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  #1  
Old 09-21-2009, 05:53 PM
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124 Differential Mounts Re/Re

I am going to replace the 3 differential mounts on my 124 wagon. i have read over the fsm a few times and looked over the job. tooling is not an issue for pulling the mounts in and out. i've searched the forums here for over an hour with no clear answer to my questions.

what i am wondering is if you must remove the centre assembly (diff) completely or just remove the three mount screws (and axle screws if required) and let it drop down enough to get at the rear mounts. it looks like you might be able to simply detach the diff and lower it a few inches, with the drive axles and drive shaft still attached.

the fsm is pretty clear that the diff has to come out, but it also tells you to remove the exhaust and the job can surely be done with the exhaust in place, at least on my car it looks that way

has anyone done this job recently and care to comment?

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  #2  
Old 09-21-2009, 06:18 PM
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124 Differential Mount R&R!

The 124 and the 201 differentials both need to be removed completely out of the way. You will likely need a sacrificial 17 mm tool to hold the top nut of the front mount, a wrench bent to fit or a socket welded to a piece of flat stock. The nut is down in a valley of folded steel making up part of the rear sub-frame. Plenty of Kroil or similar penetrant sprayed on it will help; it's an 8mm Allen head so of course you'll observe all precautions!

Unbolt the axles at the differential flanges and hang them up out of the way, I find this much easier with the tire off and a long extension driven by an impact gun. Most important to make certain that the fastener heads are very clean, an ice pick, carb cleaner and shop air does the trick nicely.

I have found that it is much better to get under the back seat and disconnect the ABS sensor wiring and then to feed that back through the body and remove the small routing bracket attached to the sub-frame.

Removing the expensive ABS sensor from the differential is problematic, sometimes the 5 mm Allen strips out, it is sometimes rusted in place, it can be difficult to pull out of the differential, and if you pull it you will need a new O-ring. It is not a standard O-ring, it is very thin and it is positioned down on the sensor body not under the mounting flange where O-rings are usually found. It’s probably a dealer item so if you go that route get it ahead of time!

With everything apart it's time to change out the rear flex disk if you've got the extra $75 and there is any doubt about the one that is there!
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Old 09-21-2009, 06:29 PM
LarryBible
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I have changed the 124 diff mounts without completely removing the differential. It could be that Billy Bob was using a different puller, but the puller I used worked even with leaving everything connected except the mounts themselves. I just put the diff on a floor jack to position it correctly.

Make sure that you have a good puller and don't plan on using a hammer and chisel or anything. The mounts are in sheet metal. Anything other than the proper puller will destroy the sheet metal carrier.
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  #4  
Old 09-21-2009, 06:47 PM
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Quote:
Originally Posted by LarryBible View Post
I have changed the 124 diff mounts without completely removing the differential. It could be that Billy Bob was using a different puller, but the puller I used worked even with leaving everything connected except the mounts themselves.
so you just lowered the diff so the puller will clear the top of it?

Quote:
Originally Posted by LarryBible View Post
I just put the diff on a floor jack to position it correctly.
are you referring to the positioning the mounts with the test arm but using the diff as the 'test arm' instead? one thing that occurred to me when reading the fsm and looking over the car was that if the diff was left on the car you could use it to get the mounts aligned correctly, without needing the test arm, which i don't have.
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Old 09-22-2009, 07:25 AM
LarryBible
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It's been a long time since I put in any diff mounts (thank goodness.) I don't remember exactly which way I had to move the diff. but I DO remember that once I had the mounts loose with the diff on the floor jack, I was able to position the diff surch that I could replace the mounts.

There is no worry about positioning the diff in order to align the mounts. The only "alignment" of the mounts is paying attention to the orientation of the mount as it is pushed into the carrier. If you don't rotate each mount to the correct position it will not deal with the torque correctly and tear up in short order. The FSM shows the correct mount orientation in the hole, OR simply pay close attention to the position of the old mount before removing it.

This mount positioning has nothing to do with how the holes align when mounting the differential. It has to do with how the mount is rotated before pressing in the hole. I hope this makes sense.

This is not a difficult job AS LONG AS you have a suitable puller. My Brother in Law made a puller that works well, but gives you a real work out when using it.
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  #6  
Old 09-22-2009, 09:32 AM
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Originally Posted by LarryBible View Post
This mount positioning has nothing to do with how the holes align when mounting the differential. It has to do with how the mount is rotated before pressing in the hole. I hope this makes sense.
yes and no. i understand that the mounts have a correct 'clocking'. the fsm refers to the test arm which is for aligning the mounts to one another. if the two rear mounts are not at the exact same depth, there could be difficulty aligning the front mount. i presume the test arm is simply a way for the dealership to do this job in a completely foolproof way and if the rear mounts are pressed carefully for depth, the front mount will be in alignment.
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Old 09-22-2009, 01:04 PM
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I believe that the mounts can be removed, by cutting from the inside out with a hacksaw blade (my brother did this once) a slot in the outer ring of the mount so that it releases the pressure and can be knocked out.
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  #8  
Old 09-22-2009, 06:17 PM
LarryBible
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Thanks for adding the term "clocking." I was having trouble describing the rotational position.

As far as the depth of the mounts in the carrier, this is no trouble whatsoever. Simply replace them one at a time. When pressing a mount into position, simply put it visually at the same depth as its neighbor. This will be plenty close enough for everything to fit up.
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Old 09-22-2009, 06:26 PM
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Quote:
Originally Posted by Billybob View Post
The 124 and the 201 differentials both need to be removed completely out of the way. You will likely need a sacrificial 17 mm tool to hold the top nut of the front mount, a wrench bent to fit or a socket welded to a piece of flat stock. The nut is down in a valley of folded steel making up part of the rear sub-frame. Plenty of Kroil or similar penetrant sprayed on it will help; it's an 8mm Allen head so of course you'll observe all precautions!

Unbolt the axles at the differential flanges and hang them up out of the way, I find this much easier with the tire off and a long extension driven by an impact gun. Most important to make certain that the fastener heads are very clean, an ice pick, carb cleaner and shop air does the trick nicely.

I have found that it is much better to get under the back seat and disconnect the ABS sensor wiring and then to feed that back through the body and remove the small routing bracket attached to the sub-frame.

Removing the expensive ABS sensor from the differential is problematic, sometimes the 5 mm Allen strips out, it is sometimes rusted in place, it can be difficult to pull out of the differential, and if you pull it you will need a new O-ring. It is not a standard O-ring, it is very thin and it is positioned down on the sensor body not under the mounting flange where O-rings are usually found. It’s probably a dealer item so if you go that route get it ahead of time!

With everything apart it's time to change out the rear flex disk if you've got the extra $75 and there is any doubt about the one that is there!

better solution: drop the rear subframe completely, do the diff mounts and subframe mounts at the same time. but if you don't have the time/balls to do this, i agree with the above method
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  #10  
Old 09-22-2009, 06:51 PM
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Quote:
Originally Posted by LarryBible View Post
As far as the depth of the mounts in the carrier, this is no trouble whatsoever. Simply replace them one at a time. When pressing a mount into position, simply put it visually at the same depth as its neighbor. This will be plenty close enough for everything to fit up.
makes complete sense.
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  #11  
Old 09-24-2009, 07:23 AM
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Removing the complete subframe or completely removing the differential when all that is necessary are new mounts would be like disassembling the engine to replace the spark plugs. It is TOTALLY unnecessary and would open up possibilities for any number of problems during and after such a service operation.

If it ain't broke, don't fix it!
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  #12  
Old 09-24-2009, 09:20 AM
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yes i agree. the subframe re/re brings a lot of extra work. the subframe mounts on my car are still good. i'll be doing this job soon and will post photos.

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