Crankshaft Nut Removal B35?

RonDwyer · Post by **RonDwyer** » Thu Aug 12, 2010 9:39 pm

I will have to post a picture of the set-up I tried using to loosen the front nut on the crankshaft. It does not appear to be a reverse thread, but I have to believe there is a recommended way to loosen that bugger to pull off the front hub. I want to re-seal the engine and do a verification teardown before putting it in the car. After flexing my Craftsman 1/2" breaker bar almost 1" with the floor jack handle as added leverage, my engineering sense is telling me that something is not right. Should I plan to fill my torch tanks and give it a good blast or drill the nut?

DMS · Post by **DMS** » Fri Aug 13, 2010 1:33 am

I had to take it to work where we have a air tool up to 720 Nm. I've been hammering with that for over 3 minutes to get it loose. So my advice: take it to a truck service station.

DEMIURGE · Post by **DEMIURGE** » Fri Aug 13, 2010 7:07 am

The above mentioned advice (from DMS) to go to the truck service station is good enough. Maybe an year ago I had the same problem. It took a few days of different trials. I was twice or maybe three times a silent witness, when different mechanics do it the same rude way - using chisel and heavy hammer. They say - it is the only way... Every time they succeed and every time the nut wasn't usable. Beside this I don't want to comment the "stress" to the crankshaft, bearings and other parts.
So, doing this for the fourth time - I decide to do it "gentle" and without my mechanics, chisel and heavy hammer. As I say - a few days of nothing.
Hammering, heating at definite place - cooling at other, using nearly 1 meter lever and I forget to say - another friend involved to help. NOTHING...
And I want just to say - it is a good idea, if the block is in the car or if it is outside - very firmly tightened to a suitable frame or something similar.
And finally - the last day, we succeed - we were three men - two of us with more than 1.5 meter levers - supporting the block and the third and strongest of us with nearly 3 meter lever (made of two metal tubes) was on the nut. Using dynamic force (hitting and jumping with full weight) he displaced us easily, together with the block. Even we broke the palette under the block.
DMS is speaking about 720 Nm. If you calculate the applied dynamic force in our case - it is a scary value - maybe more than 2500 Nm (1 Nm = 0.102 kg m).
The torque, when screw in, according the manual is about 450 Nm, but when you screw out - it is times harder.

So - much of writing, but for nothing.
As DMS have said - leaved it to the specialized heavy duty air tools.

RonDwyer · Post by **RonDwyer** » Fri Aug 13, 2010 10:53 am

I think the consensus is that this nut is not going to be re-used. Tonight I am going to get a nice new drill and treat it as if i was drilling a ring gear off a flywheel.

YouTube · Post by **Peter Florance** » Fri Aug 13, 2010 10:55 am

RonDwyer wrote:I think the consensus is that this nut is not going to be re-used. Tonight I am going to get a nice new drill and treat it as if i was drilling a ring gear off a flywheel.

If you can borrow a large enough impact gun, it will come off.

RonDwyer · Post by **RonDwyer** » Fri Aug 13, 2010 11:03 am

DEMIURGE · Post by **DEMIURGE** » Fri Aug 13, 2010 12:23 pm

Peter Florance wrote: If you can borrow a large enough impact gun, it will come off.

I agree with Peter. Please, don't give up. Besides, I am sure the old nut can be better than the new you will buy.
I like your photo - that reminds me my screw out setup. But if you want to continue this way - is the block stable enough on this stand? And maybe you'll need a little bit longer lever? Maybe you can use your friends additional force?
I'm sure - you can manage it.

jayne58 · Post by **jayne58** » Fri Aug 13, 2010 1:03 pm

Been there done that, all that you guys did. obviously the block is out of the car so load it in the truck and get it to somebody with an air tool thats what i did and after a day of bending expensive tools and everything it only took 3 seconds for the pneumatic tool to loosen that bugger off.

socalfiver · Post by **socalfiver** » Fri Aug 13, 2010 2:37 pm

And stop leaning bikes on your car!

RonDwyer · Post by **RonDwyer** » Fri Aug 13, 2010 11:29 pm

After drilling 3 holes in it, toasting the rest of my lame Dremel high speed cutting tools and all of my diamond tools trying to get it carved away enough to where a well-placed chisel strike would get it to crack I figure it's time to rent a truck to get it to a shop with an air compressor and a suitable impact gun. I'll post a picture of what is left of the nut. Oh, here's a thought, what about dabbing it with liquid nitrogen then whacking it? Am I a geek or what?

DMS · Post by **DMS** » Sat Aug 14, 2010 1:58 am

Dammit, stop fucking around and go to a truckstop! If you can get the engine out of the car you can certainly put it in the back of a different car.

It's a 20 minute job including driving to the truckstop.

DEMIURGE · Post by **DEMIURGE** » Sat Aug 14, 2010 3:20 am

Dear Ron, I'm very sorry to hear how you are wasting your time (so your money) and your tools also. Please, forget the idea to use liquid nitrogen. I count on the fact, that it is not so easy to find this stuff freely. I have worked with this stuff some years ago - this is not a joke. Everybody have seen the "Terminator 2", but it is just a Hollywood production - the real life is different. You have to use a very special container to transport the liquid nitrogen. If the container is tightly closed - it will explode after a while - some kind of liquid nitrogen bomb. I am glad - you can not find such a container. Beside this - the only way to cool and break the nut is to dip it into the stuff. Pouring or spraying will not work - you will need many liters. And of course, beside the nut you can break the shaft very easily.

I have a feeling - you are getting satisfied making your life harder. Sorry, I'm saying this, but I count at your sense of humour.

Please, I beg you - use heavy duty air tool.

P.S. I just remember, that BMW have used LOCTITE for this nut during some of the years (not all of the years) and this is an additional obstacle.

RonDwyer · Post by **RonDwyer** » Sat Aug 14, 2010 1:03 pm

Hey DMS, I am not having as difficult time with this as you are. I do not have a truck to take it anywhere, I do not have easy access to any truck stops and I do not feel there is a need to be scolded with profanity. As a mechanical engineer I relish the challenge and have been doing these sorts of projects for 30 years having started out certified on Detroit Diesel engines. If I am happy with wearing out a few old cutting tools then that is my prerogative. This is a hobby and others have managed to read between the lines to discern I am having fun here. Besides, I don't have any liquid nitrogen either.

DEMIURGE · Post by **DEMIURGE** » Sat Aug 14, 2010 2:41 pm

DEMIURGE wrote:I have a feeling - you are getting satisfied making your life harder. Sorry, I'm saying this, but I count at your sense of humour.

Ron, I'm really sorry and I must apologize.
There was no way for me to know, that you are a mechanical engineer with more then 30 years experience. And I'll take a warning - that I must read between the lines. I do not suppose you are joking about the liquid nitrogen. As a 43 years old electronic engineer I take things serious as they were written (there were no smilies or other emoticons) and I want to be useful and avert a possible injury. Thats why I hate these kinds of forums - you really don't know who is on the opposite side.
Thank you in advance for your patience and understanding.

Alexander

thomas_m535i · Post by **thomas_m535i** » Sun Aug 15, 2010 4:59 am

Peter Florance wrote:
RonDwyer wrote:I think the consensus is that this nut is not going to be re-used. Tonight I am going to get a nice new drill and treat it as if i was drilling a ring gear off a flywheel.
If you can borrow a large enough impact gun, it will come off.

I've tried with a large 36mm wrench and by blocking the flywheel, which didn't do it for me. Afterwards, I'd made an attempt with a big air gun (450 Nm I believe) and I've found that it took less than one minute to loosen the nut. Obviously, applying a multi-purpose lubricant in advance might be beneficial as well.