# More than one type TJet crown gear?



## Hoganflagle (Sep 21, 2019)

Hi;

Trying to repair an old TJet chassis I have. I ordered a crown gear and axles and a top plate with armature from a reputable online slot car site. The crown gears I rec'd are shorter in depth than the ones on my other TJets and won't contact the drive pinion gear. Attached is a pic of one of my other TJets and the problem child so you can see what I'm talking about. 

Is there more than one type TJet crown gear and if so what are the model names so I can order the right ones? 

Also the top plate I rec'd has an issue where the armature turns with some resistance. The armature pinion gear is flush with the armature shaft. I don't think it was driven in too tight. Any recommendations on how to free it up?


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## Hoganflagle (Sep 21, 2019)

Just figured it out. The car on the left has a 9 tooth pinion gear - crown gear. Guess I need to be specific with crown gears, lesson learned.

Still need some help with the binding armature though.


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## Rich Dumas (Sep 3, 2008)

The car on the left has a standard T-Jet crown gear and those are made to mesh with a 9 tooth drive pinion. The car on the right has an AFX crown gear and those matched a 14 tooth drive pinion. Back in the '60s I replaced the 9 tooth drive pinions in all of my cars with 14 tooth armature pinions, the hubs of the crown gears had to be sanded down to get a good mesh. With those modifications the cars had more top speed and were easier to drive. Original Aurora parts are getting harder to find, however there is a good selection of reproduction parts that can be used to get a car running. If you are looking to restore a car to the original configuration you would want to use Aurora parts.


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## Hoganflagle (Sep 21, 2019)

*start from scratch helps*



Hoganflagle said:


> Still need some help with the binding armature though.


Posting this in case someone else runs into the same issue:

I worked the armature pinion gear off the armature carefully by sliding a small buck knife under the pinion gear and gently prying up working around all sides. Not sure if there is a special tool out there for this type procedure. Found the problem to be a rust build up on the neck of the armature stem that rides in the plastic top plate. Removed rust and polished the neck with a Dremel with wire brush attachment. Reassembled pinion gear back on the armature and now it is fine.


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## 60chevyjim (Feb 21, 2008)

you can get the tjet type gear on ebay from a seller named ratherboring .
ho owns model motoring and reproduces many original style tjet parts.
he is a nice guy to deal with.


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## Rich Dumas (Sep 3, 2008)

I believe that One Stop Slot Shop still has original T-Jet crown gears. Dash crown gears will also work. Pullers are made for removing the armature pinion gear, however often the pinion has been pressed on so far that it is difficult to get the puller in between the gear and the gear plate. RT-HO sells a rather expensive tool that is easier to use. Prying off the pinion gear might result in bending the armature shaft, if you were going to do lots of T-Jets the cost of the RT-HO tool might be justified. For more info on T-Jets look here: https://drive.google.com/file/d/1msYjFT2HVbaSxNC5g_QhEwM8cjBHyDNf/view?usp=sharing
Note that the article includes clickable links.
Once you have removed the armature pinion gear and have pressed it back on it is very likely to work loose later on. You could use a new pinion gear or swage the old one as described in the article. Be aware that OEM Aurora T-Jet parts almost always come from disassembled chassis so the hole in the gear will need to be swaged unless you only want the car as a shelf queen.


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## Hoganflagle (Sep 21, 2019)

Rich Dumas said:


> Once you have removed the armature pinion gear and have pressed it back on it is very likely to work loose later on. .


LOL, in my case it was sooner than later. Soon as I test ran the chassis on a power track; off it came. Fortunately I had a new one ready.


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## alpink (Aug 22, 2010)

unless you have a tool, you can "swage" the hole with a ball bearing and hammer.
place the gear on a hard flat surface, place the ball bearing on the hole and tap the hammer on the top of the bearing.
this will press the metal into the hole and make for a tighter fit.
do both sides.
there are other tools similar to a finishing nail set (punch) that have a rounded tip which can be used in a similar manner.
and, of course the slot tool manufacturers make great tool especially for all purpose.
speaking of which, I have extra gear and wheel pullers and presses if you need.
PM me and we will work something out.


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## Hoganflagle (Sep 21, 2019)

*Clever*



alpink said:


> unless you have a tool, you can "swage" the hole with a ball bearing and hammer.
> place the gear on a hard flat surface, place the ball bearing on the hole and tap the hammer on the top of the bearing.
> this will press the metal into the hole and make for a tighter fit.
> do both sides.
> ...


That is a great idea about using the ball bearing, particularly since it will center itself and press the brass in a uniform manner. I tried swaging it with a tiny chisel but it deformed the gear enough to create a tight spot when it turned.


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## T-jet (May 3, 2016)

alpink said:


> I have extra gear and wheel pullers and presses if you need.
> PM me and we will work something out.




I would be interested in those tools, LMK


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## alpink (Aug 22, 2010)

*tools*



T-jet said:


> I would be interested in those tools, LMK


send me a private message through this site.
upper right of page


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## T-jet (May 3, 2016)

alpink said:


> send me a private message through this site.
> upper right of page


Thanks Al, I just got on here. Look for it in a few mins


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## Milton Fox Racing (May 27, 2014)

alpink said:


> send me a private message through this site.
> upper right of page


You can also click on the persons name to the left of a post and select the send pm line in the drop down menu. :cheers2:


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## alpink (Aug 22, 2010)

MFR, thank you. I had forgotten that.


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## T-jet (May 3, 2016)

Milton Fox Racing said:


> You can also click on the persons name to the left of a post and select the send pm line in the drop down menu. :cheers2:


 Thanks MFR, I actually figured it out. This board has changed since I was here a long time ago but I got it and sent Al a pm. Thanks:thumbsup:


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## pamgb1963 (Jan 3, 2019)

I wonder how the U-Turn Matchbox Race&Chase Cars work!


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## twolff (May 11, 2007)

pamgb1963 said:


> I wonder how the U-Turn Matchbox Race&Chase Cars work!


Tyco/Mattel made U-Turn cars that run pretty well. The U-Turn action is pretty consistent and easy to get the hang of.


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## warnergt (Feb 9, 2000)

I made a bunch of measurements on Aurora gears way back. The width of the collar varies.
I found that they seemed to fall into these basic groups:
Stock T-jet Gear: 0.080"
Slimline Gear: 0.060"
Hop Up Gear: 0.040" or 0.060"
Tuff Ones/AFX Gear: 0.030" or 0.035"
Super II Gear: 0.040"


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## Milton Fox Racing (May 27, 2014)

pamgb1963 said:


> I wonder how the U-Turn Matchbox Race&Chase Cars work!


Welcome to (posting) in the boards @pamgb1963 :thumbsup:


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