kennyyoung

Hi guys, I've been having a problem with my driveline.....About a year ago, I started getting a "clunk" in my truck (1996 Tacoma V6 4X4 SR5 Extended Cab Automatic), it felt like a bad transmission mount (which upon inspection seemed fine) or something in the driveline. I thought it was the center bearing, so I had it replaced but the clunk continued. About 4 months later the bearing went again....I thought it may have been a faulty bearing so I ended up getting another one. After replacing it for the second time, the bearing, I assume is on its way out again (the bearing seperated from the rubber the last two times). I recently found out that the clunk was do to an under greased rear slip yoke. Finally, the clunk is gone, but now the truck is viberating excessively during accelleration ever since the grease job. My question is... should I now replace the $150 center bearing for the third time now that the clunk has been taken care of......would the under greased slip yoke that caused the clunk, ruin a center bearing? I have also inspected all the u-joints and they are fine. I'm just getting tired of spending so much money on a lousy center bearing in hopes it will solve my problem. Any suggestions would be greatly appreciated. Thanks, Kenny

Maj

Well, if the bearing is separating from the rubber it should be replaced. A binding slip yoke would put axial stress on the driveline and subject the center bearing to forces it was not designed to carry which could lead to premature failure.

kennyyoung

Thanks Maj for the imput.....I just don't know if there is anything else going on to cause the vibration....I would hate to spend another $150 on a third center bearing for it to be torn up in no time!!! I have read the manual on installing the center bearing and have it torqued to spec, but there is so much play in lining up the center bearing..... what I did was jack the truck up, install the center bearing loosely, put the truck in drive to allow the driveshaft to straighten the center bearing and then tightened it to the proper torque.....does this sound right???

dirtoyboy

yes that sounds right.....

sounds to me like your driveshaft might be out of balance or possibly out of phase......

Have you ever removed or taken apart the driveshaft? Did you put it back together "in phase"?

kennyyoung

Yes, actually I did have the driveshaft out some time ago to change that darn center bearing.... I did take the precaution of marking the driveshaft before taking it down.....so I know the first time I installed it the right way. Now the second time I changed the center bearing, I marked it again, but for some reason, I got a funny feeling that I may have put it up wrong.....probably went off the mark from the first install of the center bearing....hmmmmmm!!! Think I should flip it over???? The viberation is only in accelleration though....wouldn't it viberate all the time if it were out of balance or out of phase? Thanks for your input!!

904_runner

Honestly sounds like it might be a ujoint. My moms went out on her 99 2wd 4runner and upon visual inspection it seemed fine. Once i dropped the drive shaft it was instantly noticed that the rear ujoint barley had any movement to it.

kennyyoung

I'm pretty sure it isn't a u-joint, I just checked all of them recently. The problem with the viberation has only occured after I greased up my rear slip yoke. Now by greasing the slip yoke, it does change the angle of the driveshaft a little.....I don't know...lol ... I'm so confused!!! Thanks for the input.

904_runner

Okay then, sorry i can't help you.

I just know with my mom's it was only vibrating above 55 and only on the throttle.

kennyyoung

Thanks for trying .... any help or suggestion is a good one!!!

apalmer1

does your truck have any lift on it? you might try putting a few washers in between the mount for the center bearing and the bearing itself to reduce your driveline angles. I couldnt see this being a problem on a stock truck but for the 50 cents it costs in washers from ace it might be worth a shot.

im confused as to what you mean by greasing the slip yoke changes the driveline angle aswell...

you might want to inspect the transmission/transfer case rear bearing and the pinion bearings, both are fairly easy to inspect, take off the driveline and put a dial indicator against each flange and spin them to look for excessive runout.

kennyyoung

No, my truck is completely stock..... what I mean by greasing the rear slip yoke changes the driveline angle is....when i greased it, it pushed the drive shaft out about 1 1/2 inches and before greasing .... the driveshaft was resting toward the bottom of the center bearing.....after greasing, it was more to the top of the center bearing..... I just assume it changed the angle. I know this center bearing is my nightmare!!! I just hate to buy another one, just to see if it was damaged from the slip yoke or is it something else!!! I cant keep buying these things in hopes it will work....if ya know what I mean...lol. Maybe it could be the tranfer case bearing or the pinion bearing....but if either was worn, wouldn't the viberation have been there for some time now....not just after greasing the slip yoke? Or, is the new pressure from the grease creating more of a stable driveshaft and now I can feel the transfer case bearing worn??? Just thinking....lol. Thanks for the info.

kennyyoung

Hey guys, just got from in under my truck and had a friend change gears from reverse to neutral to drive and back again..... all I can see wrong.....which I know is the vibration problem... is when the truck is put into drive, the driveshaft really pushes up hard on the center bearing (way more than it should). Shifting back to reverse...not half so much movement but, down to drive a great deal of movement. Now this center bearing is only about 2 months old ..... why is my truck eating center bearings.... I guess its back to my original question "would a under greased, under extended (after greasing it extended about 1 1/2 inches) rear slip yoke, that was creating a "clunk" before and after braking, cause a center bearing to break away from the rubber that surrounds it?" I greased the slip yoke and the clunk is now gone.....thats when the vibration started!!! Do anyone think I should try replacing the center bearing for a third time now that the slip yoke is working properly or should I keep looking for another problem? These center bearing are $150 each, very costly to take the lets try and see method that I have been taking.

Fo-runna

I think I recall reading somewhere about somebody who ran into a similar problem after greasing the slip yoke. Something to the effect that the grease created a vacuum that would not let the yoke slip. (Hope you followed that). Essentially when you put it in drive it creates some axle wrap and the yoke is supposed to prevent that from creating pressure on the carrier bearing and/or u-joints by sliding in or out... Over greasing can create an air pocket that disables the slipping of the yoke. Seems to me that since this problem occured immediatly following the greasing that this may be the culprit.
This can happen with manual hubs too where they will not engage/disengage due to a grease induced vacuum.
In any case, let us know what you find out.

kennyyoung

Thanks for the help....that do sound very logical..... if the slip yoke is completely extended without flex, then yes, it would almost be like a solid shaft not allowing movement and putting extra strain on that center bearing. That makes so much sense, I think you may have something here. Do you know if there is a special grease for the slip yoke or is it the usual stuff??? Well, back under the truck tonight....I'll keep ya posted!!! Thanks again for the suggestion.

kennyyoung

OK, I just took the grease nipple out of the rear slip yoke and it oozed out letting the driveshaft relax a bit....I took the truck for a spin and the viberation went down from a 10 to about a 2...which is good. The "clunk" hasn't return yet either, so maybe the slip yoke sticking from day one has been causing my center bearing problem. Now, do I dare put yet another center bearing in hopes that by fixing the slip yoke, it won't eat another center bearing? How can you tell if your driveshaft is out of phase??? Any info on that one....Thanks for the help!!

dirtoyboy

How much grease did you pump into the thing?

dang! haha

an in phase driveshaft will have the ears on the yokes and ujoints lined up on both ends like this....if they are not even the shaft rotates unevenly

kennyyoung

Well, I'd say that I definitely put in too much grease....I usually grease my driveline every 3 months, but that slip yoke just always kept taking it without any sign (I didn't know where the grease was going) that is, until my last grease job where I finally got some movement out of the bugger....to much!! As for the out of phase driveline... your picture really helps. Now, my driveshaft comes in 2 pieces.... the rear shaft is in phase up to the center bearing.....however, the front shaft has the ears next to the transfer case 90 degrees different from the rear shaft......So,to be in phase, does the front driveshaft ears have to line up with the rear driveshaft ears? Thanks again for the picture, it sure helps!!!

kennyyoung

Ok, I think my driveshaft may be out of phase.... I checked my buddies tacoma tonight and all his "ears" line up on the front and rear shafts. A job for tomorrow to turn my front shaft 90 degrees to try to get the darn thing in phase.....wish me luck...lol!!!

dirtoyboy

luck!

kennyyoung

Well, I took the driveshaft off the truck, re-checked all the u-joints, took apart the rear slip yoke, cleaned it up, re-greased it and put it all back together in phase. I put the driveshaft back on the truck and.......I am happy with the performance of the truck now....the clunk is gone and the viberation is barely noticable....I know the truck could still use a new center bearing, "again", but I will wait until it gets worst. My next project is to replace a sticky front caliper, which is also giving me some vibration during braking. Always something to do....I wish the chassis on the truck would just rust out so Toyota would take it off my hands...then I could get myself into a new Tacoma!!!! Thanks to everyone for their help and suggestions!!!