Author Topic: Head Stud Torque (into cases) (Read 7884 times)

OakBehringer · « **on:** December 05, 2011, 01:16:04 PM »

When putting studs back into the cases, double nutting, and tightening (this is into the cases, with the head and jugs off, NOT when torquing the nuts down on the head), what torque should be applied?

This will be on a CB160. Bolts on the head should be torqued down 11.6~15.2 ft-lbs. Should I do the same when installing the studs into the cases? Less? More? These are 8mm steel studs going into an aluminium case.

Thanks,
Adam

grcamna2 · « **Reply #1 on:** December 05, 2011, 01:32:28 PM »

Hi,
I never did this one either...so I'll guess and move this post to the top so someone "in the know" will tell us both;I NEED to know also. I hope you have measured the original length of the ones that came out?...either way I would install them close to that length & put them in with a good loctite(290 "bearing mount"?) and bring them to a reasonable torque,once the loctite dries it will keep them tight.

OakBehringer,
Did you purchase new O.E. studs or equivalent or have you found a source for Good Quality aftermarket studs;do you need to have different width on a couple of them so that oil will flow to your camshaft and valve areas ??

OakBehringer · « **Reply #2 on:** December 05, 2011, 02:22:18 PM »

I'm using the best studs from various disassembled engines I have lying around. No need to buy new studs, these are fine.

Why would I measure the ones that came out?

MCRider · « **Reply #3 on:** December 05, 2011, 02:28:23 PM »

Quote from: OakBehringer on December 05, 2011, 02:22:18 PM

I'm using the best studs from various disassembled engines I have lying around. No need to buy new studs, these are fine.

Why would I measure the ones that came out?

Had you been using an aftermarket stud, you have no assurance they cut the proper number of threads without checking. You could run the stud into the case all the way and not have enough sticking out to put the head nuts on.

I've heard 8ft lbs, stud into case, but i have no backup. If we think about it, what ever torque is applied to one end, will end up being the torque on both ends, I think? Do you?

Having the proper length exposed up high, then using some medium duty thread sealer/adhezive, just so they don't turn, may be the approach.
Curious as to what others may say.

markb · « **Reply #4 on:** December 05, 2011, 03:26:20 PM »

If it's 8mm studs I think 8 ft.-lbs. sounds about right. I don't think the torque applied to the nuts will be the same as what is on the stud threads. Certainly you tighten the nuts at a torque higher than 8, but unless the stud were moving in the case it should not change. Curious as to what other say too.

MCRider · « **Reply #5 on:** December 05, 2011, 04:36:01 PM »

Quote from: markb on December 05, 2011, 03:26:20 PM

If it's 8mm studs I think 8 ft.-lbs. sounds about right. I don't think the torque applied to the nuts will be the same as what is on the stud threads. Certainly you tighten the nuts at a torque higher than 8, but unless the stud were moving in the case it should not change. Curious as to what other say too.

My thought is, if the stud is tightened to 8 in the case. Then you draw the top down to lets say 12, doesn't that increase the effective torque at the case end. I mean you can't pull on one end of a stick with 12 lbs without increasing the pull at the other end to 12lbs as well.

Whatever you pull on the top of the stud, transfers to the bottom of the stud. Or am i thinking wrong?

Sure we're rotating a nut. But isn't a thread just a coiled lever? Should I stop thinking? $:-\$

grcamna2 · « **Reply #6 on:** December 05, 2011, 04:40:55 PM »

Quote from: OakBehringer on December 05, 2011, 02:22:18 PM

I'm using the best studs from various disassembled engines I have lying around. No need to buy new studs, these are fine.

Why would I measure the ones that came out?

OakB,
I was just saying the length is important if you want to match the Original length after the threads are turned down into the cases;some have acorn head nuts & clearance is sometimes an issue when removing & installing the engine.
I am hoping we have someone tell us who has done this so we know if we should use a sufficient type of loctite threadlocker(red or blue possibly?);it will be able to be removed later on if needed w/ heat. I think it would be great if we could find chromoly special studs w/ the correct diameter for oil flow to the head...or have a machinist turn them down to the Original dimension.They will not stretch like the O.E. ones do when over torqued; but they are very specialized indeed$ ! I imagine.

markb · « **Reply #7 on:** December 05, 2011, 05:16:57 PM »

Quote from: MCRider on December 05, 2011, 04:36:01 PM

My thought is, if the stud is tightened to 8 in the case. Then you draw the top down to lets say 12, doesn't that increase the effective torque at the case end. I mean you can't pull on one end of a stick with 12 lbs without increasing the pull at the other end to 12lbs as well.

What you're talking about is the tension on the stud, not the torque of the thread into the case. The tension will be the same on both ends.

kmb69 · « **Reply #8 on:** December 05, 2011, 05:42:39 PM »

There is usually more than 2x the thread engagement in the case as the thread engagement by the cylinder head nut. MarkB is correct, the tension will be the same and the difference in amount of thread engaged supports the heavier torque on the nut.

MCRider · « **Reply #9 on:** December 05, 2011, 06:02:25 PM »

OK, I see, sort of.

To the OP, any guess as to the torque stud to case?

kmb69 · « **Reply #10 on:** December 05, 2011, 07:08:29 PM »

Found some info on Axel's (RIP) site.

http://www.satanicmechanic.org/cylinderstuds.shtml

He says, APE says, "Dip long end in oil and install in noted location, bottoming out, then use a torque wrench torque to 8 foot pounds maximum."

BobbyR · « **Reply #11 on:** December 05, 2011, 07:44:39 PM »

I would forgo the thread locker and use an anti seize. 8 ft lbs is not much torque so they are not expecting much stretch if any on the stud. They must be just using that as a nominal torque to make it tight but not too tight. If the stud is bottoming before you are using the torque wrench you are not torquing, you are just tightening.

I have taught torquing and a bolt is like a spring. When you torque it the bolt stretches and tries to return to it;s original size. This return to it;s original causes a tension between the threads which holds the bolt in place. If you bottom there is no stretch.

When you get to torquing down the head gasket, it is best to torque once. Let it sit a day, and re torque. That will give the gasket a chance to compress and seat between torquing.

kmb69 · « **Reply #12 on:** December 05, 2011, 07:59:54 PM »

BobbyR, I would have to measure some studs and holes to be sure, but I don't think the studs "bottom" on their end. The have a "land" above the threads that I think actually "bottoms" at the top of the threads in the case.

Thought you might like that vernacular!

grcamna2 · « **Reply #13 on:** December 05, 2011, 08:10:59 PM »

That link does make it clear ! No loctite, OK...I wonder who has good after market studs(chromoly preferably)that will fit a CB350K4 twin because I have some that are a little stretched. Two of them have a special skinnier size shank & I think that is for oil flow to the upper camcase.I sure need to do more research on those 2 special type of studs(the other 6 are standard 8mm size shanks)...just wondering if someone, ANYONE will sell aftermarket chromoly special size studs that will match the O.E. items for those two.I can get standard 8mm chromoly studs that work...but not those 2.

I just want to make sure now with the stud tightening process into the upper case; you're saying to "bottom them out", correct ? and from there 8 ft.lbs ? So the length has to be exactly correct for the application.

OakBehringer · « **Reply #14 on:** December 06, 2011, 09:55:14 AM »

Got this reply from the F-160 racing forums:

Quote

Just snug the studs into the case.

All the torque is done at the acorn nut.

This video helps explain:

http://www.youtube.com/watch?v=3EQcsP2PUXQ

Interesting stuff, I think we can consider this mystery solved

grcamna2 · « **Reply #15 on:** December 06, 2011, 10:12:02 AM »

Quote from: grcamna2 on December 05, 2011, 08:10:59 PM

That link does make it clear ! No loctite, OK...I wonder who has good after market studs(chromoly preferably)that will fit a CB350K4 twin because I have some that are a little stretched. Two of them have a special skinnier size shank & I think that is for oil flow to the upper camcase.I sure need to do more research on those 2 special type of studs(the other 6 are standard 8mm size shanks)...just wondering if someone, ANYONE will sell aftermarket chromoly special size studs that will match the O.E. items for those two.I can get standard 8mm chromoly studs that work...but not those 2.

I just want to make sure now with the stud tightening process into the upper case; you're saying to "bottom them out", correct ? and from there 8 ft.lbs ? So the length has to be exactly correct for the application.

I could only hear the music on that Youtube link,but I could see what he was doing;he was bottoming the studs out & butting them right up against the bottom of the threaded hole in the block...my little CB350 twin upper case has straight thru threaded holes.I can get a new set of studs to go all the way to the end of the threads and that will work;now..to find some strong aftermarket chromoly studs of the right diameter for positive oil flow volume to the upper camcase............ the search goes on.................

OakBehringer · « **Reply #16 on:** December 06, 2011, 01:15:05 PM »

He discusses scenarios where the stud doesn't bottom out. I suggest watching again w/proper sound.

MCRider · « **Reply #17 on:** December 06, 2011, 01:43:12 PM »

Quote from: OakBehringer on December 06, 2011, 01:15:05 PM

He discusses scenarios where the stud doesn't bottom out. I suggest watching again w/proper sound.

I saw him put the bearing in to make the hole less deep. he says all his holes are "blind" ie have bottoms.

But what grcamna2 is saying is that the CB350 hole has no bottom. It is open straight thru to the inside of the cases. So it can only "bottom" when the stud runs out of threads. If the stud doesn't have a shoulder at the top of the threads the stud may go too deep into the case.

OakBehringer · « **Reply #18 on:** December 06, 2011, 02:14:20 PM »

Quote from: MCRider on December 06, 2011, 01:43:12 PM

Quote from: OakBehringer on December 06, 2011, 01:15:05 PM
He discusses scenarios where the stud doesn't bottom out. I suggest watching again w/proper sound.
I saw him put the bearing in to make the hole less deep. he says all his holes are "blind" ie have bottoms.

But what grcamna2 is saying is that the CB350 hole has no bottom. It is open straight thru to the inside of the cases. So it can only "bottom" when the stud runs out of threads. If the stud doesn't have a shoulder at the top of the threads the stud may go too deep into the case.

He clearly says around the 40 second mark to run in the stud until the shoulder (on the stud) bottoms out on the block. The other stud he shows, a different design, bottoms out in the bottom of the blind hole, putting the preload on the bottom of the stud instead of the shoulder. Better design, yes, but I'm pretty sure all Honda studs of our era have a shoulder on the bottom and thus should NOT be bottomed out in the bottom of the blind hole- you run the risk of ruining the threads in your engine case.

At the end he offers the ball bearing as a "neat trick," but not necessary. If you do this, you need to make sure your ball bearing is the correct size so that your studs are not a "new height."

EDIT - I misread your post, this reply might sound weird in response to yours, but suffice to say that studs that bottom out on shoulders and studs that bottom out in a blind hole are both covered in the video, grcamna2 should watch again.

BobbyR · « **Reply #19 on:** December 06, 2011, 02:21:42 PM »

If the stud is bottoming out on the shoulder or bottoming out, you are indeed snugging it down which is why the torgue value is so low. This is not a bad thing.

grcamna2 · « **Reply #20 on:** December 06, 2011, 03:07:45 PM »

Hi,
Thanks for all your feedback & especially MCRider!...I am going to take a closer look at my O.E. studs to see if they have a shoulder on them, w/ most of them they are manufactured w/ the non-threaded part of the suds a smaller diameter than the larger threaded area,but I will take a closer look.I want to replace them w/ stronger possibly thicker shanked(standard type)studs that won't stretch like the originals.I believe some of them need the thinner non threaded sections for oil flow from the base of the stud mounts in the upper case;the oil flows up the length of the cylinder holes & through the knock/dowel pins & then into the cyl.head and on to the cam case/camshaft area to oil the upper part of the camshaft.I have started another thread w/ this same question about these CB350K4 twin studs today.I have struck out so far trying to find aftermarket studs to match the dimensions of the originals...does anyone know of a company anywhere in the world that will sell stronger reproductions of these O.E cyl. studs ? if so PLEASE let me know. Thank You fellow members.

OakBehringer · « **Reply #21 on:** December 06, 2011, 03:28:52 PM »

Quote from: grcamna2 on December 06, 2011, 03:07:45 PM

Hi,
Thanks for all your feedback & especially MCRider!...I am going to take a closer look at my O.E. studs to see if they have a shoulder on them, w/ most of them they are manufactured w/ the non-threaded part of the suds a smaller diameter than the larger threaded area,but I will take a closer look.I want to replace them w/ stronger possibly thicker shanked(standard type)studs that won't stretch like the originals.I believe some of them need the thinner non threaded sections for oil flow from the base of the stud mounts in the upper case;the oil flows up the length of the cylinder holes & through the knock/dowel pins & then into the cyl.head and on to the cam case/camshaft area to oil the upper part of the camshaft.I have started another thread w/ this same question about these CB350K4 twin studs today.I have struck out so far trying to find aftermarket studs to match the dimensions of the originals...does anyone know of a company anywhere in the world that will sell stronger reproductions of these O.E cyl. studs ? if so PLEASE let me know. Thank You fellow members.

I don't know of anyone... are you really having problems with stretching of these studs? I've rebuilt various Yamaha's and Honda's and never had a problem using the original studs... not a single leak.

I don't think that the diameter of after market studs will make much of a difference. The metering orifice is so small, it's the bottle neck that maintains proper oil flow rate. (That's speculation, not fact)

grcamna2 · « **Reply #22 on:** December 06, 2011, 04:25:27 PM »

Hi OakB,
The original ones were stretched when I bought the bike & I think they have lost tensile strength because of it,I do hope to improve on those parts...it is really tough to locate good aftermarket ones for me & my main concern is getting a thicker stud and have them give me as much volume of oil flow as the O.E. That camshaft design on the CB350 twin w/ the aluminum sleeve bearings and splash oil bath does seem to need some improvement to me,also the stock camshaft(that I really like)isn't available anymore and I want to make it last as long as possible.

grcamna2 · « **Reply #23 on:** December 18, 2011, 09:36:12 AM »

I may be able to get away with using my stretched O.E. cylinder studs for another few miles.....

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Author Topic: Head Stud Torque (into cases) (Read 7884 times)