Tida / Samson 5aa Gearbox disassembly questions

[rficalora]

I'm continuing down the path of disassembling and cleaning my Tida / Samson 5aa. Being new to this, I'm probably being a bit too gentle for fear of damaging anything but not sure.

I have everything out of the gearbox except shaft #15 with it's associated gears, pins, and key (14-21).

From the diagram, it looks like it should be able to be pulled or pressed out. I can get it to move about 3/8" lightly tapping with a drift, then it stops like its bottoming on something. I tried a little more pressure with a shop press, but only 2-3 pumps after easy movement stopped. Its enough pressure that the gears bind but not so much that it would have bent the shaft.

I don't see any set screws or pins holding the gears on, so do I just need to use more pressure with the shop press? Or do you guys see something I'm missing in the diagram?

Pins #16 & #17 are a question for me. Why would there be horizontal pins?

 

[pontiac428]

Usually, woodruff keys or keystock is an indicator of a sliding fit. I bet you just have some caca buildup around the keys or shaft, or worse case maybe a key is rocking, but that shouldn't preclude disassembly.

If you have any manual transmission experience, it's pretty much the same deal. Try tools like gear and pulley pullers, press plates and bearing clamshells- that sort of thing will make the job easier. Pull the gears one at a time and lay everything out, you'll be on your way.

 

[rficalora]

Nevermind; I found the problem. No way I put enough pressure on the shaft to do this. It's been like this for a long time. I'm thinking my only option will be to use a die grinder to grind that mangled section of key stock down but I'm open to other recommendations.

 

[rficalora]

Usually, woodruff keys or keystock is an indicator of a sliding fit. I bet you just have some caca buildup around the keys or shaft, or worse case maybe a key is rocking, but that shouldn't preclude disassembly.

If you have any manual transmission experience, it's pretty much the same deal. Try tools like gear and pulley pullers, press plates and bearing clamshells- that sort of thing will make the job easier. Pull the gears one at a time and lay everything out, you'll be on your way.

Thanks. It is pretty much as you expected but worse in that the key is mangled. I'm thinking my only option is to carefully grind the key flush with the shaft. I'm open to other/better ideas.

 

[pontiac428]

Grinding the key down is legit. Maybe the key can be pushed out from the other side after other parts are removed and out of the way. But the key is sacrificial and easily replaced.

Once you get everything cleaned up, that looks like it'll be a good gearbox.

 

[markba633csi]

Looks like the shaft has some scratches on it but you don't want to add more if you can help it- the key is expendible
Try to tap it out if possible as John mentioned

 

[rficalora]

Thanks both. I believe once the damaged part of the key is flush or even slightly below the shaft, I should be able to get the shaft out.

@markba633csi - I didn't see scratches on the shaft when I looked at it (although I'll admit I didn't have my readers on). I think what's showing in the picture is grease lines from me trying to wipe the area to see it better.

Worst case, I do have a couple of friends with lathes so if it comes to it I could repair or remake the shaft.

 

[rficalora]

UGH!

It just occurred to me that simply grinding the key flat to the shaft isn't going to solve the problem -- because that's just the exposed portion. For the key to be doing it's job, it HAS to be proud of the shaft so it engages the key groove in the gears. If I grind that exposed portion, the rest of the key thats still under the gear will do the same thing when I go to remove the shaft again. There must be (or have been before the key got mangled) a way to slide the gears to expose the key and remove it before sliding the shaft out.

Make sense?

Other ideas?

 

[tq60]

No, not flat to shaft!

The end of the key is TALLER, preventing it from sliding out.

All you need to do is remove the tall part.

A GOOD carbide in a die grinder requires very little applied pressure so easy to control the cut.

Simply remove that high spot and the key should slide through.

Stay away from the shaft, it was slid into where it is, it will come out same way.

Sent from my SM-G781V using Tapatalk

 

[rficalora]

...it was slid into where it is, it will come out same way.

That's definitely the truth! Somewhere around 3am when I couldn't sleep, the light came on. There is no key groove in the side of the case where this shaft goes through so the key could not slide out with the shaft. That meant the gears had to have been slid over the key after (or as) the shaft was installed. I didn't see that as possible because the gears had already moved on the shaft some when I had tried to remove it so the gap wasn't a gear width wide (or even close). Once the light came on in my brain (I'm slow sometimes!), I tapped the shaft fully back in. I was then able to get the gear to move the rest of the way off the key and remove the key. It wasn't easy - there's a lot of old, dry grease and trash but once it freed up, it slid without too much effort.

So, I have the gearbox fully disassembled. Next step is to assess the damage (shaft *looks* ok but either the hole is damaged or maybe the shaft is tweaked because its not rotating freely like it should. More as I clean things up to better inspect.