Head bolts snapping

[jaymanek]

Thanks for the reply,



What precisley is 'angle tighten' ?

im wondering the same!

 

[big x]

Both arms and made quite a 'crack' when it went, your limited to the force your able to apply because of the extension required to be over the lip -

I have loosened all the bolts off in reverse sequence, I wanted to try the wrench out on a wheel nut but dont have a 3/8 to 1/2 reducer -

Can anyone rec a good wrench, the ones on ebay are very similar twisting handle type, this looks ok
http://www.halfords.com/webapp/wcs/...1_productId_178843_langId_-1_categoryId_76866

BTW the wrench shown is actually made by Norbar a top notch British company whose products are widely used in industry.
They come with calibration certificates. Mine are extremely accurate.
I have 1/2" and 3/3" ones.
It's a shame people buy rubbish Chinese made ones.

 

[Ian B Walker]

What precisley is 'angle tighten' ?

im wondering the same!

Angle tighten is to tighten the bolt a further 90 degrees. For what they cost I would invest in a new set of head bolts to be absolutely sure they are all good.

 

[spock500]

Angle tighten is to tighten the bolt a further 90 degrees. For what they cost I would invest in a new set of head bolts to be absolutely sure they are all good.

Yup, they will be ordered first thing Monday morning Ian, all 22 of 'em

There seems to be a wide range of opinion on what the correct ft lbs should be, do you think 27 is too low as rec by Haynes?

Its a long way from 80 ft -

So do you tighten the bolt a further 90 degrees even though the torque wrench has 'clicked out' ?

Cheers for your help Ian, i took the shocks back yesterday and got £76 refund :bannana: thanks to your last bit of advice

 

[spock500]

BTW the wrench shown is actually made by Norbar a top notch British company whose products are widely used in industry.
They come with calibration certificates. Mine are extremely accurate.
I have 1/2" and 3/3" ones.
It's a shame people buy rubbish Chinese made ones.

Are you referring to the Halfords one or the one I bought from ebay ?

 

[Ian B Walker]

IIRC head bolt should be at 55Nm then 90 degrees then a further 90 degrees. Purchase an angle gauge for the 90 degree bit, they cost less than a fiver. Also use a long breaker bar to ensure you get enough leverage in one shot of tightening.

 

[Number_Cruncher]

>> So do you tighten the bolt a further 90 degrees even though the torque wrench has 'clicked out' ?

Well, in your case, you'll actually tighten to 180 degrees after the last torque wrench operation. Two steps of 90 degress. This is why the torque value looks low to you - it is low, but the bolts are tightened through the further angle of 180 degrees.

The first two torque stages are just to snug the head down into position, and form a repeatable starting point for the angle tightening.

I'm glad that you're replacing all the bolts.

When doing the angle tighten part (there's a relatively cheap protractor available from motoring and tool shops that fits on your extension bar), you can soon get mixed up. I would recommend that before you begin, you mark, using some tippex or similar between the bolt and the head - preferably in a consistent way.

For example, if you put the mark pointing forwards, after the first 90 degree stage, you should see 22 marks all pointing towards the driver's side, after the second stage, 22 marks pointing towards the back of the car. This method ensures that you don't miss any (because you *can't* check with a torque wrench afterwards!)

 

[Ian B Walker]

>> So do you tighten the bolt a further 90 degrees even though the torque wrench has 'clicked out' ?

Well, in your case, you'll actually tighten to 180 degrees after the last torque wrench operation. Two steps of 90 degress. This is why the torque value looks low to you - it is low, but the bolts are tightened through the further angle of 180 degrees.

The first two torque stages are just to snug the head down into position, and form a repeatable starting point for the angle tightening.

I'm glad that you're replacing all the bolts.

When doing the angle tighten part (there's a relatively cheap protractor available from motoring and tool shops that fits on your extension bar), you can soon get mixed up. I would recommend that before you begin, you mark, using some tippex or similar between the bolt and the head - preferably in a consistent way.

For example, if you put the mark pointing forwards, after the first 90 degree stage, you should see 22 marks all pointing towards the driver's side, after the second stage, 22 marks pointing towards the back of the car. This method ensures that you don't miss any (because you *can't* check with a torque wrench afterwards!)

well put mate

 

[spock500]

IIRC head bolt should be at 55Nm then 90 degrees then a further 90 degrees. Purchase an angle gauge for the 90 degree bit, they cost less than a fiver. Also use a long breaker bar to ensure you get enough leverage in one shot of tightening.

55Nm seems to be the setting for petrol engine, the diesel version appears to have different settings for just about everything

 

[Diesel Benz]

55Nm seems to be the setting for petrol engine, the diesel version appears to have different settings for just about everything

This one should use 15 Nm first, then 35 Nm, followed by the 90 degrees, wait 10 minute and another 90 degrees.

Edited: I realise the same figures were already mentioned, but these are "real MB figures" to confirm that the Haynes manual is right.

 

[spock500]

well put mate

Seconded

 

[big x]

Are you referring to the Halfords one or the one I bought from ebay ?

The Halfords one. It's the same as my Norbar 3/8" shown bellow.

As you can see I also like Facom but their torque wrenches are over a £100.

BTW always use new stretch bolts as the old ones fatigue regardless of length.

adam

 

[Madeira Jon]

I remember getting a "Wilson" torque wrench some 25 years ago. Then it cost £40. Don't know if they still make them, but I never had any problems when re-building engines.

 

[Ian B Walker]

I have three torque wrenches, one Britool and two Halfrauds ones. The Britool one is very very good.

 

[spock500]

Yup, bolts already ordered - I think that the one pictured snapped at around 50/60 ft lb using my now working torque wrench as a guide - that said I dont have confidence in the tool which maybe further damaged by not clicking out -

Whats inside 'em - I am guessing its like the old volkswagon beetle suspension rod setup?

 

[television]

Yup, bolts already ordered - I think that the one pictured snapped at around 50/60 ft lb using my now working torque wrench as a guide - that said I dont have confidence in the tool which maybe further damaged by not clicking out -

Whats inside 'em - I am guessing its like the old volkswagon beetle suspension rod setup?

Just a spring and a sprocket, no more and no less

 

[spock500]

Just a spring and a sprocket, no more and no less

No beetle suspension type rod then

Oh well, could it be damaged by not 'clicking out' it says dont go past the point where the wrench clicks out otherwise damage may occur to the bolt, nothing about the wrench though -

Prolly get another one before the weekend, cant risk fifty quids worth of bolts to it

 

[spock500]

The Halfords one. It's the same as my Norbar 3/8" shown bellow.

As you can see I also like Facom but their torque wrenches are over a £100.

BTW always use new stretch bolts as the old ones fatigue regardless of length.

adam

Big X, do you use them or are they for display purposes only

 

[Number_Cruncher]

>>I think that the one pictured snapped at around 50/60 ft lb

What size thread is it? M10?, M12?, and what pitch (measure over a few threads, but not near where the break is, becuase the pitch is stretched there). With that, I'll be able to work backwards, and give you a rough estimate of what the torque required to break the fastener was.

 

[big x]

Big X, do you use them or are they for display purposes only

Funnily enough the 3/8" ratchet has done a ton of work including complete engine rebuilds (see if you can spot it) and is 6 years old and the black screwdrivers are 14 years old and much used. Facom make good quality gear.
The ratcheting spanners get less use than I thought they would though.