Tyre additive to balance grip front to rear?

[ThunderDragonCy 7877]

Been struggling a bit to get my RR-03RA power oversteer under control. After trying a bunch of setups i am fairly sure i can't do anything else with that. Tried some different tyres, but struggling to find anything with different compound front to rear. I think i just need a stickier rear tyre for this rwd car. I can't find or fit a wider one as HPI seem to be the only option there and they are in a state of flux right now and stock is not available in the uk. I tried some tamiya 50810 semi slivks yesterday expecting more grip than my rally blocks and they were considerably worse. Pretty much undriveable on the fairly grippy asphalt on my street. I am only running a race spec 27t brushed, so it's not mental power. 

So, with the background there, would getting additive and putting it on the rear tamiya tyres sort this out? Or maybe going to racibg slicks? If so, can someone explain how additive works, something to get? Or some good slicks? I see Sorex are used at the local asphalt race track with a load of different numbers. What do they mean in practice? Hoping @qatmix or @GooneyBird and @svenb or some of you other on road racers will come to my rescue! 

[Mad Ax 9312]

What sort of terrain are you intending to run on?  Are rally blocks the right tyre for asphalt?  Is the asphalt in your street as smooth and rubber-coated as the asphalt at the local track?

I'm not a tyre expert, but I'd imagine if you're intending to run on rallying surfaces (gravel and loose dirt) then you'd want a chunky rally block tyre and expect some tail-happy action.  You don't have the track width, suspension travel or big shocks that a RWD buggy has to tame its rear end.

If you're intending to run on smooth tarmac then you'll probably want a grippy tarmac tyre.  I'm sure the racers will have advice.  In my limited experience it's not unusual to put additive on one axle only, or even on one part of a tyre.  Last time I raced on tarmac (a dog-slow TL01LA with a Cup Racer motor and old Sorex tyres) I was liberally applying tarmac additive to all four tyres for practice and the first heats, by round 3 I was only saucing the insides of the tyres due to grip roll from a rubbering-in track and increasing temperatures, by the final I only sauced the rears to aid traction out of corners but left the fronts bare to reduce grip-roll in the hairpins.

I'm by no means a skilled racer or tyre enthusiast but I'd say if it works, it works

If you aren't competing then have you considered a gyro?

[ThunderDragonCy 7877]

1 hour ago, Mad Ax said:

What sort of terrain are you intending to run on?  Are rally blocks the right tyre for asphalt?  Is the asphalt in your street as smooth and rubber-coated as the asphalt at the local track?

I'm not a tyre expert, but I'd imagine if you're intending to run on rallying surfaces (gravel and loose dirt) then you'd want a chunky rally block tyre and expect some tail-happy action.  You don't have the track width, suspension travel or big shocks that a RWD buggy has to tame its rear end.

If you're intending to run on smooth tarmac then you'll probably want a grippy tarmac tyre.  I'm sure the racers will have advice.  In my limited experience it's not unusual to put additive on one axle only, or even on one part of a tyre.  Last time I raced on tarmac (a dog-slow TL01LA with a Cup Racer motor and old Sorex tyres) I was liberally applying tarmac additive to all four tyres for practice and the first heats, by round 3 I was only saucing the insides of the tyres due to grip roll from a rubbering-in track and increasing temperatures, by the final I only sauced the rears to aid traction out of corners but left the fronts bare to reduce grip-roll in the hairpins.

I'm by no means a skilled racer or tyre enthusiast but I'd say if it works, it works

If you aren't competing then have you considered a gyro?

I am not competing with RS200 at all. Its a converted TRF201 so i doubt it meets any class rules! The original setup was effectively a short arm buggy under a TC shell, but i use it mostly on the street outside my house so it have shortened the travel a little and lowered it a little to suit. It's still running about 10mm ground clearance, as it has to get over drain lids and driveway kerbs and the like. It's quite a course surface as its just that resealing job done rather than full resurface. The chunky rally blocks (not tamiya, off ebay and really quite soft) were pretty good, but the rears are already worn out and now i am street running i thought something more slivk would be better. How wrong can you be?!!

Generally the car is good, but it just really struggles to put the power down cleanly. On a buggy i would simply go to the next more aggressive rear tyre pattern, but i don't know what the equivalent is here. Sounds like some additive might be the easiest solution. Any recommendations? Brand? Quantity? Does a sauced tyre stay sauced as it were? Or is it more juice every time you run it? 

[nbTMM 433]

The soft ebay rally blocks are one of the best tyres for dusty on road conditions that I've found. When they do let go they are predictable (granted my cars are 4wd) which makes them fun to drive. Slicks can perform better but only if it's hot and sunny (>30c road temp) and not too dusty otherwise they get covered in dust and spin. The combination of the rally blocks deep tread and small contact area seems to effectively keep the blocks clean so they maintain traction.

I've also tried these which had more traction than the rally blocks but the included foams weren't big and/or stiff enough so the sidewalls folded over easily making the car a handful on-road. Unbeatable on grass/gravel/dirt though.
https://www.ebay.com.au/itm/4P-U-Pattern-Rubber-Tyre-Tires-10-Spoke-Wheel-Rim-for-RC1-10-On-road-Rally-Car/253705704439?hash=item3b1209d3f7:g:IisAAOSwjlBcwZyi&frcectupt=true

These are another type I've wanted to try but am waiting to wear out the tyres I've got first.
https://www.ebay.com.au/itm/4pcs-RC-1-10-Racing-Off-Road-Car-Tires-Rubber-Tyre-Wheel-Rim-75mm-RC-Model-Part/333162105121?hash=item4d92024921:g:cesAAOSwdqFcuEgW&frcectupt=true

Both of the above probably need 26-30mm wide wheels. I put the former on 24mm tamiya wheels which definitely contributed to the sidewalls folding.

[Mad Ax 9312]

It's possible that the rough surface of the road is preventing a slick tyre from getting a good enough contact patch to work properly, but your rally blocks are able to dig down into the roughness and find purchase.  It's a different way of finding grip.  However the hard, rough surface will abrade the rally blocks away quickly - as you've found.  I doubt many aggressive buggy tyres would last long either, although you could look around for some pinspikes that will fit on 1.9s if you wanted to try that route.

As for additives, there's a whole different range out there.  I've always used Nosram Carpet Additive when running indoors because that's what my local club sold, so when I went racing outdoors this year I bought some Nosram Asphalt Additive.  I was probably the only one using Nosram brand but I saw lots of different brands on the pit tables that day.

Each will have instructions on the pack which are a good place to start, but generally you apply the additive to clean rubber, leave it for 15-20 minutes to soak in, then wipe it off before you drive.  It should soften up the rubber and give it a slightly sticky feel.  If your tyres are dirty from previously running then you can use a coating of additive to clean them (it seems to work like a solvent), then sauce them up a second time and leave them for 15-20 mins.  During a race day the general approach is back from a heat, clean and check the car, sauce the tyres, then 10 mins before the next heat, wipe off the sauce so the tyres are nice and dry and sticky for the grid.

You don't have to sauce a tyre after the last run but some people "pickle" there tyres - add sauce then put them in a nappy sack.  I'm not really sure if there are additional benefits and/or risks of this method.  But the top racers used to arrive at the club with their tyres "wrapped in clingfilm to keep them clean" back in the days when additive was banned...

[svenb 3775]

Not an expert on tyres just have a bit of experience with rwd chassis's mainly the M04. I tried same compound front and rear but it just over steered even on the straights. 

Sorex 22' on the rear and 32's on the front is the best I found, higher number on the front it under steered lower over steer. 

Lower the number the gripper they are but only will wear out fairly quickly. Higher numbers work well on high grip carpet. 

I raced on dusty concrete so went for soft compound 22/32 if I went on carpet probably 28/36.

Temperature affects the grip too, lower temps lower numbers. 

There are more experts on here than me but that's my experience. 

I have a f103gt I need to try next! 

[Juls1 1661]

If your intending to go slicks, try some Tamiya Type A belted on the rear and Tamiya Type B up front. It won’t really matter if you go 24mm or 26mm but the old style 26mm have a taller wall to protect the wheel for street bashing. Both are particularly sticky tyres. 

Those semi slick tyres from Tamiya are made from probably the least grippy compound Tamiya makes. Not much better than drift tyres in my experience. 

53293 is 26mm tire type A

53294 is 26mm tire type B

53433 is 24mm tire type A

53482 is 24mm tire type B

i suggest obtaining moulded inserts as well as regular foams won’t hold up the soft rubber very well. 

53435 hard insert 24mm

or 53582 medium 24mm

i think Tamiya 26mm moulded inserts are discontinued. I know HPI fit well, but most 26mm inserts should fit ok. 

If you go the 26mm route be prepared to cough and splutter at the price...

 

 

 

[speedy_w_beans 4272]

If you want to experiment a little, lighter fluid or kerosene can be used to soften tires and add some traction.  These substances are typically banned at tracks for safety and odor reasons, but if you're just playing in front of the house there's nothing wrong with giving these common fluids a try.  I do think the porous nature of street asphalt doesn't lend itself well to slick tires; HPI X-Patterns were rated pretty highly for street bashing when they were produced.  Something with a tread pattern, softened with some lighter fluid, might give you what you're after.

Don't forget to give a gyro a try for the steering.  I found it nearly doubled the perceived rear end grip on my RM01 chassis when I was experimenting with different tires.  The gyro catches the rear end stepping out much faster than you can remotely.

[Mad Ax 9312]

18 hours ago, speedy_w_beans said:

Don't forget to give a gyro a try for the steering.  I found it nearly doubled the perceived rear end grip on my RM01 chassis when I was experimenting with different tires.  The gyro catches the rear end stepping out much faster than you can remotely.

My new Turnigy GT5 radio has a built-in gyro in the receiver.  I bought it specifically for RWD drifting but was interested in using it on some other RWD vehicles too, just to see how well it works.

I wasn't convinced it worked properly - it can be seen working but any steering input immediately overrides the gyro (regardless of the mixing settings :facepalm: ) meaning a nice smooth drift is immediately destroyed if I give just a tiny bit of lock in the direction of the turn.  This week I bought a standalone Turnigy gyro to see if that would be different but (testing it briefly in the garage) it seems to be exactly the same.

[ThunderDragonCy 7877]

25 minutes ago, Mad Ax said:

My new Turnigy GT5 radio has a built-in gyro in the receiver.  I bought it specifically for RWD drifting but was interested in using it on some other RWD vehicles too, just to see how well it works.

I wasn't convinced it worked properly - it can be seen working but any steering input immediately overrides the gyro (regardless of the mixing settings :facepalm: ) meaning a nice smooth drift is immediately destroyed if I give just a tiny bit of lock in the direction of the turn.  This week I bought a standalone Turnigy gyro to see if that would be different but (testing it briefly in the garage) it seems to be exactly the same.

 

18 hours ago, speedy_w_beans said:

If you want to experiment a little, lighter fluid or kerosene can be used to soften tires and add some traction.  These substances are typically banned at tracks for safety and odor reasons, but if you're just playing in front of the house there's nothing wrong with giving these common fluids a try.  I do think the porous nature of street asphalt doesn't lend itself well to slick tires; HPI X-Patterns were rated pretty highly for street bashing when they were produced.  Something with a tread pattern, softened with some lighter fluid, might give you what you're after.

Don't forget to give a gyro a try for the steering.  I found it nearly doubled the perceived rear end grip on my RM01 chassis when I was experimenting with different tires.  The gyro catches the rear end stepping out much faster than you can remotely.

@speedy_w_beans Any suggestions for a gyro then? I am a total noob at those, so any advice would be appreciated. It will probably also help me if I build a RWD setup on the TA06 I have on its way!

[speedy_w_beans 4272]

Interesting.  This is the gyro I used:  https://hobbyking.com/de_de/trackstar-d-spec-drift-gyro-v2.html

Initially I just used the trimpot on the front panel to set the gain, but later found it convenient to use a third channel with EPA instead.

I noticed the gyro worked best with fast servos; the 0.2 second transit specs of cheap standard servos means there is a lot of delay and therefore instability, so the gain has to be kept low.  If you use a fast servo in the 0.05 to 0.08 second range then there is less delay and the gain can be turned up some.

Too much gain and the steering chatters while driving straight.  Not enough gain and the steering isn't compensated enough, and spinning out still happens easily.

Mounting the gyro is important.  A good isolation tape/pad prevents vibrations from the chassis affecting it.  I mounted a gyro on top of a servo once, but the noise from the servo registered with the gyro and created a nasty feedback effect.  A separate mounting location on the chassis works better.

[GooneyBird 938]

Power oversteer can be a factor of many things. What are your spring rates? Generally a softer spring will take away traction from the other end. So if you go softer on the rear or harder on the front that could balance the car.

Then there's the matter of droop. Droop is how far the arms fall when you lift the car. The best way to visualize droop is to think of the car as teeter-tottering back when you accelerate. The car pivots around the exact center as the front springs decompress and the rears compress. However, as soon as the front springs hit their max decompression weight will shift to the rear, loading the rear tires. (the pivot point moves back)

Or you could simply be overpowering the rear tires. What kind of power are you running in the car?

[ThunderDragonCy 7877]

7 minutes ago, GooneyBird said:

Power oversteer can be a factor of many things. What are your spring rates? Generally a softer spring will take away traction from the other end. So if you go softer on the rear or harder on the front that could balance the car.

Then there's the matter of droop. Droop is how far the arms fall when you lift the car. The best way to visualize droop is to think of the car as teeter-tottering back when you accelerate. The car pivots around the exact center as the front springs decompress and the rears compress. However, as soon as the front springs hit their max decompression weight will shift to the rear, loading the rear tires. (the pivot point moves back)

Or you could simply be overpowering the rear tires. What kind of power are you running in the car?

I am pretty sure i have been around the setup as far as i can. Changed springs and damper oil multiple times, but i have much stiffer fronts than rear, front anti roll bar, very little front droop due to stiff springs, 600wt front 300wt rear oil. Shifted the battery rearwards, lowered the rear roll centre, raised the front roll centre. It's only runnibg a brushed 27t stock racing motor on tble02s and 2s lipo. Nothing mad. FDR is 8.9. Tried a lower 7.2 FDR, but didn't really help and made the motor very hot.