Alright, so I've done a lot of work to my car since my last posting, and being so busy with work, it's been difficult to find time to post. But I just wanted to give an update on my situation. If you are unaware of the issues I've been having, refer to my post (06 GXP Recently new owner). In a nutshell, I had a metallic rattling coming from my driver side over bumps, a vibration when coming to a stop at a light in the steering wheel, and a horrible steering wander problem.

So I thought, based on my research here and other forums, that the metallic rattling on my driver side was coming from a worn strut mount. I went ahead and bought 2 new mounts from autozone (my previous work place), a spring compressor, and any other items needed for the job. Knocked it out in a few hours with a little help of an impact after exhausting every other option to get the top nut off. I also re-did my brake pads with autozone's CMAX pads. as the pads that came with my aftermarket rotors were junk, followed by new hardware all around. Also did the sway bar links in the rear because they had a lot of play upon inspection, and I had been noticing a light thump in the rear while traveling on rough roads at slow speeds (the dirt road I live on, particularly).

So the verdict of the work I did: The slow speed vibration is gone, I guess the combination of the bad mount and the inferior quality pads/worn hardware was causing it. However, the rattle is not completely gone with the new mounts, but it has noticably been dampened quite a bit and it doesn't happen as frequent, but I can still hear it over certain bumps. I'm at a loss here, the only things I have not replaced on my front suspension are the struts themselves, and the inner tie rods. Neither one of those parts have given me any symptoms of failure. I did notice the inner cv joint had a bit of play, and I could make a clunk sound moving it back and fourth, but I was told that a bit of play is normal, but I'm not sure in my case. Could this be my culprit?

I also replaced the dog bone, it was moveable by hand and I figured that it wasn't helping my cause. I did notice the bushing inside the radiator mounting bracket for the dog bone was a bit loose as well, but I doubt that would cause a rattle. But I could be wrong, so please correct me if that's the case. I am planning to replace it anyway.

The thump in the rear is still present and becoming more frequent, and I'm now sure it has something to do with the struts. When I was raising the car to do the work on the rear, the strut made a pop noise and the tire jerked a bit. This baffled me, so I checked the mounts first. The rubber bushing on the top mount looks very, very worn, as well as a lot of movement when force is applied. I don't think the struts themselves are bad, I'm not getting any excessive bounce, but it looks like there's a lot of side to side movement when I push on the tire with the car on the ground. Not sure if that is abnormal, but I also removed the strut bellow to expose the shaft, and I saw some caked on grease where the shaft enters the assembly. Could this mean I need new struts? I'm really hoping that's not the case, I know these struts are next to impossible to find.

Steering wander doesn't happen as much now, but on certain roads I feel the wheel pull a bit still. This may be due to an improper alignment as a result of the cluster of front end work I've done so far, I'm planning to get an alignment done this weekend.

All in all, progress is being made, but still much work is still needed. On the bright side of things, I have added a few goodies to it, including a cold air inductions intake system, LED tail lights, NGK plugs and MSD wires, new alternator, drive belt, and GXP embroidered floor mats to compliment the interior. Im pretty happy with how she's coming out, and now I'm itching to get my exhaust done lol. I'm going to be needing front tires first, the road noise and uneven wear is killing me. I'd appreciate any advice/pointers you guys have to offer to make this project go a bit smoother, I really do like my GXP, I just want to enjoy driving it without the minor inconveniences haha

 

The bilsteins are very easy to find, rockauto sells them. ACDELCO Part # 505549 for the rear ACDELCO Part # 505548 for the front, suspension RPO code is FE4 for these cars. Although the only downside to the bilsteins is that they are expensive, 199 a pop for the rear right now. Any sort of grease or fluid leak around the shock is an indication of needing a replacement. Strut mounts, trailing arms, etc all could be sources of your clunk in the rear.

 

Thanks for the prompt reply, the thump sounds like it's right in the trunk, and I grabbed the shock while lifting the car and I felt the thump/pop in the shaft, Im pretty sure the struts are the issue. I know the exact strut that came on the car is discontinued by bilstein, but reading around the Internet, they made a comfort and a heavy duty shock. Are these AC Delco shocks that Rockauto has actual bilstein products, or are they just yellow look alikes? I'm not too clear on that, I did find 2 of the comfort bilsteins for the rear in stock on Amazon for $237 a pop, which is a bit steep IMO

I was going to try replacing the mounts only and see if that helps, but at 92k, it's about that time anyway.

 

they are the OEM replacements for the bilsteins, have to go by the RPO code when ordering suspension parts, so FE4 is all the correct parts for your car. I don't know if they are still manufactured by bilstein but they are going to be made to meet the OEM specs.

 

i got rear from bilstein and front ac deco number they came as bisteins but no blue boot with ac deco because it is a different paert num the bilsteins came with blue boots got the bilstein on amazon as i did the front ac delco

 

Just picked up 2 of the 505549's off amazon for $180 each. Going to replace them along with new mounts, Im probably going to reuse the springs. Based on the Amazon reviews, they do ship with he bilstein name, which makes me feel good about the purchase, but I won't know for sure until they arrive next week. Appreciate the info man, I've seen your posts a lot around here and you seem very knowledgable about these cars. I'm new to the ls4/4t65e-hd combo so any info is greatly appreciated so I don't have to learn anything the hard way. Not sure if I'm going to do any major internal work yet (ls6 intake swap, non DOD lifters/valley cover, ect.) but I definitely want to do basics like a cat back and a downpipe, maybe a tune if it really helps with engine wear and performance like everyone claims. I've never tuned a car before but I know my ****, it's something I could tackle with a little guidance. Thanks again.

 

Good info, I'm just going to reuse the blue boot on my old shocks after a good cleaning lol

 

take a look at my build thread if your really interested in getting down and dirty with the LS4, but the biggest expense is going to be the transmission more then anything, its an inevitability that it WILL have to be replaced and upgraded at some point in time.

 

canuk makes some good springs for these cars go on thriller website or call them i think about 170 for all 4

 

i learned everything i know from the guys on this site,they are very knowledgeable lol

 

i got same car as u except yours looks a lot cleaner than mine and love those leds my mod after intake swap

 

My rear clunking ended up being the lateral links.

 

Absolutely, I'll be sure to check it out. I'm really worried about the tranny, I mean I baby this car with the once in a while spirited takeoff. It had 89k when I bought it in February and I'm not sure if/how to tell if the tranny is original or if it had been replaced before. My fluid is in perfect shape, which settled me a bit. I wish I had gotten a better history on the car when I bought it, but it was one of those things that just fell into place after my 98 GT got totaled by some lady in a journey who failed to yield. I love my GXP but damn I miss it sometimes, I had a lot of myself into it haha

 

Haha thanks man, I detail it whenever it's not raining here in MI. I spent a lot of time pondering the thought of to tint, or not to tint. It was a PITA to get it perfect on my last car, so I figured the LEDs would look cool without having to mess with spray, and I would have NO issues with brightness lol

Are you doing an LS6 intake swap, by chance?

 

Mine are pretty rusty but I don't have any reason to suspect them at this time, were those hard to change out?

 

Lateral links take about 10 minutes per side

 

That's not too bad, any recommendation on a good brand for both on each side? I replaced my LCA's with mevtech at 89/pair and they seem to be holding their own well. Not sure if mevtech make the lateral links.

 

i went bmr after hearing good reviews from guys on this site

 

I'm going ls1 with throttle body I'm having the oil press send unit cut and welded now so ill post pics once it is on

 

you get could gey moog lateral and control arms whisch i did lol and they were good but not adjustable like bmr and control arms by bmr are much beefier moog is good bmr is great