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Discussion Starter #1
Hello


I am not sure where to post this. I hope this is the right place...Thanks


My truck has a pretty good driveshaft wobble from 0-13 or so in second gear. It is very noticeable.

I had to get a few loads of topsoil today for a little landscaping. I rented a trailer, and loaded it down with 3 yards of dirt. The load was poorly distributed. Maybe the loader wanted me to have an easy job, because he loaded it mostly in the back of the trailer. Left me with at least -300 lbs tongue weight. I guessed the load to be right around 5000 lbs.

I would start in first gear, and there was a little wobble, but not too bad. Im not in that gear long anyway. Then when I hit second, and get on it, I get a big wobble and shake. It will stick around until about 2500 rpm, or 13 mph. Im not really punching it either. I was accelerating gently. I had 5k lbs behind me with no brakes, so I was not on it...

This is something that has been with the truck since new. Happens when unloaded, and gradually goes away with increased payload. (I assume because of changing driveline angles and what not)

It is quite troubling. Cant be good for things. At the end of this trip, I have to climb a 1/4 mile HILL that is in excess of 25% grade. Its a steep sucker. I was in second gear at 2800 rpm, near WOT, and 20 pounds of boost for most of it. No wobble at that speed, but accelerating up to it, it was pretty bad. I am just afraid that the u-joints will wear prematurely, and bust.


I have asked a few other ZF ownere if they have this problem, and I dont know of any that have. I just cant imagine what would happen if I had to take a huge load.

Anyway, this has turned into a long post. Any thoughts? I know that some Allison owners got a free one piecer, but Im pretty sure that doesnt apply to a ZFer... Thanks
 

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I would guess that the -300 pound load on the rear lifted the truck enough to throw off the drive angles.


Or there could be a problem at the carrier bearing.


Since yours is a ZF, you probably still have the 2 piece drive shaft. If so, has it been removed/serviced at any time? The separate pieces may have been reassembled 180 degrees off and cause the wobble.


Later...
 

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Discussion Starter #3
I have never had it serviced. I am not too sure about my local dealer. I wouldnt be suprised if they didnt know crap about a ZFR setup.


I get the wobble unloaded. The added weight of the trailer made it far worse. I occasionally need to put heavy stuff in the bed. The wobble goes away at about 2000 lbs in the bed. But I do get a little vibration at 2400 rpm in 5th gear on acceleration. I assume the angles changed, and just moved the vibration to a different speed.


I am confident that if I had stepped on it pretty good, bad things would happen. It felt that bad...


So you have no wobble anywhere? From 0-80 WOT?


Thanks
 

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Discussion Starter #4
I have the exact same truck as you. Just an 02.





Do you have a one piece? I thought that the ZF's were always 2 piecers...





Anyone know if the driveshaft lengths are the same between the Alli and the ZF? Could I talk them into replacing the two pieces with a one piece?
 

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If it is assembled 180* off it is still ok.


It could be the timing of the u joint is off.


On my 93 6.5 the rear shaft was welded together about 20* off straight and the new one the dealer ordered came in and it was off too.


If the u joint aren't straight in line the shaft doesn't flex properly and can bind.


Also the carrier is mounted in rubber and that could be the problem.


My dealer would look it over, check the obvious and order a new shaft if that is what it takes.
 

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Discussion Starter #6
I guess Ill just have my dealer take a look at it...They hardly know what a 6 speed truck encludes, I dont want to know how they might fix one...


I was hoping for some DmaxAllitech imput...
 

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Take the drive shaft out and call customer service and tell them it won't GO.





Have them haul it in and they'll have to put a new driveshaft in.
 

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mannytranny said:
for some DmaxAllitech imput...

I believe that Eric mentioneded in another thread that he had never seen a ZF 6 speed
so we're on our own.






My truck doesn't have the same problem as yours, but if it did I'd take it to a good 4x4 dirveline shop an get their ideas. They'll be able to measure angles. Between shims and spacers tey aought to be able to tame the monster, or else offer an expert opinion of what was screwed up by the factory so the dealer can get the right parts for you. I don't think their is much chance in this front-wheel-drive world that you'll stumble into a dealershipo tech that knows what he is doing troubleshooting driveline shakes. Of course the help from the drivetrain specialists wont come for free, but it'll be worth it if it bothers you.





As for shaft interchange between Allison and ZF trucks that's a no go. The ZFs have bigger/stronger U-joints.





I know, lots of advice, but no help.
 

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Discussion Starter #9
Thank you all for the help. I have brought this up in the past on other boards, and just thought I would see what yall had to say here...


I really dont want to pay a dime elsewhwere to get this fixed. I want the dealership to take care of it. Seems like they should know what they are doing...


If someone has a pic of the carrier bearing setup under their truck that would be great. It would give me a chance to catch any obvious errors.


I guess these things are really rare!
 

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Discussion Starter #10
I got a tip on another board that I thought Ide run by you all...


As it turns out, the two pieces of the driveshaft are not level with eachother w/o a load. To solve this, Jelifsc showed me a pic of a spacer that he added in order to drop the carrier bearing down about an inch. C channel. Leveled out the driveshafts, and no more wobble.






Anyone have thoughts on this? He has two inch lift blocks, so he had to make his spacer a bit taller. I was thinking about straight iron with holes in it. Maybe do 1/2" or so.


Looks like I found a cure! This has been bothering me for a long time...Ill tell y'all how it went...
 

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mannytranny;


Mine is a XC XB so I don't have a carrier bearing. However, interested in how your solution worked out.


Thanks,
 

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Discussion Starter #12
So you have a one piece shaft? I didnt think there was such a thing...???


It has worked out well. The wobble is better. Still there, but not like before. 500 lbs in the bed/hitch would help out even more...
 

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Definately one piece. My guess, any longer frame will have a two piece. The '94 F250 XC LB i had before this toy also had a two piece DS and the carrier bearing went bad. Had the DS sent to a special shop and they replaced the carrier bearing an balanced the DS. Worked fine once reinstalled.
 
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