I have a vibration at speeds above 73 mph. It seems to be coming from the rear. I have had the rear driveshaft rebuilt and the rear end inspected. The mechanic is saying it's the tires on the truck. I have 31x10.5x15 pirelli scorpion AT with 1500 miles on them. I had the tires checked and balanced and the vibration is still there. The mechanic is saying that it's the AT design of the tires. The vibration stays steady at any speed above 73. If you put the truck in neutral at this speed the vibration is still there. The truck is a 91. Any ideas?

 

From what ive heard...some tires make more noise than others on the highway? and if urs is more of an aggressive tread it might just start vibrating at that speed?

 

sorry i havent been able to get to my comp. in a week.
it is true some tires will make noise at higher speeds but with 10.5?
it wouldent be somthing you complain about. try a little test. while on the highway when you start hearing it take your foot off the accelerator (maintaining as much speed as you can, like on a downgrade) if the noise drops significantly than you probably want to chech out your u-joints. if tone des not change stick with the tire idea. i am saying this because i had the same problem in my bronco and everyone always told me it was my tires. (even mechanics) i have a beefy set of 33-12.5s. whell one day my axle just droped. it was my u-Joint.
just lookin' out for ya'

 

Try swapping the front and rear tires, and see if the problem seems to move to the front.

 

sorry, should have mentioned entire rear driveshaft was replace including all new u-joints and balanced. The front axle U-joints are also new. I am going to try the swapping tires dea as soon as I get a chance. It's deer hunting season here and I just got real busy turning deer into venison.

 

I have the same exact problem on my 94. I am running 275 60 R15 firestone firehawk ss20's. I had no shake before and now I do at around 70mph or above. I had the shop rebalance them twice so far and they got a little better. I am going in monday to a different place and have them try it out. I dont think they are balancing them correctly. I would suggest you take it somewhere else. Hope you figure it out.

Bill

 

I believe your 275's equal out to the same dimensions as my 31's (don't shoot me if I am wrong) I have an ahole mechanic trying to tell me it's because my tires are too aggresive. I have Pirelli Scorpion AT. The truck had BFG mud terrains on it before which have a very aggresive tread pattern and had no vibration at all. I am just getting tired of the old I can fix that truck in 20 parts attitude of the mechanics out there. I sometimes feel like they expect you to believe this was the only Bronco created. (Well golly looky at this here thing can't bleve Ferd only made 1) This is driving me nuts. I bought this thing with the intention of using it to go deer hunting, 3 , 500 mile round trips a year, Now I am afraid to drive it for fear something will go break. I plan on also taking this back in as soon as i get a chance and have them swap the tires around also. I have had these balanced twice and I only have 1000 miles on them. The guy that rebalanced said they were way off. Oh well, let me know what you find. Thanks

 

Heh. Once I buried my bronco up to the floor boards in mud. Then I was dismayed to find that when driving it home (after getting wenched out by a buddy) that there was a really bad shudder noticable at higher speeds. If you have the factory wheels on it its probably mud under the pop-off rims. The guy at discount tire told me there was so much mud in there (I hadn't even thought to clean it) that it was basically acting like a wheel weight. Go figure.

 

Did you ever see the movie "My Cousin Vinny" where the guy is telling Joe Pesci that he has "mud in his wheels?" It's true, it will throw off the balance if you have enough crud in there.

 

Wasn't that his girlfriend in that movie telling him that?

Anyway, I had the same problem with my Expedition last week. I would only get vibration at around 70 and it got worse the faster you went. Rotate and tire balance didn't do a darn bit of good. It turned out to the be center bearing in the double-cardan u-joint near the transfer case.

Does your driveshaft have the double-cardan joint up front? If so, was the center bearing replaced? I would also check the wheel bearings.

 

i had a very bad vibration after i put new Goodyear MT/Rs on my truck. it ended up being that the wheel weights were not made for factory Ford Alloy wheels, and would fall off within 10 seconds on the high way. i would think that they were still balanced and they were for a very short time but then the wheel weights would fall off and then they were not balanced anymore. i would check and make sure that your wheel weights are still on your wheels if you are using factory ford alloy wheels cause they require special clip on wheel weights

 

I just had wheels rebalanced and rotated front to back. The vibration is still there. The tires have 1000 miles on them and I have not been mudding with it so I don't think there is anything inside the tire. The weights were still on the rims and I had the rear driveshaft with double cardan and u-joints replaced and balanced. One mechanic keeps insisting that its just because of the tires. The shop that replaced the driveshaft insisted that it was the problem. One local shop wants 600.00 for pinion bearing if thats it and another said 225.00 to replace axle bearings and seals. I think I will just drive the truck and keep my speed at 70 and see what happens for now. I have 1 deer hunting trip left in November if it gets me there and back I can have it checked when I get back. Money getting tight because of Christmas coming and wife is already in my butt about all the money i have spent so far on this thing. My Bronco has 146,000 on it and I bought it with 145,000 on it. I have no way of knowing what was done to it or what has been replaced. I picked it up through a wholesaler from an auction in PA. He knew nothing about it and I bought it with the intention of replacing the engine and trans because the body is mint. The only problem has been all the other things that I have had to replace have eaten up some of the funds to change the drivetrain. I guess it's time to work some ot and get this thing right.