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Author Topic: Understeer  (Read 6322 times)

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Muroman

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Understeer
« on: 09 July 2018, 08:02:05 »

Hellou, how to kill understeer?

Last winter I changed new Bilstein B8 shocks on front, LSD diff, front wishbone bushes and rear subframe(only the big bushes) bushes to poly bushes.

And now as the summer came the car feels much better but there also came this massive understeering....

Also the car has Stock springs front and back and also stock rear air shocks.
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Doctor Gollum

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Re: Understeer
« Reply #1 on: 09 July 2018, 09:32:50 »

Swap the B8s and vertical bushes out :y
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Muroman

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Re: Understeer
« Reply #2 on: 09 July 2018, 14:26:30 »

Is there other ways, as I hoped for something that could be done by tools. Maybe camber and toes?

Which shocks you suggest? And which bushes?
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Doctor Gollum

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Re: Understeer
« Reply #3 on: 09 July 2018, 14:35:54 »

Standard GM vertical bushes, Sachs shocks with Pedders HD Monaro top mounts. Basically you need to soften the front end slightly to stop it washing out of the corners ;)

What toe/camber are you running? And what wheels/tyres?

Full poly set up should be ZERO TOE with 1°10' camber.

Check this first and report back :y
« Last Edit: 09 July 2018, 14:39:08 by Doctor Gollum »
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Muroman

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Re: Understeer
« Reply #4 on: 09 July 2018, 16:06:18 »

I have those Elite Intra Alloys 7.5inch wide, tires Kumho 235/45 17'

I have ~2mm toe in as it helped with the car going straight on these shi**y roads that we have in Finland. It was pulling left or right on roads that have bad trails. So I guess I can't fix this if there isn't another way to stop the car jumping from another lane to other  :-\

Camber was hard to measure but the most approx measure was a little over 1°
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Doctor Gollum

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Re: Understeer
« Reply #5 on: 09 July 2018, 16:23:54 »

Those tyres won't be helping.

Mine was on 245/40/18 Goodyear Eagle Assym 2s with Irmscher Stila wheels, Sachs shocks, Plod springs all round, Pedders rear subframe bushes and solid diff mounts, Rear self levelling, Pedders top mounts, Powerflex front bushes and Powerflex Black Sierra bushes as the vertical bush. Geometry was set as zero toe and camber as above.

I don't recall it understeering much, but zero toe does make it a touch vague straight ahead ( this is an insurmountable side effect of having a recirculating ball steering box as there's always a dead spot unless you are turning), but it used to turn in crisply. I enjoyed driving that car hard.

My Elite had B4s with Pedders top mounts, Irmscher springs all round, Powerflex front bushes with standard vertical bushes, Pedders rear subframe bushes and solid diff mounts, and Irmscher rear shocks with the same wheels/tyres.

That had standard toe/camber and handled as well, but felt different because it was lowered and due to the vertical bushes being stock, the front end was a bit more forgiving...
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Muroman

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Re: Understeer
« Reply #6 on: 09 July 2018, 17:17:42 »

Okay that is good reference  :y

I think my camber is close to the default but I'll start by re-adjusting those and try to see what that does. If no help, then toe adjust and if it still stays bad I'll do something else
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TheBoy

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Re: Understeer
« Reply #7 on: 09 July 2018, 18:13:03 »

All Omegas suffer high speed understeer, presumably by design.

I made my beloved Silver Bullet more pointy by using Irmscher springs at the front and stock at rear, all set up to WIM's default Omega settings.  TBE was set the same until recently, when the front went back to stock due to excessive bumper wear.  With TBE lowered all round on Irmscher kit, it understeered the same as stock.
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Re: Understeer
« Reply #8 on: 09 July 2018, 18:21:54 »

You would be hard pushed to buy a car these days which doesn't have built in understeer as a design feature. It became standard when most cars were being driven by people who know nothing about driving.
Worth trying to design it back out though, with above suggestions.
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Muroman

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Re: Understeer
« Reply #9 on: 09 July 2018, 21:01:05 »

About the tyres, what kind of tyres would help?

Less pressure could help too, but that makes the tire wear more on the middle?
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Doctor Gollum

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Re: Understeer
« Reply #10 on: 09 July 2018, 21:13:46 »

My ex plod was always run at fully loaded pressures... 42/48 iirc.

If it did understeer, then it was not enough to cause concern when pressing on, regardless of dry, rain or snow ;)
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Nick W

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Re: Understeer
« Reply #11 on: 10 July 2018, 00:13:36 »

About the tyres, what kind of tyres would help?

Less pressure could help too, but that makes the tire wear more on the middle?


over inflating them does that.
Over 20k miles from budget tyres is easy from a properly maintained car.
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Raeturbo

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Re: Understeer
« Reply #12 on: 10 July 2018, 00:27:03 »

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Re: Understeer
« Reply #13 on: 10 July 2018, 08:11:14 »

https://speed.academy/how-to-fix-understeer-or-oversteer-suspension-handling-setup-tuning/

There you go have a read of this.


Don't confuse people.

You need to soften the front,

Tyre pressures rears 35, front 30,-32,
Check geometry

But are you saying it's understeering, because your trying to get the barge to behave like a sports car.
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Raeturbo

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Re: Understeer
« Reply #14 on: 10 July 2018, 08:31:25 »

Once he understands what’s happening and when, he will have a better chance of correcting it.
Knowledge is a wonderful thing.
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