Wandering front mech issues!!!

[Grannygrinder]

A little advice if you please.
I am currently running 8 speed Dura ace down tube shifters with a more modern 9 speed Ultegra front mech(until i find a braze on Dura ace item).
All is well when in the smaller front ring but when the big ring is called into use the front mech gradually slips back down towards the smaller ring.
I have tightened the bolt that the front shifter is attached to the frame with to the point where i'm scared i will break it in an attempt to stop it moving back, with no joy
Is it that earlier mechs for use with DT friction shifters are sprung in a different way to more modern indexed mechs which are effectively held in place by the shifter?
All help gratefully recieved

 

[Midlife]

Presumably the seat tube is a standard 28.8 mm diameter? maybe because it has a braze on already it's a nonstandard size.

Pulling down the front mech with the shifter cable is tricky to do................

Shaun

 

[glpinxit]

To be clear, is the front mech change lever gradually turning and rotating forward or is the mech itself sliding down the seat tube?

 

[Rampage]

Is it as simple as the cable securing bolts not tight enough and the cable is pulling through?

 

[Midlife]

Just re-read it............I guess the braze on mech is sliding down the slot on the brazed on retainer. Is there a washer mising and tou are tightening against the bolt itself and not the mech?

Shaun

 

[Mike Muz]

Re:

Had the same problem with mine . You need either a sprung washer like I used or one of those washers with a sort of square serrated edge for the fixing bolt to grip on to

Mike

 

[Grannygrinder]

Re:

Must be clearer in my questions
To clarify, the front mech appears to be pulling the cable back and the lever is rotating forwards. All bolts are tightened as they should be and are doing the jobs they are meant to do
To my mind the spring in the front mech must be over powering the tension on the shifter lever, but as stated previously i dare not tighten the lever mounting screw anymore for fear of a breakage :shock:

* This evening i purchased Veloce 9 speed shifters and rear mech, need to find a front mech. So i don't think i will be having anymore shifting issues
If anybody needs 8 speed Dura ace downtube shifters and matching brake levers let me know

 

[Midlife]

That's unusual.......even the old style non-indexed downtube shifters could be tightened so that they were almost locked solid. Maybe there's a washer missing on the downtube shifters.

Mind you I'm trying to think of a non-indexed 8 speed set of shimano DT shifters..... I thought by then it was all SIS ?

Shaun

 

[Mike Muz]

Re:

Sounds like the same problem I had with mine . When you attach the lever , you have to push it forward to the front stop , against the spring pressure , and tighten the bolt at the same time . But it does need the aforementioned washer to give the mounting bolt some purchase or it starts to unscrew due to the spring strength of the mech . Not much maybe , but enough to allow the lever to move on its own .

Mike