Front end shimmy 1988 Volvo 745

[Sympol]

Hi,

O previously posted a problem with my 1988 745, regarding an odd vibration that appeared and disappeared seemingly at random. I believed that this was either a wheel bearing or brake problem. After replacing wheel bearings it seemed most likely that the problem was caused by the brake pads moving slightly so that they contacted a ridge around the outside of the disc.

Whatever, the problem went away for a couple of months - presumably as the brake pads wore down.

However, now a new random problem has appeared. For no apparent reason, I start to get a slapping noise from the front, apparently from the wheels as it is a regular pattering that increases and decreases as I speed up or slow down. It is accompanied by shaking in the steering wheel. When this first happens, it only appears in the straight ahead position - turning the steering slightly left or right will stop both the noise and vibration. However, as the problem gets worse - which can take a couple of km - turning the steering has no effect. Then, after a random time - anything from 3 - 10 km, the problem disappears again.

Tie rod ends (outer) were replaced around a year ago, tyre pressures are fine, there's no sign of abnormal tyre wear and as mentioned, both wheel bearings replaced a few months back.

I intend to put it up on axle stands later today and check for wear, but would appreciate any pointers or clues as to what to look for. One thing I did notice was that the power steering fluid level was very low - could this be a factor?

Any help much appreciated...

[mrmeringo]

Renew the fluid and see if that eliminates it

[Sympol]

Thanks - I topped up the fluid to the correct level, but it made no difference, unfortunately.

I checked yesterday with the car up on axle stands and it seems all the rubber bushes are pretty well shot - probably the originals, very dried, cracking and stiff. So it looks as if next weekend will be spent trying to locate and replace all these. I'm a bit hampered as my swedish is not so good when it comes to car parts, so I think I'll need to take in a diagram of the front of the car and try to point to the various bushes I need...

[mrmeringo]

If its the pump,it would be easier just to swap the pump itself

[mrmeringo]

Originally Posted by Sympol

Thanks - I topped up the fluid to the correct level, but it made no difference, unfortunately.

I checked yesterday with the car up on axle stands and it seems all the rubber bushes are pretty well shot - probably the originals, very dried, cracking and stiff. So it looks as if next weekend will be spent trying to locate and replace all these. I'm a bit hampered as my swedish is not so good when it comes to car parts, so I think I'll need to take in a diagram of the front of the car and try to point to the various bushes I need...

When u topped the fluid up. did u keep turning the steering wheel left to right a few times?

[Sympol]

Yes, I followed the procedure in my Haynes manual - 'Fill the reservoir to MAX, Start the engine and let it idle. Turn the steering wheel from lock to lock a couple of times. Top up the fluid if necessary. Repeat until the fluid level is constant'.

I'll try again just in case there is some air in the system still.

It's still confusing me why the problem is so intermittent - when it's not there, everything is just fine and normal, but it appears without any predictability and disappears just as mysteriously

[mrmeringo]

It does seem odd,its either air locks or swap the full pump then

[Sympol]

Thanks for your comments - you seem pretty confident it's the power steering causing the problem! However, I think I'll try replacing those dodgy rubber bushes first, as they are certainly past their best (and they're cheaper than a recon pump!) before dismantling the power steering.

[stephend]

Might be worth swapping the rear tyres to the front and vice versa, in only just to eliminate wheels/tyres as the cause of the problem?

[Sympol]

Good point. I'll try that this afternoon before I have to go out to work and see if there's any difference.

The intermittent nature is still a mystery - it's as if the wheels come and go out of phase with each other. The symptoms are like a badly out of balance wheel but there are no balance weights missing, nor large stones etc. embedded in the tread. It's difficult to determine if it's just one or both wheels involved.

Another possibility that I discovered while researching the internet is the inner tie rod ends. There does seem to be some play when rocking both front wheels sideways (holding at the 3 and 9 o'clock positions) but again, being on my own it's not easy to rock and check at the same time. It seems to be quite a job to change the inner tie rod ends.

Anyway, swapping front/rear wheels will eliminate one possibility - thanks for the tip...