front end shakes (c900)

John B · 2005-11-25T23:23:21+00:00

Hi,I did a fair amount of driving over the last couple days (what with the holidayand all) in my 1992 900 (NA). All was well yesterday, and most of today, untilright around dusk. While driving on the highway, the front end of the carsuddenly started shaking violently. I backed of the accelerator, and it seemedto abate. Turning left or right had no effect. I couldn't tell conclusivelywhich side of the car was shaking, but it seemed like perhaps the right.I pulled over, jacked up the front of the car (hydraulic jack and jackstandshandy in the trunk/boot), and inspected things: wheel lug nuts, tire inflation,ball joints, CV boots, etc. Everything seemed OK, so I kept driving. And thevibration continued. I eventually determined that I could make it temporarilystop by stomping on the gas, or by laying of the gas completely. Cruising alongwith a moderate amount of gas, especially downhill, seemed to be the worst.When I got off the highway onto two-lane country roads (generally doing 45 - 50mph), the problem did not manifest itself at all. Based on the symptoms, I think the problem must be with the driveshafts. Theright side inner driver was replaced within the last two years. CV jointproblems generally manifest themselves only when turning, no?Any and all suggestions appreciated.Thanks,John

Nov 25, 2005 23 Replies

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John B 20 years ago

Thanks for the suggestion, but: A. I have the 16 (round) spoke alloy wheels, and B. This is an intermittent problem (so far).

Yes, certainly would be much easier. Although I'm starting to think that replacing the left inner driver would be good to do anyway as preventive maintenance, since it's original to the car and the right (exhaust) side has already been replaced. In which case I might as well replace the whole LHS drive axle with a rebuilt one.

For the moment, I'm waiting to see if the problem recurs.

John

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Craig's Saab C900 Site 20 years ago

A side-issue.... Apparently the seals for the pinion shaft in these power steering units can be replaced without removing the rack? One of the Ebay sellers that markets seal kits says that can be replaced with the rack in-situ, so I'm keen to know if that's possible.

Craig.

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Craig's Saab C900 Site 20 years ago

Well I guess given that, it's possible that it could simply be a wheel imbalance which only showed up when you were driving at a speed which would cause the wheel to rotate as what would be the resonant frequency of the out of balance wheel.

I'm not sure how to calculate what that would be, but I'm guessing normal driving wouldn't get a wheel to rotate fast enough for something like that to actually occur. I could be wrong though. 8-)

Craig.

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John B 20 years ago

Unlikely, as the shaking occurred over a range of speeds between 55 and 75 mph, and I've driven a fair amount at those speeds since with no problem. I still think the most likely thing is an axle bearing on its way out.

John

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