what derailleur is this?

[Estonian]

Bought I new(used) 21 speed runner! What derailleur do I have, i cant understand, so weary..anybody is smarter?
Attached a pic, i can read nothing and I have to tune up the gear system, right now is like a gamble and a bit dangerous.

Pic of the mystery gearbox

Thanks guys if somebody recognises!

Mark

[iandusud]

It's a Suntour of around late 80s vintage.

[Estonian]

The thing is that, i got brakes working fine but gears are rumbling how they want and half of gear changes just dont happen.

Do anybody knows who can tune up my gears in Liverpool area? It was a bit over my pay grade!!!

Thanks guys

[leftpoole]

Clean it! It will most likely work fine after that. It is a Suntour from 1985 era and back then was a very decent gear mechanism.

[Estonian]

The thing is, the biggest fro t silinder does not change to it at all...and the rear 7 little ones, change only half of then..it deffo need a tuneup...but a system that old it difficult to get maintenance info someware...in the middle
i have two small scruws and a 8 korner volt
What i can do..but i got srews moving but
I did not
See any movement to any direction.
I start to like my almost vintage project, best if I had some manual so I can see what something will do..

Sry about the stupid questions but It’s a struggle to fix something with minimal tools and without a stand..but i can do it! If someone shows me what each screw will do...

[Estonian]

I got somewhere. Middle cylynders- there a two srews...if you turn one of then, the position of the chain direction will move- but—i can move it to the right place when its in the smallest cylinder and it runs quietly, but of i want
To adjust it to the middle one...it does not go as well as it should and if I change gear back to the smallest- its out of place again-questin is, why is the other srew ther what is his purpose? Rear ones dont move still- noblver goest to 7(biggest) at all

[Jdsk]

https://www.sheldonbrown.com/derailer-adjustment.html

Are the two screws the high and low limit screws? Do they travel in and out nicely when you turn them?

If they are they control the maximum travel of the changer, but not the quality of change within those limits.

Jonathan

[Estonian]

Two small ones..sending you a pic of the screws

Screws

[slowster]

Watch the Park Tool videos below:

https://www.youtube.com/watch?v=UkZxPIZ1ngY

https://www.youtube.com/watch?v=ZNG7g83lI-s

[Jdsk]

You need to work through this systematically.

I'd use either of:
https://sheldonbrown.com/derailer-adjustment.html
https://www.parktool.com/blog/repair-help

...

Those are the limit screws. They need to allow the changer and chain to travel enough to put the chain on the smallest and largest sprocket. One controls the high travel, the other controls the low travel. They don't affect the change within those limits.

What's the condition of the chain?

What's the condition of the teeth on the sprockets?

Does the gear lever and cable move smoothly when disconnected from the changer?

Jonathan

[Estonian]

I got the this place that i got tha chain on the biggest in the middle and smallest in the rear..but if i change gears, the rear on does not move u til 3-4 gear..need some tuning

[PT1029]

What gear levers does the bike have?
That gear is not index compatible with anything except similar vintage Suntour gear levers due to the cable pull. I have a recollection that the lower end Suntour gears mech were not compatible with higher end Suntour levers (and vice verca, possibly), all to do with where the free play was built in (gear mech or lever) I think.
All from memory of my then boss making a comment in the late 1980's/early 1990's.
If you can't get correct lever, then friction (not indexed) levers will work.

Also check;
The gear/gear hanger (mount) is not bent, the gear tension arm should be vertical (when viewed from behind) when the bike is vertical (so not parallel with the spokes or seat stay).

[TrevA]

If the rear is not changing gear until gear 3 or 4 it sounds like you might have a slack cable. You need to set the limit screws first (as previously described), then you need to undo the nut on the rear mech where the cable runs through and pull the cable tight, then re-tighten the nut. Do this with the rear gear in the smallest sprocket. It should change better, but you can also tune the gears using the knurled nut where the cable enters the back of the rear mechanism.

However, as advised by PT above, you may be better off running everything in friction mode if possible. I had similar problems with a Suntour set up, unable to get it to index properly.