Set up theory question
 

So I'm having trouble unstanding something with a current trend in set up theory.

Why are we now making the band aid of CAing the tires part of standard set up on a car vs using the suspension and/or choosing a harder tire? Even if it's a spec tire being used, the event could go with one that is harder.

Watching the recent trend at events from local to major, everyone CA's their tires. Some do it in a very simple way with a q-tip, others have motors, and jigs designed for different heights of CA. But in both cases, it's a constant battle to keep consistency with it. And with the latter example time consuming and expensive.

I have also noticed that the tires being used are usually on softer side. 32 or less. In addition when you look at the set up sheets for these cars, the track with is sometimes on the narrowest setting.

I'm not saying that it's not a viable and quick solution, but why not let the suspension do the work? Why not go to a 36-40 or higher tire?

I'm hoping it's a fad.

I haven't seen a tire that doesn't flip on black carpet. Some don't need as much glue, but they all flip eventually. Even on the older rug sometimes you would get into traction rolling. My opinion is that if there is danger of flipping, you should glue. This is because you are much less likely to flip with glue. You may lift a tire, but it won't go over, so you have confidence to drive harder. You could potentially make the car not flip without glue, but the car will be incredibly lazy and lacking grip. So I feel you will end up with a faster car you can drive with more confidence with glue.

I do hope someone will eventually make a tire that does not require glue for black carpet, but unfortunately I think it is going to require a re think of the wheel and/or tire bead, which will require new molds which are expensive which makes it less likely to happen

The way I think of it is the CA application process is an easy way of creating a 'clipping function' that limits the traction of the tires to match the limit of the cornering lateral g's & track width of the car. Thus maximizing the performance of the car. It is an unfortunate side effect of the mantra 'more grip is more fun'.

I'm not sure what the solution is, because no matter what the surface or carpet formulation, the racers and organizers will add traction goop up to the point of traction rolling. Then the CA fun begins.

It's kind of counter to what I had to deal with in full scale racing, where if you exceeded the limit going into a corner you slid instead of flipping. The correction is to reduce veloctiy enough to prevent the slide from occuring so you stayed at the optimum slip angles and maximum cornering force of the tires, which is also the correction at the RC level. Except that the RC traction roll happens SO much faster and it takes cat-like reflexes, some CA, and a little luck to keep from traction rolling. Is that more fun? It depends.

It'll be interesting to see if the tire manufacturers can come up with a tire construction that reduces or eliminates the need for CA on the sidewalls and still has good performance and feel right up to the maximum cornering capability of the car.

Mark

easy and quick fix other words laziness lol , i have done it

But it's also effective at doing what needs to be done. Trying to do the same thing using the car's setup is extremely complex and as Mike Gee pointed out, results in a lazy car. And as the grip comes up, you'd have to constantly be chasing the setup to deal with it.

I'm not a fan of it either, as I find sudden, violent traction rolling very annoying. The penalty for 1 mph too much corner entry speed is too severe IMHO but it's part of the game and I accept that. The CA fix helps deal with it.

Mark

My view is that you won't be able to remove the need for CA on super-high-grip carpet without changing the construction of the tyres.

Compared to a full-size rubber tyre, and RC tyre is only supported by the insert (which has a large unpressurised airgap between it and the tyre, and the belt is very simple. There is no particular structure to the sidewalls (maybe the rubber is a bit thicker).

As soon as you start cornering, the tyre sidewall collapses inwards - generating a bunch of unwanted grip. I wouldn't be surprised if the collapsed sidewall actually creates a bit of a peak in the contact patch initially as well, which probably makes the grabbing worse.

CA is a very effective way of taking that part of the sidewall out of the grip equation and at taking the "edginess" out of a car.

We end up glueing the sidewalls of Mini tyres all the time on carpet, and if I race my TT-01 on carpet glueing is the best way of stopping it from rolling all the time.

I think some of the Japanese tyre manufacturers have done "special front" tyres in the past for Mins, but I have never tried them.

If you built a true radial RC tyre you might get some different results.

Spot on @sosidge!

I've made a drawing so we can have a better look at what's going on.
A1 is a 0º cambered tire with the contact patch going towards the centre of the car, as you can see it doesn't present any problem because the outer sidewall is well supported by the insert, preventing the rim to dig into the track. As sosidge said TC tires aren't well supported (at least the upper tier ones, I have cheap slicks that are really well made with open cell inserts) because that's a "cheat" where the sidewall is used as extra contact patch during cornering, with all the bad things associated with, like riding the bead. Look at this pic, the outer part is more rounded than the inner part.https://fanf1es.files.wordpress.com/...os-pirelli.jpg

A2 and A3 are extremes of camber, A2 being too much positive and A3 too much negative. Both cases would be valid, but TC tires are low profile and squarer therefore needing negative camber (rounder carcasses have more leeway about camber settings). A3 would never (theoretically) traction roll as the contact patch is smaller and the outer bead would never dig into the track.

So, which case would be better? Read the tire, if the sidewall is worn from getting under the bead then it needs more support, not glue because it's not fixing the issue at hand. If the sidewall isn't worn then it could be another setting like tire load sensitivity being high or...

Would raising your roll centre help stop rolling on the black carpet?

It would stop the car rolling but the cornering lateral forces would still roll the tire wall sideways with the same end result (car rolling over).

Like everybody said, the sidewall is too soft and we can't tune using tire pressure (not that in our situation it could work).

The current crop of tires is not that flashy either.

Bring back the foam I say.

Well I bit the bullit and CA'd the sidewalls of my tires. Didn't traction roll once yesterday. Dam!

I didn't talk about it purposely. Roll centres have a good place to be and instead of raising roll centres you should lower the CG (lower ride height or lower everything like the Awesomatix) but keep the roll centres slightly above ground (most if not all TC cars have the front roll centre underground, that's not good). That way you will have less roll, which is good in a keeping the tire from losing camber from suspension travel way but more importantly balance tire load sensitivity across all tires. By raising solely roll centre the car would be more skatey which can or cannot work, I think not because you are effectively making the suspension stiffer in roll, something you don't want when there's huge amounts of load transferred tire to tire.

Sorry if it is more technical than you wanted, got carried away :blush:

If the grip gets to a fairly high level (as it does at most US black carpet large events) raising the RC would make the issue worse. Instead of the car rolling, it will roll less and create a more violent flip. If the car is already on edge, raising the RC would make the issue more severe.

I haven't found a solution to no glue and without changes to tires/molds/etc I don't see how this could be possible. Some tracks (with the highest grip in the USA) require glue to nearly the flat spot of the tire. Fortunately, I guess, there are a lot of effective methods to gluing tires and videos to help. I agree, though, that it is certainly still a headache!

Well it is a solution to a problem that black CRC carpet brought. In the name of hauling ass each time we go race, the new carpet and tire compound gives the cars so much traction, that there is NOT a way to tune it out with suspension and stay competitive. If you try, you will have a setup that is not as fast. I have tried every wrenching technique ( roll center, shock weight, caster, camber, increase width, decrease width, increase wheel base, decrease wheel base etc ) and gluing the tires is the best option.

It is a new way to tune, and it is not going away in the foreseeable future. Now you have to learn how .045 of glue feels compared to .050 or .060

We are pushing these little cars to the absolute max of their capability.

it's a traction issue. To much traction. Convincing racers that they need less traction is a losing battle. However, I believe that is what's needed.