NightwalkerLS1

iTrader: (2)

So here is the story. I purchased new 10.5/9 TTM's with sumitomo htrz's 315/35/17's out the back and 275/40/17's out the front (I will never buy these tires again 0 traction). The car has always had noticeable vibration in the shifter (M6 car) and you can watch the passenger seat vibrate at higher speeds as well. However, I had never really noticed a vibration in the steering wheel until I replaced the stock 16x8 rim/tire combo. Since the vibration in the steering wheel only occurs from 60 to 70 I figured the tires must be out of balance. I have had them road force balanced twice now at 2 different shops and the numbers are coming up good, so I think I can rule out the tires.

Also, the shake is intermittent, sometimes I can feel it in the steering wheel and sometimes it doesn't do it at all. However, I have noticed some humming noise above 75mph. I had assumed this was the bigger tires out back but now I am not so sure. With that said after a lot of reading and research I'm thinking maybe the driveshaft is tweaked. I was hoping maybe someone that knows alot more than I do could chime in with there diagnosis before I start dropping cash.

A little more info, the car is basically stock for the most part. I drive aggressively on the street with the occasional burnout but I don't visit the track.

1 FMF

iTrader: (1)

for your steering wheel vibration i would consider replacing both front wheel bearing hub assemblies and get an alignment. hopefully it's not a bad tire.

for the shifter and seat vibration, search in here for T56 5th 6th gear vibration. A few guys found out the 5 and 6 gear cluster on the shaft in the trans comes loose and spins on the shaft causing the vibration. TDP transmisison shop in texas offers a fix for it if that is the source of that vibration.

for the drive shaft, consider a digital angle finder #95998 from harbor freight. it's about 1" square and you can easily fit it on the yokes to measure angles to check ujoint phasing and operating angles and to see if your torque arm is messed up. other than that, you would have to pull the drive shaft to have its balanced checked and the condition of the ujoints checked.

NightwalkerLS1

iTrader: (2)

Thanks for the reply. After doing a search about the 5th6th gear issue I am convinced I do Not have this issue. I think I will take your advice about the driveshaft and go from there.No

NightwalkerLS1

iTrader: (2)

I thought I would follow up since well....noone ever does and that is kind of annoying. Sumitomos are trash plain and simple. I had those stupid tires road force balanced at 3 locations, each location showed good numbers. I decided to throw my stock wheels and tires back on and I discovered there was 0 vibration. With that said I finally bit the bullet and bought bfgoodrich performance tires and the issue completely went away. No more vibration, no hums, no nothing. Feels like a new car, go figure. Moral of the story, just say NO NO NO to sumitomo htrz tires.

smokeyy_02

I have the same problem on my 02 trans am t56. I went from the 16x8 to 17x9 are torque thrust wheels with nitto z555 's and I have the same exact vibration and humming sound at higher speeds I even replaced both universals on drive shaft and I can't shake the vibe. but I don't have the cash for new tires. go figure. lol.

01ssreda4

iTrader: (96)

I've noticed with some tires, they vibrate until they build up some heat. Very noticeable this time of year. Mine will vibrate for a couple miles then they are smooth as glass after that. Just something I noticed over the years.

NightwalkerLS1

iTrader: (2)

Yeah replacing those sumitomos in the front definitely cured my issues.