NSR Rubber Radius Chunking

[cj74]

I'm steadily making progress with truing NSR rubber. One of the more frustrating aspects lately is a small amount of "chunking" when adding a radius to the sides. Anyone have tips or tricks on how to lessen this effect? Feel free to provide any other tips as well. If this becomes a wider discussion I can change the topic name.

Thanks in advance!

[Mitch58]

I've done the same thing. Try using a lighter touch or a finer grit, that seems to help.

[Impulse-ive]

Which rubber are you using? Super grip or Ultra? I find ultra chunks more and the tire fall off faster while racing. Supergrip lays rubber down on the track surface as well. if your using super try going slower so that the tire don't heat up as much.

[cj74]

Thanks for the quick responses. In the most recent case I'm doing supergrips. The crazy thing is 1 of 4 sides had no chunking with the same speed/technique. I'm going to try slower and only using a finer grit on the next set. I started with 240 grit on these. Maybe I'll start at 400 next go 'round.

[Giddyup]

Try 600 and up for grit, I use water too to help keep the tires cool. It's a pain in the a$$ as it takes a lot longer. I progress starting with 600 and usually end at 7000 grit. One grit at a time, first dry, light touch, then with water. Once done I go back, repeat all stages but only with water with each stage - for polishing. A very tedious and time consuming process, but the results are worth it.

[cj74]

Are you talking the radius or for general trying? It must take a looooonnnngggg time to radius at 600. 😮

[Giddyup]

Cj74...yep...a very long time! Time invested in tires is well worth it though.

[RichD]

Possibly your tires came from different batches, we have noticed batch to batch differences in tires in the past. The tires may have more or less grip, sand differently, respond differently to certain tire treatments or be more or less likely to degrade as time goes by.

[cj74]

Yay. Inconsistent quality. That makes it super easy to manage. 🙄

[Slotspeed]

I love them, though have noticed some batches of ultra didn't come out perfectly to shape. This was quite annoying but I kind of evened it out a bit with radiusing and even though they weren't perfect they still worked OK.

I once mixed up super and ultra on the same axle by mistake. Didn't realise for ages. Thought it was pretty funny that I didn't even notice until I had to pull the axle out one day to fix something. Running on Carrera plastic so maybe that had something to do with it. Or probably something to do with the cleanliness of my track at the time

Haven't had issues with chunking ever. But haven't bought any for probably close to 12 months.

[cj74]

Thanks for the quick responses. In the most recent case I'm doing supergrips. The crazy thing is 1 of 4 sides had no chunking with the same speed/technique. I'm going to try slower and only using a finer grit on the next set. I started with 240 grit on these. Maybe I'll start at 400 next go 'round.

Oh... I know that the time is well worth it. Just not sure the wife is convinced of that. 😂

[Audi1]

Try an emery board (light side), 3,000 rpm or thereabouts, take a little chunking on roughly a 45 degree angle to get the shape you want, then smooth out the chunking with a lighter touch on the emery board, followed by 600/1500/4000 all wet sands. Make up little profile sticks using 1.5mm plastic paddles with 3M double sided tape and the sandpaper of your choice.

[cj74]

Grabbed the double sided tape and some paddles today. Got another set to do, so we shall see...

[dungeonracer]

And they say silicone is hard to true...

[ZackM]

I use emery boards as Audi1 said in various grits. High rpm and low pressure seems to work the best for me. I don't worry about getting them super smooth however. I just them with Lighter fluid or brake clean on a paper towel with a stiff finger, takes all the high spots right off!

If they are "race" quality tires then I will usually wet sand the contact patch at 2k minimum to make sure they are perfect.

Zack

[cj74]

Good to hear that high rpm can work. I did a set earlier at high rpm and it worked okay. Think I've been scared off from the higher rpm with the talk of too much heat. Thanks for the tip.

[ZackM]

For the sidewall it works fine with light sanding, on the tread is another matter.

[cj74]

And they say silicone is hard to true...

My thought exactly.

[SpeedyNH]

ditto

[Vision34]

in our club we run nsr rubber super grip we got it down to glue and true. I use a nail file thats super fine. And I run the truer at 6v and take my time to round the edges.

[Cgyracer]

NSR rubber the contact patch and rounding the edges I true at 3 volts and watch my amperage that I’m not take too much off at a time. I also reverse my motor leads and spin in the opposite direction every other sanding adjustment.

Takes me me a while to true. I might be overdoing it most people might feel.

Rob