Accelerator cable screech

[Xylaquin]

Yesterday I fitted a new accelerator cable (my old one snapped). Once fitted, everything felt smooth and even better than the old setup.

However today it's creaking really badly and theres lots of tension when operating the pedal.

[youtube]https://youtu.be/ZDJuVRedDb0[/youtube]

The strange thing is, if I go to the other end of the cable in the engine bay and PUSH the throttle at the carb... there's no tension or apparent blockage. I can even see the cable freely push my pedal down. Yet when I go round the front into the car and PULL the cable with the pedal..... CREAK.

Any ideas? I've been told there should be a rubber grommet at the end of the thin pipe the cable goes through, but
A) I've never had one there before and didn't get this noise
B) With the amount of tension, wouldn't the grommet simply be sliced through or pushed off?

[drcdb15]

Last thing first, if the cable is properly lubricated, all the pedal/cable is working against is the return spring on the carburettor cable linkage, and the tension to do that will take some time (years) to wear through the (original hard nylon) grommet. Furthermore, the grommet holds the cable centrally in the tube to stop it dragging on the inner wall.

In my experience, there are two main causes of cable problems on the a/c (I don't know if the Bis is similar as the carb position is different) and they are "the tubes".

The first is the one on the driver's floor on RHD cars which links the throttle pedal across the floor to the cable lever/nipple inside the central tunnel. The second is the tube from the central tunnel through the rear bulkhead into the engine bay. I can't recall if this second one carries the throttle cable or not, but from what you say it does.

Both of these tubes are simply mild steel, and as you can imagine, at manufacture Fiat realised that to avoid corrosion they would have to be galvanised, Ziebarted, Waxoyled and generally anti-corrosion treated to the very highest standards.....

But as that would cost way too much they just thought, sod it, let someone else sort out the problem... and guess who that 'someone' is? Well a year or so ago it was me, but today it's you! 

The only way I can see to really get to the bottom of this issue is to remove the cable(s) from the tube, then ream it out to remove all rust, dust, grot, dead grampy grunts, spiders' nests etc, and douse it liberally with waxoyl. When you re-insert the cables, make sure they are equally doused in oil/WD40/bitumen/tar etc so as to prevent future corrosion.

The Fiats are lovely little cars, but sometimes I look at some details of the design, and I do wonder what they were smoking at the time...

I suppose in Italy where it never rains this isn't an issue. But in the Northern Isles... 

You might try something like this: http://www.ebay.co.uk/itm/White-Cleaning-Brush-Glass-Laboratory-Lab-Tubes-Instruments-Tubing-/191743850686

to clean out the tube. Thread a stiff wire through the tube, hook it to the brush and pull it through completely so that the debris is pulled completely out. Or add wire to both ends and you can push/pull back and forth to give the tube innards a really good scrub!

[drcdb15]

Just had a thought...  iirc, there's another grommet at the REAR end of the tube too, or maybe it's a ferrule on the cable, that should sit/slide into the rear end of the tube - is that fitted/properly located? It's a while since I did this job on my car, but I do recall spending ages getting the cable to sit properly in this tube, and the rear end of it turned out to be the biggest problem as the replacement cable ferrule didn't seat properly on the tube end - maybe there was a stepped ferrule/ring etc that sorted it, but I do recall taking bits off the old cable to get the new one to fit properly.

[Xylaquin]

It's not much different at all in a BIS, this is how it is in mine:


Notice how the cable scrapes against the tube. But it didn't do this before, nor on the day of the installation.
You're right about the other end, it slots nicely into the tube. Although I haven't checked that bit again, will do later.

[Xylaquin]

Well I've ordered another accelerator cable since I've bent that one whilst trying to fix it.

I also ended up breaking the banjo bolt that you fasten the cable to at the pedal end. Hopefully I've ordered the correct size for that (it's head is 13, the main part is 10 and the shank is in between).

Still, the grommet problem remains. None of the usual 126 suppliers stock a grommet for the tube, and I'm having a hard time seeing how the grommet would stay in place/remain intact.. the pressure the cable scraped against the tube was intense.

Don't suppose any of you would mind checking your tube to see what your grommet is like?

[drcdb15]

I wonder....

When you fitted the cable to the bolt at the pedal end, was the bolt free to rotate as the pedal/lever moved?

Looking closely at your video, it looks to me as if the cable is pinched up solid to the lever. The cable needs to be pinched to the BOLT, but the bolt needs to be free to rotate within the hole in the lever. Otherwise, as you operate the pedal, you are attempting to bend the inner cable upwards towards the roof of the car, which is why it is rubbing on the upper inner face of the tunnel tube.

I've had hours of harmless fun trying to get banjo bolts to work on Fiat cables, and found the best thing to do with them is the scrap bin. I had a long chat with Nathan Robinson (lately of Fiat 500/126 engine offers elsewhere on this forum) when he was supplying me with some new cables, and he had come to the same conclusion.

By far the easiest and more reliable system in our humble opinion is to use a pivot bolt or even a simple set screw drilled to take a split pin. A banjo bolt is really intended for fluid transfer, and use as a pivoting cable clamp relies on very precise location of the two nuts to clamp the cable without simultaneously also clamping onto the (in this case) lever.

If you separate the cable clamp function from the pivot function you get a much easier set up to install. You can use an ordinary mild steel set screw of appropriate diameter and length, and drill two holes through it, dia 2mm. Put the screw through a plain washer, then through the lever, then another washer, and then a split pin through the outer hole, This gives you the pivot and the bolt is secured by the split pin. Using a split pin makes it easy to undo but requires no fiddly tightening to avoid unintentionl clamping. It's secure but nice and loose.

Then feed the cable through the inner hole, between the second plain washer and the split pin (you can use a third flat washer under the split pin if you want a really 'good practice' job, but of course each extra washer requires extra lenth in the screw.)

Then add a (screw-on) cable nipple to the end of the inner cable, adjusted to the appropriate position. This gives you the cable clamp. It is substantially easier to set up these two functions separately, especially in a confined space, than it is to try to do it all with a single fixing.

If this isn't clear let me know and I'll do a quick sketch. If you worry that it sounds like a botch, a) it's not, it's perfectly sound engineering, and b) it's not a system critical link - the safety of the vehicle is not compromised in any way by this fitting failing in any position.

If you're worried about the nipple sliding along the cable with time, just put a slight (about 10-20 degrees) bend in the cable beyond the nipple so the nipple cannot slide even if the screw becomes loose.

[drcdb15]

If you want to have clamp and pivot in a single fitting, you need something like this: http://www.jensonusa.com/Sturmey-Archer-Pinch-Bolt

Here the screw clamping on the inner cable can be tightened as much as you like without pressing also on the lever. It depends of course on being availalbe in the necessary length and diameter. As this is for a cycle gear it's unlikely to be a good fit for the Fiat too! You should also add a flat washer to keep the cable from rubbing against the face of the lever.

[Xylaquin]

Thanks drcdb15, I wouldn't mind a diagram!

I'm sure the bolt was free to rotate (although the more I watch the video the more I wonder how)

There must have been something causing the tension inside the tube or further back, as when I disconnected the wire, I couldn't pull it manually with my hand (even when I was pulling perpendicular to the tube).

[drcdb15]

Sketch as promised. Might seem a bit complex for the application when ‘just a simple bolt’ is shown in the manual. However, often the ‘simple’ bolt is so simple it just doesn’t work! This set up will not let you down provided all washers are loose and free to rotate. Also there is no requirement for clamping or tightening of anything except the single nipple screw.

This set up can be used for any type of cable, solid wire as per the accelerator, or multi-strand Bowden, and for heavy or light use, eg clutch, starter etc.

1. Main lever in central tunnel

2. Main pivot bolt – can be plain round bar or threaded – threaded might seem to be worse for wear, but against that the threads will hold more grease.

3. Throttle inner cable/wire

4. Screw-on cable nipple – can be screw type or hex head. Hex preferable as easier to access in tight space, plus you can tighten more using spanner than screwdriver.

5. Split pins in dia. 2mm holes drilled in round bar.

6. Plain washer

7. Larger ‘penny’ washer – large enough that the nipple bears on the edge of the washer rather than the main lever 1. This ensures the nipple remains square to the inner wire 3. If you miss these washers out, the nipple bears on the front edge of the main lever but only on one side so it will cant to the other side and kink the inner cable.



A – this shows that the nipple 4 should be wide enough to bear evenly on the two large washers.

B – pull inner cable slightly to one side to prevent nipple sliding along it if the screw works loose. Don’t bend too far or you won’t be able to straighten it to remove nipple when repair/replacement required.

C – instead of using split pins here you can use a hex head bolt/screw in place of the round bar, but if you do this means you can only dismantle from one end. By using split pins you can assemble/dismantle either end as required.

Obviously grease both sides of all washers before assembly.

[Xylaquin]

Thanks, although I'm guessing this would require you to fabricate the main pivot bolt?

[drcdb15]

Yes, as I said before. But it's not too hard - find a bolt of the necessary diameter and length, use as-is or hacksaw off the hex head. Then drill holes through for the split pins and the throttle wire. 2mm is sufficient for split pins, and OK too for the throttle cable. You don't need to worry about the holes being dead centre or critically aligned, as the pivots in the assembly make it self-aligning in use.

Drilling a 2mm diameter hole through a steel bolt takes only a couple of minutes using a hand drill, a good support (a vice on a bench is best) and a steady hand. Helps if the drill is sharp, but any good engineer wouldn't be using blunt drills, would he ... 

You should centre punch the bolt for the holes, to get the drill started, and only use a power drill if you have a proper drill stand. Otherwise using any other power arrangement will simply result in lots of broken drill bits. Drill bits should be HSS (high speed steel), NOT masonry or wood bits. I'm sorry if I am sounding patronising here but I have no idea of your degree of practical DIY skills, so apologies if I am telling you how to suck eggs, no offence intended.

[drcdb15]

I was going to say that all of the bits you need for this  such as the washers, bolts, split pins etc are readily available on eBay. However, I recognise that being in Orkney you will be hit by delivery surcharges that us soft sassenachs don't have to worry about too much. Against that (never having been to the Northern Isles but knowing the Western Isles quite well) I would imagine you still have the sort of "Ted Glenn" local Mr Fixit and workshop where nothing is ever thrown away that was so useful here too when I was a kid but sadly is now ubiquitously replaced by Wickes and B&Q... 

If you are not too mechanically able yourself and not already on first name terms with this chap you should befriend him at once and he will be able to run up this little gadget for you in just a few minutes. Total cost of parts I'd say is well under a pound, but throw in his labour too and a large single malt should cover it nicely and send you to the top of the queue for any future jobs!

[Xylaquin]

lol, I moved here in January and wondered how the post would be like, but I've only once had an "extra" charge. I think Ricambio don't post here, but their prices are bad enough anyway.

No offence taken though, better to be descriptive for future readers too. I'm expecting a banjo bolt in the post tomorrow, so I'll see if that works first. I'd rather avoid having to get someone to fabricate something (and I don't have the tools for this).

Why on earth is the BIS lever different to the AC... it would save this hassle if they'd kept the knob and hoop arrangement!

[drcdb15]

After having watched Shetland I can only envy your move 

As for Fiat cables, I've found plenty of instances where Fiat seemed to go out of their way to make life difficult and rather silly. For example, at the front end of the 500 and 126 control cables there are assorted little nylon clips and tags designed to hold the cables in place. One cable has an L-shaped rod at its end. Apart from the difficulty of keeping spares, and making life hard for later owners, this must have made life unnecessarily complex even at manufacturing. The plethora of different parts for stocking and assembly procedures must have led to costs that could not possibly be less than any time-saving during manufacture. The administrative load alone of having all these different pre-made cables from different suppliers... well, it doesn't seem to make any sense at all to me. In my experience with the motor manufacturing business, the focus is always on reducing part count and standardising components across whole ranges, never mind just within one model.

I have never yet found a Fiat cable end that could not function perfectly well with a simple nipple/clamp arrangement similar to what I proposed to you. There is much wisdom in the old tried and tested KISS principle, and I have no idea why the good designers at Fiat - so brilliant in other ways - seemed to have this blind spot when it came to control cables.