Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Fogdevil on February 18, 2018, 11:01:30 PM
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Hello everybody
After having a fantastic day in the garage I come to the final job of the day-fastening down the cylinder head-only to find that the cylinder stud with the 'open' flanged nut(on the offside) will not grip.I can only assume that the stud has been put in too far.The other open nut/stud is fine.
If I omit the copper washer then it will fasten no problem.
If I use the copper washer with the original nut then it will fasten!(But have now stripped the original nut-and it was pretty grotty anyway).Indicates to me that the shortness of length of the stud is minimal.
I have hand tightened the nuts but just put copperslip under the problem nut for now.
Soooo.Do I:
Torque down the nuts as they are-leaving out the copper washer on the problem stud and assume that Honda overenginering will compensate?
Try to get a thinner copper washer?(Washer thickness 2.3mm)
Try different flanged nuts to see if one will 'grip' the stud.The new nut is original Honda part from DS.
I don't know enough about engineering to know if this is an irritating problem or an oil leak waiting to happen.
I am rather hoping my first suggestion is acceptable as I really,really,really DON'T want to undo all my good work so far. :(
What is the purpose of the copper washers?
Ta
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Copper washers are usually used to seal an oil path properly (you could consider them a veeeeery stiff rubber in engineering terms) so it's needed for that. In effect the copper deforms to fit the other metals and creates a good high pressure resistant seal.
All things being equal, you need to have the nut fully covering the threads to be able to reach the torque required to work as intended. If you could get a copper washer that's thin enough to achieve both aims, then it's possible to use it.
It looks like it's the answer you don't want, the correct length stud is really needed. If not, you run the risk of it releasing in use or oil leaking possibly. It's a real pain to go back over the assembly you've already completed but it's probably the last point at which it's relatively easy to correct it without much cost.
I'd pull it apart and replace the stud at this point rather than going further.
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If the difference between apparent success and the inability to get it to tighten is only the thickness of the washer, then that doesn’t even equate to two threads, so as K2-K6 says, you need a longer stud - check the other corresponding one as well. Yes, it’s a pain to have to retrace your steps but look on the bright side - if you do it now you can re-use the head gasket but if you carry on and it leaks, you have to remove the carbs and exhaust and will definitely need another head gasket.
Btw, the studs should bottom out on the shoulder anyway so can’t be in too deep.
Ian
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Oh darn and blast it!!
I wrecked some of the studs on removal so got a complete set of second hand engine studs from a 400/4 breaker and even stipulated the longer studs for an F2.
I remember measuring the lengths and they were all correct but didn't measure the relative lengths of the studs after installation.
I think I'll have to take the problem back to the engineering firm that installed them.(I wanted proper torque on the studs and haven't got that sort of ability to do it without graunching some metal)
Thanks for the info lads.
I'll let you know how I get on.
Mutter,mutter,mutter >:(
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That's a shame but, as others have said a 'bodge' will only come back and bite you on the arse. What I cant quite understand though is if all the studs measured the correct length before you had them put in why does one now seem too short?. They can only go in so far and no further so the chances of the one in question being in too far seems a bit obscure.
Edit...make sure they have not put the stud in too far and cracked the case.
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You're right Julie.
I think it needs an engineers touch.
Having seen the state of your pistons and cylinder head ,yet the bike still functioned ,made me wonder if a little problem like mine would have been coped with by Honda engineering.
Better safe now than costing lots of money later
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I think Honda engineering can put up with an awful lot but only if the correct parts are fitted in the correct places. What I have learnt recently is that Honda didn't fit certain parts for fun, they were put there for a reason. Some of the items fitted, in this cast the copper or copper covered steel washers are what contributes to making these engines so resilient but the parts need to be in the correct place, to the correct spec for optimum resilience and performance. I have learnt something this morning, I never knew the head studs were different on the F1 to the F2, I thought they were the same sizes on both models.
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I know I have read somewhere that the early F1's had a minor oil leak problem on some bikes.
Honda increased the length of some studs(couldn't tell you which ones) by 1mm to cure the problem.
However, if this info is inaccurate I am sure someone on here will inform me.
I would hate to start an 'urban myth'.
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Picking up on Julie's post about how they could be correct length but short when installed.
If they are different on each end (ie one end to set the depth into the case, one for the nut) then it's possible the "wrong ones" could be upside down, and so will allow them to go in too far.
Honda, along with any decent engineers, are very particular about studs and their loading. General practice would be that a stud should never hit the bottom of the hole it's in. They'd normally be arranged so that the top part of the thread restricts them going too far.
The true torque loading only comes onto the whole assembly once you tighten the last nut, making them kind of "free floating" in engineering concept terms.
If anyone has a set out of the cases it maybe helpful to look at them to see if the differ each end.
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Picking up on Julie's post about how they could be correct length but short when installed.
If they are different on each end (ie one end to set the depth into the case, one for the nut) then it's possible the "wrong ones" could be upside down, and so will allow them to go in too far.
Honda, along with any decent engineers, are very particular about studs and their loading. General practice would be that a stud should never hit the bottom of the hole it's in. They'd normally be arranged so that the top part of the thread restricts them going too far.
The true torque loading only comes onto the whole assembly once you tighten the last nut, making them kind of "free floating" in engineering concept terms.
If anyone has a set out of the cases it maybe helpful to look at them to see if the differ each end.
I was just talking to Trig about this and he suggested the stud may have been put in upside down, thus not leaving enough thread at the top for the nut to engage.
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I have just gone onto the DS website to have a look at a picture of a stud.
You are all quite right. There is definitely a bulbous part to the shaft, just above the thread, at one end.
Looks like it has been put in upside down!!
Oh well.A trip back to the engineers is on the cards.
I refer to my earlier comments:"Mutter,mutter,mutter"
Thanks for your help.I will let you know the outcome.
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I know I'm keeping on ::) ::) but having read your original post again, I'm a bit confused. Which stud is it exactly that your having problems with, maybe a photo would help. I'm thinking are you fitting a copper washer where there should be a Dowty washer?
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I just checked the other 400/4 - a 76 F1 and this engine has not been molested before I got it.
Steel rule measurements only
These are the results from the Orkney Jury:
[attach=1]
If they are upside down, they can be wound in much further on some of them
Ian
Oops, forgot to say those measurements are with the studs fitted and the distance is from crank case top face to top of stud
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Soooo, could one not just put double nuts on the top and wind the stud out by 2 threads?. It would save Foggy stripping the top end down again.
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It is in the front row of studs,offside, second one in.(E227 90032-377-000 in parts manual)[attachimg=1]
On Orcadian's picture it is the left hand(as we look at it) 100.
Just to complicate matters my parts manual describes it as 8x122, which I assume means 122mm long?
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Definitely a copper washer under that one then. Looking at your photo, you can really see the difference in lengths.
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Just noticed Orcadian's measurement parameters.I can relax-my studs haven't stretched by 22mm!!
Nurse Julie-what's this technique with double-nutting?Sounds very useful.Especially the part about saving me having to take the barrel off.
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Another little observation, the dowel on the 2nd stud in on the left at the back, it seems to be sitting very much to the left hand side of the stud where the one on the other side is central.
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Just noticed Orcadian's measurement parameters.I can relax-my studs haven't stretched by 22mm!!
Nurse Julie-what's this technique with double-nutting?Sounds very useful.Especially the part about saving me having to take the barrel off.
Put two nuts of the correct size on the top of the stud, wind them down a little and then wind the bottom one up, the bottom one will lock against the underside of the top one and the stud should turn.
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yes, parts list indicates 122mm but that is the overall length, not the distance above the case when fitted. Not sure if you can wind them out with the barrels on but worth a careful try. Your studs are already the right way up so initial length must be suspect.
If you back it out a few threads don’t tell Trig. I would investigate further before bodging is even contemplated.
Just a thought - there isn’t another thick washer stuck to the head is there?
If I get the chance later I’ll drop my barrels on the case and measure the distance above the deck for that stud - the only difference would be the base gasket thickness.
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yes, parts list indicates 122mm but that is the overall length, not the distance above the case when fitted. Not sure if you can wind them out with the barrels on but worth a careful try. Your studs are already the right way up so initial length must be suspect.
If you back it out a few threads don’t tell Trig. I would investigate further before bodging is even contemplated.
Just a thought - there isn’t another thick washer stuck to the head is there?
If the studs have only recently been inserted, they shouldn't be corroded in, which is a good start.
I had a copper covered steel washer stuck when I took mine apart, It took me no end of picking to get the blighter out, it was well stuck in there.
Yes, don't tell Trig anything. He would have it all apart again by now to see what the problem is :'( :'(
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Just checked the barrel height and it’s 67.4 mm plus a gasket at about half a mm means that you should have 100 - 68 or about 32 mm sticking up above your barrels. Didn’t get to put the barrels on the case - too many bikes in the way!
Ian
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The dowel is straight but the stud is 'not quite vertical'.However, once the cylinder head is on there is no problem and it is very easy to get it on.
There is no washer lodged anywhere but the offending stud is 5mm shorter than its equivalent.
I will tentatively try the double nut method(I only thought of using a stud extractor which would have caused damage) and if there is any sign of success I will take the stud out, measure it and then replace with new.
I suppose the double nut method can be reversed to tighten studs up and a torque wrench used on the upper nut if needed?
Just measured the stud heights above the barrel 28.4mm and 23.6mm
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So it's the wrong length stud, what a pain but easily sortable. Yes, you can double nut to get a stud tightened up again. Well done, you got there in the end.
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As I understand it the studs shouldn't be torqued into the cases (please correct if anyone has proof to the contrary) it looks like Honda put them in with semipermanent/heatresistant/never-come off-till-you're-dead, thread lock, which is why they are Sooooo very hard to get out.
My view would be they should all be thread locked to avoid them backing out in service.
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You are correct Nigel, the studs should not be torqued, just 'nipped' up. There is no torque setting for them in the manuals. Trig says there is no thread lock or similar used on the studs. I think they are so very tight because of the corrosion and they are somewhat 'springy' when you try to turn them to get them out.
If Foggy measured the studs before putting them in and they were all the correct length, this can only mean that a stud has broken through the casing by 5 mm, so may need investigating further when he gets the stud out.
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Thanks everybody.
This morning I was hoping I could do an easy fix/bodge but you have all convinced me that is not the way to go.I need to get the stud out,examined and check for any damage below.
It is a right royal pain but hey-ho.I've absorbed a lot of info and learnt new tips.
I will let you know how I get on.
Cheers Foggy
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Yes, that was my fear as your first post pointed out. If it's the correct stud and the case is damaged, it's certainly a different problem.
I suppose it's not included in manuals as it's generally not a serviceable routine to remove the studs. When I've removed them I've been convinced that the dry powder that comes out is thread lock though. The design seems to call for that from an idealistic point of view, and they never ever release when undoing the head bolts as far as I've found. I just don't think you'd get that consistency if it was plain corrosion.
Fingers crossed that it's an odd stud and no damage done.
Edit, I was responding to Julie and my post came in after yours Foggy.
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I find it difficult to believe that a correctly dimensioned stud - length, diameter and shoulder could be forced into the crank case top accidentally, especially by an engineering company worthy of the name. Hope it ends with a good result with minimum effort and cost.
Ian
Just noticed you are in Chorley - are you a Central Lancs VJMC member by any chance?
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Yes, fingers crossed for an easy, swift outcome Foggy.
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Hello again
Just an update on the offending stud.
I was unable to get all of the original studs out so sent the upper crankcase(with remaining stud in situ) to engineers.
The original stud broke off on removal and had to be spark eroded out.
Resultant hole was filled,drilled and tapped for new stud BUT drilled 5mm too deep.
Problem not noticed till I tried to fit cylinder head.
Long story short: went back to engineers,process repeated correctly,everything tickety boo,no charge
Thanks for all the input
Foggy
Ian:No,I am not a member.Maybe when bike on road. 2025?
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Glad you got sorted out, bike back on road by 2025? That’s nearly half past eight, surely you can miss your tea and finish it quicker? 🤓
Let us all know how things proceed.
Ian
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Lovely feeling when a problem gets sorted. Keep us posted on progress Foggy.