Chevrolet Malibu: Rear Axle/Diff problem

[Bonnewagon]

Yes, a bad move. It should have been lubed upon installation with axle oil. Also, the oil level in the carrier housing is important because the oil travels down the axle shaft, lubes the bearing, then drains back to the case along the axle tube. It does not have a puddle of oil in the axle tube to lube the bearing. I wonder if the oil level was low all along, and the bearing starved for oil, thus making the noise? One way to tell is to top off the oil level, tilt the whole car so that oil flows towards the bearing, and see if that helps. If it does, then oil starvation was the problem all along. Also you should have used fresh oil, as the old oil is probably dirty or contaminated. Too late now since there is no way to drain the oil without cracking the cover open a bit. So for now just fill it right up to the fill hole. What I do is tilt the car to the other side so I can get a bit more oil in. That way I am sure the bearings get the oil they need. I did not post that vid. Steve, Pontiacgp, did. I'm glad he did because I was confusing our cars with the "F" bodies. I have a few Firebirds and those axles have the bearing pressed on to the axle. Those are the axles that can be machined for a smaller repair bearing. Our "G" cars have the bearing in the axle tube. My mistake. Either way the factory manual says to just replace the axle- not so easy to get these days. That type repair bearing is a great idea. So get the right oil level in there, and if that fixes the noise- then some day open the cover- drain the dirty oil out- and fill with fresh new oil. If you used fresh oil last time it was open, then disregard, you are fine using that again.

 

[MalibuHacon]

I did of course use fresh oil, I refilled the diff with fresh oil a little over a week ago, and I drained it in a bucket and reused when opening the diff the third time. I did tilt the car high on its side to allow for proper oil before driving away after installing. (it was only a bit low on diff-oil) today I filled the diff oil till it was pouring over, and i will refill if i need too?!?
Hmm nobody in the auto-club mentioned to lube the bearing before installation, except for underneath (Will this cause problems??). Anyways, I am certain that the sound was not the actual wheel bearing, but something else. But that is not too import right now.... because my car PASSED inspection, after the inspector checked for play in the wheel and agreed the sound is not the new bearing. So the car is approved for 2 More years on the road !!
Thanks for the help everyone.

 

[Bonnewagon]

That's great news Hacon. But you really should figure out what the noise is. Winter is coming and you don't want something to break after the cold sets in. If that car club has a lift, ask them to get the car up off the ground and run it in gear. Find out exactly where the sound is coming from. If it is the wheel area, there are several possibilities like the brake drum or shoes scraping. If it is the differential that is a big problem. Can you hear it while driving? Or only up close?

 

[64nailhead]

Just seeing this thread. If a wheel bearing is bad, you can just about guarantee that the axle is just as bad where the bearing rides. Repalcemet ales are less than $100 new - get one. Regarding the noise, running it on a lift with no load on the wheels is not going to identify anything, unless your issue is so severe that it's dangerous to be driving. It appears that you are yet to remove the carrier and inspect the carrier bearings (side bearings nd races on the carrier). But before doing any of that you need to check the pinion for in and out movement at the yoke and check the gear lash. Both of these are accomplished with a dial indicator. With the driveshaft and differential cover removed it will take about ten minutes. If you pinion in and out is mre than .002-.003" and/or your gear lash is over .015", then you need a new bearing kit nstalled and the the ring and pinion set up properly if it is re-useable at all. These 7.5" 26 spline carriers are a dime a dozen, the bearing kit is less than $100 and the only tools needed are a dial indicator, a low budget caliper and a 1/2" torque wrench. Post some pics of the parts and report back with some measurements.

 

[MalibuHacon]

There is movement in the diff, between the pinion and spider gears. While i'm driving i can hear the sound, its not very loud, and it goes away when putting my foot lightly on the accelerator pedal. It is also there in neutral. It sounds kind of like when a car is driving in reverse, only not that noisy of course, but a similar sound. I can probably get a hold of a new axle or diff sometime in the future. If i push on my driveshaft it will move up and down, where it links to the diff and transmission. The bearings are worn, a mechanic said I had to rebuild the axle, and recommended to drive it as is, until it breaks, because its costly and difficult to rebuild the diff.

I am sure I'll get back on this topic sometime in the near future, but as of right now, I will drive with as is, unless it gets any worse. I need to focus on other things on the car, and also things i find more enjoyable, because working on an axle must be the worse/hardest work I've done on a car . I will also tighten up the bearing where the driveshaft meets the diff, because that was recommended to me.

 

[64nailhead]

There is movement in the diff, between the pinion and spider gears. While i'm driving i can hear the sound, its not very loud, and it goes away when putting my foot lightly on the accelerator pedal. It is also there in neutral. It sounds kind of like when a car is driving in reverse, only not that noisy of course, but a similar sound. I can probably get a hold of a new axle or diff sometime in the future. If i push on my driveshaft it will move up and down, where it links to the diff and transmission. The bearings are worn, a mechanic said I had to rebuild the axle, and recommended to drive it as is, until it breaks, because its costly and difficult to rebuild the diff.

I am sure I'll get back on this topic sometime in the near future, but as of right now, I will drive with as is, unless it gets any worse. I need to focus on other things on the car, and also things i find more enjoyable, because working on an axle must be the worse/hardest work I've done on a car . I will also tighten up the bearing where the driveshaft meets the diff, because that was recommended to me.

Jinkies, I just noticed you're in Norway implying that you probably don't have access to junkyards containing the same type of vehicles that we have here.

There is movement in the diff, between the pinion and spider gears. - this statement is not sensible as the pinion and the spider gears do not contact each other. The pinion gear (that the yoke is attached to) drives the ring gear that is bolted onto the carrier (differential) that drives the spider gears via the cross shaft, and the spider gears drive the side (axle) gears which engage the axle splines making the wheels turn. This is why your sentence that I underlined doesn't make any sense.

When pushing on the driveshaft to check for movement at the rear end yoke you need to identify where the movement is coming from. The options are between the u-joint cap and u-joint cross (this means a bad u-joint), the u-joint cap and the yoke (this means a loose strap or worn out yoke), the the yoke and the yoke nut, and the pinion and the housing (this means you have improper preload on the pinion bearings). The advice you were given to tighten the yoke nut is a good repair only if the rear has been reassembled incorrectly. If it hasn't been recently disassembled AND you tightening the yoke nut resolves your noise, then you need a bearing kit because what you'll be accomplishing is taking up slop due to wear in the pinion inner and outer bearings and races. If this is the case, then just be aware that at some point it will need a bearing kit installed.

Installing a bearing kit can be challenging for someone that never done it before and if you don't think you can pull it off, then it would be best left to shop to complete.

Best of luck on the other side of the ocean

 

[pontiacgp]

There is movement in the diff, between the pinion and spider gears.

The spider gears are made up of two pinion gears and two side gears. Do you mean you have play (movement) with the two pinion gears and the two side gears?

Have you checked the u-joints on the drive shaft?

 

[Bonnewagon]

Hacon, do you mean that the pinion companion flange has play? That would absolutely cause gear noise. Be sure it is the flange itself and not the universal joint that is loose. The flange nut is supposed to be tightened such that it pre-loads the pinion bearings inside the case. That can be measured with an inch pound torque wrench. What you do is remove the straps holding the universal joint in place and put a 1-1/4" socket on the nut. The pre-load on the nut with nothing else in the case should be 10-15 inch pounds with used bearings. The pre-load with the whole differential assembly in place should be 20-25 inch pounds with used bearings. Since you aren't going to take it all apart again then at least remove the brake drums so that they can't drag and affect the measurement. If you can wiggle the flange by hand then obviously the nut is too loose and should be tightened. Yes, the bearings are most likely worn, but as you said, you just want to get by for now. The right way to address this situation is to carefully tighten the pinion nut so that there is at least 15-20 inch pounds of pre-load on the whole assembly. Is the seal leaking? If not that is good and tightening the flange nut can proceed. If the seal is leaking then this is the time to change it. To tighten the pinion nut you will need to hold the flange from moving. There is a tool for that which most people don't have. But you can make your own tool for now. Just replace one of the flange straps and clamp a long length of steel pipe to one of the flange bosses. Then have someone hold the pipe and flange steady. Then SLOWLY and CAREFULLY tighten the pinion nut. You will feel the slack being taken up and when it is at zero play, begin measuring with the inch pounds torque wrench. Be aware that you can easily overdo it and ruin the job. What is happening is that inside the case on the pinion gear shaft there is a collapsible spacer that gets crushed as the nut is tightened and it holds that setting until the bearings wear and cause play. Once you tighten the nut up to the point of touching the spacer, it will feel like it can't go anymore, and that is the flange touching the spacer. But that was the setting for the new bearings when the rear was assembled. The wear on the bearings needs to be adjusted for. That is why you can SLOWLY and CAREFULLY tighten the nut and collapse the spacer a bit more to compensate for the wear on the bearings. We are talking thousandths of an inch here. That is why you measure with the torque wrench every tiny bit of adjustment. Spin the flange while you do this to seat the bearings. When you get the pre-load to 15-20 inch pounds, you are done. That should take care of the companion flange play, but, since there is a lot of bearing wear, and tightening the pinion nut will change the pinion gears position ever so slightly, it may affect the pinion depth and thus the ring gear backlash setting inside the case. I'm thinking it won't cause any problems or a new noise, but you never know. Since the bearings are worn, the backlash is probably out of specs anyway. In my opinion, having a loose companion flange, with no pre-load on the pinion gear, is a way worse situation that will eventually fail if not addressed. So, aren't you glad you decided to work on cars for fun?

 

[MalibuHacon]

I am not entirely sure of what to do now. Where is the pinion nut even located?. When i have looked at the car with others that know more than me, They have showed me that there is slack in the driveshaft, as well as where the spider gears meet each other, and where the pinion shaft meets the two spider gears that ride on top of either side of the pinion shaft. Which seal is it that could leak? and what flange has to be held?

The noise I find most concerning is the bang noise that comes when i accelerate hard, or when putting my car in drive on a hill, this noise barely ever showed up, but it became much more present after the bushings that attach to the top of the differential was tightened. If i stomp on the gas from a stop or even while moving slowly i hear a banging noise. But i was told to tighten up something.. im assuming its the pinion nut? but i don't know where its located.

I should probably look this up in my repair manual, i don't know what most of these parts are. :O

Is this the nut i should tighten? (that pic is obviously not my car) because that's where people say I should tighten it up, they told me to use a breaker bar or something like that.

 

[Bonnewagon]

Yes, look at the manual and read up on this. Be absolutely sure what is loose or has play. There is some looseness inside the differential, it is not tight as can be. The carrier and the pinion are supposed to be held tightly with pre-load on them. As they wear, they loosen up. There is free play between the pinion gear and the ring gear. It is very slight, only .008" , but you can feel it even when you turn the flange by hand. Then there is some play in the axles, so when you add it all up, it seems like it is all loose back there. But when it is too loose, that's when noises appear. So first make sure the driveshaft is tight. The universal joints at each end are a tight fit and should not be loose. If they are that would cause a "clunk" when changing direction. When they are shot they growl. At the differential where the drive shaft bolts up is the companion flange. The universal joint is bolted to the flange with straps. The pinion nut is at the front, and is hard to see when the driveshaft it in place. It is on the end of the pinion shaft and that IS a tight fit. The pre-load of 10-15 inch pounds is what holds the pinion gear in suspension so the driveshsft torque doesn't make it move out of position. If that flange is where the looseness is- then what I said above applies. Look for this exploded view of the entire rear end assembly in your manual.