Head bolts snapping

[moakesr]

I put my trust in Norbar, Facom, Snap-On or Sykes Pickavant.

I did hear that Halfords Professional range is made by Sykes Pickavant, but never seen any proof of that.

Good tools last a lifetime, bad tools break when you least want them too !

 

[spock500]

>>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, because 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.

Its M10 x 115mm, 1.5 pitch

The other thing that happened I think (hate to admit how stupid I was) with some of the bolts is they 'hydraulic locked' in the holes giving a spongy feeling

Used a turkey baster and piece of plastic pipe to empty them of oil and water

 

[spock500]

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.

I think that speaks volumes about the kit - I had seen Facom and bought some of their tools but thought they were just another Ebay type brand that I hadnt heard of.

Its ages since I have been around cars, the two brands that I used to be familiar with were Kamsa and Snap on - I regret not doing more research when buying and may consider replacing some of the stuff bought with Facom.

The 1/2 socket set I bought isnt too bad, its made by Silverline and come with a lifetime guarentee.

Where do you go to buy your Facom kit?

I have asked th Ebay seller for another brand of torque wrench, if he hasnt got one and offers a refund I'll start with a Facom t/wrench

 

[big x]

I put my trust in Norbar, Facom, Snap-On or Sykes Pickavant.

I did hear that Halfords Professional range is made by Sykes Pickavant, but never seen any proof of that.

Good tools last a lifetime, bad tools break when you least want them too !

BTW the Sykes Pickavant torque wrenches with blue striped handles are made by Norbar.
The key is to buy NON-Chinese made tools !

 

[big x]

I think that speaks volumes about the kit - I had seen Facom and bought some of their tools but thought they were just another Ebay type brand that I hadnt heard of.

Its ages since I have been around cars, the two brands that I used to be familiar with were Kamsa and Snap on - I regret not doing more research when buying and may consider replacing some of the stuff bought with Facom.

The 1/2 socket set I bought isnt too bad, its made by Silverline and come with a lifetime guarentee.

Where do you go to buy your Facom kit?

I have asked th Ebay seller for another brand of torque wrench, if he hasnt got one and offers a refund I'll start with a Facom t/wrench

Most of my Facom has come from Ebay but my local factor also has them.
BTW these French made tools are used by the Ferrari F1 team. You can see the tool cases in the pit garage.
The ratcheting spanners are the best available.
Some of the more expensive tools in the Britool range are rebaged Facom.

adam

 

[spock500]

Out of interest what do you think of Am Tech tools?

I ended up buying quite a bit of their stuff for small items such as tap and die kits, although a set of tube spanners went round when applied to a stuck glow plug

Are Bergen part of Facom/re-badged?

 

[Number_Cruncher]

>>Its M10 x 115mm, 1.5 pitch

Here's a rough estimate of the torque required (lbf ft) to snap the bolts in tension. The upper figure is for yield, the lower for ultimate stress, i.e., total failure

10.9 grade 12.9 grade

85 122
94 136

It's a bit of an over estimate, because I haven't included the torsion in the bolt shank in calculating the stress, but, it's not too far off.

If your bolt holes were full of liquid, you have been lucky to avoid cracking the block!

 

[Bazzle]

Never put oil down a blind hole,, it can crack the casting

200% agree, wipe and blow it out.

Always test a new Torque wrench too.

Bazzle

 

[Wezzel]

I have a torque wrench similar to the one in the original picture (80ft/lbs max)but I wouldn't trust it for low torque settings. In fact I wouldn't use it for anything less than about 20ft/lbs.

I would generally use a lower rated one which are more accurate at low torques.

 

[fredfloggle]

I think that the torque wrench is faulty 10ilb is equal to a 6" spanner

50 ftlbs is equal to a firm pull on a spanner of normal length.

 

[fredfloggle]

Most of my Facom has come from Ebay but my local factor also has them.
BTW these French made tools are used by the Ferrari F1 team. You can see the tool cases in the pit garage.
The ratcheting spanners are the best available.
Some of the more expensive tools in the Britool range are rebaged Facom.

adam

Facom own Britool, as Chanel own Holland and Holland

 

[fredfloggle]

>>Its M10 x 115mm, 1.5 pitch

Here's a rough estimate of the torque required (lbf ft) to snap the bolts in tension. The upper figure is for yield, the lower for ultimate stress, i.e., total failure

10.9 grade 12.9 grade

85 122
94 136

It's a bit of an over estimate, because I haven't included the torsion in the bolt shank in calculating the stress, but, it's not too far off.

If your bolt holes were full of liquid, you have been lucky to avoid cracking the block!

That's more like it, proper numbers!!

Re hydraulic lock cracking the block - I doubt it . While so much of this is guess work , I worked on an 12mm bolt and 150 ftlbs, we end up with a clamping force of around 1500 lbsF, which would give us a hydraulic pressure on lock of around 2500 psi, you would have to have extreme circumstances to crack a casting in that event .

Torque wrenches are great, but the correct use of them is extremely variable, as can be seen , two different skilled techs will get wildly different clamping values, and there are too many variables in the preparation of the fixtures. A skilled mechanic can tighten standard fasteners up to their elastic limit pretty consistently - i'm trying to find an article which demonstrates this, but for the moment it evades me.

 

[Number_Cruncher]

>> Re hydraulic lock cracking the block - I doubt it

Putting the bolts in by hand - you're probably right, it's unlikely, but not a risk I would encourage people to run!

As the bolt goes in fairly slowly when installed by hand, there will be time for the trapped fluid to leak away - and get between the gasket and the block, which isn't ideal.

If, however, the bolt were being machine fitted, or was being installed with a buzz gun, there wouldn't be time for the fluid to leak away. One thing that would happen though is that the oil would lubricate the threads more effectively at pressure, and the relationship between torque and endload would change - I think the acheivable oil pressure would be rather high.

For the M10, grade 10.9, the pre-load at yield was 57 kN, and for 12.9, 69kN.

I agree about the skilled mechanic feeling yield being a potentially accurate method of installing a fastener. Some fastener installation machines actually do just this, they record both fastener torque and angle turned, as the rate of torque increase per unit angle begins to fall, that's where the bolt is yielding, and the machine stops. It's an excellent way to get the most out of a fastener, with the provisio that you have to check the elongation before you can re-use.

I'm sure, having done a quick, back of the envelope type calc, that the MB torquing procedure for the OM606 head bolts, for example, does deliberately take the fastener just into this yield region.

 

[fredfloggle]

The other point to be considered is that hydraulicing a stud will generate no more pressure than bottoming it out, and we don't expect to crack a casting by bottoming a stud, in fact before the stud bottoms it will become thread bound which is even more likely to do some damage, but it rarely happens.

The hydraulic pressure generated as above is about right unless I have a decimal wrong somewhere

I'm sure you have already come across the tightening procedure on big marine engines, where the stud is hydraulically stretched, the the nut wound down and give a minimal angular preload, so that there is no "guesswork" in the clamping force applied, caused by thread to thread frictional differences.

An oldtimer tried to catch me a few years back with fitting precision dowels into castings of a machine that made turbine blades, the knack however was to give the pin a couple of quick rubs on a fine stone to give ain oil/trapped air to get out of the blind hole and stop the pin seating properly.

 

[Number_Cruncher]

>>where the stud is hydraulically stretched

Quite so - it's one of the very best ways to obtain a known pre-load, and avoids most of the variation that you find with other methods. Having said that, torque to yield also produces low variation in preload.

 

[fredfloggle]

As also does angular tightening if properly carried out, with the first "throw" being important.

 

[grober]

Facom own Britool, as Chanel own Holland and Holland

Facom is now part of the STANLEY WORKS EMPIRE along with Britool and Sykes Pickavant http://www.sptools.co.uk/

 

[television]

With my pre war RR you got a 2" spanner for the BA electrics, the 1/4 and 5/16 bsf were 4" long, and the C spanners 8" long,, the head bolt spanner was 8" long, but the head blots were very clever in that the shank was reduced so that any stretch took place there and not on the threaded part. there was no such thing as torque then

 

[fredfloggle]

With my pre war RR you got a 2" spanner for the BA electrics, the 1/4 and 5/16 bsf were 4" long, and the C spanners 8" long,, the head bolt spanner was 8" long, but the head blots were very clever in that the shank was reduced so that any stretch took place there and not on the threaded part. there was no such thing as torque then

They definitely had torque then Malcolm, if they didn't the nut would just have gone round and round and never have got tight. Same thing with the engine, would have run until somebody let the clutch out, then it would have stopped, no torque.

 

[television]

They definitely had torque then Malcolm, if they didn't the nut would just have gone round and round and never have got tight. Same thing with the engine, would have run until somebody let the clutch out, then it would have stopped, no torque.

We did not have torque figures or spanners then, no such thing, that was 1928