Monaro – Bad Vibrations
Discussion
I have had an infrequent and intermittent vibration problem at high speeds (80+ ish) for a number of months. Sometimes feels as though coming through the floor of the car, but no significant shake of the steering wheel. If I slowed to 60mph the noise/vibrations would slowly go away. Accelerate up to 80mph again and all is fine. On another trip no vibration problems at all. This was a mystery, and I was starting to wonder about the propshaft bearing.
However, today having not driven the car much for three weeks and not having had any time to investigate further, I got onto the motorway and accelerated to about 70mph and had very strong vibrations, this time accompanied by strong steering wheel shakes. Had to slow to about 35mph for the vibration to subside. I stopped and went around the wheels and discovered that the front right hub was extremely hot. Centre part of wheel was too hot to touch. Other three wheels were cool.
Wheel bearing problem? Sticking brake calliper? But brakes seem fine, and touching the brakes didn’t seem to affect the vibration. The tyres are good. A new set of Continental Sportcontac 5Ps was fitted about 5,000 miles ago.
I crept home at 30mph and my local trusty garage man around the corner (who services the car) is going to look at it tomorrow, but he is mystified by the story. Any ideas or suggestions of what he should look for?
Steve
However, today having not driven the car much for three weeks and not having had any time to investigate further, I got onto the motorway and accelerated to about 70mph and had very strong vibrations, this time accompanied by strong steering wheel shakes. Had to slow to about 35mph for the vibration to subside. I stopped and went around the wheels and discovered that the front right hub was extremely hot. Centre part of wheel was too hot to touch. Other three wheels were cool.
Wheel bearing problem? Sticking brake calliper? But brakes seem fine, and touching the brakes didn’t seem to affect the vibration. The tyres are good. A new set of Continental Sportcontac 5Ps was fitted about 5,000 miles ago.
I crept home at 30mph and my local trusty garage man around the corner (who services the car) is going to look at it tomorrow, but he is mystified by the story. Any ideas or suggestions of what he should look for?
Steve
Had the car up on the lift this morning and the centre prop shaft bearing rubber mount clearly split, and largely absent! (The hot front hub must be a separate issue, which I will deal with when the prop shaft has been fixed.)
Much more worrying, I called Monkfish for advice and to order parts and discovered a recorded message saying that they closed the business on 30th August. Still selling their existing stock online, but only working to fill orders and dispatch on Wednesdays. So I ordered a refurbished prop shaft online (easier to fit than the bearing).
Who do we get parts and advice from when Monkfish have completely closed?
Steve
Much more worrying, I called Monkfish for advice and to order parts and discovered a recorded message saying that they closed the business on 30th August. Still selling their existing stock online, but only working to fill orders and dispatch on Wednesdays. So I ordered a refurbished prop shaft online (easier to fit than the bearing).
Who do we get parts and advice from when Monkfish have completely closed?
Steve
Yes good point, and I was thinking about that. The fluid has been changed - but I cannot quite remember when!
It must be overdue.
EDIT: Just checked the service book and the fluid is supposed to be changed every 2 years. Looks like mine hasn't been changed for five years.
It must be overdue.
EDIT: Just checked the service book and the fluid is supposed to be changed every 2 years. Looks like mine hasn't been changed for five years.
Edited by sjr56 on Saturday 23 September 14:46
Extremely disappointed!
This morning took the car on the motorway for the first time since Friday’s prop shaft swap. Got it up to 70-80mph and the vibration started to return, but not immediately. Started with a rumble under the car, which became a strong vibration and eventually started to shake the steering wheel. Had to slow to about 40mph for it to go away, but was then able to speed up to 60 with no vibration. Couldn’t go faster again because I took an exit to turn for home (naturally) and traffic then prevented any speed.
What is going on?
Is the recon prop shaft perhaps out of balance? It was unpainted, but Roger at Monkfish assured me that it had been balanced. The centre bearing assembly was clearly new.
Has the vibration already ripped out the new rubber bearing mount? And if so why? Could it be one of the ‘doughnuts’ at the prop shaft ends that is breaking up? They looked fine. Cannot get under the car to check any of this until tomorrow.
Help!
Steve
PS – Before this test drive I did check the front hub, removed the calliper and the pads, checked the pins on which the calliper ‘floats’ and put it all back together again with the magic Copper Ease grease. Wheel bearing was fine.
This morning took the car on the motorway for the first time since Friday’s prop shaft swap. Got it up to 70-80mph and the vibration started to return, but not immediately. Started with a rumble under the car, which became a strong vibration and eventually started to shake the steering wheel. Had to slow to about 40mph for it to go away, but was then able to speed up to 60 with no vibration. Couldn’t go faster again because I took an exit to turn for home (naturally) and traffic then prevented any speed.
What is going on?
Is the recon prop shaft perhaps out of balance? It was unpainted, but Roger at Monkfish assured me that it had been balanced. The centre bearing assembly was clearly new.
Has the vibration already ripped out the new rubber bearing mount? And if so why? Could it be one of the ‘doughnuts’ at the prop shaft ends that is breaking up? They looked fine. Cannot get under the car to check any of this until tomorrow.
Help!
Steve
PS – Before this test drive I did check the front hub, removed the calliper and the pads, checked the pins on which the calliper ‘floats’ and put it all back together again with the magic Copper Ease grease. Wheel bearing was fine.
John,
We cannot get it upon the lift until tomorrow morning, but will certainly check all that when we do. I don't think 'my garage man' will have left any of the bolts loose, but you never know.
My best guess at the moment is that one of the donuts has failed, and that caused the original split in the centre bearing rubber mounting. Of course when we were under the car and saw the destroyed centre bearing mount we were certain that we had found the cause, and didn't look for anything else!
Tomorrow we will look at everything very carefully!
Steve
We cannot get it upon the lift until tomorrow morning, but will certainly check all that when we do. I don't think 'my garage man' will have left any of the bolts loose, but you never know.
My best guess at the moment is that one of the donuts has failed, and that caused the original split in the centre bearing rubber mounting. Of course when we were under the car and saw the destroyed centre bearing mount we were certain that we had found the cause, and didn't look for anything else!
Tomorrow we will look at everything very carefully!
Steve
Had the car up on the lift this afternoon, and everything underneath looks absolutely fine. New centre bearing is good. Donuts at both ends are good. Bolts all tight. No excessive movement at gearbox or differential end. Backlash in transmission is minimal. While we were there we went around all the rear suspension bushes and they were fine. Drive shafts also looked good. (If there was anything like this amiss I would expect a few clonks when manoeuvring the car, and there are none.)
So I am just left with the possibility that this recon prop shaft is out of balance.
I will try and get Roger on the phone tomorrow and discuss it with him. What else, other than the prop shaft, could this vibration be? Is it possible that this recon prop shaft was not balanced? Might there have been some confusion between them and Dave Mac Propshafts (who reconditioned it) around the time of the closure of the Monkfish business?
If it is out of balance I can probably get it rebalanced locally. There is a prop shaft specialist just a few miles away.
I suppose the other possibility it to get the car onto a rolling road and get underneath it at 70+mph to watch what happens!
Steve
So I am just left with the possibility that this recon prop shaft is out of balance.
I will try and get Roger on the phone tomorrow and discuss it with him. What else, other than the prop shaft, could this vibration be? Is it possible that this recon prop shaft was not balanced? Might there have been some confusion between them and Dave Mac Propshafts (who reconditioned it) around the time of the closure of the Monkfish business?
If it is out of balance I can probably get it rebalanced locally. There is a prop shaft specialist just a few miles away.
I suppose the other possibility it to get the car onto a rolling road and get underneath it at 70+mph to watch what happens!
Steve
So I spoke to Andy at Monkfish last Wednesday, and he thought it very unlikely (though not impossible) that the recon prop shaft would be out of balance. He recommended some proper vibration diagnostics before spending any more time/money on more parts. He mentioned Vibration Free in Bicester, and I will give them a call next week.
However, in the mean time I had all the wheels re-balanced – they were not perfect, but a test run on the motorway revealed the rumble was still there.
I then did some calculations of wheel and prop shaft frequencies and found that the prop shaft is rotating at about 56Hz at 70mph and the road wheels are rotating at about 16Hz. It seemed to me that the rumble was much more like 16Hz than 56Hz. This focussed my attention back on the wheels.
I decided to swap front right wheel with rear right, changing the direction of rotation as well as the position front to back. I also measured the eccentricity of both tyres by rotating them against a straight edge. Both tyres were only out by about 1mm, but I have no idea what might be considered acceptable.
HOWEVER, after the wheel swap I took the car for a test drive on the motorway and the rumble has gone! At least it did not appear during 5 minutes at high speed. I will swap the other two wheels across the diagonal tomorrow and go for a longer test drive.
So this residual vibration or rumble seems to be a tyre issue. They are Continental 5P’s (not directional) and have done about 5,000 miles on the car. Anyone else had tyres do this?
Steve
However, in the mean time I had all the wheels re-balanced – they were not perfect, but a test run on the motorway revealed the rumble was still there.
I then did some calculations of wheel and prop shaft frequencies and found that the prop shaft is rotating at about 56Hz at 70mph and the road wheels are rotating at about 16Hz. It seemed to me that the rumble was much more like 16Hz than 56Hz. This focussed my attention back on the wheels.
I decided to swap front right wheel with rear right, changing the direction of rotation as well as the position front to back. I also measured the eccentricity of both tyres by rotating them against a straight edge. Both tyres were only out by about 1mm, but I have no idea what might be considered acceptable.
HOWEVER, after the wheel swap I took the car for a test drive on the motorway and the rumble has gone! At least it did not appear during 5 minutes at high speed. I will swap the other two wheels across the diagonal tomorrow and go for a longer test drive.
So this residual vibration or rumble seems to be a tyre issue. They are Continental 5P’s (not directional) and have done about 5,000 miles on the car. Anyone else had tyres do this?
Steve
The handbrake was adjusted, but over a year ago, and the vibration is a relatively recent problem. We know we have a problem with the front right hub, so will fix that first before looking for something else.
With a sticky front calliper it is just a shame I cannot take part in the Bathurst 1000 this weekend!!
Steve
With a sticky front calliper it is just a shame I cannot take part in the Bathurst 1000 this weekend!!
Steve
We were able to service the front right calliper yesterday, and confirmed that one of the two pistons was sticking. There was no corrosion but there was a ring deposit in the cylinder, which was easy to clean off, and all was fine when reassembled using the service kit provided by Pedders. The whole braking system was flushed through with new fluid.
I still don't easily connect this sticking calliper piston with the intermittent vibration I was experiencing at speed, but a test drive on the motorway today was completely free from any vibration. Let's hope it stays that way!
Steve
I still don't easily connect this sticking calliper piston with the intermittent vibration I was experiencing at speed, but a test drive on the motorway today was completely free from any vibration. Let's hope it stays that way!
Steve
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