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Discussion Starter #1 (Edited)
This is my first thread started here on this forum and I hope that by opening this discussion we can have more people contribute to this analysis with a critical eye the next time they have to dig into the rear axle. I believe I have found why Tacoma and 4runner axle seals continually leak. Some would say I am overthinking this. I look at this as a common and incredibly expensive repair for most owners of these trucks. So let me start by saying this. The seal does not properly sit on the retainer. There is no way to get the seal to correctly sit on the retainer in ts original configuration. I say this because I have physically pushed the un-installed retainer into the installed seal and the retainer will grind on the axle housing before the seal could be centered on the retainer shoulder. A basic design flaw when Toyota switched from a flat seal to a angled seal in 2003. They redesigned the seal but not the retainer. My last observation is this, if the vent is clear and the bearings in good condtion, you may still be leaking and the oil is pooling in between the inner and outer seals. Its not until the vent gets blocked that the oil is forced out of the axle housing and onto the brakes. Again this is my theory and I'm looking for productive input from members here. No cheap shots or personal attacks please. So lets begn.


Theory: the retainer is not making contact with the seal correctly and allows oil to leak past.

Observation: my seal when seated in the housing all the way in,would ride right on the bevel edge of the shoulder of the retainer. Any wobble would let oil get by the seal. The retainer had a polished ring near the edge. You can see the ring next to the bevel in the top photo

Solution: I just re-did the seals for the forth time in 3 months. I found that no matter how I installed the seal it didn't sit on the retainer far enough. I even tried the Timken seal 1960 but the rubber was too stiff and it failed in two days. Its a crappy seal, stick with oem. My solution was to install new retainers backwards so there is more of the shoulder for the seal to ride on. I also moved it inboard by 1mm plus the 3mm i gained from not having the bevel there anymore equals an extra 4mm of shift in placement. If you go more than about 3mm inboard with the retainer, it will rub the housing. So 1mm is all i wanted to move it. By doing this, it will allow you to seat the seal all the way into the housing squarely. Here's a couple of pics.

Old config


New config


Status:
5/04/2012 installed
5/27/2012 still dry
6/28/2012 still dry
7/19/2012 still dry
10/15/2012 still dry
02/13/2013 Continued success. 166,500 miles on the odmeter, 6,000+ from time of the repair* not a drop of oil leaking. I ran a ribbon of cheese cloth around the ABS ring and it came up dry.

...So far so good.

When you install the axle, use MP grease on the seal and put gear oil on the retainer and be careful inserting it into the seal. Dont force it. Once it lines up it will slip into the seal nicely. The edge does have a mild bevel to it so it won't damage the seal if you don't force it. You will know that you are in the sweet spot if you feel the resistance of the rubber seal 3/16" before the bearing carrier plate mates up to the axle housing. That will put you dead center on the retainer.

* don't assume the original inner retainer is in the correct position. If your axle vent is clear, it probably wouldn't have leaked if it was positioned correctly. I would suggest before disassembling the axle, install a new seal in the housing and test the position on the retainer with grease to make sure it will be correct. I used the new retainer to check how deeply it could be set into the seal. It turns out that the retainer bottoms out on the housing before it will flush up with outside of the seal.

I have read discussions of only partially seating the seal so it sits on the retainer better. I tried it and I personally couldn't get the seal to square up properly.

I think this may well be the solution to this problem.

Feel free to share your thoughts.

This is an image taken from the TSB regarding the seal redesigned in 2003. If you notice the old seal had a long flat contact patch which would sit upon the shoulder of the retainer extending all the way to the outer edge of the seal. In the newly redesigned seal, they changed it to an angled contact point, but that contact point is too far inboard (now near the inside edge of the retainer) and rests not upon the shoulder but on the retainer's bevel.

This could explain why even new seals are failing simply because they aren't seating on the retainer at all. The TSB link is below the picture.



Axle seal TSB

The new OEM seal design allows for a lot of flex. Even with the retainer big side in, it goes in easily. This wouldn't work as well with any other seal like Timken or National brands.

Video discussion:
http://www.youtube.com/watch?v=9tdGpmpNRFU

:2cents:
 

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Wow, only the your second post. Great post and information! I have always wondered about the rash of axle seals going out as well, it seems that it plagues the tacomas.
 

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Discussion Starter #3 (Edited)
Compare the non-ABS axle to the ABS axle and you will quickly notice that the seal of the non ABS is pressed right up against the bearing. That means that if your seal is not pressed right up against the ABS exciter ring, the seal is not sitting on the retainer. But you cannot just push the retainer deeper into the axle housing because it will rub the housing.






Clearly you can see when you view through the ABS sensor hole, the seal is nowhere near the ABS ring.


This picture was taken after the bearings were changed and the the first seal failed. the retainers were setup using messurements from the FSM 122.2mm +-1mm. I found it needs to be 124mm with the retainer flipped.
 

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Nice job.
I have been trying to get this issue across to folks on this forum for years. I had no idea there was a TSB on it.
Here are a few.

http://www.ttora.com/forum/showthread.php?t=159307&highlight=axle+seals Post 4
http://www.ttora.com/forum/showthread.php?t=177265&highlight=axle+seals Post 3
http://www.ttora.com/forum/showthread.php?t=135441&highlight=axle+seals Post 5

I feel the issue with the new seal is mostly due to the use of improvised or generic seal drivers that can distort the seal along with excessive pounding to "make sure" it is seated (lack of skill). The TSB seems to confirm this. The seal is very easy to distort. The outboard metal face can get dished in (see pics in post #28) and the outer edge of the metal on the inboard side can also "flatten". It might not be apparent but it will move the effective "lip placement" even further inboard. The spec for original retainer location in conjunction the new seal lands the lip very close to the bevel. If the outer face of the seal is flattened at all the lip will end up over the bevel and leak. Any "corrective action" for the seal getting cocked while being driven in will enhance the distortion. It must go in perfectly straight the first time with a driver that only contacts the very outer edge of the seal's metal face.
I found no need to put the retainer on backwards but my driver is no "piece of pipe". PVC pipe is the worst offender here. My driver is made to "self center" in the outer bore of the tube and is the EXACT outer diameter of the seal. I had no need to reverse the retainer or even close. My retainer is a bit further inboard than factory due to me wanting the seal centered.
I have no contest with reversing the retainer and I would do it in the future just for the simplicity of it.
In any case folks should always check where the lip is resting once the seal is seated. Put a few slash marks across the surface of the retainer with a magic marker. Slip the shaft assembly into the tube and snug up 2 of the nuts. Now spin the shaft a few times and pull it back out. The (lightly lubed) seal lip will have rubbed thru the marks showing EXACTLY where it is riding. Adjust accordingly if necessary. Also don't assume that the retainer is square to the shaft, check it.
My seal driver, is an old ABS ring welded to a 1"x6" steel shaft. The ring has 4 screws around its edge to keep it centered in the larger bore section of the tube. The mass of this thing helps a lot. Usually 3 smacks does the trick. "Clang clang clunk" the change in tone is when the seal seats.

New seal on left, old on the right.



 

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Discussion Starter #7
terryj5,

Here's the problem. I found that it is virtually impossible to insert the retainer in bevel-first and get the seal onto the retainer's shoulder. Let me say it another way. If the seal is seated competely into the housing, the retainer cannot not flush-up with the outer edge of the seal before it hits the internal axle housing. If the seal is going to be centered on the retainer with the bevel positioned inboard, the retainer must be flush with the seal on the outboard side. This is the reason I reversed the retainer. It gives you the ability to get the seal to ride on the center of the retainer. You're on the right track though.

This picture shows how deep the retainer must be within the seal to be centered on the shoulder of the retainer. But it will rub the housing if you go this deep.


This picture shows the retainer where I have reversed the retainer. It allows the retainer to be outboard by 3mm (the width of the bevel) and it is not close enough to rub the housing.


The one picture I wish I had from my repair was of the retainer bottomed out in the installed seal.
**If anyone is working on their Axle seals, once the axle is removed and before you remove the seal, slip the new retainer into the seal until it hits the housing and please post a picture of it.
 

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Well, look at my second pic, living proof that it can be done. The rub mark from the seal lip clearly indicates it is riding on the center of the retainer and the retainer is not reversed or rubbing the housing. Could be the retainer is "just missing" the housing. Could also be some variance in castings and or how the casting is mounted in the mill. Most likely the failures are due to distorting the seal in combination with the new seal.
A fair amount of folks fail at this job including dealers, while at the same time many more succeed.
I guess the point should be that folks need to be aware of all these issues and check, double check.
 

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I'm going to be swapping third members here shortly and planned on replacing the axle seals, but now i'm worried. My truck is a 97 and has never leaked. Are all of the axle seals the updated ones? Will i need to reverse the retainer on my 97? Truck doesn't have abs.
 

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Compare the non-ABS axle to the ABS axle and you will quickly notice that the seal of the non ABS is pressed right up against the bearing. That means that if your seal is not pressed right up against the ABS exciter ring, the seal is not sitting on the retainer. But you cannot just push the retainer deeper into the axle housing because it will rub the housing.






Clearly you can see when you view through the ABS sensor hole, the seal is nowhere near the ABS ring.


This picture was taken after the bearings were changed and the the first seal failed. the retainers were setup using messurements from the FSM 122.2mm +-1mm. I found it needs to be 124mm with the retainer flipped.
That bearing looks just like mine did before replacement. There were bubbles on the side where the plastic had began to boil.

What concerns me is all of this talk about the seal (in others threads all over online not just this one) when in reality a bearing like the one pictured could have enough play to wear the seals out at an accelerated rate. I hope other people are not overlooking this, good to see you replaced your bearing. Any bearing that has been exposed to a lot of gear oil may have easily had all of its grease flushed right out. The very small amount of gear oil left in the bearing can not take the heat like a grease could so he bearing develops play or slop...and so the never ending seal replacement cycle begins if the bearing is never replaced.
 

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Discussion Starter #12
For the people who may want to tackle this DIY and are not sure what the grease test is, here is a picture another forum member provided to me (since I forgot to take this picture when doing mine). Mark tells me he left 3mm of the polished ring inboard of the retainer and once installed, using grease on the retainer and spinning it a few times, it will leave a foot print of where the seal lip is positioned. Note, the bevel is outboard and the retainer shows the seal riding in the center of the retainer.



*When you take your parts to a machine shop, consider printing this picture and bring it with you.
 

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nice info, but if I recall there is a specific distance the ABS sensor and spacer are to be pressed onto the axle, can't remember offhand, but I know when I changed out my axles I had to keep measuring the distance til it was within specs when I pressed them on.
 

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Discussion Starter #14
nice info, but if I recall there is a specific distance the ABS sensor and spacer are to be pressed onto the axle, can't remember offhand, but I know when I changed out my axles I had to keep measuring the distance til it was within specs when I pressed them on.
The measurement is/was 122.2mm +/- 1mm. If you follow the FSM (which was written for the older, original seal) It's way off and and puts the contact point not on the retainer surface, but on the large bevel. It is guarranteed to leak again. Which is why I have posted this discussion.
 

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Ahhh, glad I have non-ABS and Marlin seals, no problems...

Good write up though.
 

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So I have a 2001, but I have ABS/e locker. Does this affect me or not?
 

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I have a 02 tacoma with abs, 150,000 mi. and no leaky axle seals, knock on wood. I actually wasn't even aware that this was a problem.
 
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