Why does this break then

[Pedda]

Both cases show marks of bolts fixing a what looks like a nextra crash protection thingy bob. This is a force in a direction these cases do not know normally. These things might cause unwanted vibrations in addition. That would be my first suspect.

[vizman]

I'm no 'csi suzuki' investigator by any means, but they look like 2 pics of the same cases, but pedda has highlighted one of my 'state the fookin' obvious' which is said cases history.  

[KATANAMANGLER]

I was about to ask what the  drilled recess was. It's not a million mile from the fault line.

[markfoggy]

Ah, now we're on to it, good call. Exactly the horizontal thinking that is helpful.

We're hanging a big weight off that case in the hope of saving crash damage.  We've seen previous sets of cases that have had a slight bang about here and the casting is so light that it will distort enough to prevent getting the timing plate installed.

Hanging 1/2 kilo off of there might will start ringing and set up failure. 

Other teams in the paddock, though, have seen the same failure and don't employ the same  sort of engineering.

[Gsxrsam]

have you bored casings?

 

[Duckndive]

That area is about the bottom off the cylinder stud......

Stud loading causing the crack in aged casting........are the cases bored for thicker liners....

[Gammaboy]

So is this a known design flawed area where they pop on a regular basis, or is it something that we're contributing to?

Magna-fluxing only works on ferous metals doesn't it? Don't think that we're seeing previous damage contributing.

We're pretty sure that we can't detect any real stress raiser in this area and alloy tends to normalise over extended periods, we could probably get it to re normalise over a period of time just by getting it hot, cooling slowly and leaving it alone for a month or 2. If it was a cast iron block I'd be thinking ship it off to Siberia for a few years and let it weather.

Therre's a form of it that wWorks for Alloy too - the aircraft guys refer to it as Eddy current testing - it's slightly different, but works for finding cracks.

Have you got a pin to check the crank for phasing? if the crank is square, and true, with the journals in an up/down position you should be able to fit the ground pin through all four rods at the same time with the rods towards you, and away from you - it's a pain to describe, but it's a 2 second test in the flesh.

Dare say it's cracking from the end of the stud though - you're not bottoming or torquing the studs in are you?

 

[Screwriverracing]

Just get yourself a set of billet casings, sure someone could make a set.

Warpspeed perhaps.

Cheers SRR

[markfoggy]

Assumption is that the studs were designed to bottom, this is the most logical conclusion that we can come to. Studs in this area have been switched out from APE , back to standard, just in case their manufacturing tolerances were wonky. This is really unlikely, but just in case. The Torque on the fasteners only really comes from above, they only really get wound in finger tight and I've checked with Russ, they're going in dry, no chance of hydraulic lock under the base seat that could be applying a burst pressure. Even more unlikely is that we've not blown the holes out after blasting. No way that we've fooked that up in exactly the same area twice and others in the paddock have made the same mistake.

We've gone away from getting the cranks built up, in favour of letting Suzuki take the load by welding at Hamamatsu. They appear to have been quite good at it.

This was a decision based on us getting a crank built that sheared across the journal where the Falicon straight cut gear was pressed on. This can only be a tolerance issue and it's something that has happened to others.

I have a horrible feeling that we may be exchanging e-mails with Falicon shortly.

I'm guessing that they'll be of the order of,

We're an amateur race team based in a cow shed in Somerset, England @ Europe, but occasionally win some races. Can we have some cranks please, anything from 1hr to 24hrs response and delivery would be appreciated, we'll phone you first.

I'm up for suggestions of anybody in Europe that can be trusted.

 

[markfoggy]

Just get yourself a set of billet casings, sure someone could make a set.

Warpspeed perhaps.

Cheers SRR

Not legal. 

Agreed tha,t that is the answer, but we're bound by rules handed down from above.

A couple of years ago, we'd probably have got away with it on safety grounds.

Last year though, the FIM got involved. They hijacked a great independant series and gave us lot accreditation. Probably 'cause so many ex- World Champions are involved.

 

[Swiss Toni]

Was going to suggest hydraulic lock, but I see you've covered that!

Edited November 3, 2015 by Swiss Toni

[markfoggy]

Q to Swiss Tony (well it works in my brain)

Please keep up Mr Bond. 

[Gammaboy]

We've gone away from getting the cranks built up, in favour of letting Suzuki take the load by welding at Hamamatsu. They appear to have been quite good at it.

I'd still check the fucking things for square. A bloke I know had an RG that had a crank pin that was miles out of phase - had come from suzuki like that. Sorted it, and it vibrated alot less.

Not keen on welding cases back together?

 

[Arttu]

I'm up for suggestions of anybody in Europe that can be trusted.

 

Crank builders? Here in Finland is a guy who has been doing GSX cranks for over 20 years or something like that. Last time I spoke with him he was building maybe 20-30 cranks per year for drag racing, normal street use and whatever. I have got only one crank built by him but that was splendid work. And I have never heard any complaints about his cranks.   

[KATANAMANGLER]

Dave Branch is the UK's crank builder of choice.

[vizman]

I didn't suggest getting a set of cases made as I assumed the regs would say no....along with the budget, and I recon getting cranks from mr branch would be a false economy if you're using cases that are fooked.

[markfoggy]

Where we're at is, we'll need a few more donor engines. Could probably get the welding done no probs, but my guess is that the distortion introduced would lead to all sorts of leak problems at the crank end seal and barrel interface. Next problem after that is we'll just shift the area prone to fracture into the heat affected zone around the weld. 

Unless of course we can pinpoint why they started to fracture in the first place.

I'll get a 20mm Silver Steel rod and check the crank phaseing before we do anything else, thanks to whoever came up with that. Then I fear that we'll end up on the phone to Falicon offering a fat cheque.

[Screwriverracing]

Another thought, how are you mounting the engine?Could it be vibration from the frame ?

Cheers SRR

[Gammaboy]

Where we're at is, we'll need a few more donor engines. Could probably get the welding done no probs, but my guess is that the distortion introduced would lead to all sorts of leak problems at the crank end seal and barrel interface. Next problem after that is we'll just shift the area prone to fracture into the heat affected zone around the weld. 

Unless of course we can pinpoint why they started to fracture in the first place.

I'll get a 20mm Silver Steel rod and check the crank phaseing before we do anything else, thanks to whoever came up with that. Then I fear that we'll end up on the phone to Falicon offering a fat cheque.

TZ750 guys have been welding cases back together for eons, if they're done right, it's not an issue.

 

[markfoggy]

Her's the last one which points to the Stud landing a bit more.

Boatloadsoffuckwit won't rotate the image, but you get the idea.

Mounting is utterly conventional, 2 bolts through the rear

and triangular plates lower and forward.

Now, we have been tearing swing arms a little out of true. Torque monster and all that compared with what was originally destined to go in these frames.

This is a little project of mine with some help from GIA. Gone on the backburner a bit for this season.  Uses cut up ZXR 750 as a donor.

It's possible that we're twisting the frame tubes out of line by application of torque at the gearbox sprocket. If we're rocking the lower cases  clockwise as you're sat on the bike, the shear line of all of the unsuspended mass of barrels and head etc, could be operating around this line, dragging the engine appart.

Time for a head steady perhaps????

[coombehouse]

Just a thought which is most likely complete rubbish but here goes.

A while back you mentioned that you were also destroying clutch baskets. From your comments above about using unmolested cranks, I guess you must be still using the OE helical primary gears rather than straight cut gears. When I ran a nitrous motor many years ago I was warned that the straight cuts were needed to prevent the crankcase attempting to part itself so I did as I was told & had no problems.

Is it possible that the helical gears could be contributing to the failure we see here?

Nick

[vizman]

it could be, but I don't think that a normally aspirated 1230 lump is going to kick out enough power to do this unless the cases are old and fatigued and the possibility of incorrectly fitted studs/internals  and previous damage..... 

 

...or hanging half a kilo off an already weak point.

 

 

Edited November 4, 2015 by vizman

[bluedog59]

A random thought and shoot me down in flames if you think it's bollocks ( I'm only trying to help).  You're putting the studs in finger tight. Is there a chance that this is allowing a high frequency vibration between it and the casing thread (itself a stress raiser) and starting the crack ?  Maybe a bit of thread lock would help damp it out ?

Have you got a set of u/s cases that have cracked ? You could cut them back to find the root of the crack but I'd suspect it starts from the thread form.

Another option would be to reinforce the area with some weld before they start to crack. 

[sharpy]

Any chance or a build thread/link on that bike. Sorry was too lazy to look too hard but didnt see one in ure profile. Thanks

[Weapon]

it looks like what happens when you bottom out a bolt and keep tightening. do the studs get run right to the bottom? never built an engine so I don't know shit, but I have cracked a case using too long of a bolt before

 

edit: after a reread I see you guys have covered bottoming out bolts.

Edited November 7, 2015 by Weapon