Changing throttle cable

[Ben33]

I broke the end of my throttle cable the other day... About 30km from home... Thanks to Dad and his brilliant idea of using speaker wire at I was at least able to get the car home though.

So now I need to fit a new cable... How does one go about doing this? The engine bay side of things looks straight forward enough... I'm just not sure what I'm going to find when I take the interior panels off (which looks like a nightmare in itself) and see whats in there.

I'm thinking I'll give this one a go, just looking for some advice from anyone who has had to do it before. It's the 1.5 twin carb motor if that helps.

[Evan Bottcher]

I don't think you need to remove any panels.  The engine bay side runs through into the tub where the brake/clutch masters and pedal box sit, and pass through the firewall, attached via a plastic lug and screw.  On the other side of the firewall the cable attaches to the accelerator pedal arm.  There's a rubber cone stopper that pops out of the top of the pedal arm (above the pivot).  You have to pull it out, then the cable end can be attached to the pedal arm.  Putting the rubber cone back in was tough for me the couple of times I've done it.

Sounds easy right?  It's straightforward, except that you have to hang upside down with your head on the floor and arms contorted and a torch in your mouth under the dash.

[Ben33]

Thanks for your post Evan. Sounds doable, I'll get a cable and give it a go tomorrow and report back =)

[philpot]

Evans post is spot on. My Sud and 33's have had issues with cables that fray on the engine side, between the bracket where the cable moves in and out of the sheath and the linkage...
Good idea to, before you put the new/2nd hand cable on, is to run some light machine oil through the entire thing to lubricate the cable...
The rubber grommet that holds the end onto the bracket above the engine can be a bloody pain to remove/insert in one piece...
Yes, its quite a backarch over the sill to get in under the pedals, but its all straighforward enough to do yourself!

[Ben33]

Successfully fitted today with no dramas with the exception of the cable being longer than the one I took out... Not really a huge problem, just had to figure out a route for it. Reasonably straight forward job otherwise.

I oiled the cable and found the cone on the throttle pedal to be a bit of a nightmare, otherwise all good. Thanks for your help.

[colcol]

Sud \ 33 throttle cables, before you put it in give it a good squirt with silicone spray and work it through until it oozes out the other end, then continue until it is is clean, the silicone spray will not attract dust which will clogg it up, products like WD40 tend to attract dirt, if your cable that is currently installed is a bit sticky and the engine won't idle down, remove the cable from the carby end and hold it up high as you can and then squirt some silicone spray down the cable and work the cable back and forth until the silicone oozes through to the accerator pedal, then you have to adjust the cable, the pedal should have about 1mm freeplay, that is the pedal should move down 1mm before it moves the cable, then the important adjustment is that the pedal should touch the floor before the carby butterfly is open otherwise the cable won't have any freeplay and it will break, luckily there is plenty of adjustment on the cable on the carby side, and also there is a stop under the pedal so that when the pedal is hard against the stop the carby should be almost open, but not quite open, over time the inner cable stretches and this adjustment has to be done every few years, Colin.

[Craig C]

I'm about to do this for my GTV but didn't quite get the bit about the carby not being fully open when the pedal is hard against the bump stop.

Shouldn't it be fully open?

[colcol]

RE throttle cable, Carby's are designed so that the butterfly will open to ninety degrees then go past the centre, so when the carby link is fully open it has usually gone past centre, so you adjust the throttle cable so the carby link is nearly all the way open when the gas pedal is touching the stop on the floor, if the carby link has no freeplay when the pedal is touching the floor it puts strain on the inner cable that causes it to break, [usually miles from nowhere], Phill Irving once said when he did a tuneup, he would adjust the accerator cable so that the minute you touched the accelerator the engine would rev but just before the carby went past centre, and the owner would say how much more power the has after the tuneup!, i hope this makes it clear, Colin.

[Evan Bottcher]

I think I understand you Colin - the accelerator pedal should always be stopped by the stop on the floor, not by the stop screw on the carby itself.  So that you don't put unnecessary strain on the cable.  Adjust the cable and pedal stop so that it's just before the butterfly is completely open, this makes sure the cable is not strained.

Reminds me that I need to go and find a stop screw and put it in the Sud because it's missing.  I certainly put a fair bit of strain on the cable hanging on for dear life at full throttle on the way out of turn one at PI (or over the kink at Sandown, or out of the sweeper at Winton - you get the idea).

[jayarr]

Is there a rubber bung somewhere in the cable cover anchorage for the 33, so that when the carburetor shaft hits the stop, the bung is put into compression? This would presumably limit the strain in the cable until such point as the rubber is fully compressed. The pedal should hit the pedal stop before the rubber is fully compressed.

I'm thinking this is a good idea as it ensures even if the cable if stretched a bit, you will continue to get full throttle, but strain on the cable is not excessive.

Disclaimer, it's been a while since I worked on a 33!

Cheers, John

[colcol]

Rubber Bung on cable at carby is to cushion outer cable as the engine moves on its engine mounts, my car hasn't got one, the cable is mounted directly onto cable bracket and has been for 10 years and seems to work ok, if you are concerned about about getting full power[and aren't we all!], take off the air trumpet at top of carby and move carby arm to ninety degrees, then you will notice it will move a bit more, that is it will go past centre and the air flow will slow down, have the pedal touching the stop on the floor, then have a little bit of freeplay on the cable to carby linkage, and that should lesson the strain on the inner cable, unlike most car makers Alfa has an adjustable linkage to compensate for cables stretching over their lifetime, Colin.