Rear end noise

[eightbanger]

So i've just put my D/S back on the truck with my new combo U/J where it broke out of the pinion yoke, started her up and took it very gingerly out the drive and onto the road, I could not get it much over 15mph as a strange vibration and or whiring sound would start to come from under the truck. Had a look underneath and nothing had changed except for a small oil leak from behind the pinion yoke so I realise that means I need a new seal. But can anyone tell me what other unseen damage could have been done to the axle when the D/S broke out of the P/Y a few weeks back??

[gcburdic]

Well Crap Nigel!!!....Fix one thing something else goes!!!....
Not sure of the problem, but have you changed the rear end oil and gasket in awhile??.....if you do, run your fingers through the oil as it drains for any metal filings??.....Maybe something happend to the ring/ pinion when the DS broke?? (this is purely a guess!!!)

[my67chevytruck]

could the drive shaft have thrown the weight when the u joint broke? did you install the ujoint or have a shop do it. you may want to have the balance checked. is this a 2-piece d/s with a carrier bearing?

[mr48chev]

Did the driveshaft get any dings in it when the cross broke? I've also seen them damaged when someone went wild clamping them in a vise to work on them.

[eightbanger]

Originally Posted by gcburdic

Well Crap Nigel!!!....Fix one thing something else goes!!!....
Not sure of the problem, but have you changed the rear end oil and gasket in awhile??.....if you do, run your fingers through the oil as it drains for any metal filings??.....Maybe something happend to the ring/ pinion when the DS broke?? (this is purely a guess!!!)

Been looking through the service manual Geoff and that's what I was wondering may have happened.

Originally Posted by my67chevytruck

could the drive shaft have thrown the weight when the u joint broke? did you install the ujoint or have a shop do it. you may want to have the balance checked. is this a 2-piece d/s with a carrier bearing?

If you mean the ballancing weight it is still there, I did install all this myself and double checked everything, and yes it is the 2 piece with carrier.

Originally Posted by mr48chev

Did the driveshaft get any dings in it when the cross broke? I've also seen them damaged when someone went wild clamping them in a vise to work on them.

No I was real carefull there.


Here is a vid i've just taken....the exhaust noise drowns out the whiring sound coming from the rear end, but WTF is that terrible sound when I take my foot of the gas.

YouTube - C10 Driveshaft 2

[john]

Looked like the yoke was moving back and forth in the second vid. Did you use a new crush sleeve? See if you can move it front to rear.

[eightbanger]

When I was fitting the new pinion yoke tightening the centre nut the yoke would throw out forward, I assumed it did that when it engaged or something...sorry I don't know what a crush sleeve is John.

[dznucks]

i agree. i think something is wrong inside the rearend. that input shaft should not move that much. one thing i notice in the "repaired" pic, is the cap of the new u-joint doesnt look like it is contacting the "tang" of the new yoke. it could be that you have a mismatched u-joint and yoke.

i had that problem before, where my ujoint was 1/8" shorter than the distance between the two tangs of the yoke. the drive shaft would slide back and forth everytime it rotated. cause a wierd vibration and crazy sound.

[john]

OK I am assuming that is a truck 12 bolt diff. Here is a link on how to set up a 12 bolt, which explains the crush sleeve.

http://www.hotrod.com/techarticles/d...ide/index.html

In your first pic it looks like there are a couple of threads sticking out of the nut. Second pic looks more like it is flush with the nut. You should not have any noticible end play in the pinion shaft. There must be some reason why the yoke tightened up before the end play was gone, burred shaft etc.I would pull the yoke back off and find the prob. before driving it. Alot of guys reuse the sleeve in a pinch by not overtightening and overloading the bearings. If the yoke is free on the shaft you will be able to tell when you come up against the sleeve to your old adjustment. Kinda longwinded hope it helps.

[ChevLoRay]

Originally Posted by dznucks

i where my ujoint was 1/8" shorter than the distance between the two tangs of the yoke. the drive shaft would slide back and forth everytime it rotated. cause a wierd vibration and crazy sound.

It doesn't take but a few mm of movement for a lot of sound to be generated. I'd be sure that the U-Joint is located between the tangs on the yoke w/o any room for movment. At the same time, I'd be making sure that the U-Joints are not stiff. If they are, you'll also get a vibration. What I mean is that if you hold the driveshaft and shake it back and forth, the U-Joint should flop somewhat. It may not move much, but it should move some. Sometimes, the action of pressing the U-Joint into the yoke of the driveshaft will pinch the ends of the driveshaft together just enough to keep the U-Joint from being able to freely move.

[eightbanger]

Thanks for the link to that article John....really good info. It is a 12 bolt.
I'll take it apart and do another vid, and those u/j caps are tight against the tangs it 's just not showing well in the pic.

[eightbanger]

Ok....new pics showing that the u/j caps are nice and snug and another showing a closer view of the centre nut on the yoke.






Hope these vids help identify the problem.

YouTube - Pinion Yoke 1

YouTube - Pinion Yoke 2

[john]

Now were getting somewhere. Just need to find out why the yoke is not on all of the way. Did the old yoke pull off hard?

[mclairmo]

Also, be sure not to overtighten the straps holding the u-joint onto the new yoke. Most people way overtighten which can cause binding and premature failure. A suprisingly low amount of torque is specified, something like 10 ft/lbs I believe or even less. Look it up or maybe someone here knows the exact figure.

[eightbanger]

Originally Posted by john

Now were getting somewhere. Just need to find out why the yoke is not on all of the way. Did the old yoke pull off hard?

Yes, it had to be persuaded a great deal with prying and a good few thumps at the back of it with the hammer. I had to use a wood block accross the front of the new one to get it down firm before I put the nut on and tightened it up.

[john]

When you get the yoke back off pull the seal and look down the splines and make sure there is no twist in the shaft. You are using old bearings, so I just snug the nut up with some locktite on the threads. The worst thing you can do to worn bearings is overtighten them. That should get it to where it was or close to before it broke.

[71 super]

You definitely have some extra slack at the pinion. Someone stated earlier that it looked like the nut was not as tight as previous and I agree with them. You need to locate the torque spec for the pinion nut and do that again. The nut is swedged and should not need loctite on it but if you use some use blue not red. I would also pull the rear cover and with a depth gauge check the pinion as well as the gear pattern after you retorque the pinion nut. You can do this with some white lithium grease to check the pattern. The pinion gears should ride in the middle of the ring gear and since yours is obviously an older (i.e) stock rear end there should be an existing pattern worn into the gears to go by. Definitely pull rear cover , retorque pinion nut to specs and check pinion depth with guage and your movement and noise should be gone. Good luck as this can be intimidating especially if it is your first time but it can be done.

[eightbanger]

Thanks 71 super going to do that today. I must admit I can't imagine it's just down to how tight the nut is.....remember all this happened because my d/s broke out of the pinion while I was driving and it was flailing around under there until it fell off, so i'm guessing it must have done some other internal damage.

[eightbanger]

Ist pic was taken when I changed the gasket and oil about a year ago...



This pic I have just taken, it's clear something major has happened....





Hopefully someone will know what might be broke....or should I just start dismantling?

YouTube - 12 Bolt Rear

[71 super]

Give your pinion a pull forward and rotate it again holding pressure on the pinion to the front. If the noise goes away it is in the pinion and could be solved by the correct torque on the pinion nut. Give your axle shafts a tug as well just to be sure the shafts are not broken. You can do this by pulling on the wheels to see if there is give; there should be very little to none. From the grind marks on the carrier something is loose and flopping obviously and there are not many options. I think it is the pinion being too loose but check the axles and the carrier saddles for cracks just in case.

[eightbanger]

I have since discovered that the grind marks on the carrier were made by the teeth on the pinion drive shaft because it seems to be able to move in and out of the differential. I am able to pull the shaft in and out which shows way too much play........ what do i need to do to correct this play? Is it the shims or can this be corrected by further tightening of the nut on the pinion yoke? You were right 71super, when i pull forward on the pinion shaft the noise does go away but it still dosnt feel that smooth when I turn the wheels.

[Phaedrus]

Tighten pinion nut until fore / aft movement goes away and try it. If your not using an impact wrench you can tell when the crush sleeve slack is taken up pretty easily (it'll get really hard to turn the nut). Worst case you trash the pinon bearings and you need to overhaul, versus a grenaded rear end from pinon gear to carrier collisions.

[eightbanger]

Thanks Phaedrus, i'll try that cause it's got to the point were I can do no more without special tools and a lot more knowledge.

[john]

You still need the yoke to slide fairly easy on the splines or you will never know when you are adjusted right. Good luck.

[eightbanger]

Thanks John, and for all the advice that's been given to me by everyone......