Heads came off conrod bolts????

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Many years ago I hotted the hell out of a 650 Triumph. It seized one piston while the bike was going very fast. After it cooled down, I quietly rode it home and it was knocking. I'd broken the crank through one big end journal and it was holding together by about a 5mm diameter piece of steel. I have nightmares about a rod breaking, or the bottom end letting go in other ways. All you can do is to build the motor carefully.
 
I have a mechanic friend coming round to see this one night this week and I will get him to help me take some photos. In the mean time I will start disassembling the ends of the engine [ timing side first ].
Incidentally, I think I have ridden over 28,000 miles on this bike since I have got it, and never had occasion to check the timing chain. It is one of the failings of the commando that the factory expect you to check it every 5,000 miles when it is such a pain to do. Has anyone done something about a modified timing cover with a removable cover to allow access to adjusting the timing chain. Would seem such a simple thing to do. Mike bike has been going so well and no extra noise from the timing chain I decided to leave it alone. I have looked on this site at the different kinds of modifications to the timing tensioning. Ideally you would have a hydraulic spring loaded tensioner pushing the chin inwards. One of the tensioners I see does the opposite, which to me, is not a perfect solution, but as there is no room to do it the other way round, I guess this is the best compromise..
I fitted 2 new anodised carb slides [ Hobot's recommendation ] and it looks like the r/h one has been worked hard from the marks on it. The l/h one is as clean as a whistle. I still get a slight popping sound on light throttle or coasting with slight throttle and I suspect this is causing the marking on the slide. I intend to cure this or I will end up blowing another pc of slide through the engine. While the carb are of I intend having a good play with them.
She who holds the purse strings has control of how fast this job gets sorted. It would be nice to do all the mods to upgrade this bike but I don't get many chances to chase Ferrari's round here. [ once about 2 months ago ]
Dereck
 
Hi dirtymartini, that picture sure looks scary. tomorrow I will lift out the crank case as its all undone now and ready to come out. Took a photo of the pistons to show one was able to rise 7mm more than the other.
Dereck
 
Frankie17 said:
The Bolts were submitted for test by an independent UK dealer and copies of the test results were circulated ( by the manufacturer of the bolts )

the actual link comes from Wassell and they also have a copy test certificate supplied by UK dealer ( Wassell are a distributor of these Uk made bolts )

Not the manufacturer
Click to expand...

Below is the link found on the Wassell Ltd. site.

http://www.totalbikebits.com/new-pr...ads/2012/11/CommandoBoltsTestCertificate1.pdf

Thanks for the information Frankie17. The data suggests that bolts supplied by Wassell are up to the task with regards to UTS for the application.

Are the Wassell bolts the same dimension as OEM Norton? Exactly what bolts was Andover referring to on their website. So how does one know whether they have good bolts or bad bolts. This is the challenge with real or alleged counterfeit components. Let the buyer beware, ask the specific questions on source of parts and some good luck. I am just trying to get my head around the whole thing.
 
the submitted test report does not in any way indicate that they were testing an alternative vendors bolts, only Norvill /andover, and since all references to who was submitting have been covered,, the best we can take away is some tech info on the andover supplied bolts.
 
The test report shows Andover / Norvil bolts ( Norvil bolts are Wassell ) hence the link on the Wassell website

Wassell supply much of the UK trade with BSA / Triumph / Norton con rod bolts so i guess they have more buying power and can offer better prices to dealers

Hence the scare mongering by AN on their site ? if you buy your parts from a reputable Norton supplier such as RGM / Norvil / CNW ETC i guess they will be comfortable with the parts source they choose
to purchase from and the warranty recourse they provide
 
A one time gross-overload destructive tensile test is not really a good indication of the likely fatigue life or fatigue strength of a part.
Parts often break at loads well below their ultimate tensile strength, in a fatigue situation. Other factors will be equally or more important.
 
X file

you are very correct fatigue is also a factor to consider , buying new bolts which are of a good spec and hope they stay the course is all you can do

replacing rod bolts and nuts should be done on every crank re build ( especially if you have no history ) Some of the bolts could be 25 years plus in age and subject to unknown hours etc

So change them bolts and never re use the philidas lock nuts is my policy , a few bucks saved may prove expensive long term if one fails
 
Frankie17 said:
So change them bolts and never re use the philidas lock nuts is my policy , a few bucks saved may prove expensive long term if one fails
Click to expand...

so if you don't use the philidas nut, what do you use? what thread pitch is the conrod bolt? go with an interferance fit ARP nut?
 
850dunstall said:
Frankie17 said:
So change them bolts and never re use the philidas lock nuts is my policy , a few bucks saved may prove expensive long term if one fails
Click to expand...

so if you don't use the philidas nut, what do you use? what thread pitch is the conrod bolt? go with an interferance fit ARP nut?
Click to expand...

He said RE USE as in they are only ment to work once after that they are not as good.
 
toppy said:
850dunstall said:
Frankie17 said:
So change them bolts and never re use the philidas lock nuts is my policy , a few bucks saved may prove expensive long term if one fails
Click to expand...

so if you don't use the philidas nut, what do you use? what thread pitch is the conrod bolt? go with an interferance fit ARP nut?
Click to expand...

He said RE USE as in they are only ment to work once after that they are not as good.
Click to expand...

my oops.
 
I also recommend using loctite on those nuts. The reason mine starter to come loose is lack of loctite. Looking at those nuts tells ,me they are dubious as well when you see how little metal holds the locking pce to the nut body. See the picture above where 1/2 has broken off. Both my nuts were only finger loose [ I did mean to say it that way ] and one had lost its locking pc [ probably because it had been scoring the inner crank case, and luckily no damage to be found ]. Photo's to follow. Incidentally, the flywheel bolts on this machine have been assembled without lock tabs.

Dereck
 
ok. when stripped the engine down, the 2 nuts holding the l/h conrod were so loose. No locktite had been used on any of the big end bolts. I will start another thread with the other faults I found
Dereck
 
A dab of loctite will do no harm, but it is not generally necessary with the correct specification of one-time-use lock nuts, done to the correct torque.
 
so i re-read the entire topic again, and found that i have to correct what i thought about the test results. the alternative bolts (company W) looks to produce a product on par with the original factory tested item?
 
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