Vibrations at highway speeds

[yungupgrade]

The vibrations I'm getting aren't death wobble or anything. I get a constant, slight albeit noticeable shake when driving around 60. Sometimes it eases and sometimes it increases. Everything in the cab just......rattles? You can definitely see the shifter and steering wheel vibrate, loose trim pieces as well. I assume this is just because it was an old jeep built in 88, but I do need to redo my front discs/ shocks so I feel like that could be a contributing factor as well. Does anyone know of any ways to reduce these vibrations or do I have to live with it?

[eaglescout526]

Bushings, replace all the worn out rubber bushings with new ones. Chances are theres not much rubber left if no one has replaced them in 30+ years. So the control arms, leaf springs, shackles, coil spring isolators, engine mounts, trans mounts. I think thats all.

[Pete M]

what shape are the tires in?  out of balance and out of round tires tend to start vibrating 55-60 mph.

[yungupgrade]

1 hour ago, Pete M said:

what shape are the tires in?  out of balance and out of round tires tend to start vibrating 55-60 mph.

ones I bought with the truck were balding in the front. Got different ones that were used, not bald. I've had unbalanced tires before and this shake doesn't match the vibrations I'm getting tho. HOWEVER, I did not align it because I was still debating going with a lift or not, which probably is contributing to the issue.

[Airborne Janitor]

When the vibes happen can you speed up and "outdrive" them? If so I'd say your tires need balance and/or replacement. If the vibes get worse I'd be looking at steering and suspension. What are the specs of your rig, stock? Lifted? Tire size? Etc.

[fiatslug87]

Check for play in the u-joints.

[yungupgrade]

53 minutes ago, Airborne Janitor said:

When the vibes happen can you speed up and "outdrive" them? If so I'd say your tires need balance and/or replacement. If the vibes get worse I'd be looking at steering and suspension. What are the specs of your rig, stock? Lifted? Tire size? Etc.

My truck is stock suspension, on 29's I think. I don't think I was ever able to outdrive them. I'm away from home now but next time i'm by the jeep I'll take it for a drive again.

[drcomanche]

On 9/27/2022 at 10:24 PM, yungupgrade said:

ones I bought with the truck were balding in the front. Got different ones that were used, not bald. I've had unbalanced tires before and this shake doesn't match the vibrations I'm getting tho. HOWEVER, I did not align it because I was still debating going with a lift or not, which probably is contributing to the issue.

Did the used tires come with the wheels? And if so, were they balanced? Take it from experience, unbalanced tires can wobble in a very large variety of ways depending on their mounting and how out they are. Going for a balance and alignment can't hurt.

 

If you're seeing it in the shifter and cab, go for some new bushings, as eagle said. I lost a lot of driveline vibration with a new trans mount. Another easy thing to look for is if the driveshaft is out of alignment or bent. Set the rear up on jack stands and put it in gear and see if it has an uneven movement.

 

There are a lot of options for what it could be, but fortunately, most are easily debunked and a lot are relatively cheap, too.

[yungupgrade]

5 hours ago, drcomanche said:

Did the used tires come with the wheels? And if so, were they balanced? Take it from experience, unbalanced tires can wobble in a very large variety of ways depending on their mounting and how out they are. Going for a balance and alignment can't hurt.

 

If you're seeing it in the shifter and cab, go for some new bushings, as eagle said. I lost a lot of driveline vibration with a new trans mount. Another easy thing to look for is if the driveshaft is out of alignment or bent. Set the rear up on jack stands and put it in gear and see if it has an uneven movement.

 

There are a lot of options for what it could be, but fortunately, most are easily debunked and a lot are relatively cheap, too.

Used wheels were put onto stock rims that I got with my truck. Vibrations did not change from when I got serviced at the tire shop vs before I went. Bushings are certainly overdue and I'll check the driveshaft for any play.

[JimB]

Just throwing this in. My 87 Cherokee had a vibration between 50 and 55 mph. No problems below or above. Swapped the rims over to my 86 Comanche and the vibration followed. Found the right rear rim was slightly bent. Swapped out for the spares rim and problem solved. 

 

[gogmorgo]

Depending on tire size, balance issues typically show up somewhere between 50 and 70 mph. Sometimes they go away as you go faster, sometimes they don't. Sounds like you picked up some loose tires and had them installed, presumably they were balanced at the time? It's unlikely to be the issue then, but you never know. You can also try swapping the tires front to rear to see if things change, or swapping over a set from another vehicle that doesn't shake instead of putting down money to get them rebalanced. The old tires were just about bald, were they bald evenly across the tire or worn out in certain spots and not others? This can help gauge whether the alignment was off or not, or if there's a worn out suspension component. Don't overlook rear suspension if you can't find anything up front.

 

It's also a good idea to check your front driveshaft. If you can move the double-cardan joint up and down, the centring ball is worn out, which can cause some crazy shakes. Also check all the ujoints and the joints in the front axle shafts as well.

The shifter moving around suggests you should look at trans and motor mounts as well.

[yungupgrade]

On 9/27/2022 at 7:56 PM, eaglescout526 said:

Bushings, replace all the worn out rubber bushings with new ones. Chances are theres not much rubber left if no one has replaced them in 30+ years. So the control arms, leaf springs, shackles, coil spring isolators, engine mounts, trans mounts. I think thats all.

So I finally had time to look at the front end of my truck in depth and literally all the bushings are shot (from what I can see just looking in the wheel well) . On top of that it the steering knuckles, swaybars, etc all have such a thick layer of rust that I almost don't want to put new bushings on them without replacing them first. Maybe theres been worse, but to me it looks pretty bad. Don't know where to start with this.

[eaglescout526]

Could be a lot worse. Take your time, start with the cheapest and work your way up. Probably best to get all the parts first and spend a weekend or two replacing old with new rather than replace a few here and there.