Struts & Shocks Causing Vibrations? Replacement rebate found!

[Warhammer]

So...it looks like I'm forced to replace my front struts but will probably do the rears as well. To make a long vibrations troubleshooting session short, I helped a friend of mine swap out his front struts on his 2004 Mazda 3 this weekend. His passenger strut was completely dead due to oil leakage and his drivers side was very weak. While driving around to get parts, I noticed his vehicle had vibrations similar to my MO's. But after we got the new front struts in, the vibrations went away.

That sparked me to check the front OEM struts on my MO, and sure enough, the front left was very dirty from leaking oil. I check the right one and it still seemed okay but the boot was very dry rotted. Regardless of the right strut's condition, I'll have to swap them both out.

I found Gabriel is having a "Straight Up Savings Event" rebate when you buy 2 products; i.e. 2 struts and 2 shocks, until the end of October 2011: Gabriel Shocks & Struts. Monroe is also having a rebate event but their ridiculous restrictions keep our MO's out of the running.

I've read some on this forum in regards to shocks/struts and it's been a mixed bag. Lots of members go with KYB and have done Gabriel's from time to time. Looks like they're all about the same and it comes down to personal opinion and pricing?

I did some math and regardless how you spin it, I'll be about about $200 anyway do at least the fronts if I go with KYB. So I figured I would get the Gabriel Ultra shocks/strut package and call it good. After the rebate, cost out of pocket would be $201.57 +tax. I'll try to find the parts online to try and save some $$$. I also need the front strut boots as both of mine are rotted out. So that will also probably be another $25 for the pair of boots.

So I do have some questions because I'm confused why bad struts or shocks cause vibrations. I thought things like control arms, tie rods, etc would cause consistent vibes. My vibrations come and go. Sometimes they feel like it's in the front, then the back, then everywhere. So here are my questions:

1) Could bad struts in the front cause vibrations throughout the vehicle? Felt in steering wheel, seat, front, etc?
2) Why do bad struts/shocks cause the vehicle to vibrate? I thought that when they went bad the vehicle would get mushy and corner terribly.
3) How can I tell if the rear shocks need to be replaced?
4) Do I need to get an alignment after I get the struts and shocks replaced? Why?

Plus, any strong opinions as to why one brand of shock/strut is better than the other is always welcome. The Gabriel shocks/struts come with a limited lifetime warranty at AutoZone. In other words, if it fails, then they'll replace it as long as you didn't abuse it during installation or install them wrong.

Thanks guys!

[RayH]

Struts and shocks are meant to dampen vibrations. When they fail they are not able to control vibrations that are already coming through the suspension and in the worst case scenario there will be certain frequencies that the car will naturally vibrate at which will start showing.

From what I remember, shocks are not critical to alignment but struts are. Theoretically the alignment shouldn't change if everything is bolted up exactly the same as before but I've heard that just the amount of play on the bolt holes where the struts attach to the body can throw off the alignment.

[Warhammer]

Thanks! I guess I'm used to suspension parts on the older vehicles. When their shocks would go you'd get a mushy bouncy feeling.

I talked with my wife about this whole ordeal just a moment ago and I think we're going to go with fronts only and see how that goes. If I swap out the fronts and it solves all problems with vibrations, then we'll leave it at that. If we still find there are vibrations more in the seat then we'll swap out the rear shocks as well. I've got until October 31st to get the other 2 to get the rebate.

One section at a time.

[Warhammer]

Ooooooh come on guys! Just looking for a little help here...

[Pilgrim]

The one time I tried Monroe HD shock inserts in a Mcpherson strut suspension, I was completely disappointed - and removed them and threw them out. Mushy, bottomed out constantly, just terrible. I think you will do well to avoid Monroes. The only thing I'd consider putting them on is a conventional vehicle like a Blazer or an old Chevy.

Come to think of it, I didn't even put them on my 1999 blazer - I used Bilsteins.

I hope the Gabriels work better for you, but IMO you aren't missing a thing by avoiding the Monroes. Personally, I'd spend more $ and get KYB, Tokico or Bilstein.

[njjoe]

Warhammer-

I replaced my front struts with KYB units at the beginning of Spring. The right-front strut was shot and had zero damping capability. It was not a gradual deterioration in ride quality, but more of a sudden change in handling. The problem began soon after I drove the front wheel up and over a large snow pile in my yard. I figure I must have blown the seal when the strut went from being fully compressed to fully extended.

There was a definite increase in the amount of vibrations felt in both the ride and through the steering wheel. Both diminished significantly after I replaced the front struts and strut bearings.

I left the rear shocks alone because I only had 50-some thousand miles on the clock. However, I may change them before Winter comes.

-njjoe

[RayH]

Personally, when it comes to safety, comfort or just plain hassle of having to replace a part I don't mind spending a little bit more.

Not that there's anything wrong with Gabriel but there seems to be enough general complaints out there that it may not be worth the potential hassle if there's a problem. I'd say take the money you saved from not buying the rears now and get the KYB.

[Warhammer]

Well...installation is done on front end. Ended up ordering the Gabriel Ultra's and installed them today. The difference is outstanding. I had forgotten how stiff the front end is supposed to be. I guess I got used to it being so sloppy. Biggest issue I ran into was on the bottom strut bolt on the passenger side. Was really rusted. Hit it with some penetrating oil, some heat, and some finesse with a breaker bar and it came off. Cleaned off the bolt with a good wire brush attachment on my drill and it went together smoothly. Took torquing down without an issue.

So, the conclusion is that the drivers side strut was completely gone. As soon as the top center bolt was removed, the center shaft bottomed out in a couple of seconds. The passenger side strut was very weak. I did a pressure test between the passenger side new strut and the old strut. The new strut went from being bottomed out to topping out in 12 seconds. The old passenger strut took about 26 seconds. Definitely extremely tired.

I took my MO around town after the work and not a single vibe was felt between neighborhood speeds and about 60mph. I will be taking it out and getting up to freeway speeds tomorrow morning on my way to work. We'll see how it feels then. Hopefully no more shaking at all.

BTW...Gabriel Ultra's through AutoZone have a lifetime warranty! If the strut fails for any reason; outside of an accident of course, then they'll get you another one free of charge. Plus, you get to work with a local parts distributor and not an online entity. Worth it to me. Read multiple places online and the reviews are mixed between Gabriel's, Monroe's, and KYB's. So far so good. We'll see how they last over the next few years.

[Pilgrim]

Sounds very promising! Glad they feel good - it's nice to hear a report from someone who is actually using the Gabriels.

[Warhammer]

Morning report:

Ride this morning was mostly smooth. NO vibraitons in the front end but extremely slight in the rear. I can feel the slight vibrations through my seat at highway speeds. Talked to a friend this morning and he stated something very obvious about the mileage on the rear shocks as well. They also have almost 100K miles on them so why not swap those out too? Makes sense. I'll get a feel for the vehicle over the next week or so and make a determination. At least the rear shocks will be easier to remove/install as they are not surrounded by a coil spring. More of a standard shock configuration.

Got to make a decision about them rather quickly as the rebate expires at the end of this month.

[Sfordt]

Sounds good, mu wife's struts are are both weak, and the boots are gone too.
Just finished new rotors and pads, both drive shafts and new Yokohama's all the way around.