I have a bad vibration between 55 and 65. Shop says it is the rear end. When I put it in neutral and rotate the drive shaft it turns 1/4 or more. and if I turn alittle harder it cluncks alittle further. Any ideas???? When I turn it with it in park it doesnt move a bit. so i think that eliminates the u joints. what are the possibilities? thanks for any advice.

Broc

 

My 89 bronco has a vibration between 65 and 75. I replaced my rear wheel bearings and seals last weekend. When I had the cover off, I noticed that my spider gears had some chips on the gear teeth. I don't know if this could be the problem, but I intend on changing out the spider gears soon. They also appeared to have quite a bit of wear on them.

I've replace the u-joints on the drive shaft and also found that the center bearing in the Cardan joint is worn. This may also be causing the vibration. Napa has the center bearing for $62.00. The reason I've put off replacing mine is because the shaft the center bearing mates with is scored and it will need to be replaced as well. That will require taking it to a driveline specialty shop and have it replaced and shaft rebalanced.

Just some food for thought!

Bronco894x4

 

thanks for the response! I guess i need to do some more investigation.

 

I find it interesting your Bronco has Cardan joint. What year did they start installing a split drive shaft that would require a cardan? I can't ever recall seeing a split drive shaft on a short wheel base bronco as this would make for a rather steep pinion angel.

 

[updated:LAST EDITED ON 23-May-02 AT 09:39 PM (EST)]Don't know what year they started using them, but it appears as far back as 1970! It's not a split drive shaft. The cardan joint is on the end that connects to the transfer case. The yoke is attached directly to the cardan joint.
Bronco894x4

 

Not a carrier bearing, a double cardan joint:
http://www.superford.org/registry/users/33/139/DCP_0616.JPG

$62 is hella steep. I paid about $28 for the centering ball at my local Napa
http://www.superford.org/registry/users/33/139/DCP_0606.JPG

 

Oh, and to answer the original question, it could be a lot of things. This is actually a common problem on Broncos and people have never tracked it down (not always at least). You don't want to ever "check" the u-joints in Park because they're bound up at that point, ie the d/s is keeping the truck from rolling. Check the u-joints in N w/parking brake set. Yes, you'll have some movement at the pinion, this is usually just normal backlash... what you don't want is ANY movement in the d/s itself, ie the u-joints should have zero play. It can be VERY hard to detect play in the double cardan w/out dropping the d/s and feeling by hand - this is what I'd recommend for starters.

But.... are you sure your tires are balanced?

 

Yep. Tires are balanced. Had all that stuff checked. When I put it into gear and lean out and under to see the rear diff. (very wierd position but works) i can see the drive shaft engage and then torque up. looks pretty bad. i really dont trust any good shops around to do this type of work is this something that takes any special tools or machinery?

 

Well, it's normal for the d/s to torque up, that's axle wrap and it's gonna occur on all leaf-sprung rigs even under normal conditions.

As for special tools, it doesn't take any to rebuild the CV (double cardan). If it's your rearend, is probably better left to a pro and will require at least a couple special tools.

 

Our Napa doesn't carry just the centering ball. For $62.00, you got the whole assembly.

I was reading yesterday about the E4OD transmission on the web. Don't remember the link. It mentioned some problem with the torque converter causing vibrations. It said to check it, touch the brake pedal ever so slightly when you feel the vibration. If the vibration goes away, could be the torque converter also.

Bronco894x4

 

I had the same problem with my 90 EB Bronco. It turned out to be the double cardan joint ball,spring and needle bearings on the rear driveshaft. I swapped out the forward piece of the drive shaft that contains the ball, spring and needle bearings. I think I paid about $57 for the piece from a truck drivetrain shop here in south Texas. I paid the same place about $132 to balance both front and rear shafts just to be sure I covered all the bases. After that I had no more vibration and all was fine until I blew my tranny. When I took the rear shaft off and rotated the front of it I noticed that the joint locked in the same place of rotation each time. I also put new U joints in just because I had it out and had to take it apart. Take that shaft off and inspect the joint by rotating it slowly. If it locks at any point in the rotation it is probably suspect and needs to be replaced. If you separate the front joint and the spring and needle bearings are gone, like mine were, then you know what your problem is. Good luck! Hope this helps.

KJ

 

>Our Napa doesn't carry just the centering ball. For $62.00,
>you got the whole assembly.

Don't let them feed you that bs. It's Napa part #612, clear as day in the pic above. Of course that may vary by model year, I dunno. This was for a '90

 

You might try re-indexing the driveshaft.Pull u-bolts,separate shaft from yoke,turn 180% and re-install.Some are balanced in one position only.Ford vibration school!

 

Hey Thanks Everyone! I appreciate all the response. I'll post the results when I figure out what it is.