Story mode on: 2 years ago, rear end gears grenaded. With the help of my mechanic friend, I replaced the gears. 4.10->4.10 1 year or so later, the gears blew out again, the crush collar failed, and the pinion gear got sucked in. Ok, get it professionally rebuilt, at AAMCO. Gears have been working beautifully until recently, yeah remember my post about "wheel bearings or a different tree"? well it was a different tree, it was the rear end again. I had taken it to a local shop reccomended by several people, drove it with them and they said it was the strangest noise they had ever heard. Well they checked the u-joints, the check out ok, but the noise was coming from the back. They pulled the differential cover and heres what they didn't find! The Differential case magnet! The pinion gear was missing teeth, but the case magnet was no longer attached to the case. I don't think I'd be wrong if I said that magnet chewed up those gears. Now the question is the AAMCO at fault? Is this something they should have checked, run preventaive maintance on (add/re-epoxy it knowing the number of miles, number of rear end changes?) Might they have dropped the case cover and weakened the bond? I'm putting it to a poll, but please if you think you know what you are talking about post a reply!

 

I am not sure the magnet chewed up the gears but if the magnet is chewed up then it probably did. Who put a magnet in there? I've seen magnetic plugs before but mine had a rubber plug and I think a magnet back there would be pretty much worthless.

 

The magnet wasn't a plug, it was a round magnet epoxyed to the cover. The magnet is missing, the cover is scored. They said the couldn't find the missing teeth or magnet, I suspect they had enough frontal area that they fell out with the diff oil, and they didn't search through that goop. (I hate messing with gear oil!)

 

I suppose that it's possible that the magnet could have somehow gotten up into the meshing teeth. I'm not sure how big/heavy the magnet was nor am I sure how much turbulence there is in the rear-end's oil. You would think, however, that even without the epoxy the magnet would want to stick to the housing rather than being sucked/knocked into the meshing gears...just a thought though.

 

I had a somewhat similar experience with AAMCO

they suck with magnets

 

Interesing...
The magnet:
approx 1.5" diameter with a 1/4-3/8 hole in the middle. Approx 1/4 inch high. Fairly heavy magnet. With the driveshaft spinning up to 6000 RPM I am sure theres some nice turbulance in that thick heavy gear oil.

Edit: Did AAMCO do anything about the magnet problem?

 

I sure hope you still got the receit! Then you can take it up with the head at the AAMCO ya went to, remember the receit.

 

The problem: AAMCO said it had a year gaurantee (sp?) We trusted them (our fault) and looked again, it says it has a 90 day gaurantee. Plust it has been a year and 3 months....Still though, if the cover has a magnet like that, I would expect a trained mechanic to check that thing out and make sure it was on ok, cause if it comes loose, it's gonna %#*& up the gears! (Duh, a piece of foreign metal going in between 2 gears, being driven by a fairly strong motor, the magnet is gonna get chewed up, but so will the gears! (They aren't THAT strong guys! and they are really only strong for a torque vector, not some piece of metal getting in their way of turning!) I really think it is 100% safe to say the magnet screwed things up. The only thing I am really asking here is if those guys should have checked the thing?!
Also, normally it is epoxyed onto the case, epoxy will hold virtually forever. Oxidation of the metal underneath the epoxy, or a large amount of pulling/shearing force or a lot of shock (i.e. being dropped a significant distance) are really the only things that would cause the epoxy to let go. Sicne the thing was under oil oxidation is almost out of the question unless it wasn't treated well during the time it was off, and even so, that wasn't very long. So basically oxidation can be pretty much ruled out. So the more likely it either dropped, or a tool was dropped on it, or something is the only way I could see the thing haveing come loose. Unless, since they never really found the magnet (My guess it was swept away in the discarded fluid) but could AAMCO have just removed the magnet?! In which case the filings from the break in would have been free to move about the case!? That doesn't make much sense to me....
Maybe Vader has an opinion here? :hail:
Corry

 

I guess you are saying it came from the factory with the magnet? In which case I would not blame AAMCO for it coming loose. If someone put it in there, blame them. If GM put it there and did not put in a scheduled inspection for it or scheduled reattaching, then blame them. I don't believe they glued a magnet to the rearend cover though.

 

I live in Canada so the civil court system will be different, but much of the rules will still apply. I hope the following sheds some light on your issue.

To really determine whether or not AAMCO is responsible for the damages, several pieces of information need to be addressed.

First, you have to prove that AAMCO was neglegent in some way. In this case that means you will have to prove:

1. AAMCO had a duty to inspect the magnet,
2. The magnet and or epoxy was defextive and that the repair technitian ought to have been able to identify the problem,
3. That the damage was in fact due to the magnet, which of course the repair technitian should have spotted, and not something else such as defective gears, which broke loose and caused the magnet to become jarred free.
4. There are a host of other issues that also need to be addressed, but that would take me forever to type out. That said, I will only discuss those listed above.

I have some experience in the court system, and from my experiences success will be dependant upon the ability to prove your case. At the very least you will ahve to satisfy ALL of the issues identified above, and likely a few more.

The first point listed above is the easiest to prove. Just call a few repair shops, explain what service work you paid for, and see if the mechanic is supposed to inspect the magnet, and in particular how secure the magnet is attached. The best experts will be GM mechanics. Call them and tape the calls (first party consent taping is legal in Canada - so check your state laws before doing this).

The second issue will be a bit tougher to prove. The issue is not simply whether or not the the magnet caused the problem, but rather should the mechanic have been able to identify the problem. You will need to identify how the mechanics are supposed to test the strength of the epoxy bond (tug test, resistence test, visual, ect), and then demonstrate that they either did not perform the test properly, or perhaps not at all. Your arguement is that if they did the test, they would have been able to spot the problem and therefor prevent the damahges from occuring. Given the fact you do not have the evidence, this will undoubtably be the toughest issue for you to prove. All AAMCO will have to do is say they tested the bond - it was fine - but it became weaker as time went on.

The third issue somewhat relates to the second, in that you will have to prove with certainty that the damages were a result of the epoxy failure, and not something else. If you are arguing they should have identified the problem in the epoxy, their response may be that the damages were a result of something else. Possibly something they couldn't predict. To really prove this part of your case you will have to have some kind of an expert agree with your hypothosis. This will be tough to find.

If you want to be successful in your efforts to get compensated for the damages, then you will need to do lots of research. Once you can say with certainty they were neglegent, make a strong case to the manager and see what happens. If that fails your next action is court.

 

I don't think you will ever be able to prove in a court that they caused the problem. Even if you did do you really need the months of hassle? They'll drag it through small claims court for a minimum of 6 months.

Suck it up and go to a garage that specializes in gears and doesn't hire $8/hour students to work on your car.

 

Did one of the mechanics during rebuild remove the magnet?... It would solve the problem of where it is if it didn't come out in little pieces with the fluid. But to why your rear is going I have no clue why it keeps going on you.

 

Reading your post, it seems that you had the work done by AAMCO a year ago. What is their warranty period on parts and labour? Many have "limited" warranty periods also covering only the parts they replaced.

But if the length of time has expired, I think you'd have a very tough time.

 

I'm not a rearend expert but have been inside several rearends. I've seen the pinion with broken teeth a couple of times. Usually happens on higher mileage truck rearends though. What does the wear pattern look like on the ring gear? If it's majorly dorked up you might get a little bit out of them but it's not likely.

 

Looks like you're a moron :P You need to determine if they were supposed to check the magnet or not, I think it's as simple as that. Take a tape recorder in with a different car, and record the manager saying that his service techs will look check to see if the magnet needs to be re-epoxied.

 

Well, I live in Denton, TX now, the work was done in Colmar, PA. (No the car wasn't driven here, it was shipped on a truck)
First off: Does anyone know that GM installs these magnets? I really can't say for sure! The Helm manual doesn't mention much about the rear except changing the gears.
Second: Has anyone had theirs fall off? (other than tpi_roc)
As for find the magnet, I think that it's size with teeth sticking to it, provided enough frontal surface area, and it's flat shape, made for a very high drag coefficient, that when the fluid drained out, there was sufficient force to drop it out into the bucket with the fluid, and I don't think they kept the fluid....
I will take the suggestiosn of others though...In the mean time, I guess my mom is going to help me pay for a new rear end, and I think I will follow the guide on Beefing up the 10 bolt 7.625. The only think I probably won't be able to swing are the "good" axles...but the SLP diff w/ 1 gear, OEM 28 spline axles, Girdle, shockproof oil, and richmond gears. I'll change the axles out later, but right now I'm not running enough power to warrant the better axles. I'll have to see...I just know I am sick and f*cking tired of rear end trouble, I was annoyed the 1st time, angry the second, but this time I do not feel it was my fault! That makes me irate, beyond anything!