tamiya hornet help

[merlin75]

hi guys
just started building a hornet and have a few prob's
been back to the place i brought it from and they are not interested in helping at all
i have everything together and if you hold the chassis off the floor it runs fine however when you put it on the floor it will not move, you just get the motor screaming and no movement.
one thing i have noticed is that the rear tyres are really soft i.e. if you touch them you can feel the wheel underneath, there is no air? in them at all, upon closer looking there is a hole in each tyre? is this right.
Can anyone offer any insight, really scratching my head over this!!

[Sproston Blue]

Hi Merlin,

I've got a Tamiya Hornet and the tyres are exactly the same - I don't think this will be the source of your problems.

It sounds to me like it may be something in the gearbox that needs looking at.

[steveo3002]

yep tyres sound normal

sounds like the motor isnt meshing with the gearbox , whip the motor and check the grub screw is tight on its cog

then from memory it should have some method of swinging the motor a bit a to allow for differant sized gears , i cant recall its either a slotted hole or shims you fit on the motor mount , make sure thats right

[thehos]

as said that is how the tyres are meant to be, the motor will pivot to allow different pinion sizes, roll it on the floor and see if the motor turns

[B@W]

steveo3002 said:

whip the motor and check the grub screw is tight on its cog

this^

[TheEnd]

Check the diff too, they sometimes had plate or ball bearing diffs that need to be clamped up to a certain torque.

[Shuttle Cock]

Motor pinion grub screw, or pinion/spur gear meshing.

Another thing, sounds obvious, but you have put the small pins in the stub axles?

[merlin75]

so ive had it apart and rechecked everything, still the same problem/issues
what next becoming a pain now.....how long/many times do i redo it

[dr_gn]

merlin75 said:

so ive had it apart and rechecked everything, still the same problem/issues
what next becoming a pain now.....how long/many times do i redo it

There's either the extremely unlikely scenario of your gears being faulty, or you haven't checked your assembly properly. As far as I can see there's nothing to adjust.

Why not post some pictures of the gearbox with one side removed?

Are you *sure* you've put the drive pins through the driveshafts before fitting the wheel drive hubs? they are very small steel pins about 10mm x 2mm diameter. Easily lost!

[merlin75]

ok def have the pins in place, and when you turn one wheel the motor turns also, it seems to run fine when not on a surface but will not move when on a table, floor, etc....
I have also checked the grub screw and that is tight, i am reluctant to take it back to the shop for the reason stated but also because i understand that tamiya are very well made and if there is a problem its due to assembly not a fault from the manufacturer?

[Simond S]

Can you

start car. Hold one rear wheel and gently apply power. does the other turn. Now reverse and do the same for the other wheel.

If both turn all good (for now) as you know the gearbox is working correctly.

Place the car on the ground / table in front of you facing away. gently apply power, the car should move forward as there is very little resistance. If it doesnt are both axles still rotating?

If they both are you are missing the pins. If one is you are missing the pin in that axle. If neither axle is turning..

are the wheels turning within the tyres. If so then remove wheels, dissasemble and clean the rubber rim of the tyre with brake cleaner, electrical cleaner etc..

If the wheels aren't turning but the axles are check that the wheels are correctly seated on the axle hub (B8).

then you are back to the motor pinion.

Remove motor and check pinion for tightness. very slowly and dont do if you dont have good throttle control!! hold the pinion and apply power. Can you hold the pinion and the motor slowly turn.

(or, are you using the correct motor holes for the pinion you are using, i know the original had a single set of holes but this may have changed over the years???)

If all bad send the car to me and i'll rebuild it and return.

Edited by Simond S on Monday 25th July 09:43

[sgrimshaw]

Is the motor pinion spaced correctly, as per the instructions?

If you turn a rear wheel manually, whay happens to the other rear wheel .... which way does it turn?

Same way, or the opposite direction?

[merlin75]

when you turn one wheel the other turns in the op direction as you asked
good or bad, are they supposed to turn the same way

[B@W]

They turn in opposite directions due to the diff

[Anthony Micallef]

Ive just had exactly the same problem with mine and what I found was the rear wheel nuts werent tight enough. Try tightening them again and I bet you get another half turn at least.

[thehos]

take the motor out and push it along the ground, do the gears turn inside?

As you said it is user error, tamiya is very well made

[merlin75]

the comment about tightening the wheels rings a bell, i can tighten one side but the other side will only just do up when you try and get it tighter it just spins???
this is the 4th time i have had it apart and back together, i am now adamant its built 100% as per the instructions....
what else can i do/try?

[dr_gn]

merlin75 said:

the comment about tightening the wheels rings a bell, i can tighten one side but the other side will only just do up when you try and get it tighter it just spins???
this is the 4th time i have had it apart and back together, i am now adamant its built 100% as per the instructions....
what else can i do/try?

Push and hold each wheel firmly against the drive plates (ie push towards the gearbox) while tightening the nuts. They are Nyloc nuts, so will need a bit of force to tighten them. Make sure the wheels dont turn while you're tightening the nuts.

If that doesn't work, sell it and find another hobby.

[thehos]

seems your having troubles, if you were closer i would gladly re-build it for you, i enjoy it, if you want to pay the postage i will fix it for you

[merlin75]

thanks very much for the comment about selling it and finding another hobby very helpful when you have trouble with something and ask for advice