Just won some alloys, will they fit?
 

Cant get my head around the offset issue today. Just won some alloys on ebay pcd 108 offset 15. I know the offset needs to be 35-40ish. So my question is how do I get these alloys to fit or won't they?

"May" be a problem:

http://www.driverstechnologyassociat...eel-offset.htm

they will stick out about 20mm further than a wheel that is the correct ofset. if you have wide arches on the rear it shouldnt be a problem

Bumpsteer!!

I don't think that's right. Bumpsteer is caused when the steering rack isn't correctly aligned (or the right length), and doesn't have anything to do with the wheel offset. IF you ever measure it then you don't usually have the wheels attached anyway.

I think it does have some other effects though - something to do with how well the steering self centres I think.

Matt

What exactly is bumpsteer?

If they dont work I'll just put them back on ebay.

Bumpsteer is the change of the effective length of tie rods due to the suspension travel. Nothing to do with wheel offset.
A wheel offset too low will shift the contact patch out of correct alignment with regard to the kingpin axis, thus increasing the scrub radius. The effect will be unsettled steering, exaggerated reaction to unevenness of the road, especially when braking.

If you want a more detailed explanation then this site http://www.longacreracing.com/articles/art.asp?ARTID=13 has a good explanation together with instructions on how to measure and correct it.

Matt

Bumpsteer
 

Hi,
I believe there is more than one way of causing bumpsteer but i may be wrong, ive been modding cars for nearly 30 years and have experience of people fitting wheels with too much offset.
if you move the contact patch too far away from the middle of the point where the kingpin inclination hits the floor you will adversly effect the handling
when you go over a bump the car will try to steer into the bump if thats not bumpsteer what is it??
anyone remember the carlos fandango ad with the anglia with oversize wheels!!
Ray:)

That's a classic Ray.

Still makes me smile:D :D

Carlos Fandango

Using too small an offset will increase the scrub radius, not necessarily a bad thing until you get a blowout. It will increase the 'feel' of the steering, the self centring. It wont affect the bumpsteer, that is where the different geometry of the track control arm to wishbones will cause a steering input as the hub assembly rises and falls.

as i said before you need to consider the centre of the contact patch to where the theoretical kingpin inclination line hits the floor and this will i assure you create a badly steering car if its too far out from what is intended
Ray:)

BRILLIANT Chris , I wish id found it first
Ray:)

Will 20mm really effect it that bad? Could put them back on ebay without a problem but I like the alloys.

Do we have a final verdict? sell or use? :confused:

If it was me then I'd keep them until I had a chance to drive the car with them on and see what it felt like. You can always sell them later if they don't work out.

Matt