Topic: Snapped a HD cylinder head stud on bolt up, why me!!!

[Ace]

Well it's just past midnight here in Oz and I'm really disappointed.  I was hoping to get the head bolted up tonight as it's been months since I pulled it apart.  I got out my new base and head gaskets, put some hondabond around them to previous leaking problems and piece of mind, worked quickly to get the barrels on and then the head.  I was tightening down in sequence #13 nut and I heard a snap.  The nut turned very easy and as I lifted the wrench up the broken stud was looking at me.  It snapped of just before the thread finishes on the stud.  Tears didn't appear but my heart sank and all I could say was oh no.  Thoughts then turned towards the cursed engine, well it seems like it's cursed.  Torque wrench set at 23 ft lbs and I think I bought them from Dyno man, however I'll check that as I got the studs years ago but will be getting out all the receipts to find out who made it and let them know.

Has anyone else out there had this problem when putting an engine together?

Now because I put gasket sealer on my new gaskets, I wiped them off but does that mean I'm up for more money for new gaskets?

I'll replace all the studs just for piece of mind.  Wonder what the missus will say about this latest setback 

Oh well, I'm off to bed for a probably restless night.  Catcha later.

[MCRider]

Sorry for that. I've heard that happen to a few guys here. My comments aren't meant as anything but discussion and sharing.

I wouldn't see any need for that much torque unless its maybe a turbo or something. To me the HD studs are to allow me to go to the high end of the stock torque range without stretch or fatigue. That's enough to accomplish the main goal which to me is no oil leaks.

The range is 14.5 to 18.1ft/lbs. Usually they start feeling spongy around 16ft/lbs. With the HD 18 is no problem and that's as far as I'd go with a semi-regular engine. I know the studs are rated at 22ft/lbs (24?) but we see what can happen up there.

I'd just get one replacement and not risk breaking another one taking them out.

JMHO  

[the.barrage.pdx]

Been there done that.  Twice actually.  If my memory services me correctly...where is my note book...24 is a little high.  Good luck!

[MRieck]

This is happening more frequently it seems.

[dave500]

if you got all the sealant off with some thinners or metho and they arent damaged theyll be ok.,bummer.

[Ace]

Sorry for that. I've heard that happen to a few guys here. My comments aren't meant as anything but discussion and sharing.

I wouldn't see any need for that much torque unless its maybe a turbo or something. To me the HD studs are to allow me to go to the high end of the stock torque range without stretch or fatigue. That's enough to accomplish the main goal which to me is no oil leaks.

The range is 14.5 to 18.1ft/lbs. Usually they start feeling spongy around 16ft/lbs. With the HD 18 is no problem and that's as far as I'd go with a semi-regular engine. I know the studs are rated at 22ft/lbs (24?) but we see what can happen up there.

I'd just get one replacement and not risk breaking another one taking them out.

JMHO  

Righo, after a terrible night's sleep now I'm on the hunt for a HD stud to replace my broken one as MCrider suggested.  I'm after the short one as it fits on the left side of the head on front and is open to the atmosphere where #1 spark plug goes. 

Terry reckons he tightened an engine down to around 30 ft/lb, lucky bugger getting away with that one.

As for the head gasket, not sure yet what I'll do.

Thanks people.

[j squared]

if you got all the sealant off with some thinners or metho and they arent damaged theyll be ok.,bummer.

Totally unrelated, but my girlfriend is South African and she calls it "thinners" also.  Makes me laugh every time

OK carry on.

[eastoak]

i did the same thing. i was able to use an extractor to get the broken bolt out and replace it with a new bolt i ordered from APE in southern california, $10 shipped. when i put the HD studs in i considered putting red loctite on the threads, you can imagine how happy i was i didn't or else i would have had to pull the cylinders etc. you can order a single bolt from APE call them at (661) 256-7309. max torque on these bolts is 22 ft lb.

my smugmug page won't let me log in but here is a link to the picture of the snapped bolt after i extracted it, i didn't have a proper tap wrench but it worked out. the bolt is surprisingly soft, i drilled with some crappy, nearly dull drill bits i had laying around and some drilling oil. oh, i smeared thick red grease around the bolt to catch the shavings, very important.
http://haggeo.smugmug.com/Motorcycles/1975-CB750K/5188691_sgxDk#1015820502_72XWP

[Retro Rocket]

if you got all the sealant off with some thinners or metho and they arent damaged theyll be ok.,bummer.

Totally unrelated, but my girlfriend is South African and she calls it "thinners" also.  Makes me laugh every time

OK carry on.

Well it is for thinning down paint.....

Mick

[Terry in Australia]

That's no good Adam, and to clarify the 30 ft/lbs statement, that was on my Suzuki GS1000 with much fatter studs than the CB's, but I do torque H/D studs on CB750's to 25 ft/lbs regularly.

The main thing, I believe, is to do it in no more than 5 ft/lb increments up to say, 15, then in 2-3 ft/lb increments after that. I'm sure that's what you've done, but if anyone was silly enough to go from 0 - 22 in one go, I wouldn't be blaming the stud........... 

[scottly]

I have never had a problem with stock studs. After reading about these recent failures with "HD" studs, I'm glad I never "up-graded".
I tested a no-grade, hardware store 1/4-20 bolt today: it failed at 15/ft-lbs. Next, I tested a no-grade 8mm. Failed at 18/ft-lbs. Next test was a grade 5 1/4-20: at 18/ft-lbs, the nut failed, but the bolt survived...

[Terry in Australia]

If you're running a stock, or very mild CB750, stock studs are fine, even though it'd be smart to replace them with new OEM items.  Lets face it, you're happy enough to replace just about every moving component that is showing any sign of wear, so why not replace the studs that have been under tension (and for some, exposed to the elements) for up to 40 years? Of course, good quality H/D studs (APE's, for instance) would be cheaper.

If you're building a hotrod engine and intend to ride it accordingly, you'd be stupid not to spend the 80 bucks for a set of APE's studs, unless you like replacing head gaskets! Cheers, Terry.    

[Ace]

That's no good Adam, and to clarify the 30 ft/lbs statement, that was on my Suzuki GS1000 with much fatter studs than the CB's, but I do torque H/D studs on CB750's to 25 ft/lbs regularly.

The main thing, I believe, is to do it in no more than 5 ft/lb increments up to say, 15, then in 2-3 ft/lb increments after that. I'm sure that's what you've done, but if anyone was silly enough to go from 0 - 22 in one go, I wouldn't be blaming the stud........... 

Gee Terry, don't let the truth get in the way of a good story.  I'm sure someone was going wow! 

Got home from work, grabbed the multigrips, locked onto the stud and it just wound out nice and easy.  I did have one shoe on, my tongue was to the left and head tilted to the right....maybe this helped I'm not sure.

I did torque up in increments.  On the stud I noticed that I had 3 threads left from where it broke.  I didn't have to remove the barrels either.

My original studs in my K1 were stretched about 3mm from stock.  I'd rather go for the HD as Terry said, you've spend lots of money on the engine and I'm sure we'd all rather ride the beast then have it spend more time on the bench than the black top....come to think of it it sounds like this engine I've got....but when it does go you have to hold on!

So do I replace the head gasket or try and stretch my rather poor luck and hope it seals?  Maybe I just replace it as it's only money...

[j squared]

if you got all the sealant off with some thinners or metho and they arent damaged theyll be ok.,bummer.

Totally unrelated, but my girlfriend is South African and she calls it "thinners" also.  Makes me laugh every time

OK carry on.

Well it is for thinning down paint.....

Mick

Yep, it is.  Don't know why it just hits my funny bone.  Maybe its the way she says it.

[Terry in Australia]

That's no good Adam, and to clarify the 30 ft/lbs statement, that was on my Suzuki GS1000 with much fatter studs than the CB's, but I do torque H/D studs on CB750's to 25 ft/lbs regularly.

The main thing, I believe, is to do it in no more than 5 ft/lb increments up to say, 15, then in 2-3 ft/lb increments after that. I'm sure that's what you've done, but if anyone was silly enough to go from 0 - 22 in one go, I wouldn't be blaming the stud........... 

Gee Terry, don't let the truth get in the way of a good story.  I'm sure someone was going wow! 

Got home from work, grabbed the multigrips, locked onto the stud and it just wound out nice and easy.  I did have one shoe on, my tongue was to the left and head tilted to the right....maybe this helped I'm not sure.

I did torque up in increments.  On the stud I noticed that I had 3 threads left from where it broke.  I didn't have to remove the barrels either.

My original studs in my K1 were stretched about 3mm from stock.  I'd rather go for the HD as Terry said, you've spend lots of money on the engine and I'm sure we'd all rather ride the beast then have it spend more time on the bench than the black top....come to think of it it sounds like this engine I've got....but when it does go you have to hold on!

So do I replace the head gasket or try and stretch my rather poor luck and hope it seals?  Maybe I just replace it as it's only money...

Take that stud to an engineering shop Adam, and get them to make you another one. Can't you get one made on the base?

[scottly]

Hey, I had never heard of APE, the last time I had the top end off, 31 years ago....
Also, I have to wonder what type of torque-wrenches were being used with the recent failures. I prefer the good old-fashioned beam type over the "clicker" type. For these small values, I use a 3/8 drive, 300 inch/pound wrench (25 foot/pounds).

[Don R]

I wonder if any lubricant is being used on these studs that have been breaking, the type of lube will greatly vary the torque values. My rod bolts on my race engine were torqued with ARP lube and were torqued in increments then backed off several times to allow the threads to mate. For the last set I did I bought a stretch gauge, that gets scary because you exceed the torque you would normaly use while stretching the bolt to length.

[scottly]

I bought a set of aluminum big-block Mopar heads about a year ago, with matching bolts, and the instructions called out a different torque value if ARP lube was used, rather than motor oil. As I recall, less torque was specified for the ARP lube.

[Terry in Australia]

Hey, I had never heard of APE, the last time I had the top end off, 31 years ago....
Also, I have to wonder what type of torque-wrenches were being used with the recent failures. I prefer the good old-fashioned beam type over the "clicker" type. For these small values, I use a 3/8 drive, 300 inch/pound wrench (25 foot/pounds).

Ha ha, no worries mate, I think Big Jay was building Honda 750 hop up stuff "back in the day", but Russ Collins was the big wheel then. I installed a NOS set of RC H/D studs in another of Adam's engines a few years ago, and they were nice quality items, especially since they were 35 years old! I love all that old RC stuff, but you don't see much of it around anymore.

I've got a really nice Aussie made 3/8" drive 0-25 ft lbs torque wrench that I bought to do my first K1 rebuild 28 years ago, and so far, it's never let me down. Good tools go a long way to producing good results.  Cheers, Terry.

[CrankyOldGuy]

The type of bolt finish and/or lubricant can have major effects on the tensile loads put on bolts for the same torque value.  The more slippery the surface, the easier it is for the nut to slide down the threads of the bolt' thus applying more tensile force.  I will leave radial forces out of this thread but the length of the bolt being torqued is just as important.

In old structural steel manuals there were torque values given for black bolts to achieve a specified bolt tension.  When plated bolts came out there were problems with the bolts failing from being over tensioned using the torque values given for black bolts.  Now it is common to use a testing device such as a Wilhem-Skidmore testing machine to determine what bolt tension is developed from a certain torque value.

The 750 shop manual I have says to tension the head bolts to between 13.7 to 15.2 ft-lbs but do not mention if the bolts are lubed or not.  When I rebuilt my engine (37 or so years ago) I coated them with 20W50 as I assumed that's what was required.  I had no problems and no leaks.  You know what they say about assume ...  it will make an a$$ out of you and me.

I summary be careful if you are using lubricants that the bolt torque values were not specified for.  Also be sure of the minimum grade of bolt required.

This thread has answered one of my questions ... it is best to replace my 40 year old bolts.

Sorry if this is a bit rambling but I have an 11 week old puppy trying to use my computer at the same time.


Harry O.


Harry O

[Gaither]

Good info here (as usual).

First, I know nothing!

FWIW

An old fella I knew started building engines in the earaly '30's. He also built a bunch of racing engines, including NASCAR stuff til he died about 10 years back. Every race driver in the southeast knew of R. G. Nethery. Truly a self-taught wizard.

He always cleaned all threads and ALWAYS used engine oil on 'em.

He said that otherwise, your torque readings would include an unknown amount of FRICTION - when ALL you wanted to read was TORQUE. Also, friction can vary, stud-to-stud. So, WITHOUT the OIL, you would never know exactly how much torque each stud (or bolt) would actually have on it.

Yeah, I know there are folks that prefer to torque 'em dry. (I just ain't one of 'em.)

Like I said, FWIW. Also,"To each his own".

[Terry in Australia]

No, that's a very good point mate, and anyone who's torqued a head down a few times will know what you mean about the "friction quotient". I've torqued them dry and I've torqued them lubed, and IMHO, lubed is better. Cheers, Terry.    

[754]

As far as I know the HD studs should be rolled threads, I supecr if there is breakage, there is something wrong with material? If a rolled thread is necked down at the threaded end, and the shoulder gets hit in rolling, I suspect it would be damaged, ie over torqued.
 At any rate making one to complete a set, may end uyp with a different stud, that wont be the same..

 There seems to be quite a few failures for something called heavy duty studs..

[MCRider]

AS to wet or dry torquing, we've crossed this bridge many times and seem to end up at the same place... we'll each do what suits us.

It may have been Bobby R that offered some insight, can't remember for sure. The problem is, we don't know from one text to the next whether the author is quoting torques wet or dry. If its a dry torque quote (most likely I think) and you use lube you should reduce the torque by 20%. Rule of thumb.

If the author is quoting wet torque values, well... you're there.

Here's one of many results when googling "dry torque vs wet torque" and such.
http://www.raskcycle.com/techtip/webdoc14.html

Since the HD studs are rated at 22ft lbs and no more than 18 is neede to get the job done on less than the most hyper of engines, I'd feel comforatble oiling the stud and going to 18ft lbs=20ftlbs dry.

oiling always seems better in my mind.

[scottly]

 There seems to be quite a few failures for something called heavy duty studs..

Got any old stock studs laying around? It would be interesting to do some destructive testing, to see just how much torque one would take before snapping. I'm guessing at least 30 ft/lbs...