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Front Differential, CV Shaft and Alignment Problem


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#1 01blaZeR2

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Posted 15 July 2009 - 04:47 PM

I changed my front CV shaft last night. It went about as good as any front CV shaft install goes. By the time i was done i had everything within 100 feet covered in grease. I noticed some noises and weird feelings today on the way to work. So when i got home i started looking into it. I dont think i got the CV shaft installed all the way into the Front Diff. When i turn the tire i can see the front diff move and about half way around a full tire rotation the CV shaft pushes the whole front diff over about 1/4" to the driver side. I'm going to have to pull everything back apart i think to get it in correctly.

So here is my question. Is the front diff axle supposed to be fixed. What i am talking about is the actual axle that the female end of the CV shaft goes around. Where the snap ring is. I remember last night this shaft inside the Front Diff was lose. It dropped almost to the bottom of the housing when i pulled the old CV shaft out. I didnt think much of it at the time but the more i think about it i think that it should not be lose. I should have to align the CV shaft up with this part and then slide the CV shaft on. Instead last night i had to align the OD of the CV shaft with the ID of the Front Diff in order to get the CV to slide in. The front diff axle shaft just moved anywhere once i had the CV shaft started on the end of it.

So with all this talk about shafts am i getting the shaft yet again from another poor IFS?

Edited by 01blaZeR2, 30 July 2009 - 10:42 AM.

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#2 01blaZeR2

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Posted 15 July 2009 - 05:08 PM

Below is a video to help explain. After taking the video and tinkering around I think that the CV is installed correctly into the front diff. The other side (drivers) has the same amount of gap from the Front Diff outer seal to the CV shaft. It also has a little play as the new one does. Its just the other side when spun does not make the whole front diff move.

I'm supposed to take the truck to a wedding in Pennsylvania Friday thats why i decided to finally change the CV shaft in the first place. Any help or advice would be awsome.



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#3 gregg6668

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Posted 15 July 2009 - 06:20 PM

Are your a-arms at full droop when you do that ?(meaning you don't have any support under the lower a-arm)
Try jacking up the a-arms a little and see if it goes away, it's probably just the joints inside the shaft hitting each other because of the extreme angle.

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#4 01blaZeR2

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Posted 15 July 2009 - 06:37 PM

QUOTE (gregg6668 @ Jul 15 2009, 07:20 PM) <{POST_SNAPBACK}>
Are your a-arms at full droop when you do that ?(meaning you don't have any support under the lower a-arm)
Try jacking up the a-arms a little and see if it goes away, it's probably just the joints inside the shaft hitting each other because of the extreme angle.



When that vid was taken i had a jack stand under the lower A arm. Now it was not at the very end of it but it was not at the Frame either

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#5 beedle4

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Posted 15 July 2009 - 09:52 PM

Im thinking you have a reg 4x4 CV NOT A ZR2 CV?

Looks as if it is binding and poping making the whole diff shift?

And I hope that its a rebuilt, and not new CV?
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#6 01blaZeR2

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Posted 16 July 2009 - 08:01 AM

QUOTE (beedle4 @ Jul 15 2009, 10:52 PM) <{POST_SNAPBACK}>
Im thinking you have a reg 4x4 CV NOT A ZR2 CV?

Looks as if it is binding and poping making the whole diff shift?

And I hope that its a rebuilt, and not new CV?



It is the correct shaft and it is a New why?



I jacked the a arm up from the very end of the arm and this issue went away like greg suggested. Thanks man. I still have to figure out some other problems however. When i was driving it to work yesterday when the suspension would extend fully after a bump there was a banging noise like i have a bad shock. Shocks seem good i disconnected the sway bar and the noise is still there. I am wondering if when the weight of the vehicle is off the front end the CV shaft is doing what we see in the video? The driver side doesnt do it when the a arms are fully extended.
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#7 gregg6668

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Posted 16 July 2009 - 08:25 AM

Are you going to be any where near Pgh on Friday?
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#8 01blaZeR2

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Posted 16 July 2009 - 10:48 AM

QUOTE (gregg6668 @ Jul 16 2009, 09:25 AM) <{POST_SNAPBACK}>
Are you going to be any where near Pgh on Friday?



I'll be taking 70 to the pike so about 30 min or so from pburg. On Friday and Sunday. Why do you ask? Wanna buy some parts i have lol


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#9 beedle4

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Posted 16 July 2009 - 11:03 AM

QUOTE (01blaZeR2 @ Jul 16 2009, 09:01 AM) <{POST_SNAPBACK}>
QUOTE (beedle4 @ Jul 15 2009, 10:52 PM) <{POST_SNAPBACK}>
Im thinking you have a reg 4x4 CV NOT A ZR2 CV?

Looks as if it is binding and poping making the whole diff shift?

And I hope that its a rebuilt, and not new CV?



It is the correct shaft and it is a New why?



I jacked the a arm up from the very end of the arm and this issue went away like greg suggested. Thanks man. I still have to figure out some other problems however. When i was driving it to work yesterday when the suspension would extend fully after a bump there was a banging noise like i have a bad shock. Shocks seem good i disconnected the sway bar and the noise is still there. I am wondering if when the weight of the vehicle is off the front end the CV shaft is doing what we see in the video? The driver side doesnt do it when the a arms are fully extended.



Others have had nothing with bad luck with NEW shafts. They were super weak and snapping them with eaze.

That makes me think that its deff not a Z shaft.

When the suspension is in full droop it is binding badly. And if it were the wrong shaft being too short that would cause it. I would measure it to make sure you never know what the parts guys are doing.

But if it is indeed the correct one im lost? Enless they are just not built to the same angle degrees of operation?
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#10 01blaZeR2

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Posted 16 July 2009 - 12:21 PM

OK here is the latest update.

The Shaft is the correct shaft for a ZR2 and it is for the correct side. When i drive the truck if i take a hard left turn the truck shakes bad like i have a very loose wheel. Also when i go over a bump and the suspension is fully extended i get a banging noise like i am overextending a shock. This is all with the sway bar links removed as they were screwed up also. Granted with these removed it is a worst case senario but still these problems should not be happening regardless. With the truck sitting flat and parked i have 1" of travel until the front tires leave the ground. What is happening is whenever the passenger side is fully extended (when turing hard to the left or going over a bump) the CV shaft is doing the same thing that it was in the video. I checked my Z heigth and its huge.

So lets do a little timeline here.

I bought the truck with 56K on it last March

Put the wheels and tires on, cranked the T bars, and put on some Knaffle Shackles at about 60K in May of 08. I swear when i put the tires on that i was right about 5.2 or so. Just at the upper limit. I had the truck aligned at a local place that does good work. They also replaced my Pitman and idler arms under warrenty.

Fast forward to May of this year. The truck now has 90K on it and things are pretty good. The tires are wearing great. Perfectly even tread wear front and rear even with only rotating them every 10-15K. I took it in to the same shop because the steering was starting to loosen up. Plus my warrenty ran out at 93K. They did about 2K worth of stuff, Oil lines, inner tie rod ends, new steering pump, etc. This work included an alignment. Now all i have done is driven the truck between their 2 alignments a year apart. So i get the truck back drive it to work the next week when i rotated the tires i notice that the front tires were wearing uneven on the inside. Nothing bad but def. some uneven tread. I took it back in and they checked it out and said it was good.

Now about a month ago at 95K i noticed that front tires are leaning in at the top alot. I figured one of 2 things happend. The upper a arm bolts lossened up from the alignemnt or the upper ball joints went as they are still the originals. I look at the front tires which i had rotated so they were not the same that had shown wear as before. This time there is alot of uneven wear. Which would be expected if you can notice the tire leaning when its parked. So i take it back to the same place and have them look at it. They said that it was way out of alignment but everything was tight. So they corrected the alignment as best they could but it was still not perfect. You can still see that the front tires lean in a little. He said the truck was out of the factory specs for the t bars and that they couldnt get the alignment any better. Now what i didnt understand was the truck went 50K almost with perfectly even wearing tires, regardless of the Z height. And this was after 2 of their alignments, and they didnt have any issues aligning the truck either time.

Now back up to this past week the CV shaft i replaced has been bad for a while.The boot was faulty and the warrenty company wouldnt cover it. It was throwing greese but not making noises so i left it till i had time to mess with it. I decided before i went to PA this weekend that i should change it and thats where i am now. As for the Z heigth i checked it to today and it is at 6.75 on the passenger and 7 on the drivers, way out of spec. I have no idea how my entire front end is not so worn out and how i didnt have uneven tire wear issues the first 50K like this. Unless the Z heigth grew over a year or some lawn gnome cranked them up.

So i am most likely not going to take the truck to PA this weekend. I am going to get a Rebuilt CV shaft from Autozone i guess and put that in. Then possibly lower the front a little and get it aligned again.

Just more of the ZR2 IFS blues. Maybe its my fault because of the t bar adjustment but i had no issues with it like that for over a year. And most of the work that the shop did at 90K was not front IFS related. I still have the factory upper ball joints and the CV shaft went because the clamp was loose and the greese was coming out the end by the clamp not because of a binding issue or a ripped boot that was ignored.
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#11 beedle4

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Posted 16 July 2009 - 12:27 PM

Strange.

But how did you measure the Z-height.

Because since your rocking 32's the spec is measured front the groung so take away 1/2" or so for the tire.
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#12 01blaZeR2

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Posted 16 July 2009 - 12:40 PM

QUOTE (beedle4 @ Jul 16 2009, 01:27 PM) <{POST_SNAPBACK}>
Strange.

But how did you measure the Z-height.

Because since your rocking 32's the spec is measured front the groung so take away 1/2" or so for the tire.
Your tire size shouldnt matter. The Z heigth is measured from the Center of the Lower A arm where it pivots to the ground and then from the ground to the lowest point on the knuckle. Subbtract the 2. I got 16 from the ground to the arm bolt and then 9 from the ground to the bottom of the knuckle. subtract the 2 an its 7".

Is that not the correct way?
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#13 beedle4

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Posted 16 July 2009 - 12:41 PM

I thought it only worked correctly with stock tires? I may be wrong?
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#14 Miles

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Posted 16 July 2009 - 05:31 PM

Read this thread.

The problem with your CV axle is the rebuilt CV you replaced the original with. I've learned that for whatever reason, they are not built the same as OEM. I've run into this EXACT same issue on the passenger side CV shaft, and the culprit was the CV shaft inner cup. It's just the way that the aftermarket companies are building them. They are too deep and cause the shaft to do what you are seeing. The shaft goes through its' normal range of motion in a circle within the inner cup that is shaped like a tripod. If you were to take the same CV shaft (out of the vehicle), and rotate the cup all the way around in a circle, you would see that it cannot make an actual circle because of the design. Hard to describe, but that's what's happening. The fix? Buy a junkyard OEM shaft, and have IT rebuilt at a local CV shaft shop. Most driveshaft shops can rebuild them too.

On the alignment issue. The upper control arm bushings are worn out where the outer metal cups of the bushing slide into the frame mounts. These outer cups have "teeth" on them, and once these teeth get worn down, your alignment simply will not hold. That combined with the fact that too many alignments will stretch the UCA alignment bolts, and you've got what you are experiencing now. Replace the UCA bushings with Moog Problem Solver Thermoplastic units, as well as the UCA adjusting bolts & nuts with new factory GM units (approx $50) and you'll be set.

I could go into a longer dissertation of all this, but the above should take care of your problem.
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#15 TrailTamer

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Posted 16 July 2009 - 06:16 PM

it sound obiviously that somehow the front end got cranked that the z-height increased then in result that the issue with couldnt get it aligned and binding in the cv shafts

pic of the cv shaft will help as we can tell if its "too much" or "ok" etc on the angle

also just FYI the alignment shop dont touch the caster bolt (upper control arm bolts) everytime you take it in the alignment shop. all they do is put on heads (special tool that attach on wheels (all 4) that send laser signals and blah and send the info to the computer) and check the spec and adjust whatever's not in the alignment such as toe, caster, camber (caster and camber rarely needs any adjustment but they 're the what adjusted by using the upper control arm bolts)

good luck


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#16 ZR2onthego

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Posted 16 July 2009 - 06:45 PM

did you just slide this in by hand or did you pound it in? i dont think its in all the way i ran into the same problem. the hanes manual tells you to use a soft ended hammer and pound it in. i dont think you got the clip seated correctly causing the cv to be pushed out that 1/4 inch making it bind
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#17 01blaZeR2

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Posted 30 July 2009 - 10:41 AM

Problems solved thanks to everyone who posted esp. Miles for his miles of advice as always.

the problem with the CV shaft was the aftermarket CV shaft. Had the old one rebuild for less than the new one cost me and its better than new i think.

As for the alignment. I put in new upper control arm bushings(moog problem solvers) and new bolts at the upper control arm bushing location. the ones that adjust for the alignment. Once these were in the shop had no issues aligning it.

As for my Z heigth it was 7" on the driver side and 6.5" on the passenger . I lowered them both a little. I think they are close to 6.2" now. I have to measure them again after the alignment as it should have changed a little.

Now my only issues are dealing with some slightly cupped tires. I'd like to sell the tires actually and get some 265/75/16's to run on my other rims. They have about 1" more backspacing than the Zq8's that i have. But i cant do that till i get the rims cleanned up and painted. If only i didnt have to work.............The things i could get done.

Oh and one more note. When i pulled the CV shaft out to replace it the whole CV shaft came out along with the short shaft that connects the CV shaft to the Ring gear. That was a major pain in the ass to get back in. I dont know how to prevent it from happening as all the other CV shafts i have done on my old blazer i never had that issue.
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#18 beedle4

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Posted 30 July 2009 - 03:19 PM

Glad its fixed.

As for the inner shaft comeing out, it happens some times just depends on which snap ring decides to give...
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