Wobble under firm acceleration

Ezkaton · 09-08-2016, 07:14 PM

Hello all,

So, I recently purchased a used 07 Ford Focus Zetec (auto), and everything was perfect for the first month, and two weeks ago she started getting a wobble when going up hill. Having never owned a FWD car before I wasn't sure if this was normal or not, so I ignored it.

Then I started noticing the same wobble under firm or hard acceleration when travelling at, or above 45-50km/h on flat.
Light acceleration produces no wobble.

Obviously the harder the car is pushed, and the faster the speed you achieve, the more intense the wobble gets. I can feel it through the car itself, not really the steering wheel or pedals, etc. At the same speeds, as soon as accelerator pressure is released, the wobble is gone. Just cruising with light acceleration is also fine. No wobble.

The car idles fine, no engine shaking... everything is perfect until I give her the old lead foot going uphill, or at speeds over 45-50km/h on flat. The car also produces no odd, or out of place sounds.

I practiced the art of Google-Fu, and discovered this is a fairly common thing, and some suggestions led me to the following checks, which I made this afternoon...

Check for play in front wheels
Check for play in CV joints
Check for tears in CV boots
Check for grease on, or around CV boots

All a negative.
Most forum threads I've discovered never came to a conclusion... I'm assuming the owners fixed their problem and didn't come back to update others on what the problem actually was.

I should also note the previous owner replaced the engine mounts not long before the sale as well.

So here I am, looking for answers!
Hoping I can avoid a trip to the mechanics and sort it out myself at minimal cost.

Has anyone else experienced this issue?
Or perhaps have some insight as to what other things I should check out?

Thanks.

marg99 · 09-08-2016, 07:53 PM

worn CV joints usually produce a noise at low speed on sharp cornering.
Failing wheel hub bearings sometimes show up as faults in the ABS brakes as the wheel wobble means the pick up unit fails to read well. or the brake pedal depresses further than usual because the disc rotor in not traveling true and pushed the pads further apart.
Failing that it may just need a wheel alignment

Ezkaton · 09-08-2016, 08:07 PM

Quote:

Originally Posted by marg99

worn CV joints usually produce a noise at low speed on sharp cornering.
Failing wheel hub bearings sometimes show up as faults in the ABS brakes as the wheel wobble means the pick up unit fails to read well. or the brake pedal depresses further than usual because the disc rotor in not traveling true and pushed the pads further apart.
Failing that it may just need a wheel alignment

Hmm, well I hear no noise during low speed sharp cornering.
The rotors seem fine too, wouldn't I feel it during braking if the rotors had an issue?
It also had a wheel alignment before being sold to me. If it was an alignment issue, wouldn't I feel this wobble in all conditions... and also through the steering wheel?

It's literally *only* happening during firm/hard acceleration, or driving up a decent incline.

Muttley098 · 09-08-2016, 11:03 PM

Have the CV joints/driveshafts been replaced with after market parts? I had an 06 focus that needed CV joint replaced, used after market part supplied by the repair shop and afterwards there was a wobble on acceleration. Took it back, they swapped the joint/driveshaft again and then it was fine. Presumably the first replacement was slightly out/unbalanced which caused the vibration.

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DZFord · 10-08-2016, 11:39 AM

Quote:

Originally Posted by Muttley098

Have the CV joints/driveshafts been replaced with after market parts? I had an 06 focus that needed CV joint replaced, used after market part supplied by the repair shop and afterwards there was a wobble on acceleration. Took it back, they swapped the joint/driveshaft again and then it was fine. Presumably the first replacement was slightly out/unbalanced which caused the vibration.

And I had the exact same problem. I went through 3 (yes, 3) Pedders CV shafts under warranty for the exact same wobble / vibration under acceleration. I fixed it by putting in a used but genuine Ford CV shaft, problem fixed.

Peter B - CV8 · 10-08-2016, 11:50 AM

Matching tyres on the front/rear ??

CatonaPC© · 10-08-2016, 12:12 PM

Does it have the standard wheels? That is, it doesn't have aftermarket alloy wheels?

Ezkaton · 10-08-2016, 06:46 PM

Quote:

Originally Posted by Muttley098

Have the CV joints/driveshafts been replaced with after market parts? I had an 06 focus that needed CV joint replaced, used after market part supplied by the repair shop and afterwards there was a wobble on acceleration. Took it back, they swapped the joint/driveshaft again and then it was fine. Presumably the first replacement was slightly out/unbalanced which caused the vibration.

I don't think so. The previous owner is a Ford Technician... and if anything needed replacing I'm sure he'd only use genuine Ford parts.

I'm still in contact with him, so I will ask, but he didn't mention it when he told me everything that had been done/replaced/fixed on the car throughout its lifetime.

Quote:

Originally Posted by Peter B - CV8

Matching tyres on the front/rear ??

The front right is the only different tyre, but the problem didn't exist initially. If it was the tyres, wouldn't it have been there from the day I drove it home?

Quote:

Originally Posted by CatonaPC©

Does it have the standard wheels? That is, it doesn't have aftermarket alloy wheels?

Yup standard/genuine Ford wheels to my knowledge... for now. ;)

CatonaPC© · 10-08-2016, 09:31 PM

Quote:

Originally Posted by Ezkaton

and two weeks ago she started getting a wobble when going up hill.

Then I started noticing the same wobble under firm or hard acceleration when travelling at, or above 45-50km/h on flat.
Light acceleration produces no wobble.

This might be a long shot, but could this be a drive shaft problem? Or indeed the new engine mounts are not quite up to spec and causing torsional twist of the whole engine under power? My first inclination was to point to torque steer but I don't think this car would have that problem. Obviously there is something not quite right.

Ezkaton · 18-08-2016, 10:25 AM

Quote:

Originally Posted by CatonaPC©

This might be a long shot, but could this be a drive shaft problem? Or indeed the new engine mounts are not quite up to spec and causing torsional twist of the whole engine under power? My first inclination was to point to torque steer but I don't think this car would have that problem. Obviously there is something not quite right.

I took the car to the previous owner and we went for a drive... within 5 mins he said he knows what the problem is.

A Focus sedan of the same year went into his workplace the day before with the exact same problem.

It is the drive shafts, apparently.

I just purchased the left and right shafts yesterday from an auto parts supplier and we're going to fit them on Saturday morning.

Fingers crossed that all goes well and it rectifies the problem.

DZFord · 18-08-2016, 08:44 PM

You may also need the following hardware (if you're doing this job by the book, that is):
- New wheel hub retaining bolts for each CV shaft, they are single use only
- Ford also recommend a new bearing cap and the two associated nuts on the drivers side shaft. The cap retains the bearing found on the intermediate shaft section

The list price for a genuine Ford shaft is >$1000 EACH. If installing aftermarket shafts doesn't fix your issue, you can try installing used genuine Ford shafts, which are still probably better than an aftermarket shaft of questionable quality (as I found out).

Ezkaton · 19-08-2016, 03:20 PM

Quote:

Originally Posted by DZFord

You may also need the following hardware (if you're doing this job by the book, that is):
- New wheel hub retaining bolts for each CV shaft, they are single use only
- Ford also recommend a new bearing cap and the two associated nuts on the drivers side shaft. The cap retains the bearing found on the intermediate shaft section

The list price for a genuine Ford shaft is >$1000 EACH. If installing aftermarket shafts doesn't fix your issue, you can try installing used genuine Ford shafts, which are still probably better than an aftermarket shaft of questionable quality (as I found out).

Yeah I was quoted about $1800 for both left and right genuine Ford parts... bit steep for a car that cost me $7500 complete with less than 80k on the clock.

I'll mention those bolts, bearing caps and nuts to the previous owner who is doing the work for me. He works at Bayford here in Melbourne so you'd like to assume he knows what he's doing, but I'll bring it up anyway just to be sure.

DZFord · 19-08-2016, 03:25 PM

He should definitely know then! All the best with the repair

Ezkaton · 20-08-2016, 12:26 PM

Quote:

Originally Posted by DZFord

He should definitely know then! All the best with the repair

Left and right drive shafts swapped out, wobble is gone, and the car also feels more responsive.

One small thing I noticed on the drive home, the steering is slightly off.
If the wheel is straight, it will very slightly drive to the right. It doesn't pull, but I guess the balance is off now?

Easy fix?

CatonaPC© · 20-08-2016, 12:51 PM

Quote:

Originally Posted by Ezkaton

If the wheel is straight, it will very slightly drive to the right. It doesn't pull, but I guess the balance is off now?

Easy fix?

No, balance has to do with wheels and tyres.

If the car tracks slightly right when your steering wheel is straight, then this means the steering wheel wasn't centred when everything was put back together. As long as your car is not pulling to the right (which will require a wheel alignment) then it is an easy fix. Go back to your mate and get him to centre the steering wheel. It's a 5 minute job. Should have checked with a test drive.