Axial Bomber Will not roll Freely

[mikeh0314]

I just finished my bomber kit and tested it out, it doesn’t not roll freely if pushing it by hand it feels like there is some resistance. After 5min of light play the motor got pretty warm. Any advice? Thanks!


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[Crawler Cads]

Process of elimination for that sort of thing.
Start with the mesh between the spur and pinion. If that's good then remove pinion and see if you can roll freely. If still the same then remove one end of drive shaft at either axle and try it. Those axles should roll really freely. If they're fine and you've got the pinion off still try the gearbox. Without the drive shafts attached, and pinion off, you should be able to spin that quite freely at the spur gear.
Something out of that lot should be the culprit!
Good luck;)

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[allanon1965]

what tooth pinion are you using? whats the tooth count on the spur? What motor are you using? brushed or brushess...

[mikeh0314]

Originally Posted by Crawler Cads

Process of elimination for that sort of thing.
Start with the mesh between the spur and pinion. If that's good then remove pinion and see if you can roll freely. If still the same then remove one end of drive shaft at either axle and try it. Those axles should roll really freely. If they're fine and you've got the pinion off still try the gearbox. Without the drive shafts attached, and pinion off, you should be able to spin that quite freely at the spur gear.
Something out of that lot should be the culprit!
Good luck;)

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Thanks! Will try it and let you know!


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[mikeh0314]

Originally Posted by allanon1965

what tooth pinion are you using? whats the tooth count on the spur? What motor are you using? brushed or brushess...

Brushed for now 12t motor 12t pinion, not sure on the spur count. I’m using the one that came with the kit.


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[allanon1965]

Originally Posted by mikeh0314

Brushed for now 12t motor 12t pinion, not sure on the spur count. I’m using the one that came with the kit.


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12t motor could be a big reason why its getting hot...if its a 3 pole 540 motor.. what motor is it? HH, rc4wd, boom racing, goolrc, etc?


if its a 3 pole 540 size, go to a 27t or 35t 540 sized motor, if your ESC will handle that..many brushed motors that have strong magnets will have resistance to rolling while not powered up...brushless motors will have less of that..

my hunch is the rolling resistance is normal for the brushed setup you are running and the motor getting hot quickly is due to the low turn count on the 3 pole 540 sized motor running a spur/pinion ratio of 4.66:1 (12t pinion and 56t spur). Get the ratio between 5.0 to 6.5:1 with a 27-35t motor and it will like it much better. I would put in 10t pinion for 5.60 ratio...

[mikeh0314]

Originally Posted by allanon1965

12t motor could be a big reason why its getting hot...if its a 3 pole 540 motor.. what motor is it? HH, rc4wd, boom racing, goolrc, etc?


if its a 3 pole 540 size, go to a 27t or 35t 540 sized motor, if your ESC will handle that..many brushed motors that have strong magnets will have resistance to rolling while not powered up...brushless motors will have less of that..

my hunch is the rolling resistance is normal for the brushed setup you are running and the motor getting hot quickly is due to the low turn count on the 3 pole 540 sized motor running a spur/pinion ratio of 4.66:1 (12t pinion and 56t spur). Get the ratio between 5.0 to 6.5:1 with a 27-35t motor and it will like it much better. I would put in 10t pinion for 5.60 ratio...

Wow thanks for the great explanation! It’s a titan 550 12t. I have a 11t pinion that I could throw in you think that’ll work for now? Going to order a Castle creation crawler edition when it’s back in stock next month.


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[allanon1965]

Ok, the titan 550 12t should handle that without too much issue, but 11t wouldnt hurt...that 550 will definintely give you resistance to rolling freely

[NitroBugg]

Originally Posted by Crawler Cads

Process of elimination for that sort of thing.
Start with the mesh between the spur and pinion. If that's good then remove pinion and see if you can roll freely. If still the same then remove one end of drive shaft at either axle and try it. Those axles should roll really freely. If they're fine and you've got the pinion off still try the gearbox. Without the drive shafts attached, and pinion off, you should be able to spin that quite freely at the spur gear.
Something out of that lot should be the culprit!
Good luck;)

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I agree. Had a similar issue. Mine ended up being the spur gear was rubbing on the housing attached to the transmission. Took it apart and re-seated everything, and it started to turn easily then. May not be the issue in our case, but doesn't hurt to check.

[Jim85IROC]

Is the motor warm, or hot? Warm isn't likely a cause for concern, but hot might be.

Here's what I would do. I'd pull the front and rear driveshafts so that I can turn the front and rear axles independently from the rest of the drivetrain. Turn the rear axle via the driveshaft stub and see if it feels stiff or overly notchy. Do the same with the front. If both of those pass, you can feel pretty sure that the axles are OK, so you may have an issue with the transmission. While the driveshafts are disconnected, try spinning the spur gear and see if the transmission is rotating smoothly.

If all of this ends up being ok, then my guess is that you're just experiencing normal conditions. A brushed motor will get warm if you're using the vehicle at anything above crawling speeds.

[svt923]

Another thing to consider is how you are greasing the gears in the axles and transmission. Too much grease will add way too much resistance to the drivetrain, RCs don't need to be packed with grease like old set trailer wheel bearings. Way too many people cram marine grease in like they are filling a Twinkie then wonder why their motors burn up.

[durok]

In my opinion, you'd be better off swapping the Titan 550 12t motor for a 550 21t motor, either another Titan or better yet, a Holmes Hobbies Trailmaster Sport.

12t Titans are usually installed in 2WD bashers like Stampedes and Rustlers, not in crawlers...

With a 21t 550 can, stock 64/12 gearing is usually fine.

[mikeh0314]

Originally Posted by durok

In my opinion, you'd be better off swapping the Titan 550 12t motor for a 550 21t motor, either another Titan or better yet, a Holmes Hobbies Trailmaster Sport.

12t Titans are usually installed in 2WD bashers like Stampedes and Rustlers, not in crawlers...

With a 21t 550 can, stock 64/12 gearing is usually fine.

So I’m looking to upgrade to brushless next month and don’t want to spend anymore on the motor. You think 12t 11t pinion will be ok for now?


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[durok]

It's relatively easy to get a 21t Titan for around $15 new, and the Holmes Hobbies is less than $20...

Otherwise, if you must continue with what you've got - test your electronics temps after a short run - if they are too hot to touch, go smaller on the pinion.

Check temps on motor, ESC fins, and battery.

Battery shouldn't get more than slightly warm.

As long as you can hold your finger on the ESC and motor, they will likely be fine - at least for the short term.

[mikeh0314]

I tried putting a fan on it but every time I put it on the motor the fan stops. Can you put cooling fans on brushed motors?


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[Voodoobrew]

Does it roll freely with no motor in it? or just remove the pinion or spur which ever is easier. Separate the parts to determine where the resistance is. The motor will always add resistance, with that removed it should roll freely on a dusty tile floor with out sliding.

["MIS-TAKEN"]

Originally Posted by mikeh0314

I tried putting a fan on it but every time I put it on the motor the fan stops. Can you put cooling fans on brushed motors?


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Yes you need to rotate motor or fan to get it away from the motors magnets.

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[Crawler Cads]

Originally Posted by mikeh0314

I tried putting a fan on it but every time I put it on the motor the fan stops. Can you put cooling fans on brushed motors?


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You're treating the symptom and not the cause Mike.
Best thing to do for longevity and peace of mind is find the cause;)

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[Cocamper]

Originally Posted by Voodoobrew

Does it roll freely with no motor in it? or just remove the pinion or spur which ever is easier. Separate the parts to determine where the resistance is. The motor will always add resistance, with that removed it should roll freely on a dusty tile floor with out sliding.

Having an issue-

As soon as I tighten down the nut/spring on the spur gear, it gets very difficult to spin the tires. I tighten it down all the way, back it off a turn, and I can barely push the thing across my bench. Also makes a clicking sound once cranked down. Everything moves freely until I tighten this nut. Any ideas, normal?

Thanks

[Voodoobrew]

Check the clutch assembly is correct. Because that is not normal. Sounds like part of the assembly is hitting the trans housing or bearing. Cranking that nut down should only tighten the slipper clutch. Which should not slip rolling across your bench. It should not lock up the rest of the drive train. Unless your batter is in and your drag brake is on (which it shouldent be). Unwanted friction probably in red circle. Ax31067 should only touch the shaft, not the trans housing or bearing. Possibly something inside is incorect if the shaft is not sticking out far enough, but hard to say.



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Handy gearing spreadsheet