Driveline Vibration

[AnotherS197GT]

I was hoping I could get some help solving a driveline vibration I've had since I got a set of 4.10s installed. I noticed that when I went over 80 MPH, I would get a vibe that felt like it was coming from the seat, and I assumed that it was the driveshaft clocked improperly after the install. I just left it since I was going to get a 1 piece DS anyway.

After I replaced the DS, I was still getting the same vibe at the same speed. I adjusted my pinion angle to -2 and clocked the front of the DS 90*, no change in vibe.

I was driving around after I clocked the DS trying to feel exactly when and where the vibe comes in, and if I keep my foot to the floor, the vibe slowly starts coming in around 90-95 MPH. The second I let off the gas or shift the car to neutral it gets really bad and I can feel it down to around 70 MPH or so.

I was thinking of clocking the rear of the DS, but since the problem has remained the same or similar with a stock and aftermarket DS, I'm a little worried the gear install might be a tiny bit off. I do notice a bit of a hum when I get around 80 MPH...

Aside from this vibe over 75/80, there are no other vibrations or noises that popped up after the gear install.

Any suggestions of things to check? I think I'll give clocking the rear of the DS a shot this weekend if I can find the time.

 

[skwerl]

Could be in the transmission and you're noticing it now because everything is spinning faster with the shorter gears.

 

[AnotherS197GT]

Sure hope thats not it. I can't afford a 6060 right now and I'm not putting another 3650 in it. I would be really surprised if that were the case though, trans has been over that RPM before with 0 vibes.

 

[NotaHybrid]

In for results as I have the same issue.

 

[BruceH]

Is there any chance the tires became unbalanced during the install? Maybe tossed around and lost a few weights?

 

[AnotherS197GT]

Is there any chance the tires became unbalanced during the install? Maybe tossed around and lost a few weights?

I think thats pretty unlikely. I don't really trust the dude that last balanced them (just because I wasn't the one to do them), but they were totally fine before the install. The dude that did the install is a buddy of mine, and hes very careful with my stuff. Plus I have strips of stick on weights, they aren't the usual chunks of weights, they are a pain in the ass to remove, and you would have to remove the whole strip. I'm trying to find some time to take the wheels in to get rebalanced though. Hopefully tomorrow morning if the shop isn't too busy.

 

[AutoXRacer]

I have driven on unbalanced wheels (race set) and unbalanced wheels do not vibrate your seat like that.

You need to look into your rear axle, driveshaft, and transmission.

The only time I felt a vibration like that, it was do to me upgrading to a 1-piece driveshaft. The vibrations would start around 80-90 MPH, then stopped at 110MPH, and came back at around 120MPH.

I removed the 1-piece driveshaft and replaced the stocker and the car was smooth as butter.

If you had no vibes prior to the gear swap, then thats where your issue is; driveshaft or rear axle.

 

[AnotherS197GT]

I have driven on unbalanced wheels (race set) and unbalanced wheels do not vibrate your seat like that.

You need to look into your rear axle, driveshaft, and transmission.

The only time I felt a vibration like that, it was do to me upgrading to a 1-piece driveshaft. The vibrations would start around 80-90 MPH, then stopped at 110MPH, and came back at around 120MPH.

I removed the 1-piece driveshaft and replaced the stocker and the car was smooth as butter.

If you had no vibes prior to the gear swap, then thats where your issue is; driveshaft or rear axle.

Yep, I definitely agree with you there. I got the wheels balanced today and the issue is still present. I'm going to try clocking the rear of the DS to see if that helps out at all. If not, I guess I'll be calling my buddy up to double check his work. Bummer because I've been driving it like this for 1000 miles or more, and I'm sure I'll have to get a new gear if its the problem.

 

[fdjizm]

I have the same vibe till this day after getting 4.10's installed.
I have a feeling it's the pinion nut and I am going to have my rear rebuilt soon but this time with a solid spacer instead of a crush washer + new bearing all around..
Right at 80mph nothing I do helps, even with the stock driveshaft... this is going on 4 years now.

I may just drop in 3.73's if there is nothing I can do about it.

 

[BMR Tech]

Have you tried to set the "pinion angle" at -1, or even 0?

I have had some customers who had similar vibes, and had to go smaller on their Pinion Angles. It is really odd.

 

[BMR Tech]

https://www.facebook.com/photo.php?v=470937339716400&set=vb.100004004131164&type=3

 

[AnotherS197GT]

Awesome video Kelly, I'll give that a shot this weekend! When I measured my trans angle last weekend it was was 3*, so I'll need to set the rear at -3* (or whatever the opposite of the trans angle is, it may change since I'm replacing my old ass stock mounts this weekend)

I also have a new stock rubber upper diff bushing going in soon as well, should I check the PA again after that?

 

[BMR Tech]

If the OEM piece is ripped, then yes.

For anyone reading this, it is ALWAYS good to check your OEM diff bushing on a regular basis, if you abuse the car. Especially if you have upgraded UCA/LCA.

I cannot even start to tell you how many customers I have helped diagnose issues, and their OEM diff bushing is split ,cracked, or even gone! Hundreds....

To add to that, it is VERY important to ensure the UCA to OEM Diff bushing is torqued at load, as well.

The most common cause, in my opinion, of a ripped diff bushing is people lowering their cars and putting drag radials on - without ever loosening and re-torquing their OEM diff bushing.

 

[AnotherS197GT]

If the OEM piece is ripped, then yes.

For anyone reading this, it is ALWAYS good to check your OEM diff bushing on a regular basis, if you abuse the car. Especially if you have upgraded UCA/LCA.

I cannot even start to tell you how many customers I have helped diagnose issues, and their OEM diff bushing is split ,cracked, or even gone! Hundreds....

To add to that, it is VERY important to ensure the UCA to OEM Diff bushing is torqued at load, as well.

The most common cause, in my opinion, of a ripped diff bushing is people lowering their cars and putting drag radials on - without ever loosening and re-torquing their OEM diff bushing.

I might just give it a shot myself then. I don't really feel like setting PA again and again.

 

[AnotherS197GT]

Trying to set my pinion angle. (again). Shooting for 0 trying to get rid of a DS (i think) vibe.

This is my trans output flange.



This is my pinion flange.




At the risk of looking dumb, this is what I had it set at thinking it was -1*

 

[AnotherS197GT]

It's even worse. I can hear the u joints clicking at low speed and it shakes and whines like hell.

 

[AnotherS197GT]

Got it all set to zero, vibration is unchanged. After swapping DS, changing pinion angle between -2 and 0 (and -6 lol), I think I'm going to throw in the towel and have the gears checked, or get another set installed. I can't handle never being able to go over 80 without shaking my teeth out of my head.

 

[fdjizm]

We're in the same boat kid.
Glad to have company

 

[AnotherS197GT]

I'll be the Captain, you can be my first mate.

I talked with my installer today, he said to try the stock DS again and see if it clears it up. If not, we are going to talk about either checking the install or replacing the gear. I swear this car just needs to go. Nothing ever works out right for me on this thing!

 

[NotaHybrid]

I was told that my driveshaft was part of my problem as well. I'm about to just buy a stock rear end because I've had shit luck with my past gear install and this one possibly. I feel you with things always going wrong on installs. Are you on the stock uca?