[greenzook89]

Alright. So it might be night shift brain here but would there be any great difference in flex/leverage from running a NT housing with say 25mm wheel spacers each side vs a wt/nt spacing with no spacers. Theoretically scrub radius would be similar too?

Does the extra 50mm of track afforded by the spacers 'make up for it'?

Ignore the fact that spacers are illegal and chromos etc. Just random musings in my head so interested to hear your input.

Tar.

Bye

[Gwagensteve]

A NT with 25mm spacers would be ~30mm narrower than a WT and have more scrub radius which is unhelpful in a road car.

[greenzook89]

Would the scrub radius be relevant off road in regards to guard clearance? If it's 30mm narrower than a WT on equivalent wheels/tyres wouldn't it have less scrub radius by comparison, or am I looking at it backwards?

I understand that WT diffs with NT spacing is the preferred set-up but this is not going to happen on this particular car.

[fordem]

greenzook89 wrote:

Would the scrub radius be relevant off road in regards to guard clearance? If it's 30mm narrower than a WT on equivalent wheels/tyres wouldn't it have less scrub radius by comparison, or am I looking at it backwards?

Unless I am mistaken, the "king pin" axis, or rather the point at which a line drawn through the king pin axis intersects with the ground, is required to define the scrub radius - if as I suspect is the case, the kingpins on the NT axle are closer together than those on the WT axle, adding spacers will increase the scrub radius even though the overall track is narrower.

[MrRocky]

Ive run spacers on nt diffs with large offset rims for the last 40,000kms. Tyres on my setup sit 1" past a standard wt flare.
Other than no chromo option theres not really alot to report

*edit : id say the most pleasant to drive onroad out of the 22 sierras ive owned also running no steering damper and a 31" tyre.

[fordem]

There is a significant stability issue created when a vehicle has excessive scrub, it's generally not immediately observable, but, one way to experience it is to try driving through standing water so that one wheel is in the water and the other isn't - for example if you hit a patch of water at speed - the more scrub, the more speed, the more violent the vehicle will pull in the direction of the standing water.

[Gwagensteve]

greenzook89 wrote:

Would the scrub radius be relevant off road in regards to guard clearance? If it's 30mm narrower than a WT on equivalent wheels/tyres wouldn't it have less scrub radius by comparison, or am I looking at it backwards?

I understand that WT diffs with NT spacing is the preferred set-up but this is not going to happen on this particular car.

Fordem has explained it. Scrub radius is a product of rim offset. Whilst some people claim more scrub radius improves off road ability because as you're walking the steering left and right the wheelbase shrinks and grows, adding purchase, pretty much all the effects of increased scrub radius are negative, especially when the axle is driven. It's part of the reason why front wheel drive cars run very high positive offset rims, to reduce torque steer.

[greenzook89]

Ah yes that makes sense. For a bush car/shitbox it's probably a moot point but I get that narrower offset is easier to package.

It used to run 15x8 -22s and currently is on 15x5.5 1 litre rims (+5?) With a 25mm spacer and no clearance or real world lack of stability.

[Gwagensteve]

I wouldn’t describe increased scrub radius in terms of lost stability, I’d describe it as poor behaviour. It makes the steering heavier, kickback and pull more. The effect of the leverage outside of the kingpins means the car will try and drive over the tyre on obstacles if the front isn’t locked, so the driver has to muscle the steering a lot harder to keep the car positioned.