Rep Power: 210

2000 Buick Century Custom. 95k miles.
Bought the car in April 2020.

I replaced the rear struts (first time) a few months ago. I purchased KYB Excel-G bare struts and re-used the isolator, spring coil, and strut mount/bearing. I had a mechanic install the same setup for the front struts. After installing they were all making popping sounds, especially the rears. The coil springs seem fine other than their factory coating to prevent binding/rubbing dried out and a lot of it peeled off.

I made two strut-noob mistakes on the rear struts. I should have purchased new mounts to install on the bare strut assembly. I also found that the coil springs need that coating to prevent rubbing (bolton of coil). So, last week I removed the rear struts, disassembled them and installed clear vinyl tubing on the bottom half of the springs and new KYB strut mounts. No more noise afterwards.

I just purchased KYB strut mounts + bearings for the fronts and intend to use vinyl tubing on the coil springs as well. Now that the rear struts are quiet I can really hear how noisy the front ones are. Mostly when breaking coming to a full stop, sometimes make a popping sound when launching or turning.

I'm chasing down a vibration/shake that is felt from 35 mph upwards. It happens during acceleration, deceleration and coasting at speeds above 35 mph. Along with the struts I or a trusted local indy mechanic have replaced the following:
ATF drain and fill
Transmission mount and engine's bottom motor mount.
Both CV axles
Both front axle hub assemblies
Steering rack with new inner and outer tie rods
Steering pump, hoses, belt, steering fluid
Front and rear sway bar end links
Front rotors and pads
Set of four new ties that were road-forced balanced
Alignments (lifetime)

I filled in the bottom half of the transmission mount with 3M Window Weld because it has a tendency to collapse on itself when it goes bad. I figured the window weld would prevent that at the cost of possible increased NVH vibrations felt in the chassis. The motor mounts hydraulic. The front end links I installed are Moog problem solver made of polyurethane...that may increase vibrations?.

Now to the question I posed in the title of this thread.
Can worn strut mounts cause vibrations while accelerating, decelerating and coasting ?

Could it be the drive (cv) shaft angle since the engine, transmission and suspension are at or above stock height?

Could adding window weld to transmission mount and/or polyurethane end links cause front end vibration felt while driving?

 
Rep Power: 210

New strut mounts installed on both front and rear. Also, used clear vinyl tubing over the coil springs to prevent rubbing. No more noise, less resistance lock-to-lock turns, and helped calm vibrations a bit.

I can now isolate a front end popping noise at hard, quick stops and launches. Pretty sure the control arm bushings are worn and sliding during the actions above. This car has one piece lower control arms that includes the ball joint. I will replace them and if the vibration/shake issue persists I think it would narrow it down to bent rim(s) or a hard to diagnose split belt in a tire(s).

I don't think it's in the engine or transmission as I coasted in neutral at 50 mph with the engine off and the shake/ vibration is still present

 
Rep Power: 367

the mounts can decrease vibrations, yes

 
Rep Power: 210

Chasing this shake vibration is very frustrating. I think the cause will end up being control arms, tire belt seperation that isn't obvious, or a bent rim(s). Feels like it's coming from the front left side but not sure on that.

 
Rep Power: 210

Brought it back to Fartstone for an alignment check and road-forced balance. I handed a senior tech a list of all the recent suspension and steering parts installed, listed how I road tested the car which seems to rule out engine/transmission shake. They said alignment was a good amount out of factory spec (probably due to new mounts). They said they also found the left front wheel wasn't balance right and they rebalanced it.
Both of those adjustments made a significant improvement but it still has some shake (much less than before) that is noticeable around 60 mph now.

Might throw new control arms (include ball joint) and front stabilizer bar bushings on it.
Ready, aim, fire the parts cannon!

 
Rep Power: 224

Hopefully you hit something. I'd be getting real tired of the car by now.

 
Rep Power: 210

Lol..it's a love-hate relationship at this point. Oddly enough I really like this car and it if falls inline with the past two cars I purchased (95 civic ex,98 civic ex) the first year of ownership involves assorted parts repairs (I do all labor) that cost between $500-$1000. Followed by basically maintenance free driving for two to three years afterwards. AC Delco parts for this car are cheap, just like for Honda's. The only difference I'm getting lazier to work on cars than I used to be and found a reliable mechanic that is very reasonable so I used him more than I normally would.

Definitely going to replace the control arms because that ball joints because I now know for sure they are making a popping/loose metallic noise over bumps.
When this car is right it makes a great highway car. I still see a lot of them (early 2000's) on the road.

 
Rep Power: 224

When I first met my wife she had a '03 Century. That thing was a couch on wheels, very comfortable. Then, I presume, a head gasket went causing loss of coolant and overheating. The rust was also getting pretty bad. Can't say I miss that car

 
Rep Power: 210

Coolant loss was most likely due to an intake gasket leak which was very common for the GM 3.1L V6. The intake gasket was later redesigned and fixed the issue. I bought the car from my son's friend and his dad replaced the intake gasket six months before I purchased it. They are also known for rust but mine is is in good shape as it was kept in Florida throughout it's existence.

My wife and I moved from Florida to North Carolina last year and my '95 Civic EX wasn't going to pass inspections here (none in Florida). Used cars here are expensive for whatever reason and I wasn't intending on buying an American made car. $1500 for a car with 94k mile from someone I know (my son's friend since elementary school, now age 23) I figured why not? It's Sofa-King comfortable: https://www.nbc.com/saturday-night-l...fa-king/n12138