25 replies to this topic

[Robert BG]

I have a cheap little magnetic balancer that seems to do a decent job.But I am wondering if I should balance the whole assembly after I balance each part separately?

 

I seem to recall someone on here made a balancer for arms from razor blades.I think it was John but I cant seem to find it,but maybe that would work to balance the whole rotating assembly.

 

Also while posting what are your thoughts on lightening things like gears?I've done it for years off and on with no real negative affects.But its a bit fidly and I usually wonder if its worth it.

 

Thanks

[MattD]

In the 60's there was an arm balancer made and sold for slot cars.   It was 2 razor blades that sat in a plastic holder.   I always wondered how many guys thought  they should check and see if the table they worked on was level before they used it.

[Eddie Fleming]

I am thinking if you take let us say a plastic gear and drill it full of holes and run it on a car. Then you replace the gear with a stock one would you see any difference in lap times? I doubt it.

 

There are bigger gains to be made than filling a gear full of holes. But then attention to the details is huge in racing.

[Bill from NH]

In the 60's, there was also the Rand arm balancer. It had an aluminum "U" base & two razor-like blades. I recall using mine to check the balance of a French armature in 1967. I don't recall using it since.

[gotboostedvr6]

Balancing tires is worth while. Gears not so much.

There are also a crapload of variables you need to consider when building a balancer.

[raisin27]

I agree that if you do a little thing like lightening your gear the difference will probably not be noticeable. However if you do ten little things that by themselves would not make a noticeable difference you will begin to see results when the small improvements are combined.

[Robert BG]

Eddie,just so you know I'm not running sealed motors in 100 gram cars here.We're talking group 12's up to cobalt euro's and 27's where a few hundredths is a big difference at times.

 

Dave why do you say the tires and not gears?Depending on who made the gears . The gears tend to be more out of balance than  a trued tire on my Cahoza (I think) balancer.

[James Wendel]

My experience has been that the greatest imbalance in the wheel/tire combo is caused by the set screw.

[gotboostedvr6]

If your gears need to be balanced then you should be gluing them and use aluminum setscrews. That would eliminate most imbalance in the spur.

[James Wendel]

aluminum setscrews ??

[Benno - SAC]

Hey Racers,
 
I build a simple magnetic balancer, wich works really great.

 

 
https://m.youtube.co...e&v=TkTeXcoQH-g
 
On the left you see a small ball (4 or 5 mm) I took from an old ball bearing. Behind it, in the left arm of the U-shape aluminium, there are two neodym magnets in the same bore hole.
On the rigth side you see the screw, where I also attached a neo mag.
 
When I'm going to balance an arm, I put it in my com truer and grind a small but spiky tip on the com side of the shaft with my dremel. This tip will be attached to the ball side magnet, as you can see in the video.
 
Then I screw the screw side magnet as near as possible to the shaft without the arm jumping to the screw side. And voila, if you push the arm it looks like in the video.
 
With tires and gears it works the same, I prepared an axle with the tip wich you can see taped to the bottom auf the U-shape (just for not loosing it).
 
I also found out, the set screws beeing the greatest imbalance. I grind them as short as possible.

[Samiam]

Nice work Benno. 

[dalek]

I also found out, the set screws beeing the greatest imbalance. I grind them as short as possible.

 

I've been balancing my wheels and gears for many months.

 

I grind about .030" off of 1/8" setscrews (the allen wrench end).

 

I glue pieces of .032" solder inside wheels to balance them. 

 

One time I checked how much less solder I had to use when I shortened a setscrew and it was 8 mm less (hub diameter will cause this to vary).

 

When I balance a gear, I drill 1/16" holes in it.  It typically requires about two holes all of the way through, and one hole part way through.

[Kim Lander]

Benno....do you make and sell the balancer?

[Steve Boggs]

I made a balancer like that back in '96. Still have it.

 

The set screw is the biggest problem on gears and tires. Shortest answer is to use hollow set screws on flatted axles. That's as close to balanced as you can get without balancing equipment.  By the time you shorten set screws enough to balance right, you have ground enough off to make them hollow. Hollow set screws are worthless without a flatted axle. They will NOT stay tight no matter what you do to them. You will ruin a wheel trying to prove otherwise.

 

I balance them by grinding a small amount off the hub with a dremel at the heavy spot obviously, which is always near the set screw. Balancing them individually is sufficient. Balancing them all at the same time doesn't seem to make any difference. "Clocking" them made sense when they were all out of balance, but once that's done, it's ready to go.

[Benno - SAC]

Hi Kim,

 

no I don't sell it. I made a simple drawing and the trainees of the company I'm working at, milled it for me.

But one can also easily cut it from wood or screw it together from three rods of any kind of non magnetic material.

 

At the beginning I thougt, it would be important that everything is true and rectangular. But I found out it is not.

The most important thing is that the tips on the axles and shafts are centered as good as possible. And to keep the tip and the ball clean and free from burrs. I use adhesive tape for that.

 

I also just use adhesive tape to balance the rims or tires. But I found out, that after grinding down the set screw the greatest imbalance is compensated and further balancing is not as important.

[Benno - SAC]

They will NOT stay tight no matter what you do to them. You will ruin a wheel trying to prove otherwise.

 
I grind down many hollow set screws right now, use them always on round axles and didn't have any problems so far.

[dalek]

Below is a pic of my "poor man's" balancer.

 

If you're interested in the details of how I balance wheels and gears, click here to see a video I made.

 

 

[SpeedyNH]

nice.

[Robert BG]

The balancers I have are like the one Benno made.The first one I got from Tracy and I wasnt too happy with it so I got the second from either Cahoza or Dubick (sp?).While its much nicer the cheaper one from Tracy/Go Fast honestly does just fine.

 

I really like Dale's bit of kit too and I'm going to give it a go.I know its not really needed but I think I can make one to check the whole rear assembly.

 

I've got one gear just drilled for balance,one drilled to lighten and one where I took some of the hub and also drilled it.I'm, going to test them out pretty soon with drilled hubs and drilled/waffled wheels and see what happens.

 

No matter what I'll still balance them because beside possibly being a tick faster I've found they handle better without the vibration.

 

As far as adding weight,I liked Dales colar idea but lately I've just been using JB quick as weight or sometimes to hold a tiny solder ball.I try to take off as much as i can before adding anything.It takes longer and is fiddly but it's how I try to do it.

 

Also if anyone is interested I've got some titanium set screws coming,I dont know how they'll work out but I'll pass it along and the can screws I got from there have been great.........I know its not needed but I have a friend that works for Uncle Sam and he's able to find all sorts of oddball stuff.

[Phil Smith]

I don't think I've ever raced with anyone that balanced their gears and tires. Raced with 3 Nats winners and as far as I know they didn't. What kind of racing are you guys doing?

[zipper]

There were some Koford tires for Opens that were hugely out of balance due to probably uneven layer of glue in the perforated rims. And on G7 speed it really did matter! No grip and rumbling sound. Luckily I got just 10 pairs of them.

[Robert BG]

I don't think I've ever raced with anyone that balanced their gears and tires. Raced with 3 Nats winners and as far as I know they didn't. What kind of racing are you guys doing?

Most of the guys I know running 27 Lite these days are running balanced gears bonded to the axle from Hahn or do their own.Tires it's harder to tell who is and isnt because it takes so little to get them to balance at times.But I know a few guys from Skidmarks who do and a few at PJ too.

 

If they're truing tires at the race then chances are they arent but if they have a rack ready to roll I'd be willing to bet money they at least checked them.

[MSwiss]

I don't think I've ever raced with anyone that balanced their gears and tires. Raced with 3 Nats winners and as far as I know they didn't. What kind of racing are you guys doing?

Back in that era, the tires didn't stay together well enough to bother.

We were changing tires sometimes, every heat.

I remember finishing a heat, and there wasn't rubber around the whole circumference of the wheel.

The car was still going around pretty good.

Other than my qualifying axle / gear combo, I didn't balance anything.

That time was better spent regluing my back magnet(s) in.

Running with all your magnets, was way more important, than running with balanced components that might have a 5 minute, or less, existence in your car.

[Robert BG]

Mike, things really have come a long ways.I look at what I used to need to run in the 90's and today and its no wonder I was broke back then.Granted I'm still getting up to speed (I build my own gear) but I can run 2 sets of tires on 12's and 15's at PJ and 2-3 in 27's. I can run 2 races with just 2-4 I-15 motors there if i want(OM15&Pro15). Where years ago I'd need a dozen mills just to think about heading up there not to mention tires. I've even been known to get more than a race from a set of tires if its just for fun/practice these days.

 

It's funny but I don't recall trueing tires much if ever back then,I just had a little Koford trimmer to narrow them down and off i went.They just chunked off like crazy.But with how they hold up these days I feel its worth doing.