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Location:
Sydney
Registered:
June 2002
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FWD offsets
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Tue, 30 September 2003 13:46
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will fitting 1" wider rims with smaller offset upset handling to a FWD car? if offset is smaller then it increases track and wouldnt this be good? sharp turns feel very lazy and with long sweeping turns i notice it understeer more than with factory wheels. could it be because of standard shocks? or unsprung weight?
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Location:
Madrid - Spain
Registered:
August 2002
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Re: FWD offsets
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Wed, 01 October 2003 03:30
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Yes
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Location:
Sydney
Registered:
June 2002
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Re: FWD offsets
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Wed, 01 October 2003 14:11
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yes? please elaborate a bit more please. yes to all above i guess.
the car has been acting wierd since i put the factory rims back on. i took a right turn without braking in the wet today and it felt as if the hand brake was applied for a split second. the back slid out for no reason. i was thinking "what the? ohh sh!t" very strange handling.
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Location:
Madrid - Spain
Registered:
August 2002
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Re: FWD offsets
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Thu, 02 October 2003 07:39
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Any change to wheels, tyres and suspension is a deviation from what the manufacturer assessed as appropriate for the vehicle. Having said that, your idea of what is appropriate would have different criteria and accept different compromises than the manufacturer would.
The wider wheels and offset would give you a larger scrub radius which would make your steering heavier but probably more stable (wanting to go straight ahead).
Another side affect of doing this is you have increased the arm on the springs, effectively reducing the spring stiffness. You probably wouldn't notice this because you would have lower profile tyres to go with the wider rims and offset. You may notice it diving a little more under brakes.
If you have increased the rolling diameter of the tyres, you would affect the speedo/odometer accuracy. This will also change the effective caster. Once again this will change the feedback you would get through the wheel depending on whether you have increased or decreased the diameter.
The geometry changes you mention in themselves would probably make very little difference to the handling of your car. The reason why it understeers more with the stockers on has probably more to do with the stock tyres than anything else.
Shocks and unspring weight make more of a difference on rough roads. They affect how well your car can control the wheel movement. Having said that, by increasing the track, for a given tyre/wheel weight, you have increased the load on the spring/damper, so it may be a little more nervous on a rougher corner. I doubt the change would be noticeable though.
From what I have heard, early front wheel drive corollas have an oversteering tendancy from factory. You wouldn't happen to be driving a corolla would you?? It sounds like the bigger wheels might have tamed it a little.
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Location:
Sydney
Registered:
June 2002
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Re: FWD offsets
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Thu, 02 October 2003 12:30
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thanks for the indepth feed back gold28. you pointed out really significant facts about suspension i would have never considered. one question remains. how does a fwd oversteer??? no i cant say i have had the privelige to drive a carolla yet. i drive a 90 capri. but i ask in toymods because of all the forums, bbs, message boards toymods has the most helpful and accurate advice on any topic.
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Location:
Madrid - Spain
Registered:
August 2002
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Re: FWD offsets
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Fri, 03 October 2003 00:18
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There are a lot of factors that determine how well a tyre sticks to the road. Most manufacturers try to build in a small amount of understeer because in the hands of the average driver, it's behaviour is more predictable which implies that it is safer.
Unfortunatly for front wheel drive cars the front tyres have to do most of the work and consequently are usually the first to let go. Manufacturers spend a lot of time trying to reduce this tendency in front wheel drive cars. They do this with the installation of anti-roll bars and changes to suspension geometry. As it is a difficult thing to increase grip, generally the easiest way to tame a front wheel drive car is to make the back handle worse.
I am no expert on this subject but having driven a few front wheel drive cars, I think that they are designed more for an acceptable understeer in wet conditions when traction at the front is severly compromised. The results of which is that in the dry the back end handles badly.
I don't know if I have helped you any but making any car handle is a complicated task, one which generally goes backwards rather than forwards. - both metaphorically and literally 
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Location:
Sydney
Registered:
June 2002
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Re: FWD offsets
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Fri, 03 October 2003 14:54
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yes, you have definitely helped me out! i understand it a bit better now so hopefully i'll make the right decision when i drive and when i upgrade parts, thanks alot!
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