I have a '86 300E, the front strut dust boots need replacement as they are torn. The struts are good, I just wish to replace the boots. If I relieve spring pressure with a jack and remove the top mounting hardware can the boot be replaced without completely removing the strut. Also will I need the alignment checked afterwards.

The strut will have to be compressed to allow for a new boot to be installed..

No alignment needed unless you replace the upper mount.

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Thanks, I am going to try out the new tool service on this site for the spring compressor.

You don't need a spring compressor. You just need to support the car by the front subframe rails and then use a floor jack under the lower control arm to slowly let down the control arm. You may have to unbolt the strut from the upper part of the spindle but I think you will be able to change the boot without unbolting the strut from there.

Good luck,

The easiest and SAFEST way is to jack the front up under the cross member, then lower the front control arms onto jackstands. The weight of the car will ensure that the springs stay compressed.

Using a jack to hold the spring force is foolish and dangerous! The only thing that might knock the car off jackstands under the control arms is another massive object running into it or a big earthquake. A wheeled jack can slide out or slip.

Since the strut is a gas type you will have to compress it a bit to get it onto the pin on the knuckle, but I had no problem doing this by hand.

It's a very easy job. I also removed the upper strut mounts for a cleaning and inspection and mine were both like new. Also inspect the jounce bumper.

Duke

Whatever you say. I have done it this way so many times that I've lost count and it has worked great and I have had no incidents at all.

It does, however, require that you use good judgement in jack placement and fit of the jack head to the LCA. If you don't have a feel for such things, take it to a shop and pay someone to do it.

Actually when I start thinking about it, the thought of having jack stands placed under both LCA's sounds more dangerous. The reason I say that is that the angle of the LCA will change putting a side force on the jackstand. The jack stand has a relatively small base for it's height as opposed to a good floor jack with a short height and a long base. But, whatever you say. If you want to call me foolish, then I say, throw all the insults you wish.

Have a great day,

I don't know what they teach you about safety in the ASE mechanics course, but I have two engineering degrees and have been involved with safety engineering, failure analysis, and accident investigation.

Letting the front control arms set on jackstands will not result in much spring compression or side motion of the control arms that might place a side load on the jackstands, but whatever the side load, it is only a small fraction of what would be required to overcome the friction force of the jackstand against a typical concrete surface.

The stands should be placed as far outboard on the control arms as possible and one should always verify that there is some spring compression from the rebound stops as the weight of the car settles on the jackstands.

When the spring must be removed, a jack can be used, but most service publications (all makes) recommend installing a safety chain between the chassis and control arm to limit spring rebound if the jack slips.

I continue to maintain that supporting the chassis while using a typical floor jack to support the control arm/spring to remove the strut is considerably less safe (if not foolhardy) than supporting the car on jackstands under the control arms using the car's weight to keep the springs compressed.

Duke

Book learning is a very good thing and I congratulate you. Although I took the tests and got my ASE certification and did a few years working as a mechanic as a youngster, I also have an electrical engineering degree, so you don't have to look down your nose at me as if I'm some snaggle toothed Goober.

Since you have never lowered an LCA on a 124 chassis, then it must be safe to say that you have not learned that you can lower it COMPLETELY while the upper portion of the strut is disconnected and the spring will still not come loose.

I know this will come as a shock but there are other places to learn things beyond a classroom and you don't have to call someone foolish when they have done something successfully that you have never even tried.

Have a great day high and mighty professor,

Hi
I believe there is another safe and easy way of doing it:
Jack the car up on one side using the designated jack point till the front wheel gets off the ground by about an inch. Remove the shock mounting nut, compress the strut, insert new rubber sleeve,release strut, tighten nut. Do not take the wheel off since it serves to limit the movement of the control arm and keeps the spring in place.
Bruno

I have changed struts on two different 124's a couple of times. It's really hard for me to imagine why it's unsafe to jack up the front end and support the car on jack stands, then simply raise or lower the control arm with a floor jack. I have also used a bottle jack. Even if the arm comes all the way down the spring is going nowhere.

Simple job.

Steve

Now that the dust has settled on this topic and a spring compresser is unavailable I will try the larry bible method this weekend. Thanks to all for the advice.