vibration at 120 at a lost why

[rookerrobert]

I have ran at a local 1/4 dragway and trap around 140mph....with no vibration. But the last 4 four I went to the track it was at a local 1/8 track and trap 110mph. But on the drive home I got behind some folk's like they were driving Mrs, Daisy so I decided to pass and ran the car up to around 120 and then the vibration was getting worse. The only thing I have added was brm lower trailing arms.I dont have lift so I jacked it up and put jack stands under car and checked eveything nothing seems out of place everything was tight so I'm at a loss....I ever checked all the wheels/weight's there was a couple lost off the wheel. The weight s that were missing were off of the front skinny's so I put on the stock front wheels and drove the car and again around 120mph shaking started again. How in the world would you find this? any idea's? could the trailing arm's cause this?
's

 

[Unholy707]

I have ran at a local 1/4 dragway and trap around 140mph....with no vibration. But the last 4 four I went to the track it was at a local 1/8 track and trap 110mph. But on the drive home I got behind some folk's like they were driving Mrs, Daisy so I decided to pass and ran the car up to around 120 and then the vibration was getting worse. The only thing I have added was brm lower trailing arms.I dont have lift so I jacked it up and put jack stands under car and checked eveything nothing seems out of place everything was tight so I'm at a loss....I ever checked all the wheels/weight's there was a couple lost off the wheel. The weight s that were missing were off of the front skinny's so I put on the stock front wheels and drove the car and again around 120mph shaking started again. How in the world would you find this? any idea's? could the trailing arm's cause this?
's

Stock driveshaft?

 

[rookerrobert]

no it has aluminum driveshaft

 

[rookerrobert]

Stock driveshaft?

I looked at it also but nothing visibly wrong....there is a discount tire that does road force balancing I may go there and see if that help's

 

[Unholy707]

Could be anything to be honest, probably spun tires on the wheels

 

[rookerrobert]

Could be anything to be honest, probably spun tires on the wheels

yes your could be anything I'm going to an event this coming friday..after having it road force balanced it start's shaking I'll just have to let off. And look somewhere esle

 

[DavidKFla]

Aftermarket driveshaft unless you spun the tires on the rim.

 

[Unholy707]

Aftermarket driveshaft unless you spun the tires on the rim.

I spun my tire on my BEADLOCKS. How does that even happen 1/8th of an inch on 1 side

 

[Unholy707]

I did have a valve stem valve issue it came loose I think n last pass I had like 8psi in it.

 

[Unholy707]

Tightened it and all good now holding air, but that could have been a mess

 

[Unholy707]

dIsCoUnT tIrE for the L

 

[covidcommander]

driveshaft swap

 

[rookerrobert]

thinking replacing the Differential and going to carbon fiber driveshaft......has anyone tried the 3.70 diff. in a a8? Or as least go to 3.09...right now I'm running 2.62.

 

[DavidKFla]

thinking replacing the Differential and going to carbon fiber driveshaft......has anyone tried the 3.70 diff. in a a8? Or as least go to 3.09...right now I'm running 2.62.

Better ask your tuner.

 

[Unholy707]

thinking replacing the Differential and going to carbon fiber driveshaft......has anyone tried the 3.70 diff. in a a8? Or as least go to 3.09...right now I'm running 2.62.

Don’t do it

 

[Unholy707]

I have a 3.70 with an a8. It feels like I hook, but guarantee I still slip at the track even off idle. Can’t get out of 1.5 flat 60’. I know I lose a few mph (142). Best is 9.8 in about 2000 da 90% humidity and 90 degrees out. Car runs the same in the 1/4 every pass

 

[rookerrobert]

Don’t do it

yeah 3.70 might be to much

 

[Unholy707]

Have 6 9.8/9.9 142/141 1.5 60’ slips

 

[rookerrobert]

I have a 3.70 with an a8. It feels like I hook, but guarantee I still slip at the track even off idle. Can’t get out of 1.5 flat 60’. I know I lose a few mph (142). Best is 9.8 in about 2000 da 90% humidity and 90 degrees out. Car runs the same in the 1/4 every pass

I thought I read somewhere you were running the 3.70's.....so you know from experience instead of hear say I like that...so go with 3.09?

 

[rookerrobert]

Have 6 9.8/9.9 142/141 1.5 60’ slips

I'm already pulling 1.44 to 1.48 60' and running my best yet as been 6.24@110 so I also believe 3.70 would be to much