Drive belt tightness?

[jhellman(2) 0]

Hello,

how tight should the drive belt be?

I have one TA-03F and it makes somehow funny sound every now and then, just like the drive belt would jump a tooth. The drive belt is on moderate tight, it moves about 7-9 mm when pressed with thumb in the middle (it is quite a long belt anyhow). Is that too loose?

When does too tight drive belt cause friction? I bet there is some kind of optimal found where the tightness of belt doesn't suck too much power and on the other hand it is tight enough to not jump any teeth on either front or back.

Any advice of experienced belt drive pilots is appreciated.

best regards,

Juha

[retro 0]

For a TA-03, 7-9mm deflection doesn't sound too much. Mine has more than that with no problems, but I am using a pretty mild motor.

I would suggest you take the belt and pulleys off, and give them a thorough check. These parts can wear pretty fast, especially if your belt is slipping regularly. Often they look ok, but on closer inspection the teeth are quite rounded. In that case, a new belt and pulleys will work wonders.

If you are using a really really hot motor, then you could tighten it up a little to see if that helps, but a tight belt will increase the wear quite dramatically. If you have torque control on your esc, try turning it down a bit, or just be a bit more careful with the throttle []

[WillyChang 1814]

Tight belts do make more friction - you can easily hear the motor labouring away harder when its too tight. We'd usually set it just that it doesn't slip too often, the occasional 'prraaak!' is ok.

Also do you have balldiffs? If the balldiff in the motor's gearbox is set too loose, the belt will be asked to transfer more than 1/2 the power to the other end and is more likely to slip.

[jhellman(2) 0]

Hello,

thanks for responses, they are very useful.

I think it is just fine, since it doesn't do it too often. I didn't know that it is harmless if it jumps a teeth occasionally.

However, I'll give it a throughout checkup during the winter anyhow, I will check and change the belt and pulleys as well if needed.

The motor is just 17 turns, shouldn't be too hot. There is no ball diffs as far as I know (I bought this as used and looks pretty standard to me).

Thanks for tips,

Juha

[jacolouw 6]

Hi

The belt does not sound to be to loose, but as WC said check for wear. Another point is - doe you have bearings in the gearboxes. I found that in some non-bearinged gearboxes the bushes that carry the upper shaft (on which the belt pulleys run) get worn. Giving the system occasionaly more play than usual. Another cause for a slipping belt.

Jakes

[jhellman(2) 0]

Hello,

good point again! I will fully ballrace it during the winter. I bet there are standard plastic bearings inside that may be worn out. This may be the reason as well.

Good tips, keep them coming..

-Juha

[walawala_com 2]

I had experience with both the TA03F & TA03F TRF...not very good. I have been in R/C for 15 years, you should trust me.

The first problem - The front gear box or rear gear box for TA03R.

The diff gear(Tamiya ball diff) or the gear next to it(Tamiya one way gear) is like somehow don't rotate at the center point, turns ovally. When these 2 gears mesh together, there is always a very tight point. I tried another brandname's fine pitch gears, but the same thing happened. This problem applies to the front only, the rear is smooth. This problem could be slightly solved by lossing the bottom screws a bit, I mean the lower gearbox cover. I tried any possible combinations but nothing worked out. This has been a misery for years. Man, If you got a solution, please let me know.

The second problem - super tight & thick high friction belt.

Have you ever seen those colorful belts in orange or blue? They are like plastic. Get those! But will work fine after 30 -40 runs.

Keep the front and rear using 16T belt gear. No belt tensioners necessary

This could be the worst car I've ever had from Tamiya. I wonder how David Jun won with it.

[WillyChang 1814]

Never had problems with TA03 like you describe, Wala. Yours is real curious!! Tamiya is usually one of the better ones when it comes to molding plastics.

That said, yes - always run with BBs, don't build anything without them. The belt's layshaft puts a lot of stress on that 1150, I wouldn't let any plastic bearing near there.

There are too many moving parts in a TA03 to rely on bushings. You will see the difference immediately when you install them.

[RETRO R/C 59]

quote:I wonder how David Jun Won with it.

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By building it properly I would imagine [] - also the fact that he can drive rather well !!

Perhaps you car had a bearing missing wala?? my Ta03's have had no such problems - perhaps it was just a faulty part?

It is essential to ballrace any car - the FIRST hop up you should make is to ballrace every moving part possible - particularly the drive train.

Cheers

Darryn

[jacolouw 6]

Hmmmm None of the 14 Tao3s (F/R/Pro and DJ) I had ever had the problems as described by Walla.

My personal view is that its one hard, durable and quite good performing car. Im not saying I'll take on (and win) cars like the Hpi pro3 or TC3 - but I'll give them a run for their money. (btw i own botha a pro3 and a tc3) The Tao3 is by far the stronger car.

As for build quality - I NEVER had bad parts from Tamiya as in bad moulding etc.

Jakes

[walawala_com 2]

Willy,

According to what you said, may be the TA03 Family are disasters to me. I have the TA03F pro (modified to be a TA03F TRF), TA03RS TRF. I am a Tamiya fan and I know what quality they give and how I should build a car. I am really upset about this but hope this never happened to anyone.

Anyway, thanx for your advise.

[walawala_com 2]

Jhellman,

Have fun with your TA03F! But converting it to a TA03R will give tighter cornering and less push during hard acceleration.

Best wishes to you

Walawala

[jhellman(2) 0]

Hi,

not that I would do it, but just to know: how can you convert a F into a R?

I suppose the in the "R", the engine is in front of the rear tyres? I bet that requires the whole body to be changed?

Or do you just change the front tires to "back" of the body and vice versa, resulting into a "R" in which the engine is behind the rear tyres?

br,

Juha

[walawala_com 2]

jhellman,

Get a TA03R front gearbox, FRP or bath tub chassis, F/R 15T pulleys, TA03R front bumper.

Put the TA03F front gear box to the rear, the bottom guard has to be switched with the bottom guard of the TA03F rear gear box. Remember to screw 2 flanged ball bearings (5 x 8F)right behind the motor as a clearance for the belt. You will find that hole.

This is the idea, may be there are parts I am missing.

One reminder : Get CVD's for the front of the TA03F, very high stress part as the front is really heavy. Putting the one way in the front or in the rear will change the running style. The front damper stay of the TA03R will let you use some sleeker bodies. You can just use this on the TA03F.

[walawala_com 2]

I had this thought also, but couldn't place the steering system. By the time I thought this, the TA03R wasn't announced yet. But I know too good about Tamiya. Have you ever own a TA01? Noticed that the body post plastic tree, there is a part for the TA02. Tamiya is a well planned company, way better than Kyosho.

quote:Originally posted by jhellman

Hi,

not that I would do it, but just to know: how can you convert a F into a R?

I suppose the in the "R", the engine is in front of the rear tyres? I bet that requires the whole body to be changed?

Or do you just change the front tires to "back" of the body and vice versa, resulting into a "R" in which the engine is behind the rear tyres?

br,

Juha

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[WillyChang 1814]

quote:Originally posted by walawala_com

I had this thought also, but couldn't place the steering system.

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Just remove the entire suspension assembly, and reattach after swapping the whole gearbox over. You don't necessariily need the TA03R chassis tub either, the F tub works just fine. Battery position is the major difference between tubs.

Really intruiging thing is... even with the F tub and rear motor, the weight has now all moved to the back - *yet* the handling doesn't change all that dramatically!! [?] It still handles very neutrally... only now you'll get more tyre wear at the rear. Wierd!

Its hard to tell the difference, best (scientific?) way is to run them back-to-back. I have identical 03s setup for this, makes it handy to really gauge 'improvements' of any any adjustment. Currently they're setup as rear motor'd one with F tub and the other R tub.

If you want a "livelier" car... perhaps try a 'Short' chassis.