I have a 2009 G37x and it's lowered. The previous owner didn't really lower it properly so I'm going to put some nice coilovers on because I'm tired of spending $300 a tire when they blow. Inside beads are literally separating from the tire. It's nuts and I scrape too much. Anyways..

When I'm getting on it and starting to brake, the car shakes like crazy in the front end. Now, I took it to Infiniti to get a full checkup and they said something was loose in the front left but I don't remember what they said and they didn't put it in the estimate/invoice. I brought it in for VDC issues which they said mine is trashed and I need a new one. *sigh*

What is the likely candidate for this shaking issue? This week or weekend I'd like to jack it up and take the driver front tire off and see what's going on in there. You guys with experience, what should I be looking for that could be loose causing the shaking?

Ugh, and this isn't even the worst one.


Thanks in advance.

 

Ok, wow, where to start....?

How many miles on the car?

What do you mean by improper lowering? Cut springs? Ebay bags leaking? Coil-overs set too low?

Please, tires first. You shouldn’t be driving at any speed on tires that look like that, especially in SoFL where torrential rain just happens and any rain causes all the accumulated oil on the road to float to the surface making conditions treacherous.

Regarding the vibration, it could be many things, but based on your description (and don’t "get on it" until you change those tires) it could be those tires (most likely) and as the dealer said, maybe something loose up front (which could be as dangerous as those tires) or maybe even a warped rotor or two.

As long as the brakes pads are good, don’t worry about rotors until you make the car safe to drive with innocent people driving next to you. (Did I mention new tires? Or even a used set for the interim?)

Recommendations from others on here will be varied. Please realize none of us are there with you or able to drive your car or put it on a lift and look around. My general thoughts are the problem resides in some combination of what I noted above.

Be safe, change those tires! find an alignment shop that does modified cars and have them give you some recommendations.

The lowering issue could be nothing more difficult than adjusting the coil-overs or rplacing a leaky bag and the vibration may be as simple as new tires.

But it is something you should address as soon as possible before you hurt yourself or someone else on the road. (I have family in SoFl…)

 

Alright, I'll address this in order as best I can.

120k+ miles are on the car. '09 G37x Sedan

When I say didn't lower it properly, he put a cheap kit on it that isn't adjustable and it's garbage. Rough ride, scrapes on everything and when I hit like a pot hole, it's like I hit an animal.

As for tires, I'm good. Just spent quite a bit of money getting those right. When I bought it, it looked like they were almost new but I could t and didn't get down to look at the insides of the tires which were trashed. I had two blowouts. Scary **** and one time, I had my wife with me. She freaked out.

So just so you know, I'm good with tires all the way around. Firehawk Indy 500's for now. Getting Michelin Sport Cups in February.

I realize it's hard to ask these questions and appreciate your candor. I'm going to inspect it ASAP and see if things are loose or look bad/worn and replace accordingly. I don't feel safe speeding around and then braking and the shaking happens. Makes me nervous for myself and other drivers. I am considerate to others around me.

I love the car and I've done quite a bit of work but I'm now doing all the necessary and safety aspects of getting the car situated. I appreciate ya, thanks.

 

Glad you got the tires fixed... i will tell my sister she is safe on the highway again....

About the shaking:
Is it occurring during all hard braking or only braking from a high speed? different dynamics involved in each scenario.
Does the steering wheel shake in your hands when normal braking? hard braking? braking from high speed**? (front rotors or worn steering parts)
Do you feel any vibration in the pedal during the three scenarios noted above? (this would be telling you that the rotors are warped)

AWD at 120K lowered, you could be looking at loose or failed upper link or transverse link bushings, worn lower ball joints, worn tie rod ends, worn wheel bearings (you would probably hear these as a moaning or grinding noise at certain speeds), worn / failed CV joints in the front axles, loose or broken shock mounts on the top plate mount or the bottom collar to the fork or the fork itself could be loose on the transverse link. At a stretch it could be a blown shock or bad spring.

There are some quick diagnosis things i could walk you through if you want to determine or rule out some of the issues noted above.

** high speed assumed to be at or below the posted speed limits...

 

Haha everyone is safe, including your sister.

The shaking comes from only braking at high speeds. The steering wheel will shake as I'm braking and then it calms down. I don't hear or feel anything during hard acceleration or driving like normal. It's ONLY when coming down from say 80-120+ MPH. I'm not driving that fast any longer because it doesn't feel safe when that shaking happens.

Daily driving like a normal person (the hell is normal!?) Doesn't give me any issues. It just when someone wants to do a pull or I just am having fun and I go over 80. I just have to get in there and see what's going on I believe. I will take some pics and describe what I find as best I can here and maybe you guys can help.

Thanks for replying, I appreciate it.

 

More often than not any type of vibration issues that occur during braking can be tied to the brakes themselves. Bad/ worn pads, caliper issue(s), dirty/ damaged/ "warped" rotors, etc. Noticed you have drilled/ slotted rotors- opinions here are mixed on them and their performance/ reliability. Do you know if they are a reputable brand or eBay Chinese knockoffs?

If the car drives/ tracks smooth and straight at speed, with no vibration, then likely your suspension is fine, shoddy lowering attempt notwithstanding.

 

I'm pretty sure they aren't a super reputable brand and they are slotted. I'll know more once I get the wheel off and actually dig in there and see what's going on. It only seems to be on the driver front and as I mentioned in my first post when I took it into the dealer Just so they could do a once-over, they said there was something loose I don't know if it was something with the steering because they didn't put it on the estimate. They made sure to put my traction control module on there though for $1,200 bucks.

I guess I really won't know until I dig into it and then I'll be able to hopefully see visually what's going on and I'll take some pictures and maybe a quick video and hopefully you guys can help.

I'm taking it to a reputable guy around here that specializes in these cars but it's not going to be for a little bit cuz I want him to do a transmission flush and a couple other things. Since it's an '09 I suffer from that burning smell constantly so I just want to make sure that everything is cool and I also want to clean out my intake filters since I have the long tube dual CAI.

Just time for some love since it does have over 120,000 miles on it but the thing drives and pulls amazing.