I’m experiencing a noticeable vibration while driving. It comes on at low speeds (30ish mph) and just gets worse the faster I go. I cannot drive on the highway due to the vibration. In fact, I’m not driving it at all for fear I may break something else. It does not go away when I let off the accelerator. It does not get worse when I brake.

I’ve done a lot of work on this car in a short amount of time. When I first got the car (January 2023), I changed the clutch, flywheel, starter, crankshaft seal, ignition coils, spark plugs and valve cover. It was running fine for a bit. Then, a couple months later, I started getting a check engine light once in a while and power was drastically reduced. Eventually, the light and reduced power persisted each time I started it up. I tried changing the throttle body, accelerator position sensor, and relays. I ended up sending my DME & CAS module out to get tested. That was the smoking gun. They sent me a new one, and my power problem was solved.

However, shortly after the new DME, I noticed the vibration. So, I got my wheels balanced and an alignment. Didn’t help. Then, I changed out all my brake pads, rotors, and calipers. My rear calipers were shot, but not the cause for the vibration. Didn’t help. Then, I swapped out all the shocks/struts. Still no. Most recently, I swapped out all wheel hubs/bearings and the cv axel. The vibration is still there. And during all of this, I noticed an oil leak at the front of the engine (passenger side of car). I determined it must be from the crankshaft seal and replaced the seal, harmonic balancer, belt, belt tensioner, and idler pulley.
I am done throwing parts at this car. Can anyone help?

 

Does vibration persist if you shift transmission into neutral while driving?

 

That's a good question. I'll try it out and get back to you

 

Alright, took it for a drive. The vibration is still there when I shift to neutral. It feels just fine when shifting and braking. At slower speeds it feels more bouncy rather than shaky. At higher speeds (60mph+), the vibration gets very noticeable and concerning. I don't feel it in the wheel or pedals. It's more like the whole car, if that makes sense.

 

Bad motor and/or transmission mount(s)?

Front or rear suspension?

Bubble on tire?

 

Tires are in good condition. Lower motor mount looks fine. I do need to look at the upper motor mount and transmission mount though...

 

I replaced front and rear shocks and struts

 

Other suspension parts to inspect would be the front lower control arms, front subframe, front stabilizer bar and links, rear trailing arms, rear subframe, and rear stabilizer bar.

Any fault codes stored in the ECUs?

 

I'll do a more thorough check of all that again, but I've been under it looking so much and haven't seen anything apparent yet. I've taken the transmission mount out multiple times. Maybe I forgot to tighten it the last time. I dunno, will check it all out and get back to you. Thank you for all your advice!

 

Okey dokey. Did a thorough inspection. Mounts, suspension, and subframe look good. However, one of the tires wasn't in as good of condition as I thought... left rear is worn unevenly (see pic)

Do you think this is enough to cause my problem?

 

I thought you mentioned having a recent wheel alignment. Were the rear wheels checked? If not, have them checked and adjusted if necessary. Then go from there.

 

Yeah, I did get an alignment recently. However, I don't have much confidence in that specific shop after my experience with them. I plan to replace the rear 2 tires and get it realigned at a different shop

 

 

Hard to tell from the pic but that doesn't look worn unevenly, that looks like a belt shifted, or something else went wrong with the tire structure. Given your symptoms I think you've found your problem and would replace that tire if it looks that weird in person.