Vibration on Acceleration at Highway Speed (1 Viewer)

[brAvery103]

I've been doing some reading on here and think I've found the culprit, but I wanted to double-check to make sure my thinking is right.

I recently installed new CV axles (Napa. I know, not OEM) up front and Dobinson's C59-223V coils in the rear. I then cranked my torsion bars to match but they ended up needing to be re-indexed. When I re-indexed the I decided to rotate them 3 splines on each side. The ride is still good around town, but now I'm getting a pretty aggressive vibration in the front end. The vibration only happens at >50mph and when I'm on the gas. I greased my rear driveshaft recently but still need to do the front, which will happen later today. From what I've read on here it seems like rake and droop are the culprit for my vibration. I'm currently at 22.5" in the rear and 22" in the front which is not enough rake. Does this sound like it would cause my vibration issue?

 

[GerLC100]

Running through a similar scenario. Swapped diff bushings that I gave the rest with the diff drop. Just recently found lower front right shock bolt loosening up, alignment not spot on (but will have that done next week after I have every single piece of my knuckles refreshed...

You write what yo did to your suspension, but I don't see new upper control arms and alignment. has this been done?

 

[brAvery103]

Running through a similar scenario. Swapped diff bushings that I gave the rest with the diff drop. Just recently found lower front right shock bolt loosening up, alignment not spot on (but will have that done next week after I have every single piece of my knuckles refreshed...

You write what yo did to your suspension, but I don't see new upper control arms and alignment. has this been done?

I didn't end up doing a diff drop since the lift was only going to be ~1.5" and my understanding is it's only necessary if the truck is lifted 2" or more. My CV axle angle isn't extreme enough so I didn't bother. I also didn't bother with new UCA. I installed new OEM shocks ~2k miles ago and took the time to re-torque them while I was in there. I also had an alignment done this past weekend. I may need to bring it back to them to have it done again though.

Could a bad alignment cause such vibrations on acceleration only occuring at 50-70mph?

 

[GerLC100]

Bad alignment can cause vibrations, yes. If it was done after your suspension work: did it changed since it came back or "stable" or you're not sure as it was the first time highway?

Whatever:
Also not in the LC game for a long time, but what I read is rear 1" higher than front is normal.

My bet for my vibrations: all old parts that are kind of worn out and I gave them the rest with lifting. Will see...
Others generally say "no lift = no vibration, so go back and bring it down". But I personally think it has to be possible with 22" front... Whatever: will be digging further and update my thread

 

[brAvery103]

Bad alignment can cause vibrations, yes. If it was done after your suspension work: did it changed since it came back or "stable" or you're not sure as it was the first time highway?

Whatever:
Also not in the LC game for a long time, but what I read is rear 1" higher than front is normal.

My bet for my vibrations: all old parts that are kind of worn out and I gave them the rest with lifting. Will see...
Others generally say "no lift = no vibration, so go back and bring it down". But I personally think it has to be possible with 22" front... Whatever: will be digging further and update my thread

This is what I assume, too. I'm going to lower it down to 21.5" in front and have the shop redo the alignment tomorrow. I will update later with my before and after alignment specs as well as if lowering the front to comply with conventional wisdom of 1" rake makes a difference. I will also be greasing my front driveshaft.

 

[hoser]

Most likely the issue is caused by aftermarket CV’s. The fix is part time 4wd. I’m kidding…. sort of.

 

[brAvery103]

Quick update:
I had an alignment done and tried greasing my driveshafts. Nothing worked...until I removed the Napa CVs and installed my old OEM CVs. The car drives great now lol.

Moral of the story: don't cheap out. Save yourself the time and effort and use OEM CVs. I'll be ordering a new set ASAP.

 

[GerLC100]

For whomever finds this thread: mine is also solved after knuckle rebuild, see my thread