TFitzPat87

Hi All,

I've actually posted about this before, but it's been a while and I wanted to repost and get some more ideas.

So I have what seems to be a harmonic vibration/howl that starts in at about 47mph, really kicks in at 50mph, and then dissipates/pretty much goes away by 52mph. Also, it doesn't matter what RPM's I'm at, it happens at the same speeds. It seriously seems to be from the front end, but I feel it in the floor and gas pedal (from what I hear, that means I should look at the rear). I'm at 3.5" with 31's and a TC drop. I just recently replaced my u joints, and at first it seemed a bit quieter, but after a couple weeks it's back to what it was. Also, this same thing was happening when I was completely stock, but is a little bit more noticeable after the lift. I do have plans to purchase an SYE this weekend.

Do any of you guys have any direction on what I should look into? It's not super loud, but it's there, and it's been going on for quite a while, and I'd like it to go away. This noise is most noticeable under acceleration. It's gone if my foots off the gas, and is there but quieter when I'm holding around that speed.

Thanks for your help! Specs in my signature.

JeepsAreForSpeed

Which U joints did you replace? That has all the symptons of a tire not being balanced. I had an issue like that in my truck and I really thought it could not be the problem because the tires were new and balanced six months prior but tha's what it was that goes to show how fast tires can change. Have you checked the driveshafts for dents?

TFitzPat87

I replaced the rear ds ujoints myself, and the ds looked good. No noticeable dents or dings.

I honestly do need to get my wheels balanced. I have had them balanced 3 different times because the sticky weights they use keep falling off. I'll have to get em rebalanced again.

Something I've also noticed, is when I was stock and driving when the weather was warm, it would stop doing it at that speed after I had been driving for a bit. But when it was cold out, it wouldn't change. With the bigger wheels and tires, the weather hasn't really affected it. Possibly just that out of balance compared to the stock wheels and tires?

SatiricalHen

I had a vibration for a while and I could t figure it out. It ended up being my front hub assemblies. So much better now.

TFitzPat87

It's possible, but with only 77k on it, I'm thinking it's a bit early for that. Plus I checked them over a couple months ago and everything was smooth. I actually checked the hubs because of this issue. This has honestly been going on for quite some time, it's just been more noticeable since the bigger wheels, tires, and lift. I've just been dealing with it cause I don't want to throw money at it, hoping to fix the problem.

I'm going to get the tires re-balanced tomorrow, and go from there. It's the best starting point considering I know each wheel is missing some weights.

I'll be sure to report back.

TFitzPat87

Alright, so I had my wheels/tires balanced, and although its smoother through that speed range, the howl/rumble noise is still there.

Any more ideas?

Another point is, I currently don't have my front DS in, so I know it's not related to that.

Snow play xj

Tires -- just went threw this a couple months ago. Did my wheel bearing units and thing were quite and smooth. Then one day I started s little shake and hum after running the dog on county road ( dirt back road) did a look around when I got home and there it was. Only one wheel was missing weights.Took me about a week to get it done, but It was behaving the same as you described

TFitzPat87

See my last post. Just had my tires balanced earlier today.

VTJeep

Have you inspected engine and trans mounts?

SatiricalHen

Have you tried without the back driveshaft?

JeepsAreForSpeed

What about your front universal joints on the front axles? Although if it's fine going straight thats odd. A quick check would be to jack up the front tires and spin them to see they spin smoothly while turning the steering wheel in each direction. Also does it still do it at 50mph while hitting the gas and brakes at the same time? Maybe a warped brake rotor or one is sticking.

JeepsAreForSpeed

Good Idea.

TFitzPat87

I have not, but I will. Really seems to be coming from the front, but I'll give it a try. I actually spent the earlier part of my day installing 703 injectors.

It happens whether I'm turning or going straight. It's just related to that speed. I haven't replaced the front ujoint's yet, but I have them. The current ujoints just have the tiniest bit of play. You can't feel it, but they click when I push them back and forth. I also haven't tried the break test. It is about time for a pad and rotor job though. Pulls to the right while stopping sometimes.

ZJMAX

What are your rear pinion and transfercase angles at now? Also is your rear drive shaft long enough?

Max

TFitzPat87

DS is long enough, and the angles aren't bad. I have a RE TC drop in for the time being so it's alright, but I will be getting an SYE installed in the near future.

@JeepsAreForSpeed, I did the break test, but it was a little difficult to tell if it changed anything as hitting the breaks was allowing the torque converter to unlock. The combination of that and the slight resistance from the breaks made for a kind of goofy sensation. Is there anything I can do to get to that speed range without going into OD?