How did you torque the crank nut (M20) ?

[somecarguy]

I had my motor out and waited to torque the crank nut to 300ft-lb with the presumption that setting the car on the ground, putting it in gear would be the easiest way to lock the motor and apply a lot of torque.

When I've had to greatly exceed my torque wrench's 150ft-lb capacity in the past I've use the (my weight) x (lever arm) technique. Access isn't quite so good in this case, even with the radiator out. Curious how you all have gone about this?

[sienayr]

Crank holder, breaker bar with jack handle on the end. (Google e30 crank holder. It’s also possible to fab your own.)

[somecarguy]

edit - looks like the tool commonly sold would require that the harmonic balancer / pulley be removed to be used? https://www.fcpeuro.com/products/bmw...ol-baum-112150

[sienayr]

Yeah it's easy to get off, 6 bolts I think lightly torqued, then you bolt the holder to where the pulley bolts to. You may want to get different longer bolts for the holder so you don't damage the originals.

Did you replace the crank seal?

[somecarguy]

bummed to remove the belts but that's not a big deal. I'm going to poke around the output shaft to see if theres a good place to lock the crank there but in general it seems like a better idea not to test the clutch with 300 ft-lbs and lock it at the front.

i replaced the everything seals

[H.J. 1981]

I purchased that big heavy duty crank holding tool from Amazon or Ebay for €40 or so, specifically for the E30/M20 engine.

A hefty piece of metal, to say the least, weighs in at around 10-12kgs.

I heard that crank bolt/washer need to be replaced every time they are removed, heard they were stretch type. It was €10 for both at the dealership, so i just got a new bolt and washer. I replaced the front seals as well, since i do not trust the POs last workshop (everything they did was sloppy).

It is torqued to 410 nm or so, borrowed and equally hefty 3/4" torque wrench from a machine shop next door.

Had to make up a very short puller tool, since the balancer/drive gears fit really snug in there.

[msservices]

Just out of curiosity...is taking that nut loose/off a requirement for working on the motor, or just if you were rebuilding the motor and taking the crank out? I am not sure how I was able to avoid this issue when I replaced my gaskets/seals

[somecarguy]

If you want to replace front main / intermed shaft seals it needs to come off.

Would a flat stock bar as sketched clear the front shaft/intermed seal carriers?

[sienayr]

I was able to torque mine down without the holder, it's a manual shift, my neighbor was sitting in the car with the brake pedal down and the car in gear. Now he has an e30 automatic, and it just wasn't working on that car, it kept rolling under the torque, so he fabbed a crank holder that we used to get his torqued down.

I asked about the crank bolt being a stretch bolt when I did mine, and was told it is not a stretch bolt.

The only reason I took my crank bolt out was to replace the two shaft seals.

- - - Updated - - -

If you want to replace front main / intermed shaft seals it needs to come off.

Would a flat stock bar as sketched clear the front shaft/intermed seal carriers?

With the amount of torque required, I think you'll want at least three bolts going through the holder. The ones you buy have all six.

[somecarguy]

I'll ask a neighbor over and try the brakes. Mine is manual as well.

[msservices]

I think a question worth asking is... how does the 300 foot pounds of torque on the crank nut compare to the maximum amount of torque that the engine would ever produce ? in other words is it a good idea to apply that much force to the rest of the drivetrain and the even crankshaft itself ? Maybe the holding tool is the better way to go

[somecarguy]

This is an entirely good point that I agree with. I ended up fabricating a holder from a piece of 1 in square stock and some grade 12.9 bolts. Still agree this is an instance in which having the tool is probably the right approach. Certainly not needed to remove the crank bolt but I would’ve felt better using the tool to install it.

[H.J. 1981]

I was able to torque mine down without the holder, it's a manual shift, my neighbor was sitting in the car with the brake pedal down and the car in gear. Now he has an e30 automatic, and it just wasn't working on that car, it kept rolling under the torque, so he fabbed a crank holder that we used to get his torqued down.

I asked about the crank bolt being a stretch bolt when I did mine, and was told it is not a stretch bolt.

The only reason I took my crank bolt out was to replace the two shaft seals.

- - - Updated - - -



With the amount of torque required, I think you'll want at least three bolts going through the holder. The ones you buy have all six.

Well, stretch type or not it costed me €10 for a new bolt and its thick washer buddy, i was ordering several other parts as well so it was cheap insurance.

[Jeffnhiscars]

Crank holder, breaker bar with jack handle on the end. (Google e30 crank holder. It’s also possible to fab your own.)

This is exactly what I did and the crank bolt is not 1 time use

[txzaphod]

I used the crank holder tool and a 3/4" torque wrench to get the 300 ft-lb setting. The end of the crank holder was braced against the frame.

I replaced the front crank seal when I did the timing belt recently. My car had the original crank bolt with a 27mm head instead of the newer 22mm head.

If the engine is in the car, you'll probably need to pull the radiator to get enough clearance for the torque wrench and socket. You'll need an adapter if you don't have a 3/4" metric socket set, requiring additional clearance.