Wheel offsets wrong??

[nicbowman]

Hi all. Sun is out, car MOT'ed and off the axle stands for summer. Looks fantastic, sounds fantastic, goes fantastic - but the steering really p1sses me off still.

I drive a lot of really bumpy back roads, and the steering pulls with the bumps and follows the imperfections. I have renewed eveything, including bushes, rack, tr ends, rack UJ's, dampers and springs, all geometry is correct, running SO2's (205 55) in good condition. I am on the original 5 spokes (pre cat). I have checked for bump steer, no problem there.

I am now wondering if the wheel offset is wrong? It feels like there is too much offset, i.e the wheel is too far out.

Does anyone know if the offset used is the same as the Ford the uprights was designed for? Or ever tried some Sierra cosworth alloys?

I would love to fix this one, everything else is superb!

Thanks


Nic

[spend]

The wheel offsets are not so precise, @25F & 35R OTOMH.. (fronts will prob foul up if you try & put them on the back I think).

You could try experimenting with your tyre pressures & F tracking, or give your suspension supplier some grief?

Failing that post your setup & see what the missive makes of it?

Dave

[steve-v8s]

Yep, original front wheels are 7x15 et25 rears 7.5x16 et32. The offset will (or it is on mine ) be stamped on the inside of each wheel.

[nicbowman]

Hi, ta

I think the original offset is 35 to 45 (ford spec), so some difference.

Nic

[spend]

Did Ford spec 7 & 7.5" rims tho ? the ET & width are related to establish a C/L.

Are you absolutely sure your rear wheels are well aligned to the front. Mine were out of alignment and I needed to renew the rear adjusters, when realigned the whole nature of the car was completely different. Go on a straight flat road, accel / decel and see if the car stays in line (supermarket car parks are a handy place).

Dave

[Ballistic Banana]

spend said:

supermarket car parks are a handy place.

Dave

Been showing off in front of the Saxo boys again Dave

[spend]

Yup, Unlike the Beachboys Italian fantasies, I know I can see them off Just dont hang about after 9 when the ricers start to come out

Always did like stealing candy from babies

Dave

Still not seen IanB lurking around in his hoody SaxoBoy guise tho
and I'm really surprised I got away with the SealSlider line :-)

[seasider]

spend said:

Yup, Unlike the Beachboys Italian fantasies, I know I can see them off

spend said:

I'm really surprised I got away with the SealSlider line :-)

You didn't

[spend]

Ooops................. :sheepishgrin:

[Paul V]

How much camber are you running at the front? Mine pulls a lot more since the geometry was reset with more negative camber, even though it might be set to TVR specs you could find some improvement taking it to someone who could alter it to suit your driving style.

[nicbowman]

Hi, I am only running 0.75 degrees negative camber, and 0.5 toe in. Nothing too wild.

I will check front to rear though, although the symptoms are not subtle, and happen even when going slowley (20mph) on a bumpy road.

Nic

[Paul V]

How are the tyres worn? if they aren't even it could add to it. There was a topic on Wheels in Motion a while ago about tyres being paired as they have a natural run out and could cause similar problems to which you are experiencing.

[spend]

Sounds like a poor damper/spring combination recoil problem to me... But I suspect I am going to be flamed

Dave

[The AJP Griff]

Slightly off topic,but how do you calculate the required spacer thickness,when fitting the 16" reas to the front?I'm about to take delivery of my new wheels,which are all 16" with a 35mm offset,but now the fronts will be 7.5j not the 7j they were on the original 15" wheels.Am i right in thinking i need a 3mm spacer to get the centre of the new front profile in the same place?
Oh,and where can i get these spacers from?Cheers,Mike

[steve-v8s]

I would say you need a 10mm spacer to get the tyre centre in the same place because to keep the same wheel centre the same you need to keep the offset the same. You will have to choose the spacer dependent on which side of the centre you want to put the extra half inch.

[Roberto Rica]

Surely you don't need any spacer as the extra width/2 = 12.5/2 = 6.25mm cancels out the extra offset (32mm - 25mm) is 7mm. Okay a 0.75 mm spacer.

Rob

Edited by Roberto Rica on Saturday 24th February 19:44

[seasider]

The AJP Griff said:

Slightly off topic,but how do you calculate the required spacer thickness,when fitting the 16" reas to the front?I'm about to take delivery of my new wheels,which are all 16" with a 35mm offset,but now the fronts will be 7.5j not the 7j they were on the original 15" wheels.Am i right in thinking i need a 3mm spacer to get the centre of the new front profile in the same place?
Oh,and where can i get these spacers from?Cheers,Mike

Not spaced mine yet, i think Jelli said its 5mm on another thread..

[spend]

Exactly, there are a couple of sites with online calculators eg:
www.1010tires.com/WheelOffsetCalculator.asp

Dave

[The AJP Griff]

Roberto Rica said:

Surely you don't need any spacer as the extra width/2 = 12.5/2 = 6.25mm cancels out the extra offset (32mm - 25mm) is 7mm. Okay a 0.75 mm spacer.

Rob

Edited by Roberto Rica on Saturday 24th February 19:44

That was how i got to 3mm,but i was using a 35mm offset,not 32mm and taking the .5" as 12mm.

[The AJP Griff]

spend said:

Exactly, there are a couple of sites with online calculators eg:
www.1010tires.com/WheelOffsetCalculator.asp

Dave

Cheers Dave,thats a great calcuator.It also comes up with a 3mm difference.Now then,whee do i get a spacer from please?