Torque + Angle

[bobski1]

I have to replace the damaged damper pulley on an BMW E61, 535d M57 engine. Torque is 40Nm + 120°. The 1/4" teng torque wrench j have has a handy gauge for angle however the bigger wrench I'll need to use does not. I've seen videos where people mark the bolt/socket but the bolts are deep in the pulley so I can't see either. 2 questions,

1) some people say not to apply the angle after the torque wrench has clicked as this is bad, but I'm not sure how this is the case?

2) how can I best apply the 120° angle as these are stretch bolts and I don't really want them to go beyond the design but also make sure I don't have them too loose although once they hit 40Nm they shouldn't come out. Could I use some picture just to be safe?

[thebraketester]

Can you not see the head of the bolt once it’s in there and been torqued, so you can mark its position?

[GreenV8S]

bobski1 said:

2) how can I best apply the 120° angle as these are stretch bolts and I don't really want them to go beyond the design but also make sure I don't have them too loose although once they hit 40Nm they shouldn't come out. Could I use some picture just to be safe?

Presumably the crank is locked in place, else you're aren't going to be tightening anything. In that case you just look at the angle you've moved the handle through. To get up to 120 degrees in a confined space you might need to do it in several steps but you just add up the angles of each step until you reach the total you're looking for.

[InitialDave]

Cut a marker from a bit of cardboard and tape it to the top of the socket?

[deeen]

InitialDave said:

Cut a marker from a bit of cardboard and tape it to the top of the socket?

Or get a marker pen and mark the side of the socket? 120deg = 1/3 of a turn, so 1/3 of the socket to mark?

[bobski1]

the fixings are deep within the pulley and looking at the videos on youtube I won't see the fixing head and possibly the end of the socket.

I think I will have to make a cardboard template and stick onto the pulley to give me an idea of where it is.

[GreenV8S]

bobski1 said:

I think I will have to make a cardboard template

I still fail to see why you need anything at all apart from watching what angle you've moved the handle through.

[E-bmw]

As others have said 120 deg = 1/3 of a turn, you don't need to see the bolt, you can see the socket ratchet/bar you are turning.

[E-bmw]

bobski1 said:

1) some people say not to apply the angle after the torque wrench has clicked as this is bad, but I'm not sure how this is the case?

Actually, everyone who knows what they are talking about says that, you would be over stressing a highly accurate device potentially pushing it well beyond its elastic limit. Which could make it useless for the next time you come to use it.

[deeen]

E-bmw said:

bobski1 said:

1) some people say not to apply the angle after the torque wrench has clicked as this is bad, but I'm not sure how this is the case?

Actually, everyone who knows what they are talking about says that, you would be over stressing a highly accurate device potentially pushing it well beyond its elastic limit. Which could make it useless for the next time you come to use it.

Ok I got this on 4th time of reading...
Of course you can apply the angle after the torque wrench has clicked, but not with the torque wrench... when it clicks you should take the torque wrench off the socket, and apply the angle with something else.

[PaulKemp]

A friend has just done this on a 320d, needed a special pulley locking tool, a long ½” breaker bar and a scaffold bar, we bent the handle of the locking tool.
It ends up as about 300nm
We marked the pulley and marked the socket, extender bar and breaker bar, if we had to stop and reposition we marked where we got to on the pulley and remarked the socket, extender if required.
You should use a new crank pulley bolt as the old one has already been stretched and won’t stretch enough to indicate 120 degrees or if it does you will have much more torque on it.

[Captain Answer]

Just use an angle meter, lot less messing about than card or judging 120 turn by eye - and you've got one for any other bolts you do

Torque the bolt, remove torque ratchet, put this in behind a normal ratchet/breaker, secure and set the angle, loads of vids on youtube of how they work

https://www.amazon.co.uk/US-PRO-Torque-Square-Angu...