I am hoping some one can help me out here. i have come across a vibration in my bronco II that i cant find. let me give you a little history and details.

its a 88 model 4X4 and my daily driver with 293k on it. i have rebuilt the rearend(trac lok out of a 90 ranger) and frontend about 6 months ago. and went throw the tranny(5speed mazda) and replaced all the bearing about a year ago. this was done mostly because of the age on it. i had no problems untill about a month ago i started haveing a vibration while under acceleration. i figured since i still have the orginal drive shaft(CV joint type) that most likely it was about to go. those things dont normally hold up that long but i have had good wear out of this one. Found out that a replacement is a pain to get ahold of. Talked to one of the guys i know here in town that works in a drive line shop and had a drive shaft made for it (U joint type) after putting it in the vibration was still there. at first i thougth it was worse so i had the shaft rechecked. its fine. the only funny thing is i have noticed the vibration only shows up between 2000 and 3000 rpms. and in every single gear. This struck me as odd as a drive line vibration usually only show up at a certain road speed not engine speed.

Any sugestions out there.. I am open to any ideals as i have never come across any thing like this before.

Sorry that is so long but was hoping to let you know what has been done.

Thanks in advance ya'll

 

I can't think of what it would be exactly. It seems to focus on the engine though. The way you described it, the vibration is only rpm dependent, not speed dependent. That pretty much limits it to the engine in some way, especially if it does it between 2000-3000rpm in any gear(i.e. not related to road speed).

 

that is what i am thinking but i cant figure it out.

I guess i should have also let it be known i rebuilt the engine about year and half ago. Its only got 35k on the engine( yea i drive a lot, i live almost 35 miles from work one way). and its been smooth up till now.. any ideal what on the vibration on the engine might be..

i am hoping to get a chance this weekend to check out the harmonic balancer i figure something has got to be lose i check bellhousing bolts and pressureplate.

I do all my own work i been doing this professionally for about 13 years and worked with my father before that. I have come across some wierd things but i have never seen this before.

 

not sure if this will help

Check your engine mounts and mount bushings.

 

Thanks thats one thing i havent checked. and they havent been replaced. far as i know they are still the orginals from 88..

I let you know if that fixes it this weekend.

any other sugestions? that way when i start this weekend i can do them all!

 

Moved to the BII forum from the Ranger forum.

 

Quick up date. something new i noticed today. the vibration i have been having changes when going down the road at highway speeds and go over hill just as i top the hill i notice the vibration gets worse. its like the suspension gives down and the vibration gets worse and soon as it settles back out it seems to get better again. dont know but i am starting to believe the vibration is a combination of things. maybe a harmonic between the engine and the rearend.


but any way i thought i pass that along.

Any Thoughts ya'll

 

Welcome to FTE TNredneck,
Check your harmonic balancer or for uneven compression. I also agree that your symptoms are engine related!
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‘90 Ranger XLT: 2.3L, EEC-IV, EFI, DIS, 2wd, Mazda 5sp

 

Check to make sure your u-joint angles on the driveshaft are equal. You replaced the cv shaft with a u-joint type as I did. I had to install angled shims on the axle spring perches to equalize the angles and my vibration was fixed. It was most noticeable at highway speed with the driveshaft "unloaded" as when you reduce accelerator pedal pressure when going down a slight incline.
Mark

 

Hi TNredneck,

You're getting it all-the-way-around! First the symptoms pointed to the engine + now the drive-line, what's next?
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‘90 Ranger XLT: 2.3L, EEC-IV, EFI, DIS, 2wd, Mazda 5sp

 

Hey Wolfen

Right now i am willing to take advice on any thing i havent tried.
so far i cant find any thing wrong. I have worked on about every thing out there and i have never come across some thing like this.
Truth is i was hoping maybe some one might have a insight to this. but so far its a no go..

 

Ok i have been doing some checking on the drive line. And this is why i dont take my vehical to any one to work on it.. after checking the angles on the u-joints (Myself) i found that the front one is runing at about 5 degrees which is fine and well with in specs. but the rear one is running almost dead straight. Now from what i know you want this to match as close as possible so as to not create a vibration the guys at the shop who put it in said it was right. i had taken there word on it since i know most of them and trust there word.. well i found time last nite to double check that since nothing else was working. i hope to correct this tonite i let you all know if this fixes my problem if i shim it the right way i should have about 3 degress on both ends..

Thanks all and i let you know

 

The exact reason why I do my own work. I had a reputable driveline shop make me a shaft with a single u-joint at each end. They said it would "bolt right in and work properly" It vibrated pretty bad so I checked the angles and they were pretty close to what you are stating. Just make the angles equal by rotating the axle pinion flange down, hopefully they won't exceed 3-4 degrees. I also shimmed the engine mounts 3/8" to lessen the angle at the Tcase. The CV shaft will tolerate the angle difference but a single cardan drive shaft will not.
Mark

 

Looking at shaft angles may not be right. Didn't you say that this problem just started? I say to check tire balance.

 

MJB
Driveshaft angles must be correct to have a vibration free driveline. A CV shaft will tolerate different angles but a single cardan shaft will not. This will definitely cause a vibration.
Mark