Front end shaking upon fast acceleration.

[Ionizen]

I’ve had my 02 LW200 for about 5000 miles now, it has 60,000 miles on it. Over that 5000 miles I’ve noticed that if I get on the gas from a dead stop the front end will shake almost feels like the tires are loosing traction. At first I thought this was the Trac Controll as I’ve never had a car with that function.

Many threads on this site later I’m wondering if it’s the differential pin. It’s only happened a dozen times or so as I don’t get on the gas unless I’m in a situation that dictates it. It’s definitely a reproducible issue and not intermittent. Is this something that needs to be addressed before it kills the tranny? Thanks in advance for your time and opinion.

[ssicarman]

The L-series does not have a history of differential pin issues. The S-series does.

Has the suspension been checked? Axles?

Which engine? Auto or manual transmission?

[Ionizen]

It’s the 2.2 Ecotec with auto transmission. With such low mileage I’ve put a bit of cash into it. New brakes, rotors, tires. Suspension to include shocks/struts, inner/outer tie rods, ball joints, stabilizer bars. Also dropped the transmission pan and the fluid was as expected for 50,000 miles, very clean no metal shavings of concern.

Car drives and shifts like a dream. Only issue is when I get on it from a dead stop. I normally drive like an egg is under the gas peddle but on occasion have to get on it and something doesn’t seem right.

[soulsurvives]

Does it only shake from a stop or will it shake the same if you mash on the gas at any speed? Have you tried turning off the traction control to see if it shakes the same? Have you changed the spark plugs and fuel filter? An engine can shake if it's missing or starved for fuel under high demand. Does the shake happen in a particular weather condition? Try shifting manually to see if the shake happens in multiple gears or at a certain rpm.

[Ionizen]

Only shakes from a dead stop. Once I’m rolling 5-10 mph I can get on it all I want. New filter, plugs, and injection cleaner as well. I tried it once with Trac Control off and it still did it. I guess I’ll take it to my mechanic that did the suspension work and get his opinion on the matter. I’ll let everybody know the verdict.

[floridasl22002]

What is your driving style? When you say 'when I get on the gas from a dead stop". Is that traffic light grand prix style?

All vehicles will suffer traction issues when you give it gas from a standing start. On rear wheel vehicles you get 'axle tramp' where the wheels and axles want to go in one direction and spin and inertia is holding the vehicle more or less where it is. Often the axle/wheels will tramp (bounce up and down for a shirt distance) as the vehicle tries to over come all these forces.

On front wheel drive cars you have torque steer, where the power wants to send the vehicle in one direction (not straight) and the handling gets all squirrelly. You will also get a similar tramping as the tires attempt to bit and get traction. Your Traction Control does exactly that; it limits power to the axles to limit wheel spin. Launch control is another version, but Saturns would never, ever need that! LOL.

You maybe need to check you driveshafts for wear. Also control your driving style to different limits on start off and see if that makes a difference.

[Ionizen]

Driving style is fairly conservative. I’m not trying to do burn outs. I drive it the same as my two other cars one being a SL1 and have never experienced this issue before.

My first thoughts were that it just had more power/torque and Trac Control than the SL1 and the tires we’re loosing traction but I don’t think that’s the issue. Feels more mechanical to me. Definitely a head scratcher that is difficult to explain without feeling it. I’ll get it to my mechanic over the weekend.

[soulsurvives]

Without actually looking at the car I'm guessing a bushing or mount. Something has deteriorated over time allowing the front end to wiggle under stress.

[fdryer]

Broken motor mounts?

[pierrot]

Originally Posted by Ionizen

It’s the 2.2 Ecotec with auto transmission. With such low mileage I’ve put a bit of cash into it. New brakes, rotors, tires. Suspension to include shocks/struts, inner/outer tie rods, ball joints, stabilizer bars. Also dropped the transmission pan and the fluid was as expected for 50,000 miles, very clean no metal shavings of concern.

The items which are atypical for replacement on a car with such low mileage are the suspension parts, especially the tie rods, ball joints, and the stabilizer bars. Replacing one of those bars would be unusual enough, but you've mentioned both. Did you really mean this, or did you mean that you'd replaced their bushings? I've replaced only one ball joint and that was well after 200K miles. I have replaced the front stabilizer bar bushings and links (did those shortly after replacing the struts).

Saturn's factory original front brake rotors for the L-Series cars were made of a softer metal and were only meant to last as long as the brake pads. A service advisor told me that they used the softer metal to reduce the possibility of brake noise. If you've replaced those rotors with aftermarket rotors then you'll be able to resurface them and get many more miles of service from them compared with the originals. Additionally, you'll have no more brake noise from the replacement rotors than you'd had with the others.

With regard to the transmission, I've done my servicing at the 50K interval and it continues to function as it did when I purchased it in '01 with 24K miles on it. (Stick with the 50K mile service interval and never do a transmission flush. It's unnecessary and can result in erratic behavior from the shift solenoids at the valve body.)

Originally Posted by Ionizen

Car drives and shifts like a dream. Only issue is when I get on it from a dead stop. I normally drive like an egg is under the gas peddle but on occasion have to get on it and something doesn’t seem right.

I, like others, am suspicious of motor mounts being weak. If you can get under the car, look at the front transmission mount between the radiator and the engine. This one wears out first among all of them. If it is weak then you'll see it very easily at its subframe connection where the rubber surrounding the mounting bolt will have separated - broken away -from the rest of it. Additionally, if this part IS bad then you must replace the mount on the opposite side of the engine (rear transmission mount) or a new front mount replaced alone will suffer premature failure. These mounts depend upon each other to manage the torque stress of the engine. I recommend not purchasing the aftermarket versions of the front transmission mount. Use only the OE brand. I learned this the hard way. The rubber composition is not the same.

BTW, a kind of give away that this might be a mount failure is your description that you feel something odd happening from a dead stop. When these particular mounts go bad the engine "jumps" somewhat after the initial acceleration. This will also occur if there's a need to accelerate more markedly while at highway speeds.

[Sky Pilot]

Originally Posted by Ionizen

I’ve had my 02 LW200 for about 5000 miles now, it has 60,000 miles on it. Over that 5000 miles I’ve noticed that if I get on the gas from a dead stop the front end will shake almost feels like the tires are loosing traction. At first I thought this was the Trac Control as I’ve never had a car with that function.

That's interesting. I have a similar but humorously embarrassing story. From the day I bought our LW new, it was the wife's daily driver. I rarely drove it as I preferred my SS Camaro and then my Sky. So at the end of 2014, I bought the wife a new car and I took the LW as my daily driver. If wasn't long before I, like you, felt a chatter on hard take offs from a dead stop, once it began to chatter, I let off the gas. Unlike you, I thought it was the tranny, so I took it to my mechanic and asked him to check it out. He said he couldn't find anything wrong with it. WTH.... I drove it afterwards and was easily able to replicate the chatter, so, back to the mechanic, this time, I drove with him as co-pilot. Well, low and behold I hit the gas, it chattered, and I once again let off the gas. He laughed and told me it was the dang front tires breaking loose, and as they did, the front end would kinda bump around and chatter as the tires tried to break loose, then grip and the traction control would then attempt to counteract the slippage. When he turn the TC off, and I stomped it, the tires easily broke loose and as the tread would grip the pavement it would bump around, kinda like rear wheel “wheel hop”. That’s why some people install traction bars on their high performance cars (in the olden days). I have always had rear wheel drives, even the Sky is, so the front end breaking loose was a new experience for me, quasi wheel hop.

[Ionizen]

I think that’s what’s happening Sky pilot. It feels like the torque is causing the tires bounce or chatter. Next time it’s with the mechanic I’ll take him for a drive but my guess is he will say thx same as yours. Guess the L has more power than the SL1 because because that’s never been an issue. Just have to be mindful of the tires on the get go.

[pierrot]

^^That's a surprising story, Sky Pilot. I'd not heard of such a thing before, nor have I experienced the problem with the front wheels you've described. (FWIW, my car doesn't have traction control.)

You referred to traction bars and, as I understand it, they're used help keep an axle's wheels more firmly on the road. Are you stating that the front wheels on your LW300 weren't maintaining positive contact with the road surface? What recommendations, if any, were suggested to rectify the problem? How was your problem corrected, or was it corrected?

[floridasl22002]

I tried to explain the 'tramping' phenomana earlier.

We have all see the rwd cars spinning their wheels when they do a burnout. That is about torque and inertia. The torque is the spinning of the tires as they want to go forward. The inertia is the weight of the vehicle and the fact that it wants to stay where it is.

The same scenario occurs with fwd cars, except that on hard acceleration, when the weight is thrown to the back of the vehicle, there become less weight on the driving wheels at the front. With a rwd cat you see the car front rise up and the back bed down as that weight shifts to the back and plants itself over the driving wheels. Here it actually assists with grip as that weight helps push the tires down on the road. With fwd the front rises up and there is less weight and hence less the tires have less grip. The traction control artificially controls all that to limit power and thus torque going to the driving wheels to limit wheel spin.

With fwd cars you also have torque steer where the revolutions of the engine want to spin the car rather than send it in a straight line. To see that happen hard accelerate and take your hands off the wheel. The car will want to go in a different direction to the straight ahead. Saab brought out a top model in the early 00's called the Saab Viggen. it had their best performance engine that produced about 250 bhp to the front wheels. It was a brilliant car and personally I'd love one, but with so much power going to the front wheels, they suffered from horrendous torgue steer.

Tire choice can also cause issues. Satty's were never meant to be performance cars, more daily drivers that were safe, comfortable and economical. The typical family car. The tires for the vehicle were also designed to achieve that. They will not be ultra performance tires and thus will have limitations. That coupled with hard acceleration and you will get wheel spin and wheel tramping as the tires fight for grip.