MTA4 Thundertiger Starting Help

[Shubz]

Hi just needed some help my RC car wash shot starting so was told on YouTube it maybe the one way bearing . I’ve opened the pull start part and then unscrewed the 4 bolts to open the other part where the piston is . I seen this metal piece loose inside was it supposed to be like that ? Any other tips if I’m missing something thanks, ps. Any idea what to lubricate it with

 

[Shubz]

Also any idea what size this bearing is so I can order it online . It says hf0512 on it .

 

[alfredwong2003]

Also any idea what size this bearing is so I can order it online . It says hf0512 on it .

I suspect it is a 12mm one way bearing. But your pull starter seems to be completely shot.

 

[Tunedfrog]

https://www.comprasparaguai.com.br/thunder-tiger-one-way-bearing-an0992__2676114/

 

[jlobbia]

Also any idea what size this bearing is so I can order it online . It says hf0512 on it .

Bro just use calipers. It is that easy.

 

[cbaker65]

Also any idea what size this bearing is so I can order it online . It says hf0512 on it .

How is the rest of the engine ,does it still have good compression?

I may still have all of those parts from my old engine!

 

[olds97_lss]

What does the other side of the bearing look like?

The markings on the bearing are just for the bearing itself which is likely generic (not specific to the brand of truck/engine) pressed into the outer part which is what keys to the crank shaft, usually via a slot or a pin. Guessing the back of your bearing has a couple slots on it. When assembled, the bearing spins on the starter shaft. When the shaft rotates in the direction to start the engine, the bearing has springs/ramps in it that allow the "bearings" to move and lock onto the shaft. When the engine starts, tension is relieved, then the shaft just bearing just spins on the shaft with the rotation of the crank.

Sometimes, you can order just the one way bearing, push the old one out with a socket/vice and press a new one in. You just have to make sure you push it in the right way or it won't lock when your starting.

When you buy a new OWB (one way bearing), it replaces the entire piece. Typically, if the OWB is so worn that it won't do it's job, the shaft it spins on is also worn, so you want to get a new shaft as well. Or the new bearing won't grab it very well for very long.

Looking at yours, it clearly had moisture in it. You can try cleaning the outside of the bearing with a wire brush/dremel, then soak it in DA (denatured alcohol), then take a paper towel with DA on it and run it through the bearing, then spin the bearing on the twisted towel to work the gunk out of it. Once it spins and the towel is clean, let it dry then put oil on it/in it. Reassemble, then see what happens.

Got a photo of the side of the engine or do you know what brand/model the engine is?

EDIT:
If it's this one with the PRO-28BD-R engine in it, it kind of looks like it has 2 owb's... one internal and external. I've never seen one like that.
https://www.thundertiger.com/download/6228-F_MTA4_S28_Parts_Catalog(JD6270V3).pdf

Part numbers:
AN0992 - external
AN0990 - internal

@Tunedpipe linked you to one of them.
https://www.wonderlandmodels.com/pr...pro28-hex-one-way-clutch-set/?exchange_rate=3

This is the other:
https://www.wonderlandmodels.com/pr...21-engine-one-way-clutch-set/?exchange_rate=3

Didn't see any in a US based site with a quick search...

That is so weird to me that there are two of them.