High-speed vibration.

[mattblancarte]

Just had a very fun track day at Pacific Raceways yesterday, but I've uncovered a gremlin that I didn't expect.

On the half-mile straight, I was reaching speeds in excess of 145 mph, and experienced some extreme vibration. It starts at about 130, and gains until the car is shaking violently at about 150+. I was too afraid to push it past that...

So, what I'm thinking it may be:

- Flat spot(s) on tires.- Bad aero (open side windows)- Bad alignment (hoping it's not the case because I just had this done two months ago)- Some random moving part that I can't think of.

Anyone have any ideas?

[ArcherV20]

The title of this thread is Hawt.

[mattblancarte]

Haha perhaps I should change it to: High-speed vibration (due to sex toy).

[ArcherV20]

Try,

High-Speed Vibrations for cheap (inquire inside)

[ArcherV20]

Oh and I'm not post whoring sorry,

Where is the vibration coming from? And what's it sound like? Metal on metal? Plastic? Any sort of specifecs you can give us besides speed? Is the vibration in your steering wheel?

[AZ89two4Tsx]

I would see if I had the problem myself but I don't think my sohc would reach past 100, lol. I would think it would be something having to do with your alignment or some kind of moving part.

Is there any important part you can think of that's still stock? My best guess would be something in the driveline that just can't handle the stress induced at 130mph+.

[mattblancarte]

Honestly it was the whole car. The steering wheel seemed to vibrate as much as my seat did, so it was hard to tell... I really want to have this taken care of before I head to Portland International...

[mattblancarte]

Is there any important part you can think of that's still stock? My best guess would be something in the driveline that just can't handle the stress induced at 130mph+.

Nope. RB25det transmission, r200 diff, quaife lsd, custom drive shaft. This has been hurting my brain for the past 24 hours. What could it be dag namit.

[AZ89two4Tsx]

Anything that has to do with the hubs maybe? Just thinking out loud.

[mattblancarte]

Perhaps... I have rather stubby wheel studs. I am going to be installing extended wheel studs before the May event, actually.

It was really sketchy because at the end of the straight there is a slight, blind right hand turn that you take at full speed before braking into turn 2. I was worried my car was going to fall apart and I would be toast!

[koukis4teen]

Is something maybe not balanced in the rotating mass due to the swap? Like the drive shaft perhaps? Since it doesn't start until high speed a feel like thats something that would be unnoticeable until then.. If it was minor. Good lukk.

[heartofaskyline]

some bushings somewhere???

[mattblancarte]

Is something maybe not balanced in the rotating mass due to the swap? Like the drive shaft perhaps? Since it doesn't start until high speed a feel like thats something that would be unnoticeable until then.. If it was minor. Good lukk.

It very well may be the drive shaft. This has been noted, and will be checked!

some bushings somewhere???

Hmmm, I will look into this as well.

[SirSilvia]

are the wheels balanced correctly? those little weight have been know to fall off. and if it was just a little weight, you really wouldn't notice it till higher MPH

[Two Fowty]

definately your alignment, same with my old car.

[heartofaskyline]

definately your alignment, same with my old car.

ya because you took your car to 140+ all the time

[s13beast]

Im gunna say drive shaft. My Lincoln did this in the 95-140 range. And it was the drive shaft. Cant see out the rear view at all lol. I hopr you figure it out. I like to think of you car as perfection.

[user name!]

Same thing with mine. Ive been told my car has something bent that might be making my car shake at highway speeds. weeeaaak saauuce. Maybe same with you? Not sure but it might be a good idea to check if anythings out of place or a little bent?

[xX RB Xx]

maybe because a 240 isnt suppose to go that fast?

i took my old rb20 hatch up to 135 one time and it didnt shake at all.

[sloweighty]

what kinds of tires do you have and what are they rated at because if they are not ratted for high speeds then it would cause all sorts of weird stuff....(correct me if am wrong)

[Chris28]

If any 240 is to be taken up to those speeds, Matt's is honestly the only one on these boards I would trust.

I agree with the driveshaft. It's got to be something in the rotating assembly, and since the whole car vibrates I'm going to say it's something that runs the length of the car...the driveshaft. If it were a wheel or an axle out of balance then the vibration would be concentrated in the area that is out of balance.

Edit: Tires is a good point, but I'm sure his car has properly equipped rubber for the high speed vibrations that he is experiencing

[mattblancarte]

Thanks for all of the input, everone!

I've talked to a few people off the forums, as well, and most are saying drive shaft. I'll get it checked out and will report back!

[mattblancarte]

Update: Took off the wheels, and my front right tire has a huge flat spot from locking up....

[Didderson]

Most likely it's your wheels. Metal hub-centering rings will help the best. Making sure your tires are professionally balanced is a must for 150mph man.

I hope you have somewhere near Z rated tires lol.

It could be chassis rigidity, but it's more likely the wheels being unbalanced somehow.

EDIT: or your flat spot lol.

[supreamS14]

It's a good idea to have your windows up at 130mph+.

[AZ89two4Tsx]

I don't think he has sidewindows. Seriously, lol.

[s13beast]

Update: Took off the wheels, and my front right tire has a huge flat spot from locking up....

Yup. That will do it. Good you hear you found it.

[mattblancarte]

Most likely it's your wheels. Metal hub-centering rings will help the best. Making sure your tires are professionally balanced is a must for 150mph man.

I hope you have somewhere near Z rated tires lol.

It could be chassis rigidity, but it's more likely the wheels being unbalanced somehow.

EDIT: or your flat spot lol.

Wheels are balanced, tires are Falken Azenis RT-615, and the car has a 6 pt cage. hehe

I'm thinking it was at minimum partly due to the flat spot. I'm going to check everything else to be sure. New meats are on order... Toyo Proxes R888 245/40/17 and 255/45/17 muwahahaha.

I don't think he has sidewindows. Seriously, lol.

This is true. Side windows removed to save weight.

[zenki-S13]

you might want to check your transmission mountmine came loose once and my whole car would shake like crazyfor me it was only on takeoff but ive heard of it happening to others at high speeds

[mattblancarte]

Rgr that. Will do!