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spacewrench

Engine support threaded holes

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spacewrench

It looks like there are 3 threaded holes in my R1100S oil pan, which I believe are used to secure the engine when you need to pull the rear frame off (for example, to replace the clutch and transmission input shaft!)

 

I think these are M8, but probably crufted up with 20 years of dirt, so I can barely get bolts started.  I tried to clear the threads with an M8 tap, but I'm seeing metal in addition to dirt coming out, and I'm afraid of cross-threading or stripping those holes.

 

Can anybody confirm that they're M8, give me some idea of how deep they might be, and estimate my chances are of tapping right through into the oil sump?  ("I've struck oil!" is not going to make me rich in this situation, I don't think.)

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szurszewski

I checked both the Ss in the garage (‘01 and ‘04). The most aft hole is about 25mm deep, and the other two are about 20mm. I was able to get an M8 started in a couple of holes and not at all in a couple others - and even one of the holes that did start to thread, the bolt was clearly not going in perpendicular to the bottom plane of the oil pan. The one hole it seemed to go into best I sprayed throughly with PB blaster and was still only able to go a rotation or two before it was binding up and chewing on the threads of the bolt. 
 

 

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spacewrench

Thanks! I guess I'll try persuading them with some penetrating oil and a little more tap.

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szurszewski

can you get a pitch gauge up in there? mine is not narrow enough to fit...

 

I suppose if you're not using them for anything else as they are, it doesn't matter if you alter the threads anyway.

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dirtrider
15 hours ago, spacewrench said:

It looks like there are 3 threaded holes in my R1100S oil pan, which I believe are used to secure the engine when you need to pull the rear frame off (for example, to replace the clutch and transmission input shaft!)

 

I think these are M8, but probably crufted up with 20 years of dirt, so I can barely get bolts started.  I tried to clear the threads with an M8 tap, but I'm seeing metal in addition to dirt coming out, and I'm afraid of cross-threading or stripping those holes.

 

Can anybody confirm that they're M8, give me some idea of how deep they might be, and estimate my chances are of tapping right through into the oil sump?  ("I've struck oil!" is not going to make me rich in this situation, I don't think.)

 

Afternoon spacewrench

 

BMW only uses metric bolts on their 1100/1150 engines, they also don't used fine thread bolts into soft alloy castings so with 8mm bolt size  that means your bolt is an 8mm x 1.25 thread pitch.  

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