Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: heliwilly on September 05, 2019, 11:31:00 AM
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I have seen two methods of tightening the cylinder head.
1/ Tighten to 16ftlb, leave 24 hrs, retighten to 16ftlb leave 24hrs, lastly check and tighten to 16ftlb.
2/ Tighten to 14ftlb leave 24 hrs, tighten to 15ftlb leave 24 hrs, finally tighten to 16ftlb
Which, if either, is correct. TIA
Bill W.
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Whatever is sez in the Honda manual mate, do you really believe dealers back then waited 24 hours before getting the bike out of the workshop?
I never had any problems with Hondas method
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Interesting topic! In my archives I have several socalled Rider's Reports on the CB500/550 published back then in then a weekly (!) motormagazine. In these articles were the typical complaints listed that CB500/550 owners met during many years and kilometers. High on the list were the plugcaps. Also high was the almost inevitable sweating of oil at the head gasket. In one of these articles the chief mechanic of Honda Netherlands, the man at the importer that instructs the dealers, gave his advice. Before tightening the head nuts, he advised to oil the washers somewhat with Molykote and then torque down to the original torque values prescribed in the Shop Manual. Can anyone explain how this can be benificial? I always thought torquening bolts/nuts using grease is a no-no. Now here the advice concerns the washers, but still I would like to know.
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When I put my engine together I followed what it said in the manual and never have I needed to touch it again.
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Contributors are talking about the figures in the "Manual". Which Manual are they referring to? All I have is the Haynes one which is limited.
This is the first CB550 that I have rebuilt and it was a non-runner that had been taken apart previously. I am coming across things that don't seem as they should be. The cylinder head nuts are a typical example. Are they supposed to have 2.25 mm washers under the head nuts? 7 of the nuts have 2.25 mm washers with the remainder having a selection of different thicknesses.
All help would be gratefully received.
Bill W.
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Interesting topic! In my archives I have several socalled Rider's Reports on the CB500/550 published back then in then a weekly (!) motormagazine. In these articles were the typical complaints listed that CB500/550 owners met during many years and kilometers. High on the list were the plugcaps. Also high was the almost inevitable sweating of oil at the head gasket. In one of these articles the chief mechanic of Honda Netherlands, the man at the importer that instructs the dealers, gave his advice. Before tightening the head nuts, he advised to oil the washers somewhat with Molykote and then torque down to the original torque values prescribed in the Shop Manual. Can anyone explain how this can be benificial? I always thought torquening bolts/nuts using grease is a no-no. Now here the advice concerns the washers, but still I would like to know.
Torque figures are usually given for dry threads UNLESS it's stated to use a specific lubricant.
Torque wrench effectively measures friction (rotary in this case) so placing a lubricant on the washer and using the same torque setting figure will then stretch the stud more than without lubrication. A higher clamping pressure in applied, as long as the tensile strength of the stud is not breached.
It's a more involved topic for such a simple action than is generally realised, we could do a thread on that if wanted.
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Interesting topic! In my archives I have several socalled Rider's Reports on the CB500/550 published back then in then a weekly (!) motormagazine. In these articles were the typical complaints listed that CB500/550 owners met during many years and kilometers. High on the list were the plugcaps. Also high was the almost inevitable sweating of oil at the head gasket. In one of these articles the chief mechanic of Honda Netherlands, the man at the importer that instructs the dealers, gave his advice. Before tightening the head nuts, he advised to oil the washers somewhat with Molykote and then torque down to the original torque values prescribed in the Shop Manual. Can anyone explain how this can be benificial? I always thought torquening bolts/nuts using grease is a no-no. Now here the advice concerns the washers, but still I would like to know.
Torque figures are usually given for dry threads UNLESS it's stated to use a specific lubricant.
Torque wrench effectively measures friction (rotary in this case) so placing a lubricant on the washer and using the same torque setting figure will then stretch the stud more than without lubrication. A higher clamping pressure in applied, as long as the tensile strength of the stud is not breached.
It's a more involved topic for such a simple action than is generally realised, we could do a thread on that if wanted.
Excellent idea! BTW, were CB550s any better in this than the CB500?
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Torque figures are usually given for dry threads UNLESS it's stated to use a specific lubricant.
Torque wrench effectively measures friction (rotary in this case) so placing a lubricant on the washer and using the same torque setting figure will then stretch the stud more than without lubrication. A higher clamping pressure in applied, as long as the tensile strength of the stud is not breached.
It's a more involved topic for such a simple action than is generally realised, we could do a thread on that if wanted.
Strange, in my work as Mech Fitter we have to go on courses regarding use of our torques wrenches, we are told the opposite, there is little point torqueing dry threads as the torque figures are meaningless, moreover, we are given different torque settings depending on which lube we use. Copaslip or Copperslip
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Isn't that in agreement (both those two methods)? In that a lubricant is specified and torque match to those materials.
Possibly looking at it from the design point of view compared to practice in use will expose the process of arrival at final specification as directed to your interaction.
But to understand in this application, do Honda specify any lubricant for those head studs on assembly?
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Does anyone have an answer to my original question?
Thanks
Bill W.
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The first answer was the correct one. Tighten once and ready to use. Honda in later revisions made head gaskets as a "sandwich" with sealant inside which squeezed out when tightened ensuring a leakproof joint. ALWAYS use a genuine head gasket if you can get one.
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Does anyone have an answer to my original question?
Thanks
Bill W.
http://manuals.sohc4.net/cb500/service_manual/HSM500550_2.pdf
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Thickness of washers probably dont matter but material type would so i would make sure all are Honda ones to make clamping same.
Personally never used any lube BUT before fitting head made sure that nuts "ran" up and down studs freely so that you are measuring the clamping torque not friction on the thread.
Any lube on the thread makes a vast difference to the torque required so you should stick to the genuine Honda manual, available in alladins cave as provided by Ashimoto who copied my manuals and parts books.
As an asside VOSA have for years been trying to find the reason for HGVs loosing wheels and no definitive answer has ever appeared, old style cone nuts were fitted dry whilst new style integral washer type are oiled, go figure.
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Thanks for that. I too have always torqued up dry, but wondered why the 3 stage suggested by some. to me it seems a better way of doing it given the time. Thanks Bill W.
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It would appear that the cylinder head flanged nuts do have 2.25mm washers underneath them, so that is the way I will go.
I found this out by taking the head off a 550 engine that had been left in the open with no plugs in.
Now the head is off the pistons in the barrels are soaking in paraffin. Hopefully it may eventually creep past the pistons and rings.
A 2ft breaker bar wouldn't move the crank. Bill W.
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If they are really not going to move and they are stopped away from TDC, then you can use a piece of softwood near the bore size and thump each piston in turn using a lump hammer.
This'll usually break the corrosion bond and allow you to rotate the motor.
It's more sympathetic than going through the crank and rods with a really big lever.
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Bill use a 50/50 mix of acetone and tqf, the yanks swear by it and i saw it work on the repair shop on tv, also trying it on an old engine and it seems to be working
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My engine when I rebuilt it was so hard seized nothing would shift it
Eventually If I remember rightly I removed the oil pan and then managed to get big end bolts off which allowed me to lift the barrels off with the con rods and pistons.
Then I was just dealing with trying to hammer out individual pistons.
Even then I couldn’t shift them and ended up getting the pistons pressed out in a local machine shop.
The good news was that despite how badly seized it was the bores just needed honing and were still within original spec
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I had an old unit 500 Triumph engine with seized in pistons, nothing would shift them until I tried cheap nasty cola (coke) this stuff ate through the corrosion and the pistons came out easily.
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Interesting topic! In my archives I have several socalled Rider's Reports on the CB500/550 published back then in then a weekly (!) motormagazine. In these articles were the typical complaints listed that CB500/550 owners met during many years and kilometers. High on the list were the plugcaps. Also high was the almost inevitable sweating of oil at the head gasket. In one of these articles the chief mechanic of Honda Netherlands, the man at the importer that instructs the dealers, gave his advice. Before tightening the head nuts, he advised to oil the washers somewhat with Molykote and then torque down to the original torque values prescribed in the Shop Manual. Can anyone explain how this can be benificial? I always thought torquening bolts/nuts using grease is a no-no. Now here the advice concerns the washers, but still I would like to know.
Torque figures are usually given for dry threads UNLESS it's stated to use a specific lubricant.
Torque wrench effectively measures friction (rotary in this case) so placing a lubricant on the washer and using the same torque setting figure will then stretch the stud more than without lubrication. A higher clamping pressure in applied, as long as the tensile strength of the stud is not breached.
It's a more involved topic for such a simple action than is generally realised, we could do a thread on that if wanted.
Interesting point there. If it's just a quick repair and the threads are not degreased they will have oil on them and so will the nuts. I doubt anybody goes to the trouble of degreasing the casing studs for a head repair, or am I wrong? Therefore by default you will be torquing down lubricated threads so what's the calculation to get the torque required from dry to oiled threads?
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Definitely Roy, you were paying attention at back of class there ;D ;D ;D
The numbers I've got say 10 to 15 % for a change from rolled threads dry to using oil. They differ for everything that can affect them including thread manufacture, plating or not, bolt / stud material, nut / washer material and design.
As you point out, it's just as important to have them all even for the structure you are securing to get correct distribution of clamping.
Whatever method anyone uses, the Honda figures seem to be given dry so you'd have to start from there and make decisions based on that.
We did talk (torque ;D) about it in relation to the small fasteners on another thread with Laverda120, but I can't find that one just now.