# Truing up tires



## yellerstang (Feb 20, 2012)

Hey all, just wondered what you are using to accurately true up tires. I race mostly stock class Tjet based cars and a few AFX based cars for drags and road racing.

Various grades of sandpaper on something firm, like Plexiglass works ok, but, I am looking for a more accurate way to do this.

On any of these cars, I normally try to find the best hubs, true them up, glue the tires on the hub, and then true them up. Works great with rear tires, on the car. Front tires? Gotta pull them, mount them on a rear axle, same process, then move them back to the front.

Im looking for a better, repeatable way to do this where I can get the same tire size time after time.

Whats out there? Thanks.


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## Rich Dumas (Sep 3, 2008)

If you use aftermarket CNC machined wheels and tires that are made in CNC machined molds everything should run true. Normally I don't have to true tires and wheels, but I sometimes have to turn down tires. I use two techniques to do that. In some cases I put the wheel/tire on an axle and chuck that up in a drill press. I have a vise for the drill press that has machined surfaces that are parallel to the tire tread. I can put an emery board against the side of the vise to keep it square while I sand. Another thing that I have done is to use a commutator truing machine as a tire truer.
I put three wheels on a drill blank, the drive belt of the truer goes over the 3rd wheel and I can do two tires at once. With the drill press I have to check the tire diameter with a gauge after each pass. The commutator machine has markings on the adjusting knob, once I know the diameter is correct for one tire I can just go back to the same mark when I do the next tire.


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## yellerstang (Feb 20, 2012)

*Truing*

Ok, what arm truing machine do you have, I would like to see one.

Because we run bone stock racing classes, we are running the wobbly Aurora single flanged wheels and ribbed skinny tjet type tires.

I have been running double flanged set up for years and yes they are much better than stock. Our goal is to have fun with vintage cars without spending more on the cars.

I dont have a drill press, but do need one. Finding something with a decent chuck can be an issue. Most do not run true enough for this application.

I am looking to have repeatable close tolerances with little runout.y


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## Boosted-Z71 (Nov 26, 2007)

Look up Hudy, they make machines for turning inline armatures as well as tire truer's. I like the tire machine as once you get it setup you can make as many tires as you want that are 100% exactly alike, I have used it for sponge, silicone, rubber etc.

I made my own shafts and modified the tire truer for use with HO scale tires, but I think now they have made a HO specific model.

Boosted


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## slotking (May 27, 2008)

the tire truer is cheaper than the com truer.

for setting up stock tires, I use a dremel


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## Rich Dumas (Sep 3, 2008)

Here is the Cobra machine that I have, it is now set up to do inline HO armatures. I used this machine because I already had it, it would not make a lot of sense to buy one just for tires.


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## toomanyhobbies (Mar 27, 2005)

yellerstang said:


> Ok, what arm truing machine do you have, I would like to see one.
> 
> Because we run bone stock racing classes, we are running the wobbly Aurora single flanged wheels and ribbed skinny tjet type tires.
> 
> ...


Proxxon makes a very good rotary tool and add on drill press stand. Puts dremel to shame for accuracy according to ratings. I've yet to pull the trigger on one yet but the DIY pc board enthusiasts swear by this brand. It should be accurate enough for our rubber tires I would think. A bit pricier than the dremel though. 

I was thinking of trueing the mounting surface of the stock wheel first, then glue the rubber tire on and true tire after the glue has set. No chance re mounting the tire in the wrong spot this way. I really hate cockeye tires........and rims......and axles.....and gears.....whole darn t jet is cockeye


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## yellerstang (Feb 20, 2012)

*Truing*

Great info. Thanks to all.


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## Rich Dumas (Sep 3, 2008)

It does not matter that much what you use to spin the wheels/tires as long as the chuck runs true. You do need to keep your sanding media parallel to the tire tread.


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## yellerstang (Feb 20, 2012)

I mounted 1000 and 2000 grit sandpaper to a flat piece of plexiglass. Flat and smooth, works ok. Accuracy of tire size depends on me...


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## slotking (May 27, 2008)

after I get the tires where I want
I often bevel the edges a hair so that tire slides and does not hop(stutter, vibrate or whatever)


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## Boosted-Z71 (Nov 26, 2007)

One other thing that works well for tire truing is the diamond honing blocks from Harbour Freight, http://www.harborfreight.com/3-piece-2-inch-x-6-inch-diamond-hone-blocks-36799.html, 3 grit grades, they also work well for scuffing up silicone tires & they last forever.

Boosted


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## yellerstang (Feb 20, 2012)

Nice idea. Going for that one.


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## Bill Hall (Jan 6, 2007)

It think it should be mentioned that reviewing and verifying the "axle-out" basics is what is really important. Fractional variation between tire heights is irrelevant if your axle and hub runouts are excessive individually or in combination. Verification can be seemingly redundant; but it's actually a critical process, that can pay huge dividends. Waboed tires are merely the first step of a very important hat trick. Consider that you can mount a perfectly trued tire to a bent axle, an egghead rim, or both; and your chassis will still handle like crap. True must be verified on all the components, on all four corners.

What if you had one of each at three different corners? 

At the HO slot hobbyist level, put the micrometer away for the moment and skip all the rocket science. If you havent verified both the axles, or all four of the hubs, you really do have the cart well ahead of the horse. 

Keep it simple. Roll your axles on a piece of glass or a small mirror and verify that they roll smooth and true. Run your bare rims at low speed and so you can see if they wobble up and down, or walk side to side. (Put your readers on Grampa!) Bring them up to medium speed and put a wet finger or a plastic probe on them. If it pulses or thumps it's not true.

Anything that doesnt pass the simple tests should be tossed immediately. No exceptions.

Use a grind stone to true harder compound tires that are uncooperative to grind. Use quality sandpaper or equivalent for softer, easy to true compounds. Knock the flash off, roll the side wall, and level the contact patch. Run each tire separately so you can verify that you dont have an imbalanced tire with a heavy side or a knot/void. You'll feel the vibration. 

After the fundamental run-out inspections are completed, then worry fractional height differences. Consider that if your chassis isnt true you might actually need that tire differential to get all four corners to touch the mirror. :tongue: 

Keep your tires clean. Lather, rinse, repeat!


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## Boosted-Z71 (Nov 26, 2007)

"Waboed tires" Bill as a wordsmith has the vocab of a Super Genius, and its all true, much can be learned from simple observation & listen to what sounds the car makes on the track. 

Of course listening is hard to do, as I generally have the stereo cranked when I run laps.

Boosted


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## yellerstang (Feb 20, 2012)

So true, wobbly crap makes wobbly crap. In my use of pure stock class tjet racing, we are forced to use the stock tjet hubs. I do my best to true them up first, then clean and glue a tjet tire to the hub. After its dry, then I true up the tire. This seems to work ok for me. The class demands stock axles as well, so yes, you have to check them out too. One more issue is the axle holes in the chassis, it all ads up.... Great info. Thanks.


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## Rich Dumas (Sep 3, 2008)

The small Aurora wheels usually run true, if you use the Truck/Hot Rod/Dune Buggy wheels it is a good idea to check those. If you are using late production T-jet chassis the tooling was shot and the axle, armature shaft and cluster gear shaft holes are usually too large, which greatly degrades performance. I have not seen a defective Aurora axle.
You might want to take a look at this tuning article: https://drive.google.com/file/d/0BzLR42NthGeCaDVSOEhLOVRybkE/view?usp=sharing
There are similar articles available for other pancake type cars.


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## Bubba 123 (Sep 10, 2010)

Rich Dumas said:


> Here is the Cobra machine that I have, it is now set up to do inline HO armatures. I used this machine because I already had it, it would not make a lot of sense to buy one just for tires.


"Mini-Lathe".. NEAT-O !!!! :thumbsup:

Bubba 123 :wave:


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