, 2011, 12:37:28 PM »
Thread started in 2006, last posted on in 2008.

Move on guys! :)

Err no...as long as the car understeers the age of the topic doesn't matter...

FYI the load on the front is greater....so it needs less weight.  The split is something like 59% weight on the front, doesn't take much to work out that is the problem.  The Calibra is like a Porsche in reverse....The engine hangs over the front far too much.  You cant pull it back so the weight needs shifting.  I would (and am going to) put the battery in the back.  I Have already shaved 5KG off from the lightened flywheel.  Next is to poly bush it and stiffen it up.  If the limit at which the car understeers is improved then I'll let you guys know.

Simply taking out the rear tire is not the solution.  Besides it weighs virtually nothing....A battery however, is around 20KG.  Apart from that the only other adjustments I can see being of benefit is upgrading the steering rack...Other than that the LSD is the only other answer to the issue....

So this is still a valid topic as long as there are different and new things to try out on this car to improve the handling. 

S

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Offline nikp

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Re: Guide to Reducing Understeer
« Reply #23 on: February 20, 2011, 12:40:34 PM »
...A battery however, is around 20KG. 

Bloody hell, what sort of battery do you have! That is one HEAVY battery!
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Bovva

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Re: Guide to Reducing Understeer
« Reply #24 on: February 20, 2011, 15:50:25 PM »
Removing weight from the front where the power (engine) is seems daft? Surely you'd see a loss of traction, poorer cornering and generally less grip at the front resulting in excess wheel spin?

Porsches have power at the back, steering at the front so the wheels for steering only have one job, that's not a reverse of a calibra, not unless they have a fork lift setup.

Offline nikp

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Re: Guide to Reducing Understeer
« Reply #25 on: February 20, 2011, 15:52:41 PM »
In any car you want to remove as much weight as possible. Weight is not the key to handling. It's the one thing you do not want in any fast car.
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Bovva

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Re: Guide to Reducing Understeer
« Reply #26 on: February 20, 2011, 15:53:41 PM »
In any car you want to remove as much weight as possible. Weight is not the key to handling. It's the one thing you do not want in any fast car.

I agree with weight reduction but shifting weight from the front to the back isn't going to have the same effect.

Offline Gav

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Re: Guide to Reducing Understeer
« Reply #27 on: February 20, 2011, 15:53:53 PM »
My Cally with the stiffer suspension and heavier front end puts the power down a lot easier than my Astra.

The Cally (apart from the Turbo) is FWD and isn't the best chassis. It will always understeer.

Fit good tyres, good suspension, polybushes, strut braces etc and it will help quite a lot.

It will still understeer though.

Offline nikp

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Re: Guide to Reducing Understeer
« Reply #28 on: February 20, 2011, 15:56:29 PM »
I agree with weight reduction but shifting weight from the front to the back isn't going to have the same effect.

It'll depend upon the weight distribution - don't get me wrong, i'm hardly the worlds expert on handling but the 'perfect' and most desirable weight distribtion is 50/50. Therefore moving weight from the front to the back may help get close to that.
Drives Evo 8. Rocks my world - considering selling. PM if interested

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Offline Butcher

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Re: Guide to Reducing Understeer
« Reply #29 on: February 20, 2011, 16:00:23 PM »
Removing weight from the front where the power (engine) is seems daft? Surely you'd see a loss of traction, poorer cornering and generally less grip at the front resulting in excess wheel spin?

Porsches have power at the back, steering at the front so the wheels for steering only have one job, that's not a reverse of a calibra, not unless they have a fork lift setup.

I agree, removing weight from the front end of a front wheel drive Calibra is going to make the problem worse! Less weight means less grip means you put your foot down mid corner the car will go straight on. Simple science.