[zepp3lin]

Has anybody else had an issue with their aluminum 1 piece DS vibrating at speeds upwards of 50mph?

I just got the DS and 3.73 gears installed. They double checked the pinion angle when I brought it back in and said it's in spec. They're going to try installing a different shaft to see if it's some sort of imperfection with the original shaft, as the mechanic had no trouble noticing the vibration on his test drive.

Anybody have any ideas as to what else it could be or stuff I could try? There's zero noise coming from the gears. And there's no vibration below 50. Everything else is bone stock except the tune.

Also it's a 2011 automatic with 63k miles and I feel the vibration much more when I take my foot off the gas and coast on the highway.

 

[Blackpenguin69]

unbolt shaft and turn it.

edit: turn it like a 1/4 turn and line it up with different holes.

 

[JBert]

Yes vibration can be a tricky issue with those shafts; that's why the GT factory shaft has the joint in the middle and there are CV joint shafts that cost more money.

In the past, I had a similar vibration with my Shaftmasters aluminum DS. It was most noticeable when coasting at about 75+ mph; sort of a low frequency hum. It got worse as the shaft got older and worse when I went from 3.31 to 3.73 gears.

For me, it was fixed by:
1) sent the shaft back to Shaftmasters, they said the slip joint and one U-Joint were worn out, they replaced them and rebalanced the shaft
2) reinstalled with pinion angle set to -0.5 degrees per Shaftmasters instructions. This required an adjustable upper control arm. Note the pinion angle is more critical with the aluminum DS so you can't just go by factory specs.

Now it is nice and smooth under every condition I have tested; had it up to about 120 on the road track the other day and it was nice and quiet.

 

[zepp3lin]

Thanks for the responses guys. I suspected the pinion angle has to be much more finely balanced than with the 2piece shaft. I'll verify with them what it's set to next time I'm in there. I don't mind paying for the UCA's if it will fix the issue because as you said it is a low frequency hum/vibration and it's driving me nuts right now. Steeda is so busy right now that I think they are trying the easy approach of replacing the shaft instead of trying a few different pinion angles or different holes on the differential side.

The UCA's are your only suspension mod correct? Do you happen to know what the stock pinion angle was?

 

[Masterang]

Yes vibration can be a tricky issue with those shafts; that's why the GT factory shaft has the joint in the middle and there are CV joint shafts that cost more money.

In the past, I had a similar vibration with my Shaftmasters aluminum DS. It was most noticeable when coasting at about 75+ mph; sort of a low frequency hum. It got worse as the shaft got older and worse when I went from 3.31 to 3.73 gears.

For me, it was fixed by:
1) sent the shaft back to Shaftmasters, they said the slip joint and one U-Joint were worn out, they replaced them and rebalanced the shaft
2) reinstalled with pinion angle set to -0.5 degrees per Shaftmasters instructions. This required an adjustable upper control arm. Note the pinion angle is more critical with the aluminum DS so you can't just go by factory specs.

Now it is nice and smooth under every condition I have tested; had it up to about 120 on the road track the other day and it was nice and quiet.

I will be installing a DS from The DS Shop (Link), seems like it has this CV Joint shaft, can you please confirm.

Also how did you measure the pinion angle to know it was set to -0.5?

Thanks.

 

[zepp3lin]

They measure the angle using a tool when the car is on the lift.

 

[teebay76]

I bought my aluminum Drive Shaft Shop DS from CFM performance in Florida for $690. They were unavailable from American Muscle at this time ( March 2016 ). The CV joint that goes to the differential is supposed to compensate for pinion angle changes and that is why I bought it. The DS made a noticeable difference in acceleration even when I still had my 2.73 gears in. It was the most expensive single mod I've made to my car but it was worth it.

 

[JBert]

I will be installing a DS from The DS Shop (Link), seems like it has this CV Joint shaft, can you please confirm.

Also how did you measure the pinion angle to know it was set to -0.5?

Thanks.

Yes I believe the DSS shaft has the CV joint; and the CV joint is supposed to make the pinion angle less critical and also eliminate the vibrations. I had a shop measure the pinion angle because they have to tool to do it, and the lift to put the car up on while keeping the wheels on level ground.


Since it is a DSS shaft, I suspect the problem is somethign else, such as rotation of the shaft like penguin suggested earlier, or maybe a bad shaft.

 

[Masterang]

I bought my aluminum Drive Shaft Shop DS from CFM performance in Florida for $690. They were unavailable from American Muscle at this time ( March 2016 ). The CV joint that goes to the differential is supposed to compensate for pinion angle changes and that is why I bought it. The DS made a noticeable difference in acceleration even when I still had my 2.73 gears in. It was the most expensive single mod I've made to my car but it was worth it.

Dang it, I wish you told me about CFM earlier. I got mine from AM for $760! I thought their prices were competitive but $70 difference is pretty bad.

Edit: Just wanted to chime in and say that AM price matched to $695 although I placed the order a week before and had already received the DS. Excellent service.

Yes I believe the DSS shaft has the CV joint; and the CV joint is supposed to make the pinion angle less critical and also eliminate the vibrations. I had a shop measure the pinion angle because they have to tool to do it, and the lift to put the car up on while keeping the wheels on level ground.


Since it is a DSS shaft, I suspect the problem is somethign else, such as rotation of the shaft like penguin suggested earlier, or maybe a bad shaft.

So is the -0.5 pinion angle standard or does it change depending on how lowered you are?

Thanks for the clarification on the CV joint.

 

[JBert]

. . . . So is the -0.5 pinion angle standard or does it change depending on how lowered you are? . . . . .

I am not positive; but my understanding is:

0 to -0.5 is the target always (because the transmission does not move in the chassis as you lower the car) but the measurement will change when you lower (because the axle is moving upward in the chassis and it will rotate a little due to the upper control arm geometry) so it has to be corrected back to spec after lowering.

I think it is best to have this done by a drivetrain shop that really knows what they are doing, don't rely on internet board guesswork

 

[Masterang]

I am not positive; but my understanding is:

0 to -0.5 is the target always (because the transmission does not move in the chassis as you lower the car) but the measurement will change when you lower (because the axle is moving upward in the chassis and it will rotate a little due to the upper control arm geometry) so it has to be corrected back to spec after lowering.

I think it is best to have this done by a drivetrain shop that really knows what they are doing, don't rely on internet board guesswork

Very difficult to find a shop like that, I'll keep looking. Was going to install the DS myself but I'll have a shop do it instead like you advised. Thanks.

 

[JBert]

Since you have the DSS shaft, and the pinion angle supposedly does not matter, you probably can do it yourself with no issues. If I was in your situation I'd call DSS and talk with them about the pinion angle thing to confirm that it is not critical. Usually these small manufacturing companies are very happy to help their customers with their products.

 

[Masterang]

:wink:

Thanks for the responses guys. I suspected the pinion angle has to be much more finely balanced than with the 2piece shaft. I'll verify with them what it's set to next time I'm in there.

Did you get the vibration resolved or working on it?

Since you have the DSS shaft, and the pinion angle supposedly does not matter, you probably can do it yourself with no issues. If I was in your situation I'd call DSS and talk with them about the pinion angle thing to confirm that it is not critical. Usually these small manufacturing companies are very happy to help their customers with their products.

I talked to technical at DSS and they said the pinion angle is not important on their DS. Thanks for the direction, I'm off to start the install.