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Old 04-12-2016   #1
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Low velocity shake

Hello all,

my name is Ari, I'm from Finland and I have a driveshaft problem. Or at least I think so.

The problem car is a Croma 1.9 TDI, 150 hp, auto box, 260000 kms (160000 miles). It shakes at 25-30 km/h (around 15-20 mph) and no, it's not the roadwheels, I change them every spring & fall without any effect to the shake.

So it's a different symptom than the infamous 40 mph shake - I've experienced that too earlier, it got fixed by changing the inner CV joint of the right driveshaft. But pretty soon after that the car developed this low-speed shake.

I borrowed some test equipment from work & attached a sensor to the motor. It shakes at 10-11 Hz, which is quite exactly 3x the rotational frequency of the roadwheel at that speed. And the CV joint has three grooves, right? So with this ingenious diagnose I started to find for help. After that it's been a mild nightmare, two garages trying to find and fix the fault.

First an independent garage changed the left inner CV. After all, the right one had just been changed, so it surely could not be wrong? But, no help. Six months after that, a FIAT garage opened both inner CVs and found that there was significant wear in the right inner joint, which had been running maybe 30000 kms (20000 miles). They changed the joint to an original FIAT part and the shake went away for a moment, but very soon started again, getting gradually worse. So surely it must be the left one this time (they said seeing wear marks in it when they had it open). So they changed the right inner CV, again to an original part, with absolutely no effect to the shake.

I asked to get the changed part and the "tulip" shows some polishing marks but no wear that could be felt by a finger. Several experienced mechanics have also investigated the changed "tulip" and say it definitely is not worn to a point it would cause vibration, so it was changed unnecessarily. An experienced mechanic test drove the car and says the vibration with 99% certainty comes from driveshafts.

At this point I finally got p****d off. The original FIAT driveshaft parts are specific for the auto box, they come from Italy (takes 2-3 weeks) and are hideously expensive. I have paid a LOT of money and my car still shakes. So I stated a reclamation, either wanting my money back or the car fixed for what I've already paid. After all, now both inner CVs are under FIAT's 2 yr warranty for parts and work. As a response, the FIAT garage has promised to investigate the car again for free, and then we would "agree for the fix and the price". The problem is, in my eyes they have totally lost their credibility, and I certainly have become a pain in the butt for them. They may try to suggest some new expensive repair that I can't agree just to get rid of me.

So after all this rant, sorry, background info, I have a few specific questions.

- Has anyone of you experienced this kind of low-speed shake? If you have, what was the cause and how did you fix it? I searched the net and found nothing useful. I repeat: it's not the roadwheels.

- I strongly suspect that the right inner CV has failed again after only 20000 kms (or much less, it's been shaking since early summer). But can an original FIAT part really fail that fast???

- Based on all complaints about driveshaft related shakes, and how people sometimes get them fixed by small things like repacking the joints with grease, it seems likely that Croma's engine-transmission packet is somehow inherently prone to resonate due to even a weak stimulus. So how about the engine mounts, do they become "loose" by age without actually failing? What makes me think about this is that when it's cold (below freezing point) the shake much less notable in the beginning of a journey, but becomes more prominent when the engine warms up.

All help and suggestions really are appreciated.
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Old 04-12-2016   #2
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Re: Low velocity shake

steering wheel shakes?
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Old 05-12-2016   #3
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Re: Low velocity shake

Quote Originally Posted by flisko View Post
steering wheel shakes?
No. The whole chassis vibrates.
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Old 05-12-2016   #4
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Re: Low velocity shake

Quote Originally Posted by ojh View Post
Hello all,

my name is Ari, I'm from Finland and I have a driveshaft problem. Or at least I think so.

The problem car is a Croma 1.9 TDI, 150 hp, auto box, 260000 kms (160000 miles). It shakes at 25-30 km/h (around 15-20 mph) and no, it's not the roadwheels, I change them every spring & fall without any effect to the shake.

So it's a different symptom than the infamous 40 mph shake - I've experienced that too earlier, it got fixed by changing the inner CV joint of the right driveshaft. But pretty soon after that the car developed this low-speed shake.

I borrowed some test equipment from work & attached a sensor to the motor. It shakes at 10-11 Hz, which is quite exactly 3x the rotational frequency of the roadwheel at that speed. And the CV joint has three grooves, right? So with this ingenious diagnose I started to find for help. After that it's been a mild nightmare, two garages trying to find and fix the fault.

First an independent garage changed the left inner CV. After all, the right one had just been changed, so it surely could not be wrong? But, no help. Six months after that, a FIAT garage opened both inner CVs and found that there was significant wear in the right inner joint, which had been running maybe 30000 kms (20000 miles). They changed the joint to an original FIAT part and the shake went away for a moment, but very soon started again, getting gradually worse. So surely it must be the left one this time (they said seeing wear marks in it when they had it open). So they changed the right inner CV, again to an original part, with absolutely no effect to the shake.

I asked to get the changed part and the "tulip" shows some polishing marks but no wear that could be felt by a finger. Several experienced mechanics have also investigated the changed "tulip" and say it definitely is not worn to a point it would cause vibration, so it was changed unnecessarily. An experienced mechanic test drove the car and says the vibration with 99% certainty comes from driveshafts.

At this point I finally got p****d off. The original FIAT driveshaft parts are specific for the auto box, they come from Italy (takes 2-3 weeks) and are hideously expensive. I have paid a LOT of money and my car still shakes. So I stated a reclamation, either wanting my money back or the car fixed for what I've already paid. After all, now both inner CVs are under FIAT's 2 yr warranty for parts and work. As a response, the FIAT garage has promised to investigate the car again for free, and then we would "agree for the fix and the price". The problem is, in my eyes they have totally lost their credibility, and I certainly have become a pain in the butt for them. They may try to suggest some new expensive repair that I can't agree just to get rid of me.

So after all this rant, sorry, background info, I have a few specific questions.

- Has anyone of you experienced this kind of low-speed shake? If you have, what was the cause and how did you fix it? I searched the net and found nothing useful. I repeat: it's not the roadwheels.

- I strongly suspect that the right inner CV has failed again after only 20000 kms (or much less, it's been shaking since early summer). But can an original FIAT part really fail that fast???

- Based on all complaints about driveshaft related shakes, and how people sometimes get them fixed by small things like repacking the joints with grease, it seems likely that Croma's engine-transmission packet is somehow inherently prone to resonate due to even a weak stimulus. So how about the engine mounts, do they become "loose" by age without actually failing? What makes me think about this is that when it's cold (below freezing point) the shake much less notable in the beginning of a journey, but becomes more prominent when the engine warms up.

All help and suggestions really are appreciated.

Hi,
Did you share your technical diagnosis with Fiat. I'd agree that it points to the CV "Tulip" joints. For the M32 manual gearbox the fix is simple, fit Vauxhall/ Opel Vectra C drive shafts. I Think the Croma auto uses the same auto 'box (AF40?) as the Vectra so it may be worth looking at a pair of used Vectra shafts. Fitted them to my manual (not wobble but outer CV threw all its grease) without difficulty.
Engine mounts do go soft or could even have failed. I had this in a Renault 30TX years ago. Popped a CV joint pulling out at a busy junction. Garage broke another one before checking the gearbox mount. Worth checking as a faulty mount could be pulling the CV beyond it's design range of movement.


Robert G8RPI
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Old 05-12-2016   #5
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Re: Low velocity shake

There is a long thread on this subject , put " wobble" or "drive shaft wobble" into the front page search box . You will find nearly all the "cures" we found out . Mostly by trial and error
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Old 05-12-2016   #6
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Re: Low velocity shake

All the above suggestions are good.

With rear-wheel drive, this sort of vibration was nearly always due to the propshaft joints or support bearings, so looking at the driveshafts makes sense. Is one shaft supposed to have a damper on it? And has this dropped off due to the rubber failing?
Additionally, this could be a fault in the differential. Sadly, more difficult to diagnose, and expensive.
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Old 06-12-2016   #7
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Re: Low velocity shake

Quote Originally Posted by ojh View Post
Hello all,

my name is Ari, I'm from Finland and I have a driveshaft problem. Or at least I think so.

The problem car is a Croma 1.9 TDI, 150 hp, auto box, 260000 kms (160000 miles). It shakes at 25-30 km/h (around 15-20 mph) and no, it's not the roadwheels, I change them every spring & fall without any effect to the shake.

So it's a different symptom than the infamous 40 mph shake - I've experienced that too earlier, it got fixed by changing the inner CV joint of the right driveshaft. But pretty soon after that the car developed this low-speed shake.

I borrowed some test equipment from work & attached a sensor to the motor. It shakes at 10-11 Hz, which is quite exactly 3x the rotational frequency of the roadwheel at that speed. And the CV joint has three grooves, right? So with this ingenious diagnose I started to find for help. After that it's been a mild nightmare, two garages trying to find and fix the fault.

First an independent garage changed the left inner CV. After all, the right one had just been changed, so it surely could not be wrong? But, no help. Six months after that, a FIAT garage opened both inner CVs and found that there was significant wear in the right inner joint, which had been running maybe 30000 kms (20000 miles). They changed the joint to an original FIAT part and the shake went away for a moment, but very soon started again, getting gradually worse. So surely it must be the left one this time (they said seeing wear marks in it when they had it open). So they changed the right inner CV, again to an original part, with absolutely no effect to the shake.

I asked to get the changed part and the "tulip" shows some polishing marks but no wear that could be felt by a finger. Several experienced mechanics have also investigated the changed "tulip" and say it definitely is not worn to a point it would cause vibration, so it was changed unnecessarily. An experienced mechanic test drove the car and says the vibration with 99% certainty comes from driveshafts.

At this point I finally got p****d off. The original FIAT driveshaft parts are specific for the auto box, they come from Italy (takes 2-3 weeks) and are hideously expensive. I have paid a LOT of money and my car still shakes. So I stated a reclamation, either wanting my money back or the car fixed for what I've already paid. After all, now both inner CVs are under FIAT's 2 yr warranty for parts and work. As a response, the FIAT garage has promised to investigate the car again for free, and then we would "agree for the fix and the price". The problem is, in my eyes they have totally lost their credibility, and I certainly have become a pain in the butt for them. They may try to suggest some new expensive repair that I can't agree just to get rid of me.

So after all this rant, sorry, background info, I have a few specific questions.

- Has anyone of you experienced this kind of low-speed shake? If you have, what was the cause and how did you fix it? I searched the net and found nothing useful. I repeat: it's not the roadwheels.

- I strongly suspect that the right inner CV has failed again after only 20000 kms (or much less, it's been shaking since early summer). But can an original FIAT part really fail that fast???

- Based on all complaints about driveshaft related shakes, and how people sometimes get them fixed by small things like repacking the joints with grease, it seems likely that Croma's engine-transmission packet is somehow inherently prone to resonate due to even a weak stimulus. So how about the engine mounts, do they become "loose" by age without actually failing? What makes me think about this is that when it's cold (below freezing point) the shake much less notable in the beginning of a journey, but becomes more prominent when the engine warms up.

All help and suggestions really are appreciated.
Ou man... I feel your pain I have exactly the same problem with my croma - 1.9 150hp auto box - the whole cabin is shaking between 20-30 km/h under load. I also changed my driveshafts with new ones, but the problem remained. I also notice that when it's cold the shaking is much less notable in the beginning, but becomes terrible when the engine warms up and the car is under load - when climbing a hill or loaded with more baggage..... So if anyone has a guess what might be causing this ............
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Old 06-12-2016   #8
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Re: Low velocity shake

Quote Originally Posted by portland_bill View Post
All the above suggestions are good.

With rear-wheel drive, this sort of vibration was nearly always due to the propshaft joints or support bearings, so looking at the driveshafts makes sense. Is one shaft supposed to have a damper on it? And has this dropped off due to the rubber failing?
Additionally, this could be a fault in the differential. Sadly, more difficult to diagnose, and expensive.
This is a well known issue with the "Tulip" sliding CV joints on the Croma. The only difference here is the OP has an automatic gearbox so it's not clear if the usual fix of fitting drive shafts from a Vectra C is an option.


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Old 06-12-2016   #9
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Re: Low velocity shake

I was under the impression the auto had different shafts than the manual.Its got to have.So does the 2.4 have the same shafts as a 1.9 auto?
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Old 06-12-2016   #10
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Re: Low velocity shake

Quote Originally Posted by buster View Post
I was under the impression the auto had different shafts than the manual.Its got to have.So does the 2.4 have the same shafts as a 1.9 auto?
dunno for sure but atleast stub axle is same from 2.4 and 1.9 150hp, so that means outer part is same, dunno about the one that goes inside gearbox

pic below is 2.4 driveshaft, got 1.9 driveshafts too but they are still on the car, cant compare them yet


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Old 06-12-2016   #11
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Re: Low velocity shake

I was thinking the shafts from an automatic Vectra C. First thing is what model gearbox is fitted to OPs car.
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Last edited by g8rpi; 06-12-2016 at 21:15.
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Old 06-12-2016   #12
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Re: Low velocity shake

OP here again, trying to answer some of your questions.

>Did you share your technical diagnosis with Fiat.

Yes I did, and got back a "what does that amateur think he knows about cars" look.

As far as I know the Croma has an Aisin AF40-6 box. Driveshafts used with manual box definitely will not fit, different length and number of grooves. And according to my net searches (shaft manufacturers' catalogs, dealers' data) no Opel shafts fit either.

About the engine mounts: it's a known fact in physics that the less a vibrating system is damped, the more sharply and effectively it resonates with an external stimulus at a certain frequency. So I was thinking, if the mounts have become more loose it would make the power unit movement less damped and more prone to vibrate. I doubt the mounts are totally broken, I've asked them to be checked and nothing was found wrong.

> There is a long thread on this subject , put " wobble" or "drive shaft wobble" into the front page search box .

Yep, I'm pretty sure I've read everything about wobbling Cromas in here. Probably twice. But haven't found anything about this kind of low velocity wobble before.

>Is one shaft supposed to have a damper on it? And has this dropped off due to the rubber failing?

Not as far as I know. I'm quite sure that kind of failure even the FIAT garage had noticed.

>Additionally, this could be a fault in the differential. Sadly, more difficult to diagnose, and expensive.

That was also suggested by the first independent garage after their failed attempt. I then let an auto box expert to test drive the Croma and he said it can't be differential, it would make a noticeable noise. There's no noise associated with the wobble, or the 'box.

>Ou man... I feel your pain  I have exactly the same problem with my croma - 1.9 150hp auto box

Amazing! So I'm not alone in the Universe with this after all.

> I also changed my driveshafts with new ones, but the problem remained.

Did the change have any, even temporary effect at all?

I'll take the car to the damned FIAT garage again on Thursday for a new diagnose. It will interesting to hear what they find, or pretend finding.
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Old 06-12-2016   #13
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Re: Low velocity shake

this gearbox is inside croma 2.4

https://en.wikipedia.org/wiki/AWTF-80_SC
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Old 06-12-2016   #14
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Re: Low velocity shake

If the diff has failed should be easy to spot.Drop the oil and look for debris.

The 2.4 has an AF55.
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Old 06-12-2016   #15
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Re: Low velocity shake

Quote Originally Posted by buster View Post
If the diff has failed should be easy to spot.Drop the oil and look for debris.

The 2.4 has an AF55.
you sure about that?
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