Clavis gauge

Ah - you sort of 'twang' it?

WTF don't they just fit chains and save all this poncing about?

AOL

-- Malc

Exaclty what Ford engine is this for? From the various posts, I gather it's a diesel. Personally I've never even heard the mention of a Clavis gauge in any of the ford (genuine ford, not HBOL*) manuals. I've worked on most variants of the 1.8d, and have never needed any unusual tools for them.

Apparently most makers are going over to this method of tension checking. I think the op said a ford focus

Yep. Then you use an ultrasonic device to watch it move and get the frequency that way - you don't listen to the note as there is no sounder board as you say.

Well get this. The cambelt on the Focus is driven from the injection pump, which is chain driven from the crank. Why there isn't a single chain driving both I have no idea. It wouldn't even require a major re-work of the block but I guess it was deemed too expensive.

Focus Duratorq as fitted in the TDDi Similar setup in the new Fester diesels and the C-max (actually the new Fiesta is quite nice and that was unwarranted...)

Theres several tools needed - the annoying one is the puller needed to take the cam pulley off. I can probably make the rest but that one is looking awkward.

Is it even that much? I thought 440Hz was the A a Major 6th above middle C, meaning 220Hz would be the one just below, and 110Hz, the A below that (lowest space in the bass clef). I really can't be bothered to do the sums right now, but at a guess it's probably around an F (though someone said G, so it could be that).

Peter

-- "The truth is working in television is not very glamorous at all. I just go home on my own at night and sit alone and eat crisps."

Wish I'd known that a couple of days ago. I'll just spend an extra thirty quid and swap the tensioner I think!

The message from "AstraVanMan" contains these words:

No, you're right, it's a G.

I thought the TDDi (75/90PS?) was the predecessor to the tdci? As it's the 1.8, it's still the same endura block, and will be the version with a chain drive to the injection pump, with a small cam belt from the injection pump to the camshaft. If it is this one, then Ford make no mention of using a clavis gauge, as it should have an automatic tensioner fitted. It should be noted, that there have been modified tensioners + cam shaft pulleys for this. I'd presonally get a complete kit from ford (belt + tensioner). Whether the modified camshaft pulley is required depends on the part number on the one that's fitted.

I've just recently fitted a new water pump to a 1.4tdci fiesta, and the only special tools needed were the timing pins (which are an unusual size). The timing belt tension is done using a conventional automatic adjuster.

That is the only non TDCI1.8 engine listed on Ford TIS.

Correct

Early models had a manual tensioner and a clavis gauge was required. I've just been told that I should fit an auto tensioner and set it like that, the manual tensioner not being available anymore. It does require a little filing on the belt shround but that's all.

Ah. That is in fact the official method. The Ford timing belt kits comes with instructions on how the cover has to be cut/filed. Although I've never personally had to do it, I've seen another mechanic doing it. If it still has the original manual tensioner, then chances are there's a new modified camshaft pulley available. I fairly sure that if the old pulley part number finishes AA, then it should be replaced with one finishing AB. I can check this on monday if you want.

Right, again. However, if it's really 98Hz, it's not ultrasonic, but at the lower end of the human audio spectrum.

If it were ultrasonic, it would be amazingly tight. Think guitar strings, which are obviously still in the human range of hearing.

Not quite. Since the sound produced by the oscillating belt is so quiet an ordinary mic cannot hear it. What the sounding head does is measure the distance to the belt from the head using ultrasound like sonar, and measures it several thousand times a second. It uses ultrasonics to actually watch the belt move as you twang it and it can use the positional information to then work out what the oscillation frequency of the belt is.

That would be excellent if you could! I'd also be interesting in knowing if the general public can buy the special tools that Ford supply to dealers to sort this out - I have the relevant six digit finis codes if that's any help.

Thanks.

Ah. Makes sense, I suppose. Hence the cost - and the difficulty of using anything other than the correct device.

Seems a sledgehammer to crack a nut, though.

The message from Chris Street contains these words:

I've just gone and twanged the belt on my Perkins Prima - and I can hear it no trouble. It's a bit higher than 98Hz, but then it may well be 'cos it's on a shorter run than the one being measured on the Ford.

That's what I'd have expected. Which is why I was so curious about the Ford tool. Could be the harmonics present make it difficult to accurately measure the fundamental without special techniques.

I'm still surprised there's any need to set the initial tension so accurately. Given that it won't stay the same for very long.

The message from "Dave Plowman (News)" contains these words:

Perhaps listening to all that boomcrashyboomcrashyblingbling music has deafened all the "technicians".