Author Topic: Torque, torque....SNAP!! (Read 7158 times)

andy750 · « **on:** May 11, 2005, 07:13:41 AM »

Hi all,
Well I got my torque wrench last night from Sears and then rushed home to start torquing down my CB750K2 engine - from the bottom (upturned engine)...it was all going well and I got as far as #12 bolt in the sequence according to the Clymer manual (this is one of the 10mm bolts at the front of the engine just behind the oil filter) and I had trouble reaching 14.5ft/lb (the low end of the recommended torque value....when as you guessed it...the bolt snapped!! Damn!! So its broken off just at the link between the smooth shaft and the thread so all the threaded part is still in there....

......my question is - I know that I should really separate the cases and have a machine shop drill out the broken shaft and then re-tap the hole with a slightly bigger thread....but what if I just left it as is....there are 6 bolts across the front of the engine and if one is not perfect will it really matter?? Would it leak here given the amount of Hylomar gasket I have there?? Has anyone been here before??? Advice/experience?

Or does anyone know a good machine shop in the Boston area that could reliably do this work??

Thanks for any help with this,
Cheers
Andy

MRieck · « **Reply #1 on:** May 11, 2005, 07:40:44 AM »

Quote from: supersport_CB400F on May 11, 2005, 07:32:46 AM

Drill a hole in the stump, and use an Ezee out to remove the broken bolt and buy a new one and it's fixed

Yep- it should spin right out. Once the head breaks off there's no stretch on the bolt.

Bob Wessner · « **Reply #2 on:** May 11, 2005, 07:47:19 AM »

Did you lube the bolts with anything?

andy750 · « **Reply #3 on:** May 11, 2005, 07:48:36 AM »

Thanks for the replys...do I need to split the cases again? Or can I drill carefully down the hole? :-) What is an Eez out exactly and how does it work? Sorry no experience with it before. Thanks again, Andy

Lumbee · « **Reply #4 on:** May 11, 2005, 07:49:09 AM »

...sorry to hear that man...I feel u'r pain. I can't say I have alot of experience with the bottom end, but 2 things to think about. #1-These mills are pretty durable and its very conceivable that you could get away losing one bolt. #2-Weigh the time/cost of machining against picking up another motor/case. Any time I start looking at putting more than a few hundred bucks in one of these motors you have to keep in mind that they are out there, complete for a $100 or less..

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4548613041&category=35595&sspagename=WDVW

...this one is in NY...not far from u...$35, use the case and keep the rest for parts...

...just my 2 cents...

...lowes/home depot guys can explain the "easy out" to you...basically its a reverse bit. U drill the middle of the spripped bolt out, then insert the "easy out" bit and back the bolt out...

andy750 · « **Reply #5 on:** May 11, 2005, 07:49:33 AM »

Bob, the bolts had some grease on them but now Im thinking not enough. Cheers, Andy

Glenn Stauffer · « **Reply #6 on:** May 11, 2005, 07:55:01 AM »

I've also heard of using a reverse twist drill; as it cuts into the bolt, it will often twist the broken off stub out of its hole. You'd have to go to a machine shop supply place to find one.

Has anyone tried this tool in place of the typical easy-out:

http://www.aldn.com/drillout/

--Glenn

bryanj · « **Reply #7 on:** May 11, 2005, 08:16:48 AM »

You MUST replace that bolt if it is an 8mm thread 12 mm spanner size as they are main bearing bolts. If its a 6mm thread 10mm spanner you will probably get away with leaving iy.

andy750 · « **Reply #8 on:** May 11, 2005, 08:30:26 AM »

Its the 6mm thread 10mm bolt that got snapped :-( Thanks for the feedback. I think Im going to try and get it with the Ezee out as suggested. Thanks for the feedback. Cheers Andy

gerstle · « **Reply #9 on:** May 11, 2005, 09:49:19 AM »

beware the ez out! When everything is good with an ez out, it's good. When it hits the fan with an ez out (like it snaps in 2), it really hits the fan. You can't drill through an ez out. I've had an ez out break off when i didn't think i was putting too much pressure on it, and i know plenty of others that have had similar problems. Take your time and be patient, if you feel like you're pushing it and not getting any where, stop.

andy750 · « **Reply #10 on:** May 11, 2005, 10:15:37 AM »

Thats good advice! thank you!
Cheers
Andy

frostypuck · « **Reply #11 on:** May 11, 2005, 01:18:39 PM »

I have the reverse drill bits, and am willing to bring them to Andy's to try to fix his broken bolt issue, but, the way I look at it, if the bolt shank is 6mm, and I have to drill out half of it anyway, why not just drill it out and then run my M6 tap thru the remainder. I have also snapped eez-e outs, and my reverse drill bits haven't done 100% great job in the past. Espescially thinking that the bolt may be cross threaded, hence the reason for it not making it to torque.
Thoughts?
Chris (Andy's amatuer mechanic) in Boston

Einyodeler · « **Reply #12 on:** May 11, 2005, 03:00:53 PM »

Hey Andy
Check these out:

http://www.crustyquinns.com/tech/easyout.html.

http://motorcyclecity.com/Tech_Tips/Broken_Bolt_Removal/

MRieck · « **Reply #13 on:** May 11, 2005, 05:38:03 PM »

14.5 lbs is way to much for a 6mm fastner- more like 7 or 8lbs. It isn't stripped (I hope) just overtorqued. Andy, I'll give you a hand.

kghost · « **Reply #14 on:** May 11, 2005, 06:14:55 PM »

Yeah, I think he torqued the front bolt I.E. the 10 mm on the front of the engine not the 6 mm on the case halves.

Thats just a bummer, Check all the rest of your fasteners if you think you have a problem. Check the thread portions with a magnifing glass for cracks.

Bob Wessner · « **Reply #15 on:** May 11, 2005, 06:22:17 PM »

Helpful reference to torque values..

http://www.salocal.com/sohc/tech/torquetable.htm

Terry in Australia · « **Reply #16 on:** May 12, 2005, 02:54:47 AM »

Just rememberthat when the manual says "Torque the 10mm bolt........." they mean the diameter of the bolts "shaft", not it's "Head". No amount of grease is gonna stop you busting a bolt by over-torqueing it.

Easy-out's suck, and for a 6mm dia screw, if you can't just wind it out you'll probably need to drill the whole thing out and "helicoil" the hole. Cheers, Terry.

andy750 · « **Reply #17 on:** May 12, 2005, 06:31:48 AM »

Thanks for all the help and links guys - much appreciated. I had a good look at the bollt last night and realise now that Ill probably have split the cases again - just hope I can rescue the alternator gasket. Ill have another go this weekend and let you know progress. I leave for Nagoya, Japan next weekend for a 2 month work trip so my time on this is limited :-( If I can just get the engine torqued down and back in the frame Ill be happy :-)
Cheers,
Andy

P.S. I had no idea about different torque settings for the different size bolts - the Clymer manual dosent specifiy this (at least I didnt see it) - it has a photo of the bottom of the engine with torque settings 14.5 - 18.5ft/lb printed in the bottom...I just assumed...oh well live and learn!

Mikeshonda750F · « **Reply #18 on:** May 12, 2005, 04:33:04 PM »

As with anything, paticence pays in the end. Though the correct torque spec is probably not 12-18lbs, an automotive grade 6mm or 8mm bolt is plenty capable of withstanding 18ft/lbs (Look at torque specs for any modern oil pan (car)... 6-8mm.. usually 18-22lbs).

Most problems with ez-outs comes from not enough of a hole for the bit to square up in the metal causing it to cock sideways and snap off. The #1most important thing to consider when buying an ez-out set is name brand quality. Most people buy a cheapy autozone set and have problems.. get yourself a good quality set... even a sears set would be better than an off brand cheapy set. That said, a left handed drill bit would probably be your best bet. An ezout has left handed flutes that spiral down the shaft, so as you spin it to the left (turning your broken bolt out) the flutes run down the drilled hole and the taper eventually bites in. A left handed drill bit is similar in design, except it is not tapered so it wont wedge itself in the hole and back the bolt out.

I would try a left handed drill bit at a fairly slow speed. Good luck!!

MRieck · « **Reply #19 on:** May 12, 2005, 06:31:40 PM »

Quote from: Mikeshonda750F on May 12, 2005, 04:33:04 PM

As with anything, paticence pays in the end. Though the correct torque spec is probably not 12-18lbs, an automotive grade 6mm or 8mm bolt is plenty capable of withstanding 18ft/lbs (Look at torque specs for any modern oil pan (car)... 6-8mm.. usually 18-22lbs).

Most problems with ez-outs comes from not enough of a hole for the bit to square up in the metal causing it to cock sideways and snap off. The #1most important thing to consider when buying an ez-out set is name brand quality. Most people buy a cheapy autozone set and have problems.. get yourself a good quality set... even a sears set would be better than an off brand cheapy set. That said, a left handed drill bit would probably be your best bet. An ezout has left handed flutes that spiral down the shaft, so as you spin it to the left (turning your broken bolt out) the flutes run down the drilled hole and the taper eventually bites in. A left handed drill bit is similar in design, except it is not tapered so it wont wedge itself in the hole and back the bolt out.

I would try a left handed drill bit at a fairly slow speed. Good luck!!

I agree with the ezout passage but there is no way a 6mm fastner (even marked "9") will survive an18lb pull. If it does it is strecthed to beyond any standards. There is a BIG difference betweem 6mm and
8mm fastner torque values. I don't want to start a slinging contest but I do know what is correct. $:-\$

Bill Vaughan · « **Reply #20 on:** May 12, 2005, 08:59:20 PM »

The warnings about EZ-outs are absolutely on target - when they work, they're great; when they break, you're worse off than you were to start.

For what it's worth, I've had good luck with the Micro Power Extractor Set from Sears (Model 52157). Same principle as an EZ-out, but a bit finer thread for more bite. The correct size drill bit is built into the other end. The set cost about $40.00.

Spear · « **Reply #21 on:** May 13, 2005, 12:04:29 AM »

Talk, talk ..... SLAP!! Better known as 'contact counselling' for a woman who never shuts up!

cb650 · « **Reply #22 on:** May 13, 2005, 03:33:20 PM »

Somethin we do at work is if there is a little bit of the bolt still up is put a bigger nut over it and weld them together. Also if drilling out a bolt use a left hand drill.

Terry

screwtheman · « **Reply #23 on:** May 15, 2005, 11:04:08 AM »

Unbelievably, I did the same exact thing last night! Even after having read this thread!!

It's true, the shop manual basically reads like those smaller bolts should torque at the same reading as the crankshaft bearing bolts. But they do not!! BTW, I got it out with an EZ-Out in about 5 minutes. Watch those shavings from drilling!

kghost · « **Reply #24 on:** May 15, 2005, 02:12:27 PM »

You gonna change your name to just Screwed?

MRieck · « **Reply #25 on:** May 15, 2005, 06:18:29 PM »

Quote from: screwtheman on May 15, 2005, 11:04:08 AM

Unbelievably, I did the same exact thing last night! Even after having read this thread!!

It's true, the shop manual basically reads like those smaller bolts should torque at the same reading as the crankshaft bearing bolts. But they do not!!

I told you so

andy750 · « **Reply #26 on:** May 15, 2005, 06:27:36 PM »

Update on snapping bolts and torquing....
.....so I spent a lot of time in the garage today...I split the cases again and found the snapped bolt was flush with the lower case meaning I had to use a 5/64 drill bit to put a hole on the centre of it...then I used a reverse drill bit that Chris had given me last night only when used with the drill it was fairly useless...I tried like this for a while with no success and numerous phone calls to Chris...finally I went back to the web site about how to remove broken/snapped bolts and followed the instructions...I tapped in the reverse screw into the failry big hole I had drilled in the snapped bolt and then used an adjustable wrench to twist ot out...took 2 mins! :-) Then I put the cases back together and torqued down the bolts - 15ft/lb for the 12 mm bolts and 8-10ft/lb for the 10mm bolts...no problems. Turned the engine over so it was upright and put in the top bolts and startor cover ;-) Now just to re-assemble the gear mechanism, the clutch and the dyna and then I can put it back in the frame :-)

Thanks to all those that replied as it really helped me a lot!
Cheers
Andy in Boston

Bryan Boyle · « **Reply #27 on:** May 16, 2005, 05:46:31 AM »

I would tend to agree with you, Chris.

Be careful with ezouts. If the broken stud is accessible, it is much preferable to drilling it out as
far as you can (using wire size drills) and then retapping the hole, versus trying to use those infernal
back-out thingies.

They work, in my experience, oh, about 30% of the time. And if you snap em, well...they ain't coming
out (ionization is the expen$ive option)

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Author Topic: Torque, torque....SNAP!! (Read 7158 times)

Lumbee

gerstle

Mikeshonda750F

Spear

screwtheman