Suntour dual pivot deraileur

[astrocan]

Does anyone know anything about these?
Its a Suntour deraileur fitted to a mid 80's Raleigh mixte frame. The only other identifying mark on it is 'Maeda Ind Japan' stamped on the inner paralelogram plate.
I hope that the pictures show that it has two pivot points, one at the end of the paralelogram and another built into the upper jockey wheel.
I just can't figure out how to get it working and maintain good tension on the chain. I wouldn't be surprised to find that chain length might be more critical than usual, more worrying is I think that it will only work properly if the paralelogram rests nearer the horizontal, about 30 deg anti clockwise from where it currently rests.
I have tried the adjuster screw but it is not nearly enough to make a significant improvement and wonder if the donor bike this came off had the stop on the hanger in a different position.
Any advice or insight gratefully recieved, I would like to get this built for my better half before our aniversary next week.

 

[midlife]

Suntour slant pantograph mechanism is meant to be nearly parallel to the chainstay. Have you go it a pic from the side?

Suntour had their own dropouts with a bigger bit of metal firming the stop, shouldn't make that much difference apart from the screw not quite touching the dropout notch.

Shaun

 

[astrocan]

I have a picture from the front which shows that the paralelogram is much nearer vertical than horizontal and, as you suggest, nowhere close to paralel to the chainstay.

 

[astrocan]

I've been spending a bit of time looking at pictures of slant paralelogram Suntours and notice that many are fixed to claw type hangers like this.

The hanger on my bike is cast into the dropout and wonder if this is where the problem lies.
Any suggestions about if I can get this derailleur to work on this hanger?

 

[midlife]

It shouldn't make any difference, have you screwed in the screw that touches the hanger stop too far? If anything the hanger you have allows the mech to rotate too far forward.

Can you post a pic of yours identical to the above?

Shaun

 

[ChrisEyles]

This site might have some interesting info on the derailleur:
http://www.disraeligears.co.uk/Site/SunTour_derailleurs.html

Should give capacity and maximum sprocket size, but probably no practical advice on setting it up... Good luck though!