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Twisted Axle Shaft, or just bad bearings?

11289 Views 22 Replies 4 Participants Last post by  DJAlsip
Alright, here goes. When I bought my car I took it to a mechanics and had it checked out, he said there were some rust on the rotors and that the chirping/squealing sound it made would go away after a few weeks. This is on my right-rear wheel. Now, two months later, it's still here, just worse. I took it for my first "long" trip today, about two and a half hours on the highway. I have only used it to and from school and when hanging out with friends locally before. My mom got really worried about it since it got louder and louder over the past few days, so she made me and my dad take it to a local ford dealership to have it checked out today. They got it on the lift and had a look at it. We came to the conclusion that the chirping sound is caused by bad bearings, which is an easy and cheap fix; however, we also noticed that the wheel doesn't even spin right, it wobbles, kind of. We discovered this after having another mechanic sit in the car while up on the lift to put it in gear and run the motor. The chirping is usually just present at speeds above 10mph, and goes away during braking. Our conclusion for the day was that the bearing has gone bad and we also think the axle shaft has somehow been twisted.

I want to hear other peoples opinions on this as I really do not have any money at all to spend, except for about a thousand dollars in an emergency account I have, which is money I would prefer not to use for this even though I have to get my car fixed asap.

Ford said we could come back on Monday and they would take my rear end apart to correctly diagnose my problem for 95 dollars, which also means I will get new differential fluid at the same time (something I would have to get soon anyways). There is a good side and a bad side about this. The good side is that if it is nothing more than a bad bearing, then I'll get that fixed at the same time, and it won't cost me too much. Also, if it turns out to be something more serious than the axle shaft and/or bearing, I will get to know. The down side about this, would be that I could save money on just buying the fluid my self and a new axle shaft and put it in. This would be no problem for me and my dad to do in our garage, although it would suck if it turns out that was not the only problem because we decided to go the cheaper route and fix it ourselves. This is why I ask all you guys about what you think my problem might be, what might be the best solution, and what I should decide to put my money in.

Thank you all in advance! I will appreciate any response. I am a poor live-at-home college kid with no job and I am dependent upon my car to get me from A to B in a safe manner.
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That's what I've been thinking. I see that autozone sell the axle shaft with a bearing and seal kit for $104 (for one side). I'm not sure about the quality of the product though.

I know you have a lot of knowledge on these Mustangs, would you recommend replacing both axle shafts, or would it be fine if I just replaced the bad one? I want to do both so I have the same ones on each side, but will it make any difference?
Alright, thank you! I'm taking it to Ford tomorrow so they're going to look at it (my dad is paying for that), and then we'll see what I do.
Update: My car is going on the jack stands when I get home from class today. Ford diagnosed that it was just bad bearings after they had a professional look at it. They say the car would have been shaking a lot if the axle shaft was twisted or bent somehow (he took it for a 10 minute test drive). So I got new bearings (saver/repair bearings with seals combined with them), new gear oil and 6 quarts of transmission fluid. Is this the correct amount? I was told the transmission contains about 12 quarts, but when you empty it from the oil pan only about 6 quarts come out and will need to be replaced. I bought Mercon V, of course.
Sorry, it is a 2003 GT. I got the new transmission filter and gasket, do you recommend me to reuse the original gasket? I bought my parts from NAPA, which is the parts supplier for both my local Ford dealerships. Should I go ahead and drain the torque converter as well when I'm at it? I do not have a torque wrench, but I might go get one since I am planning on getting a new Motorcraft fuel filter too today.

Edit: Yes, it is an automatic transmission. I believe it is the 4R75W that is in the 03 and 04 GT's? I heard they upgraded the GT's for the 03, but left the 4R70W in the V6's. Is this correct?
Yes. The gasket that comes with the replacement filter is a cheap cork gasket.
I noticed, I will reuse my OE gasket then.

Not 100% sure but I thought the 4R75W's are in the 04 MY. However, I'm not sure it makes any difference in this case.
I believe the differences are on the inside only and should not make a difference.

Thank you for all your help, sir. I appreciate it! I am about to jack up my car now.
Ran into a few problems and got delayed, but my dad is putting on and sealing the differential lid as I type. I have a night class, so my dad said he could do it for me while I'm in class. I will come back with an update when I am done with this. I am also putting in a new fuel filter later tonight.
She came back on the ground today with new axle shaft bearings, new gear oil, and a new fuel filter. She runs smoother and I feel less vibrations from the rear end, but the chirping sound is still there. It is not as loud as it was, so I guess the new bearings helped a little. The bearing on the right rear end was shot though, unlike the one on the other side which was still in reasonable condition. With the wheels up in the air and the engine running on idle, the right rear wheel still "wobbles", which leads me to believe that I either have a warped rotor, or a twisted axle shaft. I do not feel any heat from the brakes after driving, except from what would be normal. The brakes feels good, although I wish they would have a better initial bite than they do.

I am currently thinking about new rotors and new brake pads, as well as one new axle shaft for the right side. My funds are very limited and I will not be able to go for any high performance parts, so I will probably end up getting everything from Autozone for now. Later on I might look into rebuilding the rear end with 31 spline axles and new gears, but that's far ahead in time. Please feel free to leave a comment with your thoughts or information you would like to share. Thank you all.
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Update: Earlier this week the chirping sound stopped, so I figured everything was good. On Saturday I was taking my moms car to pick up a friend that was staying the weekend because her car gets about 40mpg, so my dad asked if he could take my Mustang to work that day because he usually drives my moms car to and from work. Anyway, to the point: My dad noticed that my new axle saver bearings are leaking. The ones I bought were from NAPA, and they had the seals on them, so no need for extra ones. We changed them on both rear axles, and they both started leaking. The passenger side more than the drivers side, I assume it has to do with the chirping from the passenger side rear wheel.

So while I was having two of my friends over my family took the trip to a store in a city about 40 minutes away because they were the only shop to carry two rear axle shafts for a Ford 8.8 inch rear end with 28 splines and ABS. They got the kit so it came with a new bearing and new seal. They also got new gear oil, LSD additive, and silicone for the differential housing. So tomorrow when I get back from school she will go back up on the jack stands and I and my dad will replace both axle shafts and bearings/seals. This time with regular bearings and seals.

I am still a little concerned that I might have a warped rotor and that the rotor and brakes might be the source of the chirping sound, not the axle. Is this possible? Would any of you recommend me to take the rotors to a shop and have them resurfaced, or should I go ahead and invest in a pair of new rotors and new brake pads from Autozone?

The right rear wheel still "wobbles" when it spins, as I have previously mentioned. I doubt a warped rotor would have so much effect on the wheel, so I can only assume it is the axle shaft, I just want to make sure. Would really suck if I did have a warped rotor and it ended up damaging another set of bearings and possibly the axle shaft.
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I forgot to include that I have no vibrations at all. My rim is not bent, only a few months ago I got it balanced and new tires. I also got my brakes flushed and checked out about a month ago. I also took it to Ford and they diagnosed it and told me it was only the bearings, but switching them out did not fix the problem. My brakes also work fine, no vibrations during braking. This is why I think it is so weird. Could it be the axle housing?
1. Wheel appears to wobble, most wheels can be balanced out to take car of vibration from a warped rim. It may have 4 lbs of weight in it but they can be balanced out.
The wheel appears to wobble, but it is in balance. If my rim happened to be damaged somehow, wouldn't they notice that when they were balancing it as they put new tires on? I don't know if this is an old problem or one that has recently come up, so it is hard to tell.

2. Your axles are leaking. This could be the result of a bad install. Bearings could have been damaged when they were pressed on to the shafts. May not be in the right location on the shaft. A lot of things could have happened here to cause that problem.......If, you would have had no previous symptomless before and you had only changed the bearings because of bad bearings and then they started leaking. However, that's not the case...but, I still wouldn't rule it out.
The bearings I bought only had one O-ring on them, and that was supposed to be the seal. I was skeptical, but I figured I would just trust it since it was an axle saver bearing with seal. The axle saver bearings have the bearing itself located a tad further in on the axle shaft than the original bearings, this is so it won't have to run where the axle already has worn down.

3. twisted shafts or bad shafts. This very well could still be the problem. Good way to find out is to take the shaft out and and use a straight edge to check and see if the axle is bent. I would also remove the wheel, rotors and brake calipers from the axles while the car is on jackstand's and see if you notice "run out" on the hub.
This is my main suspect, They didn't look bad when I pulled them out to put in new bearings last time, but then again the damage might be too small for the bare eye.

4. Bad axel housing. Only way I know to check this is with a bore gauge. If you don’t know what Micrometers and a bore gauge is…best to skip trying to check it.
I doubt it is the axle housing, but we never know! If it turns out to be a bad axle housing I will end up going to a junk yard and pulling one off of another Mustang. I haven't checked into pricing for a new one, but I need to keep the cost as low as possible for now.

Your bearings could have been going bad on the axle shaft. Caused wear on the axle shaft bearing surface. That wear (missing material) on the axle shaft allowed the old bearing to get in a "bind". Effectively "cocking" the bearing in the bearing race....not allowing it to leak out of the ends of your axle housing. Would also account for a low speed chirp.

You replaced the old bearings with new ones. Effectively...allowing the bearing to run true again...thus allowing the gear oil to leak out of the ends.
I suspect the leak comes from the axle saver bearings I put on. I trusted them to be of high quality, as these are the exact same ones Ford use in their shops around here.

I haven't seen two axles do this at the same time. Usually just one or the other. Also, if the axle shaft had wear on it in the area that the bearing rides....someone should have caught that when the new bearing was pressed on...Unless your dad pressed them on, he may not have known what to look for. Also, did your dad have them pressed on or did he give the "ol' heev ohh on the bench vise"
It was just one of my axles originally, but the leak started after I replaced the bearings, so I am confident when I assume those are the reason for the leak. My dad went to NAPA and bought two new axle shafts with bearing and seal kit, this time with normal bearings and separate seals. Because the axle saver bearings have the bearings sit a tad further in on the axle, you have no choice but to replace the axle it self when you need new bearings. Or so I was told, due to the wear locations of these bearings.

And yes, it was my dad that pressed the bearings on. First he put them into the axle housing carefully, then he took the old bearing in his hand and a hammer in the other and gently knocked it all the way around in a cross pattern to get it even. We just used the old bearing to even the pressure on the new bearing and to not damage it. Because the axle saver bearings are wider/longer than the original ones, we figured it would set evenly inside the axle housing, which it seemed to do. I just keep thinking that it is the O-ring on the axle saver bearing that didn't do it's job since it started leaking. I guess I'll find out in a little when I go out to the garage to take the rear end apart again.

Everyone that has looked at your car is right. Bent axles will cause a lot of drivetrain vibration because it is causing the wheel to "run out" and no amount of tire balance can compensate for that. Bad axle bearings usually don't cause too much vibration because at a high enough speed where you would feel it....its pretty much just forced to spin and the axel runs true. Same case with an axle that has worn down where the bearing is. At low speed it will skip along and chirp. At high speed its pretty much forced to spin…either in the bearing or its going to spin on the shaft. One of the two will happen. Usually can't tell from vibration alone for either unless it has gotten really sever and your about to have axles shot out the side of your car.
It just strikes me as very odd that I have no vibrations at all. I had vibrations at speeds over 40mph the first day I had the car, but when I went and got the wheels balances and new tires the next day it was gone.

Just as I am typing now I came with the thought; what if the problem is not the axle shaft or bearing, but the "head" of the axle. What I'm saying is, what if it is the end where you mount the brakes and tire that is a little off? The center of the wheel seems to be running smoothly when it is up on jack stands, but one can clearly see the wheel wobble back and forth as it is spinning, as if it was the very end of the axle shaft the problem lies in. This would explain the chirping sound, as the brake disk would wobble slightly and maybe make metal-to-metal contact with the caliper? Just a thought, and if I didn't make myself clear, please let me know. Explaining my thoughts isn't exactly what I do best.

My advice is to back up. Start over and look at everything as being an independent problem. Then put the clues together and see if it adds up to one diagnostic. But first…I would resolve the leak. This may have nothing to do with your previous issue and could be something that you had induced to the problem.
I did not have a leak before, so as I mentioned above in this post I assume it is the new bearings I put in.

Check run out of the hub without a wheel of rotor and calipers on it. After that, I would pull the axles back out. Take them to a driveline shop. One that may specialize in driveshaft’s balancing and axles to have them checked for run out and let the use Micrometers to check the diameter of the bearing surface.
Because my car has miles there are very few shops that are willing to even have a look at it, except for the Ford stealership.

Have new bearings pressed on. I would not recommend doing this at home!
I have a slide hammer and the set to pull out bearings (rented from Autozone), but I don't have any tools to press them on. My dad has a degree as an aviation mechanic and I have my fair share of knowledge on the subject + I know most there is to know (mechanically speaking) about my Mustang. I just do not have the money to take it to a shop and getting it done. Ford wanted 470 dollars for each side, and we've already bought the axle shafts and bearings anyways. I guess we'll just have to try one more time by our selves!

Or….suck it up and order a set of new axles from strange or moser that already has bearings pressed on them……also can just replace with a set of OEM spec…Junkyard…so forth and so on.
I'd really like to, but as stated above I already got new axle shafts. I need my car for school, and with the leak I can't really drive it before I get it fixed. If I had time and money I would probably get some Strange or Moser axles, preferably 31 spline if really wanted to put money into it.

Thank you very much for your post, getting another perspective on what is going on really helps sometimes. I appreciate you taking your time to help me out, I will be sure to update you guys as how it goes once I'm done.
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Are you sure the chirping is coming from a wheel bearing and not the pinion bearing or U-joint?
Yes, I am positive. A month ago when I took it to Firestone to get a brake flush they test drove it and thought it might be the U-joint or a pinion bearing, but they said I would have had more vibrations then. Plus the sound came from the rear right wheel area, not the center of the car. I am posting a small update in my next post.

Edit: The update turned out to not be so small after all.. Sorry about that! I have a tendency to include even the smallest details sometimes, which leads to me writing a longer post than planned.
After too many hours of work my car is finally on the ground again. We changed the bearings from axle-saver bearings to regular bearings with regular seals and we got new axle shafts put in on both sides. Both of them were purchased at a NAPA store, but my mom noticed they were produced in different countries. One of them had the wheel bolts already pressed on, and we had some problems getting them on on the other axle shaft. After a while we decided to let it be and just put everything together. My dad put the C-clips back in place on the axle shafts and remounted the differential cover while I were cleaning off the calipers and caliper brackets with brake cleaner. The spilled oil made them pretty greasy, but I got them clean enough and started putting everything back together. We ended up buying some Duralast Gold brake pads and a pair of Duralast brake rotors for the rear, since my old rotor and old pads were pretty greasy and not evenly worn due to my earlier problems. I did, of course, purchase anti-rattle clips and brake grease to put on the back side of the pads to prevent squealing. I also rented a caliper tool kit to compress the caliper piston for the new brakes. As it turns out, my right rear brake was turned a whole 360 degrees further out than the left one, which seems a little odd, but oh well, it's all fixed up now.

Before she came back on the ground and we mounted the wheels (the brakes were mounted though, and tightened up with a few bolts so they would stay in place) I pumped the brakes a few times to build up pressure before I turned on the engine. The brakes worked fine and we noticed no wobbling at all with the new axle shafts and new bearings. We put the wheels back on and got her back on the ground. We took her for a test drive and I could hear no more chirping and the car feels smoother even though it never gave off any noticeable vibrations in the first place. I will take the family car to school tomorrow and then me and my dad will take my Mustang for a longer test ride tomorrow just to be on the safe side. I will also check for oil leaks tomorrow, even though I doubt there will be any.

Speaking of oil leaks, when taking apart the rear end again today my dad noticed a small tear in the seal on the right side, which explains why it leaked so much oil on that side. The left (driver) side seal seemed undamaged but still leaked a little. We made sure to be as careful as possible avoiding touching the seal while putting in the new axle shafts this time and we inspected them visually before we put the C-clips back in.

I don't have much more to add. I will come back with an update in a few days about how the car runs, and I am still open to suggestions and information from anyone! Thank you all for your great help so far, it's good to have you fellow Mustang geeks around! I really appreciate it.
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So far so good! My brakes have a better initial grip and I have less of a nose dive when I brake now. No oil leaks, no chirping or squealing sound, and no rattle or vibrations. The entire car feels smoother now. I guess my next step will be to get new bushings for my rear springs, as they are all worn out and make metal-to-metal contact on the LCA's.
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