vibration when accelerating

[FourXFred]

i did a search and didnt find anything relevant, so dont yell at me for asking a stupid question. alright, ive got a 1991 explorer, and i recently had my torque converter and all seals in the tranny replaced. the vibration was allready there before i had the work done. when im getting on the highway, like above 50 mph, there is a violent vibration comming from the rear of the vehicle. it only happens when i am hitting the gas, and when i let off, regardless of speed, it completely goes away. i just climbed under the ex and checked the u-joints. i can only move the driveshaft about 1/4 of an inch, and i dont appear to have any freeplay in the u-joints.im not saying it isnt the joints, because it might be. any idea what it could be? the vibration also happens while just maintaining speed on the highway also, but like i said, only while hitting the gas. thanx for info.

 

[Majisto]

Driveshaft? Is it balanced?

 

[dogfriend]

Random thoughts from a madman:

Sounds like your rear axle could be rotating or shifting when you give it gas. Or possibly the engine/transmission are moving instead. This would change the angles of the ujoints and cause vibration.

I would check the rear suspension visually to make sure nothing is broken/ loose somewhere allowing the axle to shift under power. Also check motor mounts / trans mounts to make sure nothing is broken there.

Another possibility would be a damaged pinion and ring gear in the rear axle. The teeth come into contact during acceleration on the faces (where the damage is) and on the backs when coasting.

Much luck to you.

 

[FourXFred]

suspension visually looks ok in the rear, and so do the tranny mounts also. u-joints are cheap, so im going to replace both of them on the rear driveshaft tomorrow. hopefully it goes away. any other ideas?

 

[dogfriend]

Can't think of anything except when you have the driveshaft off to replace the ujoints, turn the pinion on the rear axle to see if it feels rough. Make sure to index mark the flange first so you don't lose track of the driveshaft indexing

 

[MazdaGreg]

I had a 87 ranger with the same problem. Because you say it goes away completely when you let off the throttle, it sounds like Ring/Pinion. I had a severe whine/vibration at highway speeds. When i would let off, the noise went completely away. Turned out i had 2 broken teeth on my Ring gear.

I believe that a driveshaft that was out of balance would still vibrate whether you were under load or not, but i could be wrong. The thing turns whether your on the gas or not.

good luck, and let us know what you find!

MazdaGreg

 

[POSex92]

Not trying to steal a thread but my 93 xlt vibrates when im accelerating from a stop with the wheels are turned. I was told its probably my u-joints but it was never bad enogh to check. Just recently it has gotten a little worse and id rather it not do that. Any help is appreciated. Thanks.

 

[FourXFred]

i just installed my shackles and spacers! woo hoo! when i was installing them i discovered that my shocks are completely gone. they are rancho 5000's and i had to push really hard to compress them, and pull really really hard to expland them, they would not expand on their own. could this vibration be related my shocks being in need of replacing?

 

[dogfriend]

Maybe....Did the vibration problem go away?

 

[FourXFred]

i dont know, i havent been on the highway today. i didnt replace the shocks, i just put the crappy old beaten broken ones back on.

 

[Skugga]

My X seems to have the same problem. I could notice the vibration when I was going up hills around 40 mph and anytime accelerating above 55. The engine was also racing when that happened so I thought it was from the clutch slipping. I just picked the X up from having the clutch replaced so now it shakes but the engine rpm stays at the normal level for my speed.

I'm going out now to check the u-joints and motor mounts(although I don't really know how to tell if one is bad )

 

[victorb]

HI,
I had just about the same problem. There was a distinct power loss first, then, as soon as the truck drops back into ovewrdrive and is under load, a nasty vibration and the Tach goes grazy. Let off the gas and it clears up. I had just finished replacing the u-joints so I suspected that as the cause of the problem. After removing and balancing my drive shaft, the problem remained. I took my mechanic out for a test drive and we both agreed that there were probably 2 different problems. The loss of power was possably due to lack of fuel and the shaking could be the transmission.
Turns out that the "Lifetime" fuel filter isn't. After replacing that and putting in new spark plugs (minor tune up) the truck is back running fine again. No shaking, no power loss. I have gone 500 kms since and I believe it is fixed. My 92 now has 377,000+ kms. When it hits 500,000 I have promised it to my son.
Ihope this helps, sorry it's a little late.

Vic

 

[FourXFred]

i dont have a problem with my tach going crazy though in overdrive. i found out what it was, my rear u-joint was completely destroyed. i mean fubar'd real real bed. no bearings at all and only 3 caps. i actually had to go buy a new driveshaft cause the joint was soo gone it started eating through the "ear"(possible wrong term) when i looked under there, the driveshaft was actually comming in contact with the yoke on the rear axle. now i need a new axle too, cause the pinion bearings are shot (1/2 inch of free play), and im too lazy to rebuild a 13 year old axle.

 

[Skugga]

I think I found the most expensive cause for this problem. I was just told its going to need a new engine. And this is with only 89k miles. I always thought the 4.0 was tough but I don't know why I'm having such bad luck. The X was in my family since it was new so I know it was always taken care of. Up to this point the most expensive repair was for a new a/c compressor. They told me it has no compression in the #4 cylinder and theres a knock in the bottom end. At the dealer they said it would cost $4500 to fix.

The only good thing I can see coming out of this is that I might get to drive a newer car for the next few months. I'm at school now but I'll get a used engine put in the X when I'm home. My mom was talking about replacing her car for a while so now she might get something used and let me drive it for the rest of the school year. Then when summer vacation starts I should have the X back and she can get the car she wants.

 

[bronx explorer]

hay guys i just notice the same thing with my 92 ex when am in the high way and going up a hill i notice a vibration and a noise when i let go of the gas it goes away any help will be good. also how can i check the u-joints to see if they are good am just learning how to fix my truck.thanks you can e-mail me if you like at aj422310@aol.com

 

[FourXFred]

Bronx, it sounds like the same problem as i had . to check your u-joints, set the e-break and put it in nutral (this is to check the rear one, which usually goes first) crawl under there and try to turn the driveshaft by hand, there should be NO freeplay between the driveshaft and the yoke on the rear axle (the yoke is the thingy connected to the other side of the u-joint). if there is freeplay, you need a new u-joint. if not, try pushing up and down on the rear yoke, if it moves, your pinion bearings are shot.(inside your rear axle) make sure your friend is there to make sure the explorer doesnt run you over too, that allways helps! if your u-joint is gone, they cost like 10 bucks at any autoparts store, but are kinda a pain in the ass to do if you cant take off the driveshaft. i cant get my driveshaft out, so it was real hard to do my u-joint (bolts holding it on have 12 years of rust keeping them in place) good luck!

 

[bronx explorer]

thanks i will look at it today and i will let you now what i find

 

[RFR2212]

Originally posted by FourXFred
i found out what it was, my rear u-joint was completely destroyed. i mean fubar'd real real bed. no bearings at all and only 3 caps. i actually had to go buy a new driveshaft cause the joint was soo gone it started eating through the "ear"(possible wrong term) when i looked under there, the driveshaft was actually comming in contact with the yoke on the rear axle. now i need a new axle too, cause the pinion bearings are shot (1/2 inch of free play), and im too lazy to rebuild a 13 year old axle.

I'm lost on this one or too giddy! So you got a bad u-joint, and took yer d-shaft yoke ears to ****... How would that have beat yer pinion at all? I could see a slight wear, but assuming this u-joint was a receint problem, i dont see how it caused ya a 1/2 of play in yer pinion...

On that note, isn't it easier to rebuild the axle, than hunt for a used one, with the same gearing... which still has miles?
Pete

 

[Naga Sadow]

Sorry to hear about your engine skugga, I saw your ex today. My poor ex just came out of the shop because of a bad starter. Its the cold weather thats cursing us I tell you.