Thread: banjo bolt torque setting

Originally Posted by uninformed

hey all,

does anyone have an idea of what torque value a 10mm (OD shaft/thread) banjo bolt should be fastend to? this goes in to the top of my turbo between the compressor and turbine.

cheers,
Serg

Serg, just do it up to where it feels right, I wouldn't torque a banjo bolt, you can't use the normal values for a 10mm bolt as the banjo bolt is hollow and usually seals on copper washers, Regards Frank.

thanks Frank. Only problem is "my feel" im a wood butcher and we do our bolts up with a rattle gun haha...ill just have a crack and see how it goes. I guess it will only leak a bit if not done properly. Yes im reusing the copper washers, I know that is not best practice but they are the only ones I have.

Originally Posted by Tank

Serg, just do it up to where it feels right, I wouldn't torque a banjo bolt, you can't use the normal values for a 10mm bolt as the banjo bolt is hollow and usually seals on copper washers, Regards Frank.

Ahhhh - while what you say is sound advice....your point of normal values for a 10mm banjo bolt are not actually correct as there is a torque for them.

I recalled a torque value after reading Serg's post and had a look through a few of my engineering reference books and various bike and car owners manuals and found this......

Torque values for a brake hose oil bolt (Banjo) M10X1.25 = 3.0 N*m
Torque values for a oil return bolt turbo (Banjo) M10X1.25 = 3.0 N*m

The conversion is - 1 newton metre = 0.737562149 foot pound which is about 3 foot pounds......not much but as you say - all the bolt has to do is seal the washers.

By the way Serg, if you have a gas stove.....hold each washer with some long nose pliers and heat to you see a colour change (Dull red) and then drop them into a container of water. This action will 'anneal' each washer and allow you to re-use them again.

Tightening an oil-drain plug or a banjo bolt against a copper or aluminium washer 'works' the metal making it hard. 'Annealing' means 'making it soft so it deforms again'.

Cheers!

wow 3nm or 2.2ft/lb is bugger all, Id say I did it up some more than that. But I didnt heave on it either....I do wonder if when reusing the old washers (now hard) that it would require more torque to get a seal...

thanks for the tips Matt, Ill give the anneal trick a go.

Originally Posted by Catmatt

Ahhhh - while what you say is sound advice....your point of normal values for a 10mm banjo bolt are not actually correct as there is a torque for them.

I recalled a torque value after reading Serg's post and had a look through a few of my engineering reference books and various bike and car owners manuals and found this......

Torque values for a brake hose oil bolt (Banjo) M10X1.25 = 3.0 N*m
Torque values for a oil return bolt turbo (Banjo) M10X1.25 = 3.0 N*m

The conversion is - 1 newton metre = 0.737562149 foot pound which is about 3 foot pounds......not much but as you say - all the bolt has to do is seal the washers.

By the way Serg, if you have a gas stove.....hold each washer with some long nose pliers and heat to you see a colour change (Dull red) and then drop them into a container of water. This action will 'anneal' each washer and allow you to re-use them again.

Tightening an oil-drain plug or a banjo bolt against a copper or aluminium washer 'works' the metal making it hard. 'Annealing' means 'making it soft so it deforms again'.

Cheers!

Catt, all this is fine if you are using a new bolt in a new thread, for all we know this bolt could have been overtightened, the thread may be stretched to buggery, so I treat each bolt according to how often it would have been on and off the engine (whatever) and use my head (not literally) when refitting secondhand bolts into secondhand threads, was going to suggest annealing as well, this does not apply to Head bolts, bigend bolts, main caps etc.. These do need proper torqueing, but if you torqued every nut and bolt to their "Correct" values it would take forever to rebuild an engine, I think the worst bolts to torque to specs are rocker shaft bolts, esp. into an aluminium head, I would like a dollar for every stripped rocker shaft bolt threads I have come across, bit of Loctite and do them up to brain torque, Regards Frank.

Originally Posted by Tank

Catt, all this is fine if you are using a new bolt in a new thread, for all we know this bolt could have been overtightened, the thread may be stretched to buggery, so I treat each bolt according to how often it would have been on and off the engine (whatever) and use my head (not literally) when refitting sechand bolts into secondhand threads, was going to suggest annealing as well, this does not apply to Head bolts, bigend bolts, main caps etc.. These do need proper torqueing, but if you torqued every nut and bolt to their "Correct" values it would take forever to rebuild an engine, I think the worst bolts to torque to specs are rocker shaft bolts, esp. into an aluminium head, I would like a dollar for every stripped rocker shaft bolt threads I have come across, bit of Loctite and do them up to brain torque, Regards Frank.

Be cool Frank - there was no criticism and I acknowledged your sound advice to Serg....

My point was simply that there IS torque values for each and every nut and bolt available.

For the record - I torque everything on my engines and have never had a failure with aluminium, steel, titanium or incanel. Yes it takes a little more time but the 'peace-of-mind' factor is worth it....particulary on some of the very exotic race engines I've rebuilt (Diesel and petrol)

for me its a case of: #1 if it has a torque value there is usually a reason and #2 I dont have years of experience and feel built into me.....I guess the more one used a torque wrench early on in life/training the better "feel" they would get built in.

when I rebuild my chainsaws I torque wrench almost everything...

Hey I'm not criticising you, I was explaining that bolts and the threads they screw into become work weary ( for a better word/s) and if an engine has been pulled down a few times. Like rocker arm bolts, sump bolts, water pump/timing cover bolts, inlet and exhaust bolts MAY fail if you apply new bolt/thread torque values to them. I'm not trying to be a smart-arse, just trying to save a lot of unecessary flailing about with a torque wrench.
The reason I come across so many stripped threads in alloy is because people apply new torque values to old bolts and threads. I used to in my youth use a torque wrench to refit old bolts and nuts, but ended up busting or stripping threads all over the place till the boss booted me up the arse and showed me the light.
Last head job on my 300TDi I was tightening the rocker shaft bolts 28-32Nm in 2 stages @ first stage 15Nm and every thread in the head stripped before I got to 15Nm, this was the 3rd time this rocker shaft had been removed/replaced since new. I would be willing to bet that this is the cause of loose rocker shaft bolts that I have come across on diesels with alloy heads, never seen it on iron heads.
My point is use commonsense when replacing old bolts into old threads esp. on alloy and take the new torque values in the workshop manual with a grain of salt, Regards Frank.