Some background on my car before we get to the question.
I drive a 1994 Satrun SL2 with 220,000m on it. In trying to fix this problem, my dad has done the following: replaced the tie rods, belt, spark plugs, spark plug wires, fuel filter, and power steering fluid. Now the car’s all sporty and fast and handles like a dream. But the initial problem is still there.
Anyway, to the problem.
No problem at lower speeds. But between 50 and 70, the steering wheel shakes when I press on the accelerator, and less so when I let off completely, but not when I’m cruising. The car itself doesn’t shake (I sat in the passenger seat while my dad drove it around, and didn’t notice a thing - and I was feeling for it).
I need to know if this is a serious problem, because I’m driving 1,200m in 3 weeks for a move.
I’d take a look at your tire balancing. That often causes shake at those speeds, though not exactly exhibiting the conditions you describe. It is easy and cheap to check, so that is one thing I would try.
Another vote for balancing the tyres (I love that spelling). If that ain’t it ya might have…what…a bent axle or halfshaft or whtever it is they call them things these days.
Normally poor alignment will be manifest as a “pull” to one side or the other while you drive.
The fact that the comdition shows up in the 50/70 range points in the direction of balance.
However it might also be loose wheel bearings.
While experiencing the problem"whip": the wheel quickly left and right–if it clears up momentatily it’s in the wheel bearings,
Have them repacked and adjusted.
You might also carefully observe the wheel at the 25/35 range--------the condition could be there at that speed but less noticeably.
The symptoms of unbalance appear as harmomnics and the 50/70 syndrome could a second harmonic.
I recommend testing at the 100 - 140 mph range, where the symptoms will be more pronounced. This will not only make diagnosis easier, it will also allow you to more precisely define the key harmonic (112mph? 113?) :eek:
Well, near as I can figure it the material composing the tire and rim are not homogenous. In any case, the is a hole in your rim (metal removed = weight anomally) where the rubber valve stem is inserted (rubber added = weight anomally). Additionally the tires themselves may have small variances in materials making part of the wheel assembly heavier in some spots. Flip a bicycle upside down and give the wheels a spin–you’ll notice that when the wheel stops spinning part of it “wants” to be closer to the ground. that’s because that part of the wheel is heavier for one reason or another.
When you get a car tire spinning at higher speeds, the momentum of that heavy spot will be great enough to notice–essentially, because it is heavier, that spot wants to have a larger orbit and so the tire deforms, producing the bounce. The geniuses in the tire shop add weights to strategic point to counter this effect.
Shimmy from wheel imbalance doesn’t normally change with acceleration/deceleration. I suspect a problem in the driveline, most likely related to one of the front drive axles. I’d certainly have it addressed before taking a trip.
A 10 year old car can simply have a worn worm gear. They don’t last forever.
The rule of thumb is to try all the simplest and cheapest things first. Because the things most likely to fail are also the cheapest. Low fluid level is more common than unbalanced tires. Unbalanced tires more common than bad tires. Bad tires more than major mis-allignment…
No one appears to have mentioned this yet but the first thing you should always check with this sort of problem is your tire pressures. If your car is front-wheel drive, the front tire pressures will be 2-3 lbs higher than the real (something like 32 front, 29 rear). Look in the owners manual or inside the door or console for the correct recommended tire pressures. Tire pressures should be checked when the car has been sitting for a while and the tires are cold. And don’t depend on one of those pencil type gauges. They can be more than 10 lbs off. You can find a good digital gauge for $10-15 at most auto parts stores. btw: Tire pressures should be checked at least every month.
Once the pressures have been set correctly, if the problem still exists, then try wheel balancing next. Unfortunately, I have found that some machines are maintained and/or work better than others. So sometimes this has to be done twice at different shops. If you get the tires rotated, remember to check and readjust tire pressures.
Given all that has been updated on the car, pressure check and/or balancing should fix the problem. If not, then you’ve got something seriously wrong.
Balancing all 4 tires shouldn’t cost more than 30-40 bucks. Has your dad looked at the control arms. They have something called Ball Joints. If your ball joint suddenly failed, it could result in a bad accident. On a car with that many miles it may be on its second set of them and need replacement badly.
Another possibility, admittedly it doesn’t go with the symptoms, is a broken motor mount. You can check this by having someone rev up the motor while you look at the engine. If it moves around much it could be a broken mount.
Pardon this question but is the Saturn a front wheel drive? If not, stop reading.
If it is, worn constant velocity (CV) joints in the front drive shafts can cause shimmy. Jack up the front wheels of the car one at a time and up hold one end of the drive shaft and try to turn the other like you are wringing a dishrag. If there is any, and I mean any, even the slightest, play at all in the joint or a clicking noise when to twist back and forth it needs replacing. I bought two replacement shafts for an 85 Honda at a wrecking yard for $50 each and the guy installed them for an additional $75.
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So far, I have ball joints, idler arm, universal joint, and driveline. Am I missing anything?
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I know you said you checked your tires and they’re fine but I’d still have someone else look at them. The 3-4 times I’ve had steering wheel shake it’s been due to the condition of one or more of the tires.
I think Inigo Montoya (first post), David Simmons, and I have made the most plausible suggestion – something related to a front drive axle ( = halfshaft = drive shaft). A key point here is in the description of the symptom: …the steering wheel shakes when I press on the accelerator, and less so when I let off completely, but not when I’m cruising. This indicates that the symptom occurs when there is significant tension between the engine and the drive wheels, which exists during acceleration and coasting but not during cruising.
I have never seen a tire balance or ball joint symptom that changed with the presence or absence of this tension.
Misalignment does not cause steering wheel shimmy. Neither does motor mount wear.
I’m not sure where the universal joint and idler arm suggestions came from, but your front wheel drive, rack and pinion steering car doesn’t have either one.
