Differential drive flange leak.

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gwittman

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I replaced the differential drive flange seal about 2 years ago and it is still working well. However, I have discovered there is a leak coming out of the center of the drive flange where the nut is.

I have studied the Blue Book extensively and can find no reference of a seal for the collar nut area in the drive flange. If I am over looking something please let me know. My plan at the moment is to remove the nut, clean every thing there very well and use a liquid sealant on the collar nut face and first few inner threads. I have used SealAll on the lower bolts of a float bowl of a Holley carburetor with good results. These bolts are wetted with gasoline and if it will seal gasoline, it should seal gear lube.

I have a crush sleeve but plan to just use the nut/flange position marking method and re-tighten to the same position and verify drive torque value.

I am open to any other suggestions.
 
There is a large rubber O ring for the side loader cover too but that is all. E12 era diffs use a c-clip inside and no nut so the drive flange can just pop off.
 
If there is no nut in the E12 era, how does the preload in the pinion bearings get established? We may be talking about two different things. I am talking about the input drive flange that connects to the drive shaft. It looks like I was not clear on that.
 
Chris probably thought about side cv joints mounts, not about main input.
Corteco seal number for main shaft is on photo below, before full re-assembly clean the surface of main shaft mount internal with fine sand paper or steel wool.
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Wladek, that seal you are showing is the seal I replace a couple years ago. It is not leaking there. It is leaking through the center where those splines are. This is where the pinion shaft connects to the flange and is held in place with the nut. Somehow the gear lube is getting past the nut, either through the thread or nut face (possibly both).

The flange seal area is totally dry. Gear lube is coming out in the area where the differential flange and driveshaft yoke meet and are bolted together. What you show in replacing the flange seal is basically what I did a couple years ago. It worked very well. Now I must resolve the new leak.
 
Before putting flange on shaft & bolting it put fair amount of copper grease on teeth. In that place it should do the job as barrier & shouldn't be flushed by oil.

Your inner diff shaft or flange have slightly worn teeth, that's why have some leakage while stress work.
 
That sounds like good advice. I will take it a step further and put a liquid sealant that hardens on the flat contact surface of the nut and the first few inner threads. That will be a backup in case the grease does not hold the gear lube back.

I don't want to put the sealant on the splines because it makes pretty good adhesive and I may want to remove that flange some day. :)
 
Hi
I have the same problem with the differential in my E3.
I marked the flange, pinion and nut before I started disassembling. When I unscrewed the nut I discovered that it was way too loose. Probably the cause of the leak.
I’m going to replace the oil seal and crush sleeve. Bearing looks ok.
Now that I’m going to put things together the markings on the nut and pinion will probably not be valid anymore?
Repair instructions says a minimum torque of 150Nm has to be applied and something about a frictional value that has to be measured before and after.
I’ve read about measuring preload when turning the input shaft while torquing the nut.
What would be the correct approach and what would the correct preload be?
 
Hi @E3AV ; i think our resident engineer supreme @deQuincey has a thread on this somewhere on our dear forum. Let me see if i can dig it up for you.

edit: here it is:
deQuincey

Thread 'differential repair question'

hi,

some months ago a set of drops started to fall in the floor of my garage under the rear part of the e9, in the diff area

now i am sure that the diff is leaking from the front side, in which the seal probably is worn

so i am now in the position of changing the shaft seal (ref. N. 5 in the following drawing)

diferencial.jpg


but one question arises: you might know that in a diff the part number 7 (clamping bush) has to be preloaded when the diff is mounted, that preload modifies the part geometry and it is said that if...
It is however not really answering your question I think, but it may still help you move along?

The blue books indeed are explicit on this point: when re-installing the nut, a new crush washer is needed + an friction setting on the drive shaft.
 
eriknetherlands said:
Hi @E3AV ; i think our resident engineer supreme @deQuincey has a thread on this somewhere on our dear forum. Let me see if i can dig it up for you.

edit: here it is:
deQuincey

Thread 'differential repair question'

hi,

some months ago a set of drops started to fall in the floor of my garage under the rear part of the e9, in the diff area

now i am sure that the diff is leaking from the front side, in which the seal probably is worn

so i am now in the position of changing the shaft seal (ref. N. 5 in the following drawing)

diferencial.jpg


but one question arises: you might know that in a diff the part number 7 (clamping bush) has to be preloaded when the diff is mounted, that preload modifies the part geometry and it is said that if...
It is however not really answering your question I think, but it may still help you move along?

The blue books indeed are explicit on this point: when re-installing the nut, a new crush washer is needed + an friction setting on the drive shaft.
Click to expand...

Thanks!
45-50 inch pound of preload is mentioned.
Would that apply to all e3/e9 differentials?
 
from the blue books: Here it gives the friction force to be achieved. However a few steps are described that you must do before; see below in reverse order:
1739809320275.png


Before being able to set the friction however, the blue books firsts require that you measure the play, and use shims accordingly. That covers ~3 pages in the blue books....
Still, before that step, it also asks you to press in the bearing BUT WITHOUT COMPRESSION BUSH and OIL SEAL with a bearing press to set the friction:
1739809621459.png
 
I have the blue books and this instruction is for replacing the drive pinon and ring gear.
And the frictional value in this instruction is without the ring gear installed I think. I rather not pull the whole differential apart as this basically is just an oil seal job.
There is a repair instruction called "Replacement of shaft sealing ring for drive flange" nr. 33 11 011 that describes how to measure frictional values before and after. However I did not measure before, I just marked the pinion, flange and nut as mentioned. And it turned out that the nut was too loose so measuring before probably would have given a false reading.
So now I have a new crush sleeve, oil seal and nut and just need a torque value to apply.

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