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Need advice with VANOS reassembly (how to torque piston plug caps)

2003 - 2009, roadster, coupe, facelift
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tomrdy
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Need advice with VANOS reassembly (how to torque piston plug caps)

Post by tomrdy » Wed Jan 16, 2019 8:46 am

Job done!

What I ended up doing/notes for others:


The T30 reverse torx bolts

Having seen a story (I can't remember who) about stripping it, I opted to get new ones as recommended by that member.

I could get my torque wrench in for that one and set it to just under 8nm... however when I went to do it up, it got suspiciously tight and still did not click (my wrench can do both directions). 8nm really is very little so I figure maybe there is some give somewhere that wasnt letting me hit the torque (I saw the sprocket was rotating a minor amount) so I left it at hand tight.


The cylinder caps which this topic was originally about

I bought a set of long allen keys and this made winding it on SOO much easier than what I did with my socket. I had got the socket because I planned on use my torque wrench without realising it wouldnt fit.

The allen was quite long at 17cm+ so I could get pretty good leverage on it. I pulled quite hard on it but still felt uneasy. How much did I need??? Then I realised there's probably a calculation I can do to work out how much force/weight I need.

Torque = Length x Force

This ended up working out to be about 3.7 kgs of force on the end which isn't actually that much. I had thought 50nm was a tonne but its not. So, I went and picked up some weights and felt how much ~4kg was and... winged it.



First start


I was expecting the car to have some temporary grumpy idling as noted by guides but mine came back to life beautifully and idled nicely! Did a spin around the block and the car ran smoothly. I got it up to temp and then took it home as the coolant light had come on (expected). Will let the car cool down now and top everything back up.

Not yet put the C110 back in to see if the VANOS numbers are changed but I'll drive around for a while before doing that to butt-diagnose it first :)
Last edited by tomrdy on Wed Jan 16, 2019 12:43 pm, edited 1 time in total.
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GuidoK
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Need advice with VANOS reassembly (how to torque piston plug caps)

Post by GuidoK » Wed Jan 16, 2019 12:28 pm

tomrdy wrote: Wed Jan 16, 2019 8:46 am
The allen was quite long at 17cm+ so I could get pretty good leverage on it. I pulled quite hard on it but still felt uneasy. How much did I need??? Then I realised there's probably a calculation I can do to work out how much force/weight I need.

Torque = Length x Force

This ended up working out to be about 3.7 kgs of force on the end which isn't actually that much. I had thought 50nm was a tonne but its not. So, I went and picked up some weights and felt how much ~4kg was and... winged it.
If your allen key is 17cm long your calculation is way off :cry:

50Nm is 50N (or about 5kg) at 1m lenght.
If your allen key is 17cm, that means its 0,17 part of a meter or about almost 1/6th of a meter.
That means that the force at the end of the key to get to 50Nm should be 5:0,17=29,5Kg! , so about 8 times as much....

Thats why I said you should get the piece of central heating pipe (a foot or so is enough) to use as leverage. I wouldn't have said that if you had to pull 4kg... :wink:
(although pulling 30kg on an L key is still possible)

I'd remove the cylinder cover (20min. work) and retorque those screws. I dont know if they really need that 50Nm.
(50Nm is quite a load to put on a 8mm hex, on the other hand, 8mm hex is used on m10 bolts and 50Nm is standard on an 8.8 M10 bolt so both key and screw will be allright)

But now they didnt even recieve 7Nm. Thats barely enough for a 6mm thread.
Last edited by GuidoK on Wed Jan 16, 2019 12:45 pm, edited 1 time in total.
Z4 3.0i | ESS TS2+ | Quaife ATB LSD | Brembo/BMW performance BBK front/rear | Schrick FI cams | Schmiedmann headers+cats | fully polybushed | Vibra-technics engine mounts | H&R anti rollbars | KW V3 coilovers | Sachs Race Engineering clutch

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tomrdy
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Location: Sydney, Australia

Need advice with VANOS reassembly (how to torque piston plug caps)

Post by tomrdy » Wed Jan 16, 2019 12:42 pm

Crap you're right Guidok my mistake! I'm such a goose I think I was too rushed.

I'm going to strike out that part on my post so it doesnt misinform .
GuidoK wrote: Wed Jan 16, 2019 12:28 pmI dont know if they really need that 50Nm (50Nm is quite a load to put on a 8mm hex), but now they didnt even recieve 7Nm. Thats barely enough for a 6mm thread.
I should mention that before I did the maths (wrongly) I did actually put nearly as much force as I could through the Allen (it started flexing) and my hands so I'm thinking it might be enough - conservatively probably half my body weight which is roughly 30kgs.

I might just see how this goes. Opening it back up and pulling again (even with correct math) will still be a guess.
Image
-SOLD- Nardo grey 2004 Z4 3.0i E85
-SOLD- 2016 Long Beach Blue M2 DCT
-Wishing- Z4MC Interlagos blue... :oops:
___
Australia

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