Throttle embarrassment today

[RobinLegin]

Having tightened up the inlet manifold nuts as suggested I needed to take the car for a test drive. Just 300 yds from home the throttle opened up and had me accelerating away with 3,000 rpm.
A fellow Stag owner stopped to help as did a neighbour. The problem was identified as the casing to the throttle linkage where it joins the carburettors. It appears the cable casing does not return to the female part that holds it to the carburettor.

it seems I have 2 options. Either crimp the cable casing into the female part or apply grease so as it slides back in.

would appreciate advice

[Rod1883]

I'm a bit confused by your set up Nigel. It does look like the brass part is catching and holding the cable too tight?
Here a couple of pics of my standard set up.

You don't seem to have the bar linkage arrangement?

[KOY 23]

Not funny, I had similar brown trouser moment after fitting an aftermarket carb conversion, the supplier did not deem it necessary to fit a throttle return spring until some years later!

[trunt]

The linkage looks wrong.. maybe that’s just how the image is cropped but there should be some “lost motion” provided by a slit that ensures the cable is not pushed back when the choke is on, I can clearly see it in Rods pics but not yours.. I see there is a non standard kickdown cable..

mine is loose like that but not been a problem as it does have the lost motion that keeps the cable under tension and therefore it does not push back to disengage like that.

less cropped picture would maybe answer that?

Terry

[wilf]

I suspect there is too much slack in your throttle cable which then allows the cable outer to move back out of its socket?

[MandM]

I suspect there is too much slack in your throttle cable which then allows the cable outer to move back out of its socket?

+1 for too much slack, also Rod1883 your throttle cable is too long, that fee end might become snagged on the linkage when you give it a boot full and you will find that your on full throttle, happened to me and mines a auto , had to turn the ignition off but not engage the steering lock , then get out and empty pants as John said. so my cable is now cut right back.

P1090838.JPGP1090839.JPG

[sujitroy]

also. if the return spring it too weak. on pedal or at carb end. It may be returning too slowly and pops out.

[DJT]

My similar 'brown trouser moment' years ago was caused by the excess inner cable fouling the linkage and causing the throttle to stick open!

I'm with Wilf. Looks like too much slack in the cable.

The 'non-standard' kick-down arrangement is the same as mine - ZF 'box.

[mole42]

Having tightened up the inlet manifold nuts as suggested I needed to take the car for a test drive. Just 300 yds from home the throttle opened up and had me accelerating away with 3,000 rpm.
A fellow Stag owner stopped to help as did a neighbour. The problem was identified as the casing to the throttle linkage where it joins the carburettors. It appears the cable casing does not return to the female part that holds it to the carburettor.

That looks exactly the same as mine. Is yours a ZF gearbox?

I've had mine do the same high revs thing but never in an awkward situation so I've never bothered to work out if it's a problem or not. It's only happened when I've been fiddling with the throttle/choke/linkages....

[RobinLegin]

Hm. I’ll take a look as Rod’s looks different to mine. There’s no difference to the set before I took the elbows off to access the inlet manifold bolts.
The bright brass at the bottom of my pictures is I think the kick down linkage to my ZF 4 speed automatic box.
Back to the garage then - management won’t appreciate move hand towel washing!

[trunt]

So that kickdown bracket was normal? My bad.. looked like a modification Which I guess it was!

+1 on it happening when you fiddle around!

Can’t see the slot that keeps the tension on in the original pics.. is it adjusted OK? spring strong enough?

[Rod1883]

Thanks for the comment on my cable MandM - I'll look at that.

Yes, I can see now, it's the kick down linkage that was confusing me.....

[NeilR]

Manually opening the throttle by pressing the linkage (obviously with bonnet open) with the cable too slack can allow the
cable outer to get pushed back & wedge itself against the ferule.

Does look too slack to me, assuming you have the correct gap between the two parts of the linkage.
I thought it's in the ROM, but can't seem to find it, though 19.20.06 step 9 says no play or tightness.

Neil

edit: Found it - 19.15.02 - 'lost motion' they call it.

[RobinLegin]

Been in garage looking at the linkage as suggested. The throttle cable has a little play when I press the pedal. Interestingly the cable for ZF4 auto box cable moves instantly. Best leave that as it is.
I’ll try and take the play out of the throttle cable and see if that helps.

[trunt]

This is hard to describe..

There should be no play in the cable its always under tension., its the lost motion slot that is the key to its operation. You adjust the pin in the slot just before the end of the slot (Distance A in the ROM) so that when you depress the accelerator the pin moves to the end of the slot and only then moves the carb linkage, the rest of the slot allows the carb linkage to move without affecting the cable, for when you pull the choke.. When adjusted correctly the pin is always inside the slot at idle and with choke and the spring on the linkage (NOT the carbs) keeps tension on the cable.

So yes, the cam for the kickdown will move immediately, the carb linkage will move slightly later due to gap "A"