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  Cattle Grid Effect

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Gearbox (auto)
Vibration at speed
Cattle Grid Effect
Autobox Filters
Oil Cooler Pipes
Manl Gearbox Manual
Auto Gearbox Manual
Rear Axle Manual

Vehicle Various with Autobox
Year Various
Mileage 55,000
Repair Cost circa £650
Repair Part(s) Torque Convertor repair kit
On three occasions over the past six months the same subject has cropped up on the List and we pooled information from many owners to pin the subject down, and perhaps to answer the question.

The question was about a vibration which appeared to be from the rear in automatic cars, when changing up. The first owner compared it with the noise made by the car passing over 'rumble strips' or the illusion lines painted on a major road approaching a roundabout.

Andy started this off on the 31st January 2002: Talking about his wife's Scorpio 2.0 16V auto-

...when the Gearbox changes up to top gear either with O/D on or off, there is a serious vibration from the rear somewhat like running over a rumble strip. After a few seconds this goes away and the car drives smoothly after this.

Jon replied at once with, as it turned out, a very perceptive observation.

Mine also makes the rumble when changing up. A bit more investigation leads me to believe it's the torque converter clutch shuddering as it engages -- if I put my foot slowly down in fourth, the engine revs jump by a couple of hundred revs (upwards) when the engine starts to labour, which I presume is the torque converter clutch letting go (if I put my foot down further the box kicks down with a rev change of 500+). If I then move off the gas I get the rumble again as the torque converter clutch re-engages. Also the rumble seems to occur more obviously when the torque converter gets locked up under significant torque. I haven't been able to observe the rumble in third at all -- if I could I'd expect that the rumble would not be present in third when in sports mode, but would be in economy mode. Is this representative of your experience of the shuddering when you've got the O/D switched off?

Owners replied to other issues that Jon had raised about straight-line stability and aggressive gearchanges, while I posted a TSB that I had seen.

If the build code of your Scorpio is TR or TA then there are issues which have been notified to main dealers.

1) The rear seat belt anchor bolts must have at least 4 mm clearance in the holes stamped in the rear axle crossmember, and
2) There should be a minimum of 10mm clearance between the fuel filter and the differential and a minimum of 13mm between the fuel filter and the rear stabiliser bar.

If you jack the rear wheels up and use axle stands, look up underneath the rear axle crossmembers - there is a hole drilled through them to allow clearance for the seat belt anchorage points. Check the clearance there. If there is insufficient clearance it could be the cause of the rear axle noise you can hear - these holes need to be enlarged, either by a main dealer or a local garage.
Look up at the fuel filter, on the passenger side next to the diff. Check for 10mm clearance there. Then unhook the stabiliser bar and swing it upwards and check there is 13mm clearance. If not you can bend the filter mounting plate until there is.
These items could be the noise you can hear when changing up. (TSB52/1996)

Another cause of vibration could be the prop shaft damper, which was revised in 1996.

This was not helpful, as it turned out. Meanwhile, Andy replied to Jon,

My wife's car doesn't actually make a rumbling sound just has a vibration that feels like running over the rumble strip at the side of the road. The Box is actually not leaking - in fact nothing on the car leaks which is a first for a car that I have had involvement with, even my V reg Galaxy leaks occasionally. The vibration occurs only going up to top gear with OD on or off, so I think it is a speed related thing. As has been suggested by some other emails, I am going to check the Propshaft damper. The car was an ex company Director mobile (as opposed to a repmobile) so I would have thought it should have gone in for any recalls, but then the guy might have been lazy.

After a short pause, the same symptom was posted by another owner on the 6th February:

I am having trouble with the auto box on my 24v Ultima estate 1995,the problem is with the lock up, when in overdrive the car feels as if you are driving over a cattle grid!! Switch the o/d off car is smooth- I have had car in transmission shop at present, been there a week to replace the torque converter. The question is has anyone experienced this and if so was it the converter? I have had the ecu checked for errors: only 3 appeared - right/left bank lean and solenoid c error. A recon box was fitted by previous owner approx 20k miles ago but not sure about the converter. Are boxes a week point on these cars ?

So the phrase was coined - Cattle Grid.

Suddenly I realised that the noise which Jon and Andy was talking about was the same that I had noticed on my 24V Estate, but in my case occurring only on acceleration under load up hill: -

I have the identical model to yours. Occasionally when thrashing I can hear an odd noise from the rear of the car as you describe, but only if I apply too much welly before the box changes down. If I ease off and then reapply the pedal pressure the noise does not re-occur. Recently I had a software update, and I've since noticed that the odd cattle-grid noise is much rarer. I find now that if I know I'm going to need acceleration, I switch out the o/d and raise the revs in anticipation, and then floor it and the noise doesn't happen. I've also noticed that in Sport mode the noise does not occur either. Over the past 3 years the noise has not got worse and the software update has improved it.
If I floor the throttle from stationary the box will change smoothly through all the gears right up to 140mph without the noise, so I think its the lock-up timing rather than a serious problem, at least with mine. If you get the noise every time you try to accelerate hard then your problem is definitely worse.
BTW I had a tecchie listen to the noise once. He agreed it was there and checked the car for two TSBs which mention rear axle noises but the car didn't have those faults, so it was never solved. He reckoned it was axle-tramp due to the sheer torque coming through to the rear wheels. He believes that the 2 litre and 2.3 litre cars don't get it. I would be very interested if any of those owners have experienced the same thing, because it will blow his theory out!

I drive mine with mechanical sympathy and avoid it but if you get the noise all the time then it will have to be sorted.

Andy recapped what he had written earlier:

This sounds like exactly the problem I am having with my Wife's Ultima Saloon 2.0 16V. However mine happens when it changes into top with or without OD on. Feels like running over a rumble strip however the vibrations feels like it comes from the back of the car. I am going to book mine in to check the rear axle, shocks, propshaft and bushes. It doesn't feel like it is coming from the Auto Box itself. I have problems with the Autobox but I am going to get that re-programmed as there is the known harshness problem which can be cured by having the box programmed.

Mike came up with another possibility - programming in the EEC-V - and gave a warning about assuming a mechanical problem instead of a software issue. He had had bitter experience of this, as he relates;

I have had this problem in the past on various occasions on my 24v 1995 saloon. I don't think it is the rear axle though I think it is in the box. and I don't think it is the box at fault I think its the PCM not making its mind up about what it is telling the box to do.

I have just had the engine wiring loom replaced on my car, corroded due to a water leak between the heads from the heater take off manifold. my box has displayed all kinds of unbelievable problems and in the end there is nothing wrong with it. The car has been road tested with the new loom in and it runs perfectly with no quirks and no errors in the FDS.

Also one ford dealer told me that the box was knackered and would need replacing. Stan at Meteor Ford (Brum) tells me it is ok. Apparently one measure of the box condition is how long it takes to put on the power when first put into gear. Allowance is up to 4 secs. mine is just around 2 secs. Over 4 secs and the 'seals' are knackered (which ones I don't know). Stan says mine is fine plenty of life left in it yet the car has done 105k, all but 3 done by me and I have these problems on and off for 3 years.
You can see the story of my box under fault finding - water leaks...
I will ask Stan more about these gearbox issues when I speak to him next and let you know anything interesting.

Meanwhile, on the 7th February Andy replied to my point about axle tramp, and we could rule that out:

My wife's car that does this is a 1995 2.0L 16V Ultima Saloon so I don't think torque causing axle tramp is the problem. Also the car doesn't do this changing through the gears until it hits top gear. I wonder if having the box reprogrammed to fix the harsh gear changes (mentioned in a TSB) will make any difference.

I replied,

Right, that's that excuse out the window, then, thanks m8. It appears its a common thing. Because on mine it happens only on high torque on acceleration, I also wondered if it could be the box not changing down quick enough, and causing the rear axle/prop shaft to resonate. If I'm in sports mode it doesn't happen, which would fit. Have you tried yours in Sports mode to see if it happens?
I just ease off whenever I get the noise so it doesn't bother me too much.

Another owner, Jim, now reported the same symptom:

My 1996 2L / 16V saloon also has the resonation ... normally about 55 - 65mph, always in top, and worse when fully laden. Backing off a little or harder acceleration seems to cure it. I'll try in Sports mode tomorrow.

So the noise was much more widespread than I had ever expected, and indeed it seemed so common that I was surprised that Ford has never recognised the issue in a TSB. So I posted a mail asking for reports from later vehicles, trying to pin down the years for the effected vehicles.

This is fascinating, because I have heard this noise for the past three years and just thought it was my car, or if not then it was just the 24V Estate. Now it seems that the noise effects all Scorpios. If the car had remained in production Ford would probably have researched it and changed the design of the transmission to cure it, but since production ended in 1998 they didn't bother.

The TSB mentions a clearance of the rear seat anchor bolts in the rear suspension arms and the location of the fuel filter too close to the diff or the rear nearside anti-roll linkage. Perhaps my techie was wrong and it is this issue in which case I will re-work mine and report back the result with photos so that everyone else can do the same.

Just to check that it is the axle noise mentioned in the TSBs, can anyone with a 1997 or 98 model reply and say if they have heard the resonation (cattle grid) noise on acceleration in top? Positive as well as negative replies would be useful, thanks. The rear axle was revised in March 1996 so vehicles after that date should not have the noise.

Three owners replied with a good cross-section of Scorpios:

Never heard it in my October 1995 24V
Smooth as a whistle.....our one :-)
Not a dicky......chaps quiet as the proverbial grave.....etc...etc (fingers crossed)!
I've got a '98 24v Estate (nearly 90,000 miles), and have never had any problems with noise from the axle.

Meanwhile Jon persisted with his own theory about the Torque Converter:

If you find a steep hill (I can do it on most gradients, but the 2.9 will
need some load I imagine) and push put your foot slowly down, does the torque converter release noticeably before kickdown? If you then release the throttle so the torque converter locks back up (under high torque as you're on a hill) do you get the noise again?

On my 2l these exact same symptoms seem to be associated with torque converter lock up. (I've been moaning away in the background about this one for months ;-). Someone suggested a leaky torque converter? If I take out my starter I certainly have an accumulation of transmission fluid in the conv
erter housing.

My symptom was different from Jon's Scorpio.

No the only time I ever hear the noise is when I'm accelerating hard between 55 and 65mph - and I'm talking hard acceleration for overtakes - and only for a few seconds and then it dies away. If I ease off the accelerator and then re-apply it the noise has gone.
I am never aware that the torque converter clutch has operated unless I look at the rev counter which suddenly rises or falls - there is no other indication of the lock-up operating at all and the noise does not re-occur.

Meanwhile Mike had had some work done at a Ford dealer, and asked him what the noise might be:-

I asked him about the juddering and when I said it was like going over a cattle grid and that several of us had suffered from it he immediately sparked up and said he knew what it was. He took me to a draw full of auto box bits etc and said the following.

The ATF pump connections to the torque converter - there is a seal and depending on the working of the seal the torque converter lockup clutch is on or off.
The seal is like a piston ring, metal square section and about 1.5 inch diameter and 2 mm by 2mm cross section. This sits in a groove in the body of the torque converter somewhere I think but I am not sure. This ring/ seal is always pushed in one direction and that side of the ring gets worn, so the ring rather than having a square section ends up with a notch worn in the one side. This the allows leakage of oil and the ring can move back and forward in its groove. this causes the problem, the worn ring results in the converter lock up clutch at the front of the box to go on and off rapidly.
Ford describe this as the auto box cattle grid problem. Ford say fit a new converter. Stan says fitting a new metal seal will cure it and he has done it several times.

This may be the answer or it may be something else!!

Well, this certainly fitted the symptom. I replied,

Thanks for that, Mike. Did he happen to say about how much the replacement cost? (gulp)
I've had the noise on mine since 46K miles and it's not got noticeably worse to 91K.

Mike had asked that question!

Well he said it was about 10 hours at £50 an hour to get the box out
and then some work on it. The kits are only 20 quid - he was talking about checking seals and various things once the box is out. So it could be 600 (plus the dreaded vat) unless you are vat registered and can claim it back as business expense of course.

As if to confirm this, Colin Lewis posted his result of work in an Auto Specialist on the 8th February:

Just got my 24v estate back from a transmission specialist ,new torque converter, seal and lock up seal fitted, the very harsh vibration (cattle grid effect) ,seems to have all but disappeared ,but after spending £635 I suppose it should have. The car is now much smoother and the lock up almost unnoticeable. I can highly recommend QAS transmissions in Bristol - very helpful people who seem to know what they are talking about, but the same cannot be said of OLYMPIC WARRANTIES ,who underwrite the warranty that came with car, waste of time and money, basically because converter did not break!! no claim would be considered.

This was by no means an unusual complaint about the 'Warranty' cover sold with used cars.

So from a lot of individual questions in isolation we seemed to have reached a conclusion. The 'cattle-grid' effect was not the matter mentioned in the TSB that I thought it was. The symptom appears to be caused by the wear in a seal in the pump to the Torque Converter.

Then there was nothing on the List for over a month, until Nick posted a mail on the 14th March, reporting some issues with his ABS and air con, but also the following:

MOST Worrying is the throbbing vibration that rocks the whole car when accelerating hard through 60-80 mph as the auto box changes up. I first though that rumble strips had appeared at all motorway junctions! But when accelerating gently none or only slight vibration is felt. The vibrations are very like those felt going over rumble strips or the hard shoulder white lines and only last around 1 second but come in sets of two or three.

Any views?

Mike answered with the result of his investigation into the symptom:

If there are no other strange symptoms it could be a worn seal in the torque converter. There is a seal in a cylinder type pipe that feeds the torque converter clutch and it is like a piston ring in a piston, except it is a ring in a cylinder wall not in a piston, and this gets hammered back and forth and wears thin and then it can vibrate in its groove. My Ford mechanic who is pretty knowledgeable said this was the cattle grid vibration and is well known to Ford. But perhaps only well known to few Ford mechanics.

Now Colin was able to suggest another cause, and this was pause for thought.

I have a 24v estate ,and recently had similar problems with vibration eventually getting worse until on one long run I also lost o/d. I took the car to a company called QAS in Bristol who road tested the car and diagnosed a torque converter problem. Apparently this cattle grid effect is quite common, but they also suggested that the airmass meter may also be having an effect on the problem, and suggested that the converter and seals, be replaced and to run the car for a while. After this was done, the vibration had gone, but the o/d was still slipping on occasions, so the car went back to QAS, a new airmass meter fitted and o/d fault cured. This also cured a problem I had at idle with CC on the revs used to hunt up and down - when cc was turned off it would idle ok. Apparently I have heard since that when Ford were first aware of problem they used to change converter and airmass meter as a matter of course. Hope this helps

This was intriguing - since the airmass meter (or MAF - mass airflow meter) is easily and relatively cheap to replace, perhaps this could be done first? Nick had taken this on board and visited the same specialists, and on the 15th March posted this:

I have been to QAS in Bristol and they suggested it was the airmass meter which needed replacing and this should fix it. But, they also suggested that damage will have been done internally by this fault and I should have the converter and seals done at the same time - £580 gulp!
Should I just get the airmass meter changed? or go the whole hog and have the torque converter and seals changed? or is there a simpler (cheaper!) fix?.

Steve advised a test substitution:

I'd get them to change the airmass meter (10 minute job) and then take it for a drive - if the same symptoms were there I'd get them to put the old one back and book it in for a new convertor/seals

On the 19th March 2002 Allan posted the question again. Had we got to the bottom of it?

Did anyone get to the bottom of the 'rumble strip' sensation some of us are getting when the auto box changes up? I read about possible torque converters or prop shaft but I would like to know if anyone has actually cured the fault. If so, did you do the work yourself? It does feel as if the vibration goes from front to back and I wondered how the torque converter could give this effect. I am not keen to let a garage do the work and I have not been stumped yet with previous mechanical repairs on my last Mk3 Scorpio.

Nick replied to him, hoping that it could be the MAF sensor for economic reasons:

From the conversations I have had, I am a little confused as to how the airmass meter could cause this effect. I hope I can be convinced because it does look very easy to replace DIY, although at £109 it's still not pocket money. Otherwise it's £400 for seals and torque converter replacement which I am assured is a specialist job - poo!

On 20th March I tried to sum up with the following post:

Yes, this thread was fascinating because I had experienced this noise for years and learned to change my driving style slightly to avoid it. I always assumed it was connected to the design of the rear axle, which had been slightly redesigned, and it was a revelation to know many others had noticed the same thing. I think it was Steve Congrave [actually Mike Walsh] who posted that his autobox specialist immediately identified the noise and pointed out the culprit - which meant a gearbox out job. I think someone else said the same thing. One voice did say that it might be the MAF - and this is a possibility. If you look at the page EECV you will see that a fault with the MAF can cause faulty gearshift scheduling and late or early disengagement of the torque converter clutch. I can say, with mine, having experienced the noise from the first at 46,000 miles, that it hasn't got noticeably worse at 94,000 miles and 4 years later. I would have thought that if the MAF were faulty it should have failed altogether. Another thing I might add that since I had a software update the noise occurs much less often. I personally don't plan to start tinkering with the autobox unless something else happens (I'd better touch wood here)

Things were quiet again for another month or so - and then on the 26th May another posting reminds us how common this symptom is In reply to a posting from Oliver asks:

Problems again with my 24v Estate auto box back in Jan this year I had the dreaded cattle grid effect and then complete loss of overdrive, so into transmission shop new torque converter

What is the dreaded cattle grid effect? I wonder if it's the same thing that I get when for example I overtake someone on the motorway and when it changes up into top gear it sometimes feels as though I'm going over a corrugated surface!.

Jon posted : -

Yup, that's precisely what the 'dreaded cattle grid effect' is. Welcome to the 'cattle grid effect club' :) The problem is due to a worn seal causing the torque converter lock-up clutch to oscillate in and out several times when it engages.

The reassuring news is that it may not be as 'dreaded' as we make out. Certainly list members have reported having this problem in excess of three years and suffering no other ill effects. I find that by timing my acceleration to avoid the transmission being under high load when the torque converter locks up (ie. changes to third and fourth and after long medium acceleration when the torque converter lock-up has dropped out) I can avoid the problem to a large extent; which can't be a bad thing.

Mike posted his experience which mirrored mine - heard for some years but not worsening:  

I have had this cattle grid thing over three years but only occasionally.  It may be a combination of a worn part and then the electrics not sure what gear to select and the timing thereof based on a varying hydraulic pressure coming from the worn part. mine always just last a second or so and clears by just taking the foot off for a moment and then letting it settle down and carry on. Whole process just a second or two and only once every month or two, so not too bad.

On 11th June 2002 the subject was raised again in connection with the use of cruise control on the 2 Litre Scorpio. Steve B posted:

I'm sorry if I'm going over old ground - but here goes!
I took my 1995 2.0 16v Ultima auto on its first long run down to Devon last weekend. Taking the opportunity to use the cruise control, I found that on even the slightest inclines the box shifted down a gear and then back up again, seemingly undecided about which gear to be in. I just put this down to the 2.0 engine being a bit under-powered, although I hadn't really noticed anything when motoring without cruise engaged.

After this, I got a couple of jerky gear changes and in a couple of instances I felt what is very accurately described as the "cattlegrid effect."
On the way home I didn't bother with cruise in case it happened again and had a good trip back.
Around town since it has been perfectly normal but I have checked the fluid level and suspect that it is a little low (just above the first notch).
As there is no reference in my handbook to checking this, I'm not sure what level it should be or what fluid to use to top up.
Does this ring any bells with you boffins out there.

After some advice about checking the autobox fluid levels, Allan went on:

Regarding the cruise control and erratic gear changes, mine is exactly the same and it's annoying and disappointing. I usually disengage the cruise just before a hill to avoid the constant up and down shifting and screaming revs that ensue.

I feel there is something amiss with the setup of the 2L cars, although I have checked for software updates and none were available. I would love to have this problem solved by one of the lists electrical boffins.
My previous 2L 8v Mk3 Scorpio auto suffered no such problems and once in cruise mode it never changed up on hills. Generally, I find the new 2L unrefined and it revs too highly at low cruising speeds (3000 at 70mph). Boy do I wish I had gone for the 2.3 or 24v.

Welcome to the cattle grid club! Mine also does this on a regular basis but only usually uphill with cruise on. I am increasingly concerned with the number of reports of list members with this problem on low mileage cars (mine s done 72,000 and the problem has been there for the last 20,000). Perhaps there is some value in approaching Ford about their failing torque converters (this is cited as the culprit) as it may have warranted a TSB or recall.

Again, with reference to my Mk3 with the ALD4 box, it did 170,000 sterling miles and is still going strong with the new owner without ANY gearbox attention needed.


Now, how can we sum up?

On 24V cars the symptom appears to effect only acceleration, can be avoided by easing off slightly on the accelerator and then resuming power. The effect has been noticed for some years without apparently getting worse.

On 2.0L cars the gearbox seems to 'hunt' more when using cruise control, and the cattle grid noise is apparent while the cruise control is breasting a hill and on both up and down changes.

Some cars, of all production years, report no symptom at all, but may be explained by gearboxes or torque converters replaced in service.

Owners have reported that the symptom is well recognised by Ford technicians as the Cattle Grid effect, and it has been reported that a seal ring in the Auto Fluid Pump to the torque converter wears unevenly and causes fluctuations in the TC or TCC. Several owners have reported that a renewal of the torque converter has cured the symptom. A repair of this nature has cost owners in the region of £600 including labour, excluding VAT.

Other owners report that the MAF sensor may aggravate the problem and changing this can have a beneficial effect. This would cost in the region of £120 and can be replaced at home quite easily.

And where is this seal? On the right is the diagram of the A4LDE gearbox pump housing. It is the open end of the autobox in which the Torque Converter sits when the unit is bolted to the engine.

Ringed is the seal, exactly as Mike described it. His mechanic mentions that the seal kit only costs £20, but the labour in changing it is about 10 hours!

Thanks to all contributors for permission to use their posts.

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