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Discussion Starter · #1 ·
Hello everyone
I’m a current owner of a 93 900 SS. Its has approx 25000miles/45000kms. I believe it has the original headbolts.
I might be seeking that bike and am looking at another 900. It has about 13000miles/20000km. It also has original headbolts.
Are both of the above examples in jeopardy of these bolts failing? I’ve been told regarding the first bike that “if they are not broken then they probably wont break”
How concerned should a person be on headbolts?
Thanks
Shayne
 

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What year is the ‘other’ 900?
 

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I am no expert but I believe those bikes are in danger of the head studs breaking. Some people say just wait until one breaks before replacing but I would rather be pro-active and fix them just for peace of mind. I am in the process of dropping the engine on my Superlight to take a crack at replacing the studs.
 

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If you look at the studs and they are shiny (chrome) they are likely the ones that CAN break. If they are not broken and the bike is not apart and you are not startiing on a around the world tour with the bike then I would wait until that changes. There is / was no warning of one about to break, there is no promise that one will. I would just give you a 30% chance that one day 1 of 8 studs will fail so I always prefer to pick the time vs wait and be without the bike in the middle of riding season.

I also must add that Nichols (iirc) used to have some chrome looking studs that you could tell apart only once a head is off. With chrome studs I would not Touch one to re-torque as any playing with it could push it over the edge.
 

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So what you’re saying is; buy the head studs and tuck them safely away for when the day comes that one breaks? Sounds like sage advice.
 

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As of right now getting upgraded studs is not too hard so no rush at this time but simply ride the bike knowing it can happen.
 

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Could be something said for replacing the studs before they break in that they usually break close to or below flush with the case surface. They don't take to being drilled with anything but cobalt bits. All the more reason to put in the hi compression pistons or 944 kit you know you want!
 

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IIRC 91-97 had them.

Thing is many bikes already have had them changed but I have also seen ...
one stud changed.
one head changed
studs changed for same chrome studs.

I have had plenty of chrome studs break when removing them so even pb blast and heat is not 100% that you will not break one in a bad spot so when you go in plan for the worst.
 

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Discussion Starter · #11 ·
Thanks for all the info on the subject. A couple of more questions then I think I’ll have all the info I need.
1) What are the signs of a failed stud(oil leakage/weeping, loss of compression, the stud nut and stud pulling out) ?
2) Does the stud routinely break at the same place? ie, in the threaded area or non threaded part of the shank?
Shayne
 

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If I'm reading this correctly.
Ducati actually installed chrome head studs in a motor.........REALLY? That's absolutly the stupidest engineering mistake known to man NEVER EVER use chrome fasteners on ANYTHING clamping two pieces together especally aluminum with any kind of tourqe value especally components that have thermal expansion heat cycles.......like an engine!

It's called 'hydrogen embrittlement' it turns fasteners into glass, I'm surprised any of them lasted this long.

Call ARP have good ones made or find a replacement stud from another Ducati engine with the same dimensions.

And NOT chrome
 

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You read it correctly , not sure of the alloy but yes they are silver and shiny. Only used on the 900 motors from the early-mid 90's. later studs were the same as the superbikes and no more issues.

Studs will allow blow by between head and cylinder if broken so some times a oil leak between them. You often also hear the rattle of the free part with a nut and washer on it as it can not fall out. They usually break on the non-threaded portion but can be below the case.
 

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You read it correctly , not sure of the alloy but yes they are silver and shiny. Only used on the 900 motors from the early-mid 90's. later studs were the same as the superbikes and no more issues.

Studs will allow blow by between head and cylinder if broken so some times a oil leak between them. You often also hear the rattle of the free part with a nut and washer on it as it can not fall out. They usually break on the non-threaded portion but can be below the case.

Would you imagine that ‘rattle’ might be thought of as ‘pinging’ ??
 

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Bolts & studs break right at the end of the last thread specifically cut threads it's called a stress riser.
When you tighten a fastener to its specified tourqe value your stretching it to a predetermined length that value depends on diameter, material, length, what it's clamping & material it's clamping, when fasteners are made (cheap ones) the threads are cut into the major diameter down to the valley of thread @ the end of the last thread cut thats a stress riser & that's where they always break on CUT threads.

NAS, MIL SPEC, ARP, fasteners have ROLLED threads made without stress risers because the threaded part of those fasteners are larger than the major diameter of its shank including the last thread plus made from better material they don't break if you ever do break one (i highly doubt it) something is seriously wrong somewhere besides the fastener.

I've personally wrenched on grenaded AA/FUEL dragsters between rounds that literally blew the crankshaft & most of the rods straight out the bottom of the block WITH half the block still attached to the crank & titanium scattershield (belhousing) still bolted on the back of the block.

Not one ARP bolt was broken
 
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the service bulletin was 96 sometime i think, so maybe the end of production with stainless studs was late 95. i did an e900 engine recently that had done about 200k km and it still had stainless studs on the vertical. had steel on the horizontal, not sure if that was oem or they'd been replaced. you could do the horizontal ones with the engine in the frame.

not seen many break, and they did sound quite odd. not really that obvious.

i did an engine rebuild that went from big talking "full rebuild" to "fucking how much?" pretty quick and in the end it got only mains as the plastic cages had come out the sump plug. i assembled it with the stainless studs still in it as the tight arse fuckwit who owned it refused to spend a cent more than necessary, and by the time the engine came out of the box at the other end of the country, one of the studs had snapped. you can imagine how the pissy moron whined down the phone at me.
 

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I'll bet & $20 says he either wanted it covered under warrantee or smeared your good name around.

People like that are the ones you need to sign a release warning them and the work order/customers receipt needs to be filled out accurately to a "T" right down to what brand of solvent you used cleaning parts & what temperature it was at time of cleaning parts to how much gas, brand, octane, amount & where you purchased it for startup.

There are two types of Ducati owners.....the ones that just drop it off & say fix it.
And the ones that have every cheep pos China built bolt on component ever conceived on the bike whining about $8 each exhaust crush gaskets.

BTW how's the marriage to it going? I'm betting the honeymoons over.... lol.......
 
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