Vibration at higher speeds

Ok man, I'm not the main guy on anything...except stupidity...I just know what I've ran into over the past 3 years owning 3 and working on a few.

Higher speed vibrations after a lift typically point to a change in pinion angle causing the drive shaft to be at mismatched angles and not cancel itself out as normal, with opposing equal angles.

I'd first pull the front shaft, then drive it. Then do the same in 4 wheel drive with the rear out if you think it's the driveline.

Next, see if anything is loose or got changed. Really go through it.

Sometimes, I wonder ....and may be wrong....can a u joint that has ran at a certain angle for ages, then when slightly changed it may act up or be stressed where it hasn't been before..or was the shaft split at the slip joint and reassembled out of phase...this is a real possibility with some type drive shafts.

Also, was a wheel weight knocked off.

Make sure your transmission mount is solid.

Basically..it can be a number of things, but I'm not trying to say it's unsolvable...guys work it out constantly. It can be elusive, but 2.5 inches is typically not problematic.

There are certainly way more things than I'm saying...I'm just using what comes to mind...we have some great guys here... like @jjvw , @JMT , @Chris and many others, hopefully they will chime in and walk you through the basics.

I say the basics respectfully, because I've been on here 3 years, and I'm still needing to be drilled on the basics. I made a good gain with one tonight because of going back to the basics.

AztekSkull said:

Hi, I just installed a RC 2.5 lift w/ shocks and springs, I feel a real difference but now I feel some vibration when going on a street in 30+ mph, do I need a rear track bar bracket or something? Im sure some have been in this situation, also feels little vibration on the steering wheel.

Merry xmas to everyone.

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2.5” is enough lift to cause driveline vibrations. There are three ways to solve it at your lift height.

First, drop the Transfer Case about a half inch with washers to confirm that your driveline vibrations are due to the lift. If you want to keep it this way, that’s fine. ($)

Second, once you determine that it is caused by driveline vibrations, get a 1” motor mount lift and remove the Transfer Case drop. You should be good then, if not, add a washer at a time till you are. ($$)

Third, get a SYE and DC. This is the best solution, but not required. ($$$$)

Did you pull any driveshafts for the install? Did you put them back 'in phase', as in, did you mark the position of each end in relation to the pinion and transfer?
If you are good there then as AndyG said it is likley the Ujoints in the shaft now at bad angles. If you feel it in the steering wheel try pulling the front shaft. Be sure to mark the shaft and the pinons so you can return it to the exact same location. Take a test drive. Any better? I will also say that you need to re-align the steering after a spring lift. Even just 2 1/2" lift will need to adjust back to get true 12:00 at steering wheel and reset toe in. Check pinion angle while there, but not much you can do about that.
If your vibes are gone, yes! You know the problem and what will fix it. If no change in vibration then we head to the rear.
Drop the skid down a good 3/4". Easy way is to go get longer bolts and 6 oversized nuts to fit between skid and frame to lower the skid. Any change?
If either a bit better or all better means it's in the rear.
Pull the rear shaft. Remember to mark the end to return it in correct phase. Shift to 4H. Take a test drive. How's the vibe? All gone? Neet to (1 or more) lift the engine, lower the trans skid, get a SYE and new rear shaft.
That should deal with any vibe you picked up from the longer springs. Also take a look at the front shaft to confirm you have plenty of room at the skid throughout its range of movement.

A MML works better than a t-case drop, doesn't lower the Jeep and costs around $50. Thick washers at Lowe's for under $5 is way less work to see if that's the issue.

I see an oil leak at the rear pinion fyi.

Goatman said:

Did you pull any driveshafts for the install? Did you put them back 'in phase', as in, did you mark the position of each end in relation to the pinion and transfer?
If you are good there then as AndyG said it is likley the Ujoints in the shaft now at bad angles. If you feel it in the steering wheel try pulling the front shaft. Be sure to mark the shaft and the pinons so you can return it to the exact same location. Take a test drive. Any better? I will also say that you need to re-align the steering after a spring lift. Even just 2 1/2" lift will need to adjust back to get true 12:00 at steering wheel and reset toe in. Check pinion angle while there, but not much you can do about that.
If your vibes are gone, yes! You know the problem and what will fix it. If no change in vibration then we head to the rear.
Drop the skid down a good 3/4". Easy way is to go get longer bolts and 6 oversized nuts to fit between skid and frame to lower the skid. Any change?
If either a bit better or all better means it's in the rear.
Pull the rear shaft. Remember to mark the end to return it in correct phase. Shift to 4H. Take a test drive. How's the vibe? All gone? Neet to (1 or more) lift the engine, lower the trans skid, get a SYE and new rear shaft.
That should deal with any vibe you picked up from the longer springs. Also take a look at the front shaft to confirm you have plenty of room at the skid throughout its range of movement.

Click to expand...

When you say mark the end to return it to phase, what does that mean?? I just bought a new Tom Woods driveshaft and there are no marks?! How do I know if its in phase on the initial install??