Grrrrrr! Fire Dragon Gearbox Clicking

[Saito]

Well I guess it was bound to happen. I finally purchased a Tamiya vehicle with a problem I can't overlook. My re-re Fire Dragon has been driving me crazy with a clicking noise in the drivetrain. First I removed the driveshaft and the sound went away, thusly isolating it to the front gearbox or prop shaft. Second, I made a solid prop shaft to replace the stock "fluttery" wire one. I didn't think this was the issue as my Dirt Thrasher doesn't click with its wire prop shaft. I was right. The new solid prop did not fix the problem, so into the front gearbox we go. I noticed it seemed to have a tight spot in the rotation no matter how many times I tore it down and rebuilt it (which was ALOT). Finally I took off my glasses and gave the gears a close eyeball. It appears that the molding is sloppy particularly at the roots (base) of the gear teeth. I ordered a spare set of gears and they appear sloppy as well. The pic below gives a good look at some of this mess. I think this might be the cause of the binding but am unsure about the clicking. I'm a bit at a loss of what to do since the replacements are no better than the originals. I realize the older 4wds a on the noisey side and I don't mind this a bit but...the clicking sound is driving me nuts. It sounds as though its broken somehow and makes driving it seem "cheap" in a way. Any similar experiances from Thundershot/Fire Dragon owners or thoughts/ideas on how to proceed with fixing this problem?

[Origineelreclamebord]

I don't own a Fire Dragon or similar car, but that indeed doesn't look like it should. The one in the picture, is it a new one on the tree or after use? If it's the used one, check if your bearings are ok. If you still use bushings, replace them immeditately. They wear out, one quicker than the other, sacking the gears in wrong angles and ending up with messed up gearboxes. Also check if the axles on your gears are straight. As a last thing, do you have a mad supply of torque in your Fire Dragon or do you run pretty regular motors?

[taliesin]

as you have tried two sets of new gears, i would guess this is going to be the quality that you get. too bad, really, because that does not look like proper tamiya quality to me either.

my suggestion: grease the dog snot out of it, and let the gears "run themselves in". eventually, the natural friction will wear any high spots down. in the meanwhile, heavy lubrication might ease the strain on the drive train and quiet the clicking.

the gearbox on my stadium thunder always sounds like it is screaming in pain, so i know how annoying it is, but i've just left it alone and it shows no sign of giving out. it just keeps making horrible noise and i just keep driving it, because i don't know what else to do about it.

[HILUXMR]

Hi, I just had a look at a gear set from the first release thundershot and they look just as bad as the new one's, so i don't think this is the cause of your problem.

If you want to try these gears let me know and you can have them if you cover postage.

[28yoKid]

Sorry to hear about the clicking. I run brushless with my FD and the gearbox is fine, no clicking. The only thing I would suggest is looking at which holes you are using to attach the motor to the rear gearbox case. In my wild dagger I used the wrong ones and although it drove there was clicking as the contact between the pinion and the spur was too light; which allowed some play in the other cogs. When I changed the holes, the contact between the pinion and spur was greater, tightening up the whole gbox, and the clicking was gone! I know the FD motor plate has lots of diff hole options depending on the pinion you are using, so have a play around! Good Luck.

28

[Saito]

The car is bone stock except for bearings which installed from the beginning. The gear pictured is the new one on the tree but the kit ones are the same. I'm going to try to file/polish them. Arrgg. This is what I get for chuckling at those original RC10 racers 23 years ago that had to file all their gears straight out of the kit just to get the old 6-gear tranny to run smoothly.

[Wile E.Coyote]

I have a terra scorcher which is the same car, and an egress, I am suprised everytime how noisy is the transmission of the terra in comparison with the Egress one.

Nevertheless, there is 2 pieces of hollow shaft to place on motor screw to avoid damages on the plastic gearbox. Did you place them properly?

[Origineelreclamebord]

Taliesin's suggest is a good one I think, but maybe it would be better to remove the high spots on the gear without having to 'run them in.' Maybe you could slice, cut, vile or sand the high spots off? I know it's a small space you're working with, but that may be the best option.

Have you also looked if the troubled gears of the Fire Dragon are interchangeable with gears from other chassis'? If they are interchangeable, you could have a look if the other chassis uses a different parts tree - and you sould have replacement gears without warts on it

[taffer]

Hi, the Thundershot is my favourite tamiya model, my runner in my showroom has been going without trouble for over two years with a RZ super stock in, I also have two NIB re-release kits, two re-release runners from friends that have been stripped down for parts and a re-release Fire Dragon Kit that I intend to build and leave as a Thundershot.

I also own a few original gear bags.

I have spent the last half hour looking through all my parts and the conclusion seems to be the re-release Fire Dragon kit has this problem on the moulding where all my others do not, the colour of the plastic is also lighter.

[Saito]

Thank you for all the suggestions. I ran my Hot Shot back to back with the Dragon and the Dragon gearbox is noisier (checking to see if I was just paranoid). I checked the motor screw's hollow shafts and the mount itself to make sure it was assembled properly and it was. I went to work on the gears last night with a knife and small file. This greatly deminished the "tight" spot I felt while rotating the front prop input. I packed the area with grease as suggested. The noise seems to have deminished somewhat so maybe futher running the gears in will help. Thanks for looking through your gear collection Taffer. Its good to know that there are some good parts out there. I'm a bit of a perfectionist and this is why I choose Tamiya for their accurate molding abilites. This little adventure has irked me quite a bit but alas no one is perfect (glad I wasn't involved in the Juggernaut fiasco). Thanks for all the help.

[Saito]

Well, I've torn the whole car appart, cleaned, filed and lubed all the gears yet the noise still persist. This is most fustrating. Honestly, this might be the only Tamiya car I sell (I'll take a beating on it). At the very least I'm gutting it of its radio gear and tossing it on the shelf. Its a shame. I really liked how this car was designed and drove but I can't take all the racket it makes. I guess I'll stick to running my reliable old Hot Shot. Sigh.

[DeadMeat666]

I am almost done with my Fire Dragon and have experienced the same grinding noise that is described. I've managed to narrow it down to the bevel gears in the front gearbox. Needless to say, this has halted my build until I find a solution.

I've ordered a set of NOS vintage gears I found on eBay to see if that resolves the issue.

[TurnipJF]

There are four possible solutions to my knowledge. First of all, find a NOS set of vintage gears that were moulded properly. Secondly, find a used car with vintage gears, and re-use them, as they wear really really slowly and even old ones are likely to still be in excellent condition. Solution 3 is to carefully trim off the mis-moulded bumps from a set of new gears to make them the right shape and run quietly. Solution four is to run your car a lot and let the gears bed in naturally, which takes ages but eventually gets rid of the noise too.

On mine, I used a combination of Solutions 3 and 4, getting rid of the worst of the bumps with a craft knife and file, then letting them bed in naturally to get rid of the last of the noise.

[Frog Jumper]

You could try a vintage Tamiya #50602.  

Keep in mind, the new(ish) versions of this will likely have the same issues as the kit version, ie the come from the same molds/factory.

Terry

 

 

[nel33]

4 hours ago, TurnipJF said:

There are four possible solutions to my knowledge. First of all, find a NOS set of vintage gears that were moulded properly. Secondly, find a used car with vintage gears, and re-use them, as they wear really really slowly and even old ones are likely to still be in excellent condition. Solution 3 is to carefully trim off the mis-moulded bumps from a set of new gears to make them the right shape and run quietly. Solution four is to run your car a lot and let the gears bed in naturally, which takes ages but eventually gets rid of the noise too.

On mine, I used a combination of Solutions 3 and 4, getting rid of the worst of the bumps with a craft knife and file, then letting them bed in naturally to get rid of the last of the noise.

Are these big bumps very distinctive or do you need to manually fit the gears by hand to locate the high spots?

[TurnipJF]

1 hour ago, nel33 said:

Are these big bumps very distinctive or do you need to manually fit the gears by hand to locate the high spots?

They are pretty easy to spot with the naked eye under good lighting. You can also feel them with the tip of your craft knife.

[nel33]

Just now, TurnipJF said:

They are pretty easy to spot with the naked eye under good lighting. You can also feel them with the tip of your craft knife.

thank you for the reply. so you basically just run the craft knife with a good light source and search for the high spots.

[TurnipJF]

30 minutes ago, nel33 said:

thank you for the reply. so you basically just run the craft knife with a good light source and search for the high spots.

 That pretty much sums it up, yes. 

[Saito2]

Blast from the past back when I had my original screen name. I remember being quite disgruntled over this back then. Never really had a faulty Tamiya part up until that point. Can't believe that was back in '08. Time flies. Anywho...

2 hours ago, nel33 said:

Are these big bumps very distinctive or do you need to manually fit the gears by hand to locate the high spots?

I dug back in my pics and here's a shot of one of my gears, as it came new.  Its not too bad too see like @TurnipJF said when they are fresh out of the packet. Things get harder to see when they a smeared with white ceramic grease. I did go back into the gearbox and continued to carve/filed away at the gears to the point where it got quiet. I may be a pessimist, but I'm doggedly persistent. I probably didn't learn my lesson because I have a Thunder Dragon on the way (supposedly, if it ever arrives) and it will no doubt have similar issues.

[nel33]

1 minute ago, Saito2 said:

Blast from the past back when I had my original screen name. I remember being quite disgruntled over this back then. Never really had a faulty Tamiya part up until that point. Can't believe that was back in '08. Time flies. Anywho...

I dug back in my pics and here's a shot of one of my gears, as it came new.  Its not too bad too see like @TurnipJF said when they are fresh out of the packet. Things get harder to see when they a smeared with white ceramic grease. I did go back into the gearbox and continued to carve/filed away at the gears to the point where it got quiet. I may be a pessimist, but I'm doggedly persistent. I probably didn't learn my lesson because I have a Thunder Dragon on the way (supposedly, if it ever arrives) and it will no doubt have similar issues.

thank you for posting the pic, those pimples look horrible and sloppy. gotta get rid of them. id also attack those bad bevel edges.

[Ferruz]

On 5/24/2021 at 7:49 AM, TurnipJF said:

There are four possible solutions to my knowledge. First of all, find a NOS set of vintage gears that were moulded properly. Secondly, find a used car with vintage gears, and re-use them, as they wear really really slowly and even old ones are likely to still be in excellent condition. Solution 3 is to carefully trim off the mis-moulded bumps from a set of new gears to make them the right shape and run quietly. Solution four is to run your car a lot and let the gears bed in naturally, which takes ages but eventually gets rid of the noise too.

On mine, I used a combination of Solutions 3 and 4, getting rid of the worst of the bumps with a craft knife and file, then letting them bed in naturally to get rid of the last of the noise.

Solution 3 worked well for me on my Terra Scorcher. It was MUCH needed and not only on the bevel gears, can't believe the amount of bumps I've (carefully) shaved off wity an exacto knife. Did the trick though: no more tight spot and not much noise, especially once the gears bed in a little.

[nowinaminute]

About to go through this with a TD in the coming weeks. I had a Boomerang that had a gear like it one too. Got a replacement gear and it was no better. Just ended up filing and scraping it till it would at least turn relatively smoothly and without major tight spots. Pretty disappointing from Tamiya, really.

And this sounds awful but, worst case, running the gearbox for a period of time on the bench with a little lapping compound or even some sand mixed with grease will bed the gears in quite effectively. They won't look too pretty afterwards but they will turn very smoothly. That's a last resort for me but it does work and new gears are relatively cheap so risk is low. Obviously it will require cleaning up afterwards.

[Saito2]

I have to admit, while mistakes with Tamiya are rare (though getting more common these days it seems) when they do make one, they make no effort to rectify it. These gears were bad in the '08 re-re and are still bad today. It seems to take a Juggernaut-sized fiasco to motivate them into doing something.

[rwordenjr]

16 minutes ago, Saito2 said:

I have to admit, while mistakes with Tamiya are rare (though getting more common these days it seems) when they do make one, they make no effort to rectify it. These gears were bad in the '08 re-re and are still bad today. It seems to take a Juggernaut-sized fiasco to motivate them into doing something.

Is the only chassis that has had these kind of problems ? 

[Saito2]

8 hours ago, rwordenjr said:

Is the only chassis that has had these kind of problems ? 

Gear molding problems? I don't recall it being brought up with the '05 Thundershot re-re. My '08 Fire Dragon had it and then my Terra Scorcher re-re did too so its definitely an issue with this chassis family. nowinaminute evidently had this issue with a Boomerang gear although I've been lucky enough not to encounter it in any of my Hotshot series cars.

If you mean gearbox problems in general, The ORV cars, particularly the monsters like the Blackfoot and Monster Beetle suffer from diff separation and Tamiya did nothing to change it. The FAV and Wild One have issues too, sharing similar gear sets. The ball diff in the Madcap/Astute/King Cab/MR has been an issue for some. I've been lucky with that one, but I've also seen bent diff housings and melted diff gears in some of my used acquisitions of these chassis. The DF03s have an aluminum gear that wears out quick in the drivetrain. The original Juggernaut was so bad, it shouldn't have made it out the door for public consumption. I'm probably missing some. On the plus side, the Hornet/Lunch Box and Clod Buster all feature bulletproof gearboxes as well as others.

Molding issues in general seem less common and more sporadic, though I remember reading reports that some of the parts in the Black Super Clod had molding issues.

That's not to say Tamiya is alone in this. Heck, the original RC10 gears were reported egg-shaped in the worst cases. Overall, Tamiya quality was top notch compared to everybody else BITD.