Saturday, July 25, 2009

Fixing Strut Mounts

Tonight, I'm having writing withdrawals...

For the past few weeks, the Dodgeasaurus Intrepidus has been handling like a pig, the steering has been hard to turn and there was a combination rubbing/snapping noise coming from the front end when I turned the wheel, regardless of the speed or direction of the said car.

Remember, do these projects at your own risk.

I had my wife turn the wheel while carefully feeling and looking at the spring seats under the wheel wells. The right side hesitated and was the source of this obscene noise. A similar check revealed the left side was hesitating, but not enough to cause problems. In short, the right front strut mount was shot. There is a bearing that allows the coil spring to turn with the rest of the strut without binding on the body.

Problem is that bearing is mainly a plastic, doughnut-shaped cage with about 40 to 50 ball bearings inside covered with grease. A new, or otherwise good bearing will feel gooey and smooth when it's turned. A worn one will feel rough and hesitate when turned after being pulled off the strut.

I jacked up the car and removed the tire and wheel. Looking carefully at the strut, it is a cylindrical, vertical object with a spring at the top and fastened with two bolts on the bottom to the steering knuckle. There is also a tie rod and a stabilizer link attached. The latter is hard to get off and may require cutting and replacement. If either the tie rod or link has been on the car awhile; better to replace them now. I had to use an 8mm and a 17mm box end wrench to get the link off the strut. An 18mm box end wrench will get the tie rod end nut off. A couple good licks to the steering arm adjacent to the tie rod with a ball pien hammer will extract the tie rod. Do not use a pickle fork as it will wreck the boot.

Remove the two bolts with a 1 inch wrench or socket on the nut (do not turn the bolts or you will wreck the steering knuckle). Carefully tap them out with a hammer, but before you do, brace up the knuckle with a tire. It will save the driveaxle from being overextended. If this happens, don't panic. Just don't turn the hub, lift the knuckle and shove the joint back in. If this doesn't work, or the tripod falls apart, you may be buying a driveaxle. Mine overextended and I managed to save it without a lot of grief and no curse words.

There are four nuts holding the strut to the tower and the manual suggests taking off the cowl, wipers, brace, etc. This adds about an hour to the job. I use a 13mm ratcheting box end wrench. The newfangled ones that at like a socket wrench. Just be careful not to drop the nuts. Remove the two in back, loosen the front, all the while holding the strut. Once freed, this thing is heavy and wants to land on the driveaxle. Don't let it hurt the boot, but it will take a little bumping.

Take it out of the car and try to twist the bearing. If you can't turn it easily, the bearing needs to be replaced.

Now let's get dangerous...

Really, the spring needs to be collapsed with a strut compressor you can borrow at some auto parts stores for about $50. Get the one that grabs the spring from the outside. The inside ones won't work. There's more than enough tension in one of these springs to critically injure someone. I've been fixing cars for 30 years and know the risks. They never go away, but you can minimize them by following the directions and using the safety hooks on the tool. One you can wiggle the spring seat with your fingers, this means you can take the strut apart.

The nut holding it together really needs a special tool to get it apart, but I've had no luck finding it. So the other options are an air or electric impact wrench or rattle gun and a socket, or the redneck method. This is peeling back the boot and moving the little orange plastic bumper away from the mount (this is the jounce bumper). The area formerly covered by the bumper can now be held with a pair of vise grips. Don't do this anywhere else on the rod or you'll be replacing the strut. Now take the nut off with a breaker bar and remove the mount and bearing.

The bearing should feel gooey when you turn it. If there is any roughness, replace it. Don't handle the strut too roughly and you won't have to fuss too much with trying to line the spring up. A paint mark on the bottom is a good idea. I just used the indentations in the isolator and was careful.

The new mount/bearing will have hole in the plate with the studs and an indentation that need to be lined up before you put the nut on. Once you line up the spring with the new seat/mount/bearing, line up the hole and indentation. If you can look at the top of the strut as it would be installed in the car from the outside and draw an imaginary line through the steering arm through the rear part of the mount, the hole should be just inside the line when it's put together correctly.

Make sure the compressor can span over three coils on each side of the spring or you will never get the mount back on. Also avoid putting the tool on areas where the spring will be under the mount or strut when you release the tension. This is embarrassing. hold the rod with vise grips or use an impact wrench to reinstall the nut. The rest is reversing to get the mess back together. If the ball stud on the tie rod spins when you try to install and tighten the nut, replace the tie rod with a MOOG part. I've found the TRW parts are junk and will not hold up. Carquest sells MOOG parts under their brand name and they are worth the money.

Make sure everything is tightened to spec before you put the tire back on and again, tighten the strut nuts only or you will be replacing the steering knuckle. It took me about two hours because the driveaxle popped out and I had difficulty getting the strut apart. But it should take about an hour with the proper tools.


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