Torque settings?

S

stivesvelo

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Cambridgeshire
Just about to fit the cylinder head to the engine & looking at the manual it has somewhat conflicting advice, one page says assemble fixings dry, a couple of pages later it says use a dab of molybdenum grease under nuts and on threads.

Internet also had a range of opinions but seems to lean towards the lubricated version some say using manufacturers torque, others say lube & manufacturers torque less 10%.

One train of thought is (particularly used bolts etc) that lubing enables more consistent torquing.
I'm confused & don't want to overdo it .....but on the other hand?

Rob
 
As Hamish says , I would use a ( small ) dab of lube ........... and generally speaking use torque settings as a guide , rather than gospel ........... erring towards under , rather than over obviously .....................

My original Green Book recommends the 25 / 18 ft/lbs settings btw .........

Having said that .......... speaking generally ....... I would expect the fasteners to go in dry when the bike is being assembled on a modern factory assembly line ....... so the torque values would presumably take that into account ............



Having said that ( again ) ......... as far as torque settings are concerned ......... A little while ago I removed an R1 oil / coolant pump for a check ........... The pump lives inside the oil filled sump and is driven by chain from the clutch , which lives directly above it .

The two manuals I have say you have to remove the clutch ( ! ) ...... in order to release the chain driving the pump ......... Jesus , talk about one job turning into two or three ........

However , I found there was enough room to release the driven sprocket ( and therefore the chain ) from the pump using a ring spanner without disturbing the clutch ...... ( thank Christ ) .........

Only trouble was is that there was not enough room to get a torque wrench in to re-tighten the sprocket bolt to the recommended setting , so I tightened the bolt with the ring spanner , plus a small dab of blue Loctite in this case ............ tightening to the point where you hit that "wall" ....... where you get the feeling to push it any further will result in tears ............ and six years later it`s still fine .


That`s one thing with torque wrenches ......... once you select a setting , there`s no give and take , no feel for what`s going on as you would get when you tighten by hand ........ It`s that setting or nothing .........

A little like speed cameras ..... there`s no discretion ..........



On a ( slightly ) related subject , there`s also the thing about soaking new clutch friction plates in oil before fitting them .........

No harm in doing that if you want to I guess ....... but do you think the factory goes to the trouble of doing that when assembling the bike ? .......

Of course they don`t ...... they go in dry , as a kit .........

In any case the clutch plates will soon get all the lube it needs once the engine is filled with oil and started ......... ( unless it`s a Ducati , of course .... ) .........
 
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Triple or twin? Not that it matters re your question in general. I don't lube but am very careful with torquing down. Interesting question. I might experiment next time I'm fitting a head.
 
Thanks for the guidance, also be grateful to know of any other errors.

IT'S a triple - SFC1000.

In the workshop manual in technical specifications it says:
(p 39) 'All threads should be clean and dry unless otherwise specified',
(p 41) - 'NOTE - We recommend the application of molybdenum grease on the threads and underside of the nuts'

I'm going for the lubed setting, but cautiously.

Manual amended:
note next to the primary drive sprocket torque - 120 ft lbs (was originally 52-59 ft lbs)
Also previous owner has amended the cylinder head studs to 25 & 18.

Just checked the diagram it has 31 ft lbs for the 6 long studs through the cam blocks, 28 for the others and 18 for the short cam block studs.

Should the long ones through the cam blocks be 28 also?
 
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My opinion is worth exactly what you paid for it...... I'm not adverse to applying a drop (literally a drop) of engine oil on the threads of studs and another drop on the thrust face of washers. I also use thread chasers, NOT taps or dies, on any blind holes or studs to remove any debris or loctite and to help reform any distorted threads.

A wise man once told me that more damage has been done from over torquing than by under torquing.
 
IMPO lubricating the studs and washers is a must (and even more important in engines that use stretch bolts since they are usually torqued up, and then a measurement of degree turned is ADDED this might be 40 degrees or more, lubing is vital in this case contrary to what Hamish says) BUT>><>BUT>>>BUT the ACTUAL torque wrench is very important as well, the bendy bar type with a remaining straight pointer onto a scale should have hopefullly all been scrapped by now, a 3/8" drive tool is more likely to be "in range" than a 1/2" one. A wrench that can do 200ft/lbs or even 300ft/bs will not be very good at a mere 25ft/lbs! idealy you need a wrench that goes to about 50 or 60ft/lbs, then the magical 25ft/lbs will be somewhere in the middle of the scale. my wrenches are decades old (SnapOn) my son took them to work a year or two ago to be sure they are calibrated correctly and they were, so that can be an issue as well, but to be fair, they dont get the use they would in a professional environment.

The next thing is the tightening sequence, its not just "start in the middle" and work out, it nearly is but not quite, see below, then, I always start at 10ft/lbs, and go all round the 9mm (long type from crankcase 12 of) studs (be carefull the 9mm and 8mm studs have the same size hexagon heads in the Laverda triple) then go all around at 15, then 20, then 25. (do this in reverse if removing) the two studs front and rear cam chain tunnel, 8mmx2 and lastly the studs by the plugs.7mmx2
 

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My lower range wrench says Nm ......... My upper range one says kg/m and ft/lbs at the same time ..... ( take your pick ) .......... I take kg/m as being the same as Nm , once you`ve divided by ten ....... ( ok , 9.8 ... but I`m not that fussy ... although I guess it does make a slight difference the higher up you go ... ) .......
 
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Most manufacturers knew what they were doing when specifying using lube or not when referring to their torque specs. Differing and largely overwhelming figures stated in the Laverda manuals throws this out the window somewhat... :rolleyes:

It must be considered that any manufacturers specs were based on production processes and conditions, all with new components. Sadly, most Laverdas have been badly butchered over the past decades, resulting in many weakened studs and case threads. Hardly any engines are still in such prisitine condition that wear and tear doesn't need to be considered upon assembly.

FWIW, I use oil-lubed nuts for the heads and stick to lower than the factory stated figures, ie, 25Nm max for the M8 studs (factory spec 3.5mkg~35Nm), 32Nm for the M9 (factory spec 4.0mkg~40Nm). Same for the crankcases. My figures are based on standard engineering norms. All accessable threads are chased and mating surfaces flattened as needed. Most triple heads require spot-facing and I have gone over to using flanged nuts to spread the loads more evenly over a greater area than the original hardened washers (that are all too often missing or have been replaced with mild steel items!). Most 750s have large raised portions around the bottom of the cylinder studs where the thread has begun to pull out... no more than 40Nm there. Although I cannot state for certain, but I reckon my actual torque values end up slightly higher than my figures due to the lube (my wrenches were recently calibrated), but still considerably lower than the factory specs. Along with a thin bead of Loctite 510, I have had zero leakage issues, as long as a suitable head gasket is used, but that's a different story again.

piet

IMG_1105.JPG
 
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IAG said:
& Harleys
Click to expand...
Heads fitted and torqued this afternoon to an indicated 42 Lb/ft.

It's also worth pointing out that you can "cheat" a bit depending on your head gasket type and reduce your torque values. An annealed copper head gasket (especially if gasgacinch has been applied to all four surfaces) is going to behave differently than a Multi-Layer Steer gasket or Composite head gasket.

At the end of the day a leaking head gasket, while embarassing, is still much cheaper to correct than a buggered head.
 

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CLEMTOG said:
IMPO lubricating the studs and washers is a must (and even more important in engines that use stretch bolts since they are usually torqued up, and then a measurement of degree turned is ADDED this might be 40 degrees or more, lubing is vital in this case contrary to what Hamish says) BUT>><>BUT>>>BUT the ACTUAL torque wrench is very important as well, the bendy bar type with a remaining straight pointer onto a scale should have hopefullly all been scrapped by now, a 3/8" drive tool is more likely to be "in range" than a 1/2" one. A wrench that can do 200ft/lbs or even 300ft/bs will not be very good at a mere 25ft/lbs! idealy you need a wrench that goes to about 50 or 60ft/lbs, then the magical 25ft/lbs will be somewhere in the middle of the scale. my wrenches are decades old (SnapOn) my son took them to work a year or two ago to be sure they are calibrated correctly and they were, so that can be an issue as well, but to be fair, they dont get the use they would in a professional environment.

The next thing is the tightening sequence, its not just "start in the middle" and work out, it nearly is but not quite, see below, then, I always start at 10ft/lbs, and go all round the 9mm (long type from crankcase 12 of) studs (be carefull the 9mm and 8mm studs have the same size hexagon heads in the Laverda triple) then go all around at 15, then 20, then 25. (do this in reverse if removing) the two studs front and rear cam chain tunnel, 8mmx2 and lastly the studs by the plugs.7mmx2
Click to expand...
I can only support what Clem says here regarding the right (quality) tool for the right job. I was always uncertain about my torque wrenches and how good they really are. I bought me a tool to measure the actual setting against what was set on the torque wrench and found surprising results...

-some cheap ones were correct in a certain setting but WAY off in others
-the higher the range, the more off they were at some point
-quality tools were off just a Nm or two mostly
-even 40 year old but only rarely used professional tools were almost spot on still
-even on high-end tools, the first "click" is a higher value than all following ones, sometimes (on cheap tools) the difference between first and the following was 5-8%! On the quality tools, it was in a range of a Nm or max 1,5Nm.

The highest difference I found was on supermarket tool which had a range of 40 - 300Nm. Setting it to 130Nm showed a real torque value of way over 200Nm, so more than 50% difference! We adjusted it to 130Nm, which caused every other setting to be way off still.

I measured around 30 different ones meanwhile for friends and family, neighbours etc., adjusted them best possible and made tables for them so they know what values they produce by every 10Nm setting (on the ones with very small ranges like 10 - 40Nm, I did that for every 5Nm). Most torque wrenches also need to be "relaxed" after usage (adjusted to "Zero"), which is critical to keep them accurate. Some modern ones don't need that, but surely it is a good habbit to do, just to avoid using it with the wrong setting and/or for peace of mind.

For the Cylinder heads of my bikes, I bought me a Gedore 10 - 50Nm. Even that one, I check before using every time... Borrowed the "Würth" one that I normally use for the tire bolts on my cars to someone who I can not remember who it was and it wasn't returned unfortunately, so I used one cheap one and just set it with my measuring tool to the needed 175Nm for the Tesla's screws and same for the 120Nm of the Mini and the Astra of my son. Took me 3 minutes to find a setting that lasted beyond the first 2 clicks... :mad:

Will never borrow any tools again without taking notes to whom...
 
sfcpiet said:
Most manufacturers knew what they were doing when specifying using lube or not when referring to their torque specs. Differing and largely overwhelming figures stated in the Laverda manuals throws this out the window somewhat... :rolleyes:

It must be considered that any manufacturers specs were based on production processes and conditions, all with new components. Sadly, most Laverdas have been badly butchered over the past decades, resulting in many weakened studs and case threads. Hardly any engines are still in such prisitine condition that wear and tear doesn't need to be considered upon assembly.

FWIW, I use oil-lubed nuts for the heads and stick to lower than the factory stated figures, ie, 25Nm max for the M8 studs (factory spec 3.5mkg~35Nm), 32Nm for the M9 (factory spec 4.0mkg~40Nm). Same for the crankcases. My figures are based on standard engineering norms. All accessable threads are chased and mating surfaces flattened as needed. Most triple heads require spot-facing and I have gone over to using flanged nuts to spread the loads more evenly over a greater area than the original hardened washers (that are all too often missing or have been replaced with mild steel items!). Most 750s have large raised portions around the bottom of the cylinder studs where the thread has begun to pull out... no more than 40Nm there. Although I cannot state for certain, but I reckon my actual torque values end up slightly higher than my figures due to the lube (my wrenches were recently calibrated), but still considerably lower than the factory specs. Along with a thin bead of Loctite 510, I have had zero leakage issues, as long as a suitable head gasket is used, but that's a different story again.

piet

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Excuse my ignorance Piet, I’m not a mechanic or engineer, what do you mean by spot facing? Similar to surface facing, but in spots?
 
chrisk said:
Excuse my ignorance Piet, I’m not a mechanic or engineer, what do you mean by spot facing? Similar to surface facing, but in spots?
Click to expand...

Something like this, Chris.

DSCN7646.JPG
This is how the area around the stud holes normally looks. Not too bad actually, otherwise these holes would have gotten the treatment as well! Holes already chamfered to ease reassembly. Reduced oil supply funnel to exhaust valve stem is also visible here. Helps to reduce smoking on the over-run and oil comsumption on a whole.

DSCN9554.JPG

A lot neater and straighter after facing. Gives the fixing nuts/washers a better area to again spread the load evenly, a decent chamfer (not yet applied in pic!) also avoids the holes being squashed tight, as is so often the case! All rather acedemic I'm afraid, but that's how an engineer would do it. If the factory had used sturdier washers in the first place, the results might be less dramatic. The stamped-out, hardened washers are a tad small for the torque applied and tend to dig into the soft alloy, especially if they are fitted wrong side up. Casting quality may also be a factor... :rolleyes: But then, nobody at the factory at the time ever envisioned that selected tragics would still be mucking around with their stuff 50 years on.

piet
 
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