wheel spacers and handling

Matt82 · 7 Jul 2009 at 09:42

im looking to go for 20mm front and back, hubcentric.

at the rear, the widened track should increase roll restistance, which i hoped would improve turn-in but should also increase stability, making the front have less influence on the rear

when i space the front, the increased scrub angle, i think will cause the front to have less influence overall and hence maybe more tendency to understeer..

what do you think?

Prophet · 7 Jul 2009 at 09:49

What car?

Dogbreath · 7 Jul 2009 at 10:23

It'll mess up the scrub radius so the car will be less stable, reacting far more to road imperfections under acceleration and braking.

Matt82 · 7 Jul 2009 at 10:28

Orange Peel said:
What car?

mk3 golf

as for the scrub radius, thats the bit i was most concerned about tbh.

the one thing im not happy with handling wise at the moment is a slightly dull turn in, which could probably be fixed with a touch of toe-in. theyre paralell at the mo

maybe i just need fat wide wheels then

Dogbreath · 7 Jul 2009 at 10:40

What tyres are you using? Toe in almost certainly isn't what you want, that tends to dull response. A touch of toe out may well help, and a stiffer rear ARB would be a good move.

Matt82 · 7 Jul 2009 at 10:42

im sure its toe in that would sharpen in the response/turn-in

im currently on tiny 195/50/15s

Prophet · 7 Jul 2009 at 10:43

Dogbreath said:
It'll mess up the scrub radius so the car will be less stable, reacting far more to road imperfections under acceleration and braking.

This.

20mm is a fairly big offset. I could tell the difference with 5mm spacers which I used to stop my brake calipers fouling the wheels.

Dogbreath · 7 Jul 2009 at 10:47

Matt82 said:
im sure its toe in that would sharpen in the response/turn-in

Toe in makes the steering less responsive, but aids straight line stability. Toe out can improve turn in, but can make the car twitchy on straights.

I meant the tyre brand/model. Soft sidewalls (e.g Toyo Proxes T1S/T1R) can really blunt turn in response on some cars.

Wayn0r · 7 Jul 2009 at 11:29

i ran 20mm spacers on the rear and 10mm on the front of my r32. none of the above were affected, including coilovers and forge adjustable control arms it was a hell of a lot more stable and handled far better with them.

Dogbreath · 7 Jul 2009 at 11:44

Spacers on the rear won't cause stability issues anyway. A 20mm increase in scrub radius is going to have a detrimental effect on stability under braking or power, though it may still be acceptable.

As for the big improvment in handling, I suspect that was more down to the rest of the suspension changes rather than just the spacers.

Matt82 · 7 Jul 2009 at 11:54

theyre kumho ku31s. the sidewalls are quite soft tbh, not as bad F1s back in the day.

6.0x14 ET45 4/100 Orlando
6.0x14 ET45 4/100 Imola
6.0x15 ET45 4/100 Imola
6.0x15 ET38 5/100 Le Mans
6.0x15 ET45 4/100 Solitude
6.5x15 ET43 5/100 Solitude
6.0x15 ET45 4/100 BBS
6.5x15 ET43 5/100 BBS
6.5x15 ET43 5/100 Long Beach
6.5x15 ET43 5/100 Monte Carlo
6.5x15 ET43 5/100 Brands Hatch
6.5x15 ET43 5/100 Speedline
7.0x16 ET43 5/100 BBS (Anniversary

mine is et38, 6 by 15 on the 5/100 pcd wider axle

my et etc seems abuot right, maybe i could go down to low 30s to keep it sensible,

Defcon5 · 7 Jul 2009 at 12:25

What do people mean by scrub raduis? (in simple terms preferably!)

Dogbreath · 7 Jul 2009 at 12:32

Defcon5 said:
What do people mean by scrub raduis? (in simple terms preferably!)

http://www.familycar.com/Alignment.htm#Scrub Radius

It's the distance between the steering axis and the centre of the tyres contact patch. The further apart they are, the more "leverage" the tyre has on the steering.