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Press depth of new rear main seal


dduelin

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I'm going to replace the rear main and the balance shaft seals while the engine and gearbox are separated. The Haynes manual details pressing the new main seal in until it is flush with the outer edge of the seal housing in the block. However the original seal is pressed in beyond that to a recessed depth of ~ 4.2 mm from the edge of the housing. I would think it is best to place the wiping edge of the new seal in the same spot on the crankshaft as the old one? Or should I follow instructions and install it to flush with the housing edge?

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I'm going to replace the rear main and the balance shaft seals while the engine and gearbox are separated. The Haynes manual details pressing the new main seal in until it is flush with the outer edge of the seal housing in the block. However the original seal is pressed in beyond that to a recessed depth of ~ 4.2 mm from the edge of the housing. I would think it is best to place the wiping edge of the new seal in the same spot on the crankshaft as the old one? Or should I follow instructions and install it to flush with the housing edge?

 

Morning Dave

 

On the 1200 rear main seals that I have installed (only a few) they were originally pressed in below flush. I never measured the depth as I used the (special) flanged BMW seal driver & bushing to install the new seals. That special BMW driver drives the seal to well below flush (that 4.2mm would be a good guess, but as I mentioned, I never measured it).

 

I can't remember if there is an oil drain back hole in front of that main seal but if there is then make darn sure your new seal doesn't block any oil holes.

 

The only time I would mess with a seal depth change is if there is a worn ring on the crankshaft, if you do change the seal depth, then as mentioned above, make sure that you are not blocking an oil drain-back hole or that the seal will contact a spinning flywheel bolted to rear of crankshaft.

 

 

 

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Thanks D.R. I posted that because the Haynes does show the BMW special tool set installing that seal and mentions a flush set. The BMW tool and how to use them (guide, sleeve, and driver) are shown in the pictures. Mine is clearly set deeper however. It's been fine for 189,000 miles so I'll try to reset to the same approximate depth. I'm using a DIY seal guide and driver that another owner used to install this seal 90,000 miles ago on his 1200.

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Thanks D.R. I posted that because the Haynes does show the BMW special tool set installing that seal and mentions a flush set. The BMW tool and how to use them (guide, sleeve, and driver) are shown in the pictures. Mine is clearly set deeper however. It's been fine for 189,000 miles so I'll try to reset to the same approximate depth. I'm using a DIY seal guide and driver that another owner used to install this seal 90,000 miles ago on his 1200.

 

Afternoon dduelin

 

If you look closely to the BMW 1200 rear driver set you will see that the flange on the intermediate collar is the thickness of the seal recession. The DRIVER TOOL is driven flush but that drives the seal in farther due to the intermediate collar thickness.

 

 

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Edited by dirtrider
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Thanks. Although the Haynes lists these three part numbers to use, the text and pictures indicate to press the seal flush. Mine is clearly not flush but like your posted drawing. I will do likewise. The drawing indicates the seal does seat against a small ledge or land. I suppose it will be clearer when the old seal is out.

Edited by dduelin
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My angst was misplaced. The engine block is machined so that the rear main seal can only be set so deep and the DIY tool I was using also had the inner bore turned in a lath or something so it could only press the seal in so far. Both the new compensating shaft and main oil seals are in place and the process of putting everything back together has started.

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  • 2 years later...
On 11/15/2017 at 6:32 AM, dduelin said:

My angst was misplaced. The engine block is machined so that the rear main seal can only be set so deep and the DIY tool I was using also had the inner bore turned in a lath or something so it could only press the seal in so far. Both the new compensating shaft and main oil seals are in place and the process of putting everything back together has started.

 

I've got to replace that seal on my 2012 r1200GS - looks like the same "special tool" part numbers you mentioned. Do you still have the tools you used? Or can you share any info about them with me so I can see if I can figure out how to make my own?

 

Any help would be most appreciated! (FWIW, I measured the depth of the stock seal and it's sitting 3mm below the surface of the crank case. 

 

Thanks!

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13 hours ago, Tshort said:

 

I've got to replace that seal on my 2012 r1200GS - looks like the same "special tool" part numbers you mentioned. Do you still have the tools you used? Or can you share any info about them with me so I can see if I can figure out how to make my own?

 

Any help would be most appreciated! (FWIW, I measured the depth of the stock seal and it's sitting 3mm below the surface of the crank case. 

 

Thanks!

Afternoon  Tshort

 

If you can't find a proper BMW seal driver then I believe that seal is about 83mm OD, (slightly over 3-1/4"), you might take your new seal into Home Depot, or Lowes,  or a plumbing shop & see if you can find something like a 3" PVC pipe coupling (or something) that is about seal OD. 

 

I usually get something slightly larger then stick it in my lathe & turn it down to the correct size to drive the seal. If you have access to a lathe then get something slightly larger than the seal  & turn it down to correct OD for only 3mm as that will then act as a depth stop. (probably not needed on the 1200 as I believe the engine block has a built in seal  depth stop)  

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