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Looking for Crankshaft Specialst

Tonerjockey

High Miler
GT Contributor
Joined
Oct 28, 2008
Messages
788
Location
San Jose
Well I managed to spin the rod bearings on the V7 Sport.

Anyone recommend a crank specialist?

Tried Jeff Bratton but I believe he is off working on an RV he inherited.

The Carillos look OK but who knows.

Alex
 
Hi alex

why dont you give it a try to ask the guy of replica maschinen who is now in san jose (previously he was in Scotts valley) for a recommendation as he seemed quite solid and supernice to me , also i remember behind the shop of C.C. products (bmw race bikes etc.) which is now a bmw dealer used to be years ago a very good engine reconditioner who did a lot of my race engine stuff.
Other competent people that come to mind are bob wirth in hayward who i would consider above limits for knowledge and professionality, also you could try to give sandy kosman a call i guess he could also know.
As most of those shops are in your vicinity i assume they could recommend a good close by engine shop.

Hope that helps :)

kind regards

Christian
 
Have you worked out WHY it did it? Absolutely no point in repairing it until you've found out why it torched the bearings. Plain bearings either work or they don't. Two things'll kill 'em. Wrong clearance or insufficient oil, (Pressure rather than volume.). Did you check the big ends for out of round before you installed them? I've seen way too many Carillos that were delivered with out of round big ends? What did the nip measure as? How did toy tightene them? Specified torque or bolt stretch? What's the condition of the oil pump? Wasd the crank sludge trap cleaned out prior to assembley?

Finally If this is a super-dooper hot-rod motor are you still using the 'Filterless' crank case with only a strainer hanging off the front of the block? If so bin the case and start using a later case with the filter in sump. The earlier engines will expose the pick-up under hard acceleration and starve the pump and thence the bearings. I know this as an absolute certainty as I killed one of our race bike engines by using the earlier cases off an 850T and creating exactly the same problem for myself.

Pete
 
Good stuff, all. Thanks.

Update:

Jeff Bratton retired. I have a call into Brian Terfrey. He did a fabulous job on my buddy's lakester engine.
GT, Falicon looks like a great place. I'll contact them Monday to see if they like Guzzi's.
Christian, I didn't even think of talking to San Jose BMW. They are even members of the SCTA racing club I belong to (Eliminators). I'll run over there today. Great ideas thanks.
I am a little hesitant to take the crank (etc) into a hot rod shop that isn't Guzzi savy. I know that many people can "repair" this thing (if it IS repairable) but I don’t have the depth of knowledge needed to resolve WHY this happened... yet. I still need educatin’…
You are spot on, Pete. I need to address why this happened, or it may happen again… explosively & AT SPEED!
The crank was magnufluxed and inspected etc. before assembly. Sludge trap cleaned, new plug installed. Mains mic’d and inspected.
The rods (and bearings) were new but I didn't mic them. Torqued to max spec, not stretch.
It is possible the failure was made worse by an undiscovered / self- induced issue with the rods/bearings/crank.
The oil pressure valve release trigger is about 60 PSI. I’ve read about pressure targets of 10 PSI per 1000 RPM. According to that school of thought I’m about 25% low on oil pressure at 8000 RPM (my max).
Hey Bill, what pressure do you run at?
For an in-case filter, I have a G5/Convert/SP1000 case that looks good. Looks like there would be some areas to address before I can use it in this application. The cylinder holes in the case are larger than the V7 Sport cylinders. I need to think about that s’more.
I am starting to believe the high RPM is a driving factor in this failure. I’ve run the bike at 6500-7000 RPM for 30 or so WOT runs (El Mirage and Bonneville) and never had any issues or crap in the oil. After a massive ignition, piston, and cam “upgrade” the rod bearings (or crank…) failed at 8,000 RPM. Possibly the failure was building up and the three 8K runs at El Mo pushed it past the failing point. I’ll probably never know.
MOOP.jpg


What's that brown hairy stuff in the screen? Looks like a squirrel got in there.

Oil viscosity and type, oil pressure, filtration, bearing-rod-crank dimensions, squirrels in the case, all areas for further understanding on my part.
Thanks for all ideas etc. I’ll post as thing progress.

Alex
 
hi alex,

did you look allready at thye piston top?? maybe your new hi dome pistons touched slightly and in unison with perhaps (im not a plain bearing expert) a slightly too low oil pressure and allready hotter piston tops (compr. + the new ign?) maybe the collapsed the hydrodynamic oil film, even if just to the point that the hi spots touch would be enough, i assume, to eventually cook plain metal bearing shells. Along with the obvious crap in the oil that by itself would produce allready hi spots that knock any bearing plateau into k.o. status. Sorry for what happened, hope it turns out fine in the end!!!
About the crankgrinding specifics of guzzis i dont know too much (in order to be honest) but i would assume a good shop that applies the most likely needed corner radii with the correct grain should be not too hard to find. maybe it would make sense to get the crank also gas nitrided as i allways liked the nitrided hardness besides that it strengthens also through skin tension the structure, which could be perhaps helpfull on the long run.


kind regards

christian
 
Went out to Brian Terfrey's new shop in Oakdale yesterday. Talked over the crank and how this might have happened.

Jeff Bratton and Brian will inspect the shaft (and parts) this week and I'll have some ideas on how to best proceed soon.

Befor the trip to Oakdale, I mic'd the journals and the crank needs grinding. Funny thing about the damage, appears to be focused on the underside of the journal away from the piston. As if the problem happened on intake stroke or soemthing.

I'll probably have the crank welded and ground.

More as it occurs,

Alex
 
I think your problem is the new rods and lack of measuring.

I did the same thing when I built my racer. I installed Carrillos but didn't clearance them. Ended up wearing out the rod bearings prematurely. Turns out the Carrillos were tighter than Guzzi rods.

Talked to Mike Rich and Charley Cole who gave me a figure of .0017" clearance between rod bearings and crank. This is on the looser side of Guzzi specs. Instead of grinding the crank I had the rods reamed. You should tighten the rod bolts to stretch not max torque. Mine ended up at 41lbs.

You might be on the low side oil pressure wise too. Sean at Guzzi Classics can adjust your blow off valve to 80lbs.

Run Amsoil 20-50 full synth or Mobil 1 V twin 20-50 full synth. They are nearly identical in performance. I use the Mobil in my racer. Ran Valvoline VR1 20-50 before but the Mobil is WAY better.

8000rpm shouldn't be a problem. Bill is higher than that with a 80mm crank.

I would try to find a new crank instead of welding up what you have..

Good luck.
 
GuzziGray,

Thanks for the infos. I will certainly take it all into consideration.

Alex
 
Your blowoff valve is set way too low for a race motor. Your rod bearings and /or rear main are probably starving.

If its a 78mm crank, replace it rather than grind it. Getting the radii right is critical and unless you have experience with the shop grinding it, there's a fair chance that they will get it wrong. Here's what can happen if they grind the radii too tight.

https://www.guzzitech.com/shrapnel/crankbroke.jpg


Ed
 
Eiiii chihuahua!!!!

That puts the ugh in ugly!

It's a 70mmm stroke crank. I'm considering an Ambassador crank and running total loss electrical system.

I amcertainly gunna address the 60# pressure thing.

Alex
 
Yeah 70mm stroke... but they had a generator. Gotta leave out the alternator from the V7 Sport.

Hopefully the Ambo crank I have as "next project" is good enough.

Alex
 
Latest update.

Jim Wellington sez V7 Sport crank is OK for grinding to 1 under. I'm not sure about the mains right now, except that the bearings are contaminated from the journal debris. (see other thread Looking For Mains).

We'll either chrome the journals or nitride or whatever is simpler / more reliable / easier ($).

Carillo's are OK crack wise.Will be sized when I get the new bearings etc. Think I'll follow the stretch tightening procedure this time.

Great fun.

Alex
 
Crank ground to 1st under.
Nitrided (sp?)
Journal holes chamfered.
Polished to fit 1st under rod and main bearings.
Rods checked for straightness etc.
Oil Pressure relief valve set to 80#
new Daytona large pump now sought.
Hopefully the bike will be ready for Bonneville in August.
 
I think the V11 oil pumps are the same as the Daytona. Also the oil ways in your older engine case are smaller than the late model blocks. I think the older ones are 8mm and the newer ones 11mm. Enlarging the holes is a mod that's done with the oil pump upgrade I believe. It probably wouldn't hurt to get a California sump pan so you can run a late model oil filter.

Check out this webpage: http://tinyurl.com/2cq47ur
 
I like the idea of an oil filter but am hesitant to modify the case etc. Someday I may wanty to return this bike to stock.... if I don't destroy it.
Maybe enlarging the pick up passeages would be a process that prevents a return to stock as well...

I have a "spare" case I think I'll look at for this purpose.

Nice article.

Eventually I need to decide upon a stopping point. Or reconsider my goals. I believe I am about the lowest cost configuration at Bonneville, and I'm STILL alarmed at the prices of this education.
That freakout aside, I think I may be edging closer to the record.

Thanks all,

Alex
 
Machining the case would be straight forward for a good machinist and there wouldn't be much point in getting a higher flow oil pump if you didn't make the changes. It would be a good upgrade for the street too.

You wouldn't be able to 'undo' the changes. A spare case would be the way to go.

If you are worried about cost don't go racing. Trying to save $50 here and there will cost more in the long run. Spend the money and do it right once.
 
Increasing oil pump volume is not always a good idea as it increases parasitic losses. I'd only do it if you have a good reason to. We sometimes gear down Ducati pumps to spin slower.


Ed
 
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