Martin Crisp

Good to hear you like that approach

In terms of timing...I think something like 6 to 12 months. It will be done in my spare time when not running my software company

corallyman

iTrader: (101)

Very good Martin. That sounds great!

EDWARD2003

iTrader: (8)

"I also prefer the smoother feel the car has with a lower roll center...it is less edgy....but can be a bit too lazy and also can have the chassis rub the driving surface."

Thanks for your lengthy yet well written input Martin.

How would you go about preventing the car from being "lazy and generating chassis scrub"? Add rebound dampening? The book mentions that "rebound damping helps control the transitional roll when entering a corner." Is this true?

How much rebound should one use on different surfaces? i.e carpet and or asphalt?

Martin Crisp

Yes...going with thicker oil, smaller holes or less holes can help reduce laziness in chicanes.. however it makes it worse in normal corners, because the car rolls slower.

Going a little stiffer on the swaybars will help reduce overall roll and thus reduce some laziness....but you will loose some lateral grip with the stiffer swaybars.

Going up on the spring rate is also an option.

In terms of how much rebound for the different surfaces....

First, I don't like to run any rebound in my shocks...ever. The purpose of the shock is to slow down the speed of the spring.... both during the compression of the spring (ie. bump) and the extending of the spring (i.e. rebound). So if you build your shocks where the shock shaft comes out on it's own after you press it into the shock cynlinder, then in my opinion you are not building your shocks correctly.

Having clarified that, lets talk about how much dampening you will want for the different surfaces. where more dampening will slow down the spring compression and rebound. The reality is there is no simple answer for this. One might think that for low grip tracks you want less dampining and for high grip tracks you want more dampening. However if you take this too far having too much dampening on high grip tracks will cause a traction roll because it is not allowing the car to roll into the carpet fast enough before it pole vaults over the outside wheels.

Also you don't want to go too thin on the oil or make the holes to big or plentiful so that you have too little dampening as that will make the car very twitchy, because it transitions too fast.

One thing to keep in mind is how bumpy the surface is. the more irregularities or bumps on the surface the lighter the dampening you will want.

Also another thing to think through is how the hole size affects the high speed bump v.s. the low speed bump. For example a thin oil with small holes tends to have a lot more dampening on a high speed bump than a thicker oil with larger holes.

rc car guy

Hey Martin, I have a question about what sweep does? What does it do haha... and how come its not mentioned in your chassis settings explained portion of your app?

On another note you mention the angle of the camber link, and how the more it leans downward on the inside the more camber gain you have. Which is also roll center, say you want more steering, you want to adjust this by more camber gain, or raising your front roll center on the shock tower... a problem then occurs yes? you cannot raise the roll center on the tower and increase camber gain is that correct?

j.d.roost

iTrader: (32)

I would like some thoughts on arm sweep as well.

Also rear inboard vs outboard toe ( angled outer hubs vs inner pin angle). Have you played around with offsetting inner pin angle with +.50 or 1 degree outer hubs?

theproffesor

iTrader: (66)

While I dont know all the dynamics involved, when you change rear toe inboard vs outboard (hub) it has a greater affect on wheel base. Example 3 deg rear toe from inboard will have a shorter wheel base than 2 deg rear toe from inboard. Also changing toe from inner hinge pin block vs outboard blocks will have a different affect on track width. Using inboard narrows car, using outboard widens. Most manufactues offer both in multiple degrees to narrow or widen car on purpose.

Atechbh

iTrader: (5)

What is the best thing to do when car works perfect for first 2 heats and then starts traction
Rolling in 3rd with no Change to chassis. Using full tire sauce as recommended on here. Switched to no tire sauce in main but seemed to lose too much traction

rc car guy

Well you could raise your inner roll center on the tower 1mm all the way around to give you less camber gain or lower your entire camber link 1mm if thats possible but still keeping it level ish not to increaee camber gain but still lowering your roll centeror adjust your sway bar mounts so that theres a smaller distance between the mounting point and the pivot point or increases sway bar size all the way around just some small things also you could decrease your camber by -.5 to give it less and you could also take like .2mm over ride height of droop out of the front and rear to allow it to roll a hair more but that might be a slightly lsrger change than the others

Skiddins

Fit softer springs all round to maintain the balance

san.

iTrader: (61)

Only go with softer springs if you're flipping it during mid cornering. If you're flipping as soon as the wheels turn direction, then go with thicker shock oil. I usually increase my oil from 400cst to 550cst during the last rounds if we have a huge turn out. Mind you, I keep the same springs on (HPI Silver Front, HPI Blue Rear) the whole day.

Even simpler, try dialing down your Steering Dual Rate or don't steer lock to lock so aggressively.

Might be a little unorthodox, but works for me.

jdeadman

iTrader: (41)

+1 Changing your dual rates is the first thing I do when the traction starts to come up. I don't usually change my oil. as I have the right mix of oil and carpet fuzz (jk lol) but sway bars can also help with rolling

theproffesor

iTrader: (66)

I was having traction rolling issues a day yesterday. I switched to stiffer swaybars on both ends and it made my issue worse. I increased droop (less downtravel) and it made it worse again. I was rolling even with barely any traction compound. I did notice I had a bit of a tweak issue going on so I am going to do a ground up rebuild on a tweak board and see if that helps some. But I know it wont get rid of the roll issue. Glad I wrote down a previous set-up that worked, but was a little loose. Go back to what I know works

bkspeedo

iTrader: (5)

If my understanding of sway-bars is correct they increase the suspension stiffness, and reduce roll. Which are to things you don't want to do when trying to fix traction rolling issues. I would suggest softer sway-bars all around but than again you may have an in-balance all ready so try one end first than the other. On that note try lowering the roll-center of the car at each end.

As for droop, go with less up-travel when measuring with car at rest with tires on. More droop will make the car want to traction roll more as the CG of the car will actual raise up slightly half way through the roll. Where reducing up-travel can lower the CG of the car as it rolls into the corner.

As a side note make sure you don't have to much camber up front or in the rear, these may have so much effect that a sway-bar and roll-center change will not be effective.

snuvet75

iTrader: (16)

How do u guys get rid of snap oversteer? It happens at the exit of corner when throttle is applied. The car understeer entering corners and after the snap oversteer.