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Discussion Starter · #1 ·
I finally got some time to play with the AW Tjet and the T-Dash Mondo. I oiled them both and put them on the track.
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The T-Dash was faster at first, but after a while it became slower and slower, then after another while it was faster again.

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Any idea of what could cause inconsistent performance? The pickup show contact patch seems perfect and there's no squeal or rubbing noise.
 

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Discussion Starter · #3 ·
Doubt it, but, possible binding and heat...?

Alternatively, heat affecting brush tension?
I don't see any binding and thought about the heat, but the car doesn't feel hot and it gets faster again after some laps without letting it cool down. The AW car stays the same all the time.

If the heat was affecting the shoes, woukd they look heat discolored?

Maybe it needs more break in?
 

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Could be heat. I wouldnt look to the shoes for heat problems though. More like an arm heat problem. Could be too much brush tension. Id try removing the brushes and magnets and feeling by turning the wheels, for binding/friction first to eliminate that. Then Id add the brushes back only and feel again if there is noticeable more friction. Its tough to tell if you have too much tension, but if you run it on a power supply and press the brush springs with a tooth pick and it dont pickup speed its safe to say you dont have too little, you could try backing them down a hair.
Also check for things that may come and go, like say a sloppy rear axle that may cause the crown/pinion to bind then unbind. A body that may be slightly rubbing on the tires as it rocks. Or pickup shoes that have too much side to side play, Ive had it were a shoe would ride off the rail and jam between the track rails.
I have a Tjet with poly mags and a 6ohm arm that runs real fast but after a bunch of laps slows up and you can feel the bottom of the chassis below the brushes feels warm. Let it cool and its fast again. Havent looked at my brushes yet but its definetly a heated up arm slowing my car.
 

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Oh yeah, for sure pull the body. Run it chassis only for a while and check to see if it is the same or no.

Every now and then (well, "then" gets to be years somehow) my fleet gets to be unreliable due to worn shoes, dust and hair, a binding wheel here and there...and I snap off every body and just test one chassis after another and tune on them until they are smooth. Then I determine which body goes with which car, having no idea where they started.
 

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Glock24 said that he oiled the cars, but he did not say what sort of oil that he used. T-Jets are very fussy about oil, any sort of oil will work for a short time, but if you want the oil to last for a long time you have to use the right stuff.
 

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The Mondo chassis uses a 10-Ohm armature. AW typically uses a 15-Ohm arm. Dash arm will heat up faster than the AW.

Also. A touch too much thin oil on the bottom of the chassis near the brushes can contaminate them. That might mess with your speed consistancy. I like Bill's idea of a light grease/oil mixture.
 

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Back in the 60s we had aurora red oil. Never thought about using anything else.

My experience was that once a brush was oiled, the only remedy was replacement. Kind of like spark plugs.
 

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Discussion Starter · #11 ·
Could be heat. I wouldnt look to the shoes for heat problems though. More like an arm heat problem. Could be too much brush tension. Id try removing the brushes and magnets and feeling by turning the wheels, for binding/friction first to eliminate that. Then Id add the brushes back only and feel again if there is noticeable more friction. Its tough to tell if you have too much tension, but if you run it on a power supply and press the brush springs with a tooth pick and it dont pickup speed its safe to say you dont have too little, you could try backing them down a hair.
Also check for things that may come and go, like say a sloppy rear axle that may cause the crown/pinion to bind then unbind. A body that may be slightly rubbing on the tires as it rocks. Or pickup shoes that have too much side to side play, Ive had it were a shoe would ride off the rail and jam between the track rails.
I have a Tjet with poly mags and a 6ohm arm that runs real fast but after a bunch of laps slows up and you can feel the bottom of the chassis below the brushes feels warm. Let it cool and its fast again. Havent looked at my brushes yet but its definetly a heated up arm slowing my car.
Axle is not sloppy on the T-Dash, but it is on the AW car. There is no tire rubbing, shoes are tight with no side play. I didn't think of checking brush tension, will try that. Tjets are a different beast that the other slot cars, this is my first experience with them (as an adult).

Oh yeah, for sure pull the body. Run it chassis only for a while and check to see if it is the same or no.

Every now and then (well, "then" gets to be years somehow) my fleet gets to be unreliable due to worn shoes, dust and hair, a binding wheel here and there...and I snap off every body and just test one chassis after another and tune on them until they are smooth. Then I determine which body goes with which car, having no idea where they started.
Will try that too, just chassis with no body. Will also compare to the other T-Dash chassis I got, that one I have not run yet.

Glock24 said that he oiled the cars, but he did not say what sort of oil that he used. T-Jets are very fussy about oil, any sort of oil will work for a short time, but if you want the oil to last for a long time you have to use the right stuff.
I used full synthetic motor oil for the gears and axles, for the bottom hole I used a little Labelle 106 grease. The motor oil I've used for all other slot cars, incluiding AFX cars. Will check the brushes for contamination though.

Back in the 60s we had aurora red oil. Never thought about using anything else.

My experience was that once a brush was oiled, the only remedy was replacement. Kind of like spark plugs.
Someone here (sorry, don't remember who ATM) recommended puting a soldering gun to fouled brushes, I tried it for AFX cars and it worked great!
 

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If you have strong alcohol, I suspect you could wash the brushes. But for me, writing on paper technique seems to work. But perhaps I could try the heat trick.
 

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Re: Brushes--Maybe swap other, known, dry T-Dash brushes since you have other cars for a "Scientific Method A-B-A" methodology test thing.

Clearly, Ken is on the maple syrup again!
 

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Funny, Glock's AW that was side by side for the event didnt succumb to over oiling ... ? Hmmmmm.

None the less, over oiling the comm pit is why I never use any of that runny specially formulated goo on the lower hole. Oil sling and commutators dont mix, ever. Thats why the original red oil was thicker.

Growing up in the boondocks ya didnt toss wet brushes. We werent that affluent, and when Hamlin's Hobbies was out of stock, so were you. Uncie Herb taught us to drop a 40 watt iron on fouled brushes, and smoke them clean. Rinse them off with some LT or alcohol in a bottle top; then scuff them off on some (rag) rough paper.

Truthfully, compared to the ancient carbons, at 80/20 it's pretty hard to get today's high metallic brushes to sponge up oil. Generally oil fouling is relegated to a topical consideration. Wipe up the Valdez, ease up on the crude, and carry on.

No worries, the death squeal is pretty clear indicator if you have under oiled.
*

The Poor Mans Dyno.

Tune your AM radio between stations down towards the bottom of the scale. Put your test leads on the chassis. You want the weight of the running gear, so you can use full throttle. Your commutator will talk to you this way.

As Jetter recommended ease a toothpick (non conductive) under the lever springs GENTLY, and listen for change. Typically it's the rear spring but not always. Could be both. All you have to do is tune in.

Dump the guts out, then using the flat of a small jeweler's screwdriver tease the offending spring up. GO EASY. Less is more. If you over bend, it's tough to get it back. I'd much rather take two pokes at it than have to try and undo an over bend.

Note: This is not a remedy for worn brushes. You should make the adjustments with new(er) brushes to keep everything in it's intended working range. Specifically: the stroke of the spring. Typically, I'll make the adjustment, and then let the brushes run in a while, and then repoke if a little more tension is warranted.

Wink, wink ...

My quick test. You can also take a quick look see/hear simply by lightly touching the pad of your index finger onto the running armature gear. It takes a gentle touch, to compress the vertical thrust, load the comm, and determine any lack of adequate tension. It wont tell you which brush/spring is the culprit, but it's a good indicator that something is afoot.
 

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A few more points about the heat issue.

Dash Mondo uses a 10-Ohm armature with a 9-tooth brass pinion.
Auto World uses a 15-Ohm armature with a 14-tooth plastic pinion.

The Dash Mondo will need to spin much faster to keep up to the Auto World's low gearing. Probably why Dash installed a 10-Ohm arm.

Also. 2-traction magnets on the Mondo chassis probably create a little more drag to the rolling assembly. You might be able to run a Mondo up a wall.

I would expect the Dash to run hot compared to the Auto World.
 

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I run 12v so 🥵 hot cars usually isn't an issue. I do have a classic Tjet that feels tight. I think it's the drive train. I have some plastic idlers that I might swap in.
 

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One more question, I have skinny tjet tires that tend to get pinched and tore off. (Slip between tracks etc) Any tricks to treat the original shiny hubs?
 
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