Stiff linkage on carbs when hot

[Stewart Vacher]

Took my GT6 Mk 3 out for it's first run of the year on Sunday all went fine until up to normal engine temperature when the linkage from the accelerator pedal to the carburetors became tight making pulling away and accelerating jerky. On reaching my destination I lifted the bonnet and checked the linkage but couldn't find anything amiss. Coming back to the car a couple of hours later when it had cooled down ready for the homeward journey it was back to normal, but on reaching normal running temperature the fault returned. I have checked the pedal and the cable and both move freely. My feeling it it must be something to do with the carburetor linkage or butterfly spindles.

Has anyone got any ideas on what it might be and how to fix it?

Any advice that stops me kangarooing down the road would be appreciated. 

 

Regards

Stewart

[Pete Lewis]

HVebyou tried a squirt of grease on the spindles ?

 

if its cable related get a push bike brake cable , cheaper better, but will need a solderless nipple

(end fitting with a screw clamp)

[68vitesse]

Had same problem with my Vitesse some years ago, just moved carbs as far apart as fixings allowed when cold.

Or adjust link bar length at the joint used when setting up the carbs.

Think I have seen carb links with a flexible arrangement to allow for expansion.

 

Regards

 

Paul

[Pete Lewis]

Pauls right yes the z shaped clamp sprung connectors were introduce to improve the older semi fixed plastic and pin arrangement

pete

[68vitesse]

Thanks, couldn't think how to describe it.

A question to ask yourself, what has changed.

 

Regards

 

Paul

[Stewart Vacher]

Thank you Pete and Paul for you ideas.

I Will start by trying the spindle grease option.

My linkage has, I think, the z shaped clamps you discribe and I will try to see that they are not over stretched and still have room to expand when warmed up.

Hopefully I will get a chance to fiddle tomorrow and will let you know how I get on.

 

Cheers

 

Stewart

[Pete Lewis]

make sure its not the outer cable expanding with under bonnet heat which then opens the throttles    always keep some free play in the outer cable to its abutment.

 

Pete

[Stewart Vacher]

Just a quick update guys.

Tried lubrication on the spindles and adjusting the z clamps but nothing changed.

Then replaced the cable with a new one and all now seems OK.

Yesterday I enjoyed a 60 mile trip around the New Forest organised by the Wessex Group for their 'Drive it Day' (Extremely well  run as in previous years).

Not a sign of the problem throughout, so one happy member again .

 

Thanks again for your advice.

 

Stewart

[JohnD]

Had this on Silverback, Pi throttle bodies.  Stuck, wide open.

Finished the race on the FIA cut-out;  ON for the straights, OFF for the bends.  Worked, but could not get back to the paddock, as feathering the clutch was also either full speed ahead or the engine heading for MaxRevs oblivion.

 

Needed new throttle spindles, but I've also added three return springs and it's been fine since.

JOhn