9 replies to this topic

[PurpleEd]

1971 mini with a 1275 A+ fitted, stage 1 with a SU HIF44 carb.

After driving for a while when the engine gets warm the accelerator pedal becomes stiffer and needs quite a bit of pressure to push the pedal down.

A new cable was fitted a couple of months ago and I have removed the pedal bracket and greased it and checked the carpet isn't fowling it.
Does anyone have any other suggestions as to why this happens?

Thank you.

[Dan]

Check that the engine earth cable is in good condition. If it's not the engine tries to earth through the control cables and brake lines which is fine for the normal running current but not for a couple of hundred amps of starting current. This tends to degrade the cables very quickly as they overheat and start to weld up internally. The plastic lined types melt a little inside. So a new cable would only take a few weeks to turn into a worn out cable.

[MRA]

May also be on your exhaust manifold

[PurpleEd]

Thanks, It's not in contact withe the manifold and I shall check out the earth cable.

[MRA]

Is the stiffness over the complete travel of the pedal or just at certain points, such as immediatly after a throttle off position ? ie if you take your foot off the pedal does it do it then ?

If so have you just had the carb fitted with new spindle bushes ?

[PurpleEd]

The stiffness only appears once the engine has been running a while and yes it is after a throttle off position and it is the initial re-pressing of the pedal that is hardest, makes for a jerky start sometimes, but the pedal feels tight throughout it's travel. I haven't had new spindle bushes fitted to the carb myself and I have had the mini six months and done a a 1,000 or so miles in it.

I have re-routed the cable so it's not as close to the manifold but as yet I haven't had time to take the mini out to test it.

I replaced the engine earth strap a while ago and have checked it is still secure and it is. I have the battery earth running through a cut out switch (the one with the big red plastic key) could this cause a weak earth?

[Dan]

Could do because those FIA cutout switches are absolute garbage but a high impedence earth at the battery wouldn't affect the performance of engine earth at all. It would just stop the starter and usually everything else working!

[MRA]

Have you adjusted the throttle linkage at all.... ie turned the idle down ?

[TopCatCustom]

Have you detached the cable from the carb, so you can eliminate the pedal on its own, then the cable, then the carb? There are only 3 seperate items involved so if you isolate which one it is it should be easy to sort it out!

[PurpleEd]

Hello again,

Thanks for more suggestions.

Yes the idle screw has been 'used' when I re-set the timing after a new electronic ignition module was fitted.

I removed the FIA cut out switch took it for a drive and throttle became as tight as always. I then disconnected the cable to see whether it was cable or carb and it was the cable. I have squirted lots of WD40 inside it and left it to sit. The cable feels much more free now. I shall take it for another drive shortly to see if the problem returns.

Thank you.