Driveshaft Help Wanted

[Red-GT500]

I've been getting some noticeable vibrations from my car after installing a DSS single piece aluminum drive shaft a few months ago. I had it installed by a local drive-line shop because i don't have access to a lift at home and i had no way to load the suspension evenly. After purchasing some Race Ramps 10" wheel cribs i was doing some scheduled maintenance to my car today with it up in the air evenly on 4 cribs. I was going to rotate the rear flange of the drive shaft to see if that would eliminate some of my vibrations. After a quick look i noticed the shop had installed a second set of lock washers on two bolts on one side of the flange. Im not totally sure if this was the vibration issues i was having or if i should still rotate the shaft 180 degrees. The two washers pictured below are the ones they incorrectly installed. I removed them and re-torqued the shaft with some loctite.

I haven't had a chance to drive it yet because i want the loctite to cure completely. Doing some simple math, the vibrations where happening about 100-120mph and my drive-shaft speed would be around 4700-5600 rpms. Would these two washers placed on one side of the shaft cause that much vibration? Or should i still rotate the shaft? I'm kinda upset with the shop for making such a bonehead move but its what i get for not doing the job myself. I plan to call DSS and see if they can provide any incite, but i thought i would see if anyone here has had this kind of issue with such a small part causing vibrations.

 

[SuperFly03]

I will say that when I installed mine I did not add any of those washers. I locked it down tight and I have zero vibrations at this point. I'll be running the Texas mile in a few weeks so I will have a better idea then.

 

[Cuda426]

I've been getting some noticeable vibrations from my car after installing a DSS single piece aluminum drive shaft a few months ago. I had it installed by a local drive-line shop because i don't have access to a lift at home and i had no way to load the suspension evenly. After purchasing some Race Ramps 10" wheel cribs i was doing some scheduled maintenance to my car today with it up in the air evenly on 4 cribs. I was going to rotate the rear flange of the drive shaft to see if that would eliminate some of my vibrations. After a quick look i noticed the shop had installed a second set of lock washers on two bolts on one side of the flange. Im not totally sure if this was the vibration issues i was having or if i should still rotate the shaft 180 degrees. The two washers pictured below are the ones they incorrectly installed. I removed them and re-torqued the shaft with some loctite.

I haven't had a chance to drive it yet because i want the loctite to cure completely. Doing some simple math, the vibrations where happening about 100-120mph and my drive-shaft speed would be around 4700-5600 rpms. Would these two washers placed on one side of the shaft cause that much vibration? Or should i still rotate the shaft? I'm kinda upset with the shop for making such a bonehead move but its what i get for not doing the job myself. I plan to call DSS and see if they can provide any incite, but i thought i would see if anyone here has had this kind of issue with such a small part causing vibrations.

Yes that could be the sole cause of the vibration and yes it was a bonehead thing for the shop to do. No need to wait for the loctite to dry if your wanting to test it.

 

[Red-GT500]

Ill test it out tomorrow and report back. Thanks for the replies guys.

 

[SCGallo2]

I am running the same driveshaft and initially had a similar vibration under load at the top of third and fourth gear. Having full poly bushings in the rear, I adjusted my pinion angle to -1.8 and it resolved my issue. Instead of rotating from the differential end, you can rotate your shaft 180 degrees at the transmission flange also (only 4 bolts).

 

[Tob]

Are all the bolts at that juncture exactly the same? I ask because I'm wondering if they ran out of thread (hit a solid portion of the bolt shank) on only two of them, and if so why they wouldn't have run out of thread on all of them. The pinion flange holes are not blind - can you see differing amounts of threads coming through it? Are these bolts different than stock?

 

[Silver_Serpent]

Yes that could be the sole cause of the vibration and yes it was a bonehead thing for the shop to do. No need to wait for the loctite to dry if your wanting to test it.

I would agree ... my money would be on the washers being the sole cause. Esentric rotating mass = vibration

 

[Red-GT500]

Tob,
I did check the others and they where all fine. The pinion flange bolts all showed the same amount of thread. The DSS has an adapter plate for the pinion flange so there is a total of 12 bolts back there. I just think they goofed up and where not paying attention to how many washers they where using.

If this doesnt solve the issue ill try rotating the shaft and possibly changing pinion angle slightly.

 

[Tob]

And if that doesn't work I have a solution for you.

 

[Red-GT500]

Tob,

I cant afford a CF shaft... but yes I was very tempted by your flange making. Maybe one day when the stockers come down in price.

 

[heatsoaked12]

My cf drive shaft from dss is balanced with small washers glued to the drive shaft so I could see your extra washers causing a little vibration. Hope it works out for you.

 

[Red-GT500]

Happy to report that my vibe issues when away. Now to re-balance these wheels.