Handling Help.

[oldtimeracer]

OK so can someone please explain to me the effects of changing the front blocks (the blocks that hold the wishbone hinge pins).

It seems that all the set up sheets I have seen list an equal block front and rear (we are only talking about the front end of the car here) So if you have a "2" on the front you have a "2" on the rear.

When talking specifically about the REAR of the car the blocks are used to create toe in but what happens at the front of the car if you have unequal blocks and if you do have unequal blocks should you have wider at the front of the wishbone than at the back.

Does changing these blocks purely alter track width if the blocks are equal and wishbone toe if unequal. Is there any advantage to having toe set this way or is it a certain no!

[Mark Townsend]

Essentially it alters track width, but will also change the fulcrum point of the wishbone and assuming your shock stays in the same holes you will have a softer damping effect. The wider track will increase stability but reduce the 'sharpness' of turn in.

As for sweep, the angle of the wishbones affects the mid corner phase of steering. More sweep = more steering mid corner. Most racers use C-C or D-C (wider front) on the 416 with the narrow wishbones.

[oldtimeracer]

Thanks Mark.

So is it always better to run parrallel front blocks? The AVID is set up with a 2.5 front and a 2 rear. That was why I was asking as it seems at odds with other set ups I have seen.

[oldtimeracer]

The other thing I forgot to ask is .....


does the height of those blocks from the chassis make any significant difference. Assuming the spacers underneath are equal of course.

[Simon Crabb]

I'll let Mark answer properly, but it seems that the favoured settings are parallel, or wider at the front - giving some wishbone 'back sweep'.

Spacers under the blocks change the roll center height, so a spacer under, a higher roll centre. You can put different spacers under the rear-most or fore-most block for anti-dive or kickup respectively.

[Mark Townsend]

As with all things it's down to driving style and there is no 'best' way to do it. Try it as is and if you have spare 2` blocks go parallel and try that. Don't forget you will also be altering wheelbase, toe and ackerman very slightly so you may need to reset them before launching off.

Anti dive means the wishbones effectively point towards the floor at the front of the car. This will act by reducing your castor (quicker turn in) but will slow down the weight transfer to the front of the car under braking. Might be worth giving it a try if you're twitchy under braking. Kick up will help you ride the Bashley moguls a lot easier but will reduce initial turn in.

Suck it and see.

[oldtimeracer]

Will have to experiment.

I thought kick up increased caster and camber therefore giving more front grip as front tyre contact area will be greater or does that depend on what camber settings you start with?

Might try a bit of kick up and see how it affects it.

[Mark Townsend]

Increased castor reduces initial turn in but allows increased mid corner grip due to the way the wheel angle changes as the car rolls into the corner. The camber changes more to the negative than positive angle. It's the reverse principal to a castor wheel. The greater the angle of castor, the more the trailing wheel will be wanting to go straight. Unless you have a Sainsbury's shopping trolley!

Try this. Hold a wheel or CD between your thumb and forefinger held vertically, and the CD at 90`. Then rotate the CD as if it was a steering block. When castor is 0` (vertical) you'll see no camber change as you rotate the positions of your fingers towards vertical, you'll see a massive increase in negative camber as you turn.

While this demo doesn't take into account the suspension compression or static camber, you can see the effect of castor on the wheel.

Hope that helps.

Mark

[Simon Crabb]

It's worth remembering that using kick-up or anti-dive on the front results in a compound change, there are several things changing at once. Roll centre, castor, compression 'resistance' are all affected, at least, maybe more things!

I recently tried some kickup, and it didn't work. But, it might have had a different effect if I had kicked up, but also reduced the castor back to closer to what it was before I kicked up with a different castor block. Complicated, certainly confused me!

[oldtimeracer]

Yep. Everything is tied together. Do one thing and it surely affect something else. I suppose the trick is knowing firstly what you are trying to achieve and then what will happen when you take a certain action. Trial and error a bit for me. I want to try all these things and see what the effects are so I know for the future.

Dont suppose for a moment it will help me but seems like the right thing to do. ;D

[TryHard]

Ok, Arm sweep helps give mid-corner and exit steering. It's a tough one to explain, but works by stabilising the camber change on the front of the car as it rolls. More arm sweep will give slightly less initial steering, but makes the car transition better through the rest of the turn...at least thats how I understand it!
What it also does for certain is shorten the front wheelbase slightly, as the wheels are swept back. Obviously, this can be compensated for by changing the wheelbase shims (hence why the kit setup on a 416 is 2.5mm behind the arm with 0.5° of sweep, and most of the team drivers only use 2mm with parallel arms).

And your right about how everything interacts... an example I'll use it that recently I was struggling a little for mid corner steering. With the bumps bashley has, kick-up was certainly the way to go, but by increasing the castor, whilst giving more mid corner, I had now lost some initial steering. To rectify this, I dropped the front roll centre, by changing how the blocks were mounted (originally had a 0.5mm shim under the front block, switched to removing 0.5mm from under the rear block). This still gave the same amount of kick-up (good for bumps), same amount of castor (good for mid corner), but now also improved the initial tun-in as the front rc was lower...

One word of warning.. if you do alter the block heights, don't forget to reset your droop!!

HiH
Ed

[Simon Crabb]

How does one remove 0.5mm from below the rear block?

[Mark Townsend]

Aah Ed is talking about the 416 blocks which are flipped versions of your MSXX bridge block. You could try a standard 1A block flipped over and use 2.5mm spacers to achieve the same as Ed or raise the front by an extra 0.5mm.

[Simon Crabb]

Ahh, there's a standard 1A and a bridge 1A in MSXXland? I need to find a block set.

[TryHard]

actually simon, your best bet is to get hold of a 416 A block, flip it, and use that. Mount it with 2.5mm, rather than 3mm of shims. Simple really.
The standard flat blocks mean you can't lower them anymore... one more advantage of the 416

[Simon Crabb]

What if I wanted to go D-C on the MSXX, would that work in the same way it does on the 416?

[TryHard]

Certainly would. However, I always found the 415 better outdoors with the narrower front blocks, and a little bit of sweep... however, the 416 seems to prefer the wider option.

[Simon Crabb]

Ahh, right, I'll stay narrow then, and maybe try and upside down A on the front-back sometime.

[samuraiblade]

heres something i found which is useful for new peeps regarding setups

crcc.org.uk/rc-technical.php