1LikesHow tires scrub setting on 1/8 car works? HELP
12-18-2010, 02:43 PM
#1
How tires scrub setting on 1/8 car works? HELP
how are the tires scrub works on the 1/8 scale cars?
which setting give more scrub?
-more spacer on the dog-bone side or wheel side of the drive axle?
does more scrub on the front mean that the car will slow down more when making a turn around the hairpin and thus causes the rear end to 'kick out'??
which setting give more scrub?
-more spacer on the dog-bone side or wheel side of the drive axle?
does more scrub on the front mean that the car will slow down more when making a turn around the hairpin and thus causes the rear end to 'kick out'??
12-21-2010, 04:52 PM
#2
anyone help please
12-22-2010, 07:37 AM
#4
Doesn't really work like that. There is one setting that will give the least scrub, anything to either side of that will give more scrub. What that setting is depends on the offset of the wheel.
12-22-2010, 08:13 AM
#5
Are you talking about the scrub radius or just tire scrub?
The scrub radius can be adjusted with changing the offset on the wheelaxle.
As you can see in the picture the scrub radius is influenced by the wheeloffset and the location of the pivotpoints on the outer side of the wishbones. This picture is of a Mcpherson strut, for a double wishbone like we use in our modelcars the dotted line is drawn through the outer pivot points/pivot balls.
The distance between the two dotted lines is your scrub radius, so by moving your wheel more to the outside by increasing the amount of shims on the outside of the upright (or changing to +0.xx hexes on your touring car) you will increase the scrub radius.
It's pretty save to say more shims on the outside of the upright increases the amount the scrub radius.
On some cars you can also get different front uprights with a different kingpin angle to change the scrub radius.
The scrub radius can be adjusted with changing the offset on the wheelaxle.
As you can see in the picture the scrub radius is influenced by the wheeloffset and the location of the pivotpoints on the outer side of the wishbones. This picture is of a Mcpherson strut, for a double wishbone like we use in our modelcars the dotted line is drawn through the outer pivot points/pivot balls.
The distance between the two dotted lines is your scrub radius, so by moving your wheel more to the outside by increasing the amount of shims on the outside of the upright (or changing to +0.xx hexes on your touring car) you will increase the scrub radius.
It's pretty save to say more shims on the outside of the upright increases the amount the scrub radius.
On some cars you can also get different front uprights with a different kingpin angle to change the scrub radius.
12-22-2010, 08:51 AM
#6
Simple english : help the car to turn rounder
Shims on the outside ( wheel rim side ) = more grub rate = less rounder turn = feel like pushing
0 shims on the outside, ie. shims on the axle or cvd side = less grub rate = more rounder turn = quicker turn
your front tires possibly also wear faster due to excessive scrubbing.
Shims on the outside ( wheel rim side ) = more grub rate = less rounder turn = feel like pushing
0 shims on the outside, ie. shims on the axle or cvd side = less grub rate = more rounder turn = quicker turn
your front tires possibly also wear faster due to excessive scrubbing.
12-22-2010, 09:04 AM
#7
With the "kick out" with rear end, it could be a few things. Setup up of rear suspension, camber of rear end, toe-in of rearend, Diff adjustment, oversteering problem, some examples.
Scubing of tires when useing foams. Much is if you use a truer. Camber and diameter you cut them at. Customized to a track you race at. They all are different.
Good luck with it!!!
Scubing of tires when useing foams. Much is if you use a truer. Camber and diameter you cut them at. Customized to a track you race at. They all are different.
Good luck with it!!!
09-11-2021, 01:35 AM
#8
There are other geometry considerations on an RC car that have a far greater impact on handling & performance.
On a full size 1:1 car, scrub angles affect the stationary steering effort (ie - when trying to turn the steering wheel whilst parked but off the brakes) and what happens under braking, especially if braking effort to the wheels become unequal.
Negative scrub angles cause a toe-in force and are usually considered safer, as when one of the cars wheels travels through a puddle under braking (resulting in reduced traction/aquaplaning/braking effort) the car's tendancy is to veer away from the puddle. With positive scrub, the reverse is true, as the geometry induces a toe-out force.
With RC cars, there isn't a human holding onto the steering wheel - there's a servo via a servo saver. It's ability to hold it's centre, torque and speed will determine steering accuracy.
Scrub Angles Explained
I've seen some pretty interesting videos on the subject in relation to RC cars, but I genuinely think that the effects are less relevant, due not only to the fact that our steering is electronically controlled via digital servos, but also because our car's control arms/suspension etc are much more robustly constructed due to scaling.
On a full size 1:1 car, scrub angles affect the stationary steering effort (ie - when trying to turn the steering wheel whilst parked but off the brakes) and what happens under braking, especially if braking effort to the wheels become unequal.
Negative scrub angles cause a toe-in force and are usually considered safer, as when one of the cars wheels travels through a puddle under braking (resulting in reduced traction/aquaplaning/braking effort) the car's tendancy is to veer away from the puddle. With positive scrub, the reverse is true, as the geometry induces a toe-out force.
With RC cars, there isn't a human holding onto the steering wheel - there's a servo via a servo saver. It's ability to hold it's centre, torque and speed will determine steering accuracy.
Scrub Angles Explained
I've seen some pretty interesting videos on the subject in relation to RC cars, but I genuinely think that the effects are less relevant, due not only to the fact that our steering is electronically controlled via digital servos, but also because our car's control arms/suspension etc are much more robustly constructed due to scaling.
Last edited by Horatio; 09-11-2021 at 02:18 AM.
09-11-2021, 09:58 PM
#9
Simple english : help the car to turn rounder
Shims on the outside ( wheel rim side ) = more grub rate = less rounder turn = feel like pushing
0 shims on the outside, ie. shims on the axle or cvd side = less grub rate = more rounder turn = quicker turn
your front tires possibly also wear faster due to excessive scrubbing.
Shims on the outside ( wheel rim side ) = more grub rate = less rounder turn = feel like pushing
0 shims on the outside, ie. shims on the axle or cvd side = less grub rate = more rounder turn = quicker turn
your front tires possibly also wear faster due to excessive scrubbing.
09-12-2021, 02:53 AM
#10
Scrub radius will make little to no difference to your RC tyres' wear rate - unless of course you spend all of your time competing in parallel parking! 
Ackerman, camber, castor, toe etc will all have a much more profound effect on both handling/tyre wear rates and in most cases is far more readily adjustable by the user.
Ackerman, camber, castor, toe etc will all have a much more profound effect on both handling/tyre wear rates and in most cases is far more readily adjustable by the user.
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