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T-Jet pickup shoes question


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#1 Dallas Racer

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Posted 25 March 2020 - 08:36 PM

OK, I was trying the rail cleaning suggestions, and was still having problems. I was starting to suspect the pickup shoes were the problem. I tweaked them a little and cleaned them. That helped a little but not much. So I lifted up the rear of the car to put more force on the shoes. It made contact and ran, in most places that were otherwise dead! Set it down again and no-go.

 

I suspect that tilting it up that way creates pressure where the shoes hinge on the copper plates. That the shoes are not making good contact in the hinge.

 

But, to confuse the story more, I grabbed an AFX car, the fast ones, whatever they're called, and pulled the front axle off. This was to make it rub harder on the rails to hopefully clean them. It ran fine with few dead spots, which it ran past anyway because it's so fast.

 

After 5 or 6 laps I tried the T-Jet again, and it ran fine! I eventually ran the AFX car 15-20 laps on each lane and problem solved. Good contact on all lanes. This is after only cleaning a very small portion of the rails. 90% of the rails had not been cleaned at all, but the AFX car fixed it all. And the AFX car had no problem getting around on any of the lanes. It never stalled once.

 

Everything's good to go now, but I don't understand why the T-Jet had such problems while the AFX had none, and why the AFX fixed the problem the T-Jet was having. It makes no sense.


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#2 Revtor

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Posted 25 March 2020 - 08:47 PM

Maybe the increased current drawn by the AFX had some cleaning action at a microscopic level.. ?

Good observation, hopefully this works for others!
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#3 Tim Neja

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Posted 25 March 2020 - 09:01 PM

Dirty rails affect some cars more!! THe AFX had enouhg down force to work through and clean the spots the T jet couldn't!


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She's real fine, my 409!!!

#4 bbr

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Posted 26 March 2020 - 03:35 AM

Check if the pickups have even wear from front to back. You want them to be flat as possible. Increase the springs tension a little, but not too much that the handling goes away.
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Mike Low
Cry like a baby, drive like a girl, walk like a man.
Give me enough rope and I'll build a fast car... or hang myself?

#5 Dallas Racer

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Posted 26 March 2020 - 04:50 PM

Thanks gentlemen!

 

I do know to check the wear pattern on the shoes, and I knew it was off. Wearing on the back end. But decided I was not going to bother with that anymore because I thought of it was more of a wear issue (shoes not lasting as long) than a performance issue. So I didn't check it on the setup block until last night. They are way off! Partially due to running O-rings on the front, which really lowers the front too much.

 

So I guess I need to grind some tires down. I've never had to do that. The only time I raced HO was in the early 2K's for about a year. None before that and none after, until now. Back then fellow racer Lee gave me ground tires. I'd give him stock ones in exchange. Heck of a nice guy. He had them in various sizes, I think to 0.01" tolerance. I don't remember for sure.

 

I've got a lathe and could do it precisely with repeatability, but I'd have to rig up something to solidly mount my Dremel to the carriage. I'd rather buy some than go to all that trouble, if possible.

 

So what do you guys do about the front tires?


Phil Smith ® ©


#6 bbr

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Posted 26 March 2020 - 08:57 PM

https://wizzardho.co...rts-and-ttires/


Mike Low
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Give me enough rope and I'll build a fast car... or hang myself?

#7 Dallas Racer

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Posted 26 March 2020 - 10:53 PM

Thanks Mike! I'll order some in the morning.


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#8 Revtor

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Posted 27 March 2020 - 04:33 PM

You should be able to tweak the pickup shoes to get a flat wear pattern.. might be easier than grinding tires down?
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