Failure!!

[Guest Gary Cheek]

Ok...ok . I still think they will find someone forgot to safety wire the filter clamp. O yeah it's an UFI filter too.

[pete roper]

If you don't mind, could you post another note on "nip"?

 

Gladly. The actual clearance of the bearing between the shells and the journal is primarily a function of sizing. This is checked by installing the shells in the rod, tightening both the bolts to their specified torque or stretch and then measuring the diameter of the inside of the rod eye with the bearing shells installed ether with an internal micrometer or a bore guage and external mike. This should be done in several *directions* across the eye to ensure that the 'ole is perfectly round. This measurement can then have the journal diameter subtracted from it to ascertain the clearance. Alternatively the rod can be installed on the crank and plastiguage used to check the clearance but this is generally less accurate.

 

The thing is that to prevent the bearings spinning in the rod pressure has to be applied to the bearings to force them out against the rod and cap. For this reason the shells will have an ever so slightly larger diameter to the rod eye. If they are too large though the bearings will deform, producing high spots and buggering up both the roundness and clearance. If they are too small there won't be enough pressure to minimise the back-clearance and the bearings will have a tendency to loosen in the rod and spin.

 

The way this pressure is guaged is by a process called checking the 'Nip' on the rod. The bearings are installed and both bolts tightened to their specified torque/stretch. The rod is then held in soft jaws in a vice or whatever and one of the bolts is loosened. The pressure of the shells will spread the cap away from the rod on the loosened side leaving a small slit betwixt rod and cap. This can be measured with a feeler guage. From memory with Guzzi rods the nip should be about 8 to 10 thou. If the rods are sized properly and the correct bearings are being used this won't be a problem. If the nip is too small or too large then the rods will need to be re-sized again.

 

When rods are removed from a crank the shells can be pried from the rod and cap and the back of the shell and the surface of the rod/cap examined. If everything is as it sould be it will be clear where the bearing back has been crushed up against the rod/cap surface. The greater the area where the bearing has sat flush in contact with the rod/cap the better. Guzzi rods are generally very good in this regard.

 

Pete

[Guest ratchethack]

Ah, many thanks again, Pete. I've always used plastiguage, and have yet to find a crank journal out o' spec using this method on many different kinds of engines with new standard size bearing shells.

 

RE: Nip = .008"-.010" is "from memory". OK, unless I read somewhere that you've corrected this, this is what I'll use. Will most certainly check it when it's time on the Guzzi!!

[todd haven]

Points are to be given to the best predictions.

 

What we have here is, failure to lubricate.

[slug]

What we have here is, failure to lubricate.

 

Todd wins!!!

[badmotogoozer]

Slipping in a new set of hells with the motor in situ is fiddly but quite doable.

 

snip

 

Thanks Pete. I thought it would be fairly simple (and fiddly, being upside down & tight space) once I was at the Slopper point. Once the upper sump is off is there anything else before the crank ie. are the rod bearings accessible at that point?

 

I think I'd like to be sure with all the stories here of people who had their bearings replaced when they had their cases swapped and didn't know it was needed. I've heard the same thing from the mechanic at my shop. I'd expect the lack of bolt availability speaks volumes of how often they've needed replacing... And knowing that my light has been on at least once, that I've noticed, may as well do it.

 

You probably meant to type "shells" but I think "hells" is more appropriate!

 

cheers,

 

Rj

[Guest Gary Cheek]

Definately do-able. One of the strangest in the case bearing replacements I've ever done was the BSA 650 unit. Done from the top. Requred making a special wrench that hooked around the side of the rods. BSA unit twins had all aluminum rods and if they had seen much high RPM time at all the bigends were stretched, a lot. One of the methods used to gain "nip" when re-sizing split bearing bores is the shim the joint when re-honing. The bearings themselves actually have the nip designed in.

[Guest ratchethack]

Definately do-able. One of the strangest in the case bearing replacements I've ever done was the BSA 650 unit. Done from the top. Requred making a special wrench that hooked around the side of the rods. BSA unit twins had all aluminum rods and if they had seen much high RPM time at all the bigends were stretched, a lot. One of the methods used to gain "nip" when re-sizing split bearing bores is the shim the joint when re-honing. The bearings themselves actually have the nip designed in.

Gary, you just settled an unanswered question I've had since I tried (and failed) to make my own custom "go-'round-the-side" wrench for access to the big-end caps on an A65 Thunderbolt thru the case mouth. This must've been back in about '72. I've still got the goofy thing, which I tried to make out o' a 3/8" extension -- I wound up doing nothing other than taking the temper out of it with heat in an attempt to put two 90-degree angles on it!!

 

Here all this time I thought I was the ONLY ONE to've come up with the idea of a special wrench, which (if it'd worked) sure woulda beat the pants off splitting the cases. . . . . . I'd finally given up and decided the ol' bird wasn't THAT loose on the bottom end, after all. . . . . .

 

I remember coming to the conclusion that a flexible extension just wouldn't cut it. . . . . . So tell me -- did you make y'er own tool, and if so, how'd you do it??

 

Enquiring minds just gotta know. . . . .

[Guest Gary Cheek]

Gary, you just settled an unanswered question I've had since I tried (and failed) to make my own custom "go-'round-the-side" wrench for access to the big-end caps on an A65 Thunderbolt thru the case mouth. This must've been back in about '72. I've still got the goofy thing, which I tried to make out o' a 3/8" extension -- I wound up doing nothing other than taking the temper out of it with heat in an attempt to put two 90-degree angles on it!!

 

Here all this time I thought I was the ONLY ONE to've come up with the idea of a special wrench, which (if it'd worked) sure woulda beat the pants off splitting the cases. . . . . . I'd finally given up and decided the ol' bird wasn't THAT loose on the bottom end, after all. . . . . .

 

Now tell me -- did you make y'er own tool, and if so, how'd you do it??

 

Enquiring minds just gotta know. . . . .

 

 

Yessir, made it up from a weldment. I thought you were a kindred spirit!

Ever find a BSA big end that was round?

I never used the shim packs BTW. I always fitted a one piece spacer to the PTO side, .001 > '0015" end play. Used a filter in the return line and Texaco AV oil. Never had a bottom end problem with a Beezer. I did hold the revs below 6K too. I would glady build one today and ride it anywhere I would take a Guzzi.

[badmotogoozer]

What's the big deal?? Splitting a Beezer 650 (or Tri for that matter) ain't much of anything... Lets you clean out the sludge trap while yer in there too. Bet I could have one apart and back together before you could make a special wrench.

 

How would you ensure proper torque on the nuts with such a special wrench? Calibrated wrists?? This isn't like you Ratch!

 

Cheers fellas,

 

Rj

[Wick]

O.K. I'm still waiting to see if Todd was correct. End the FOOKING drama!!!!!!!!!

Happy Thanksgiving to all............

 

Wick

[mike wilson]

Ever find a BSA big end that was round?

 

Long time ago, I met a guy who worked in BSA from the late 50's to the end. He told me about the major reorganisation the plant had that ended up with the presses for the tinware being installed next to the machine shop. Every time the press went whump on a Bantam side cover, the grinding machines next door put wavy ripples in whatever was being made at the time. When "management" saw the reject figures at the end of the quarter, things were shifted around really sharpish.

 

Makes me think of the practices of a certain Italian motorcycle manufacturer......

 

Sorry about the diversion. Normal service will resume as soon as possible.

[Guest Gary Cheek]

What's the big deal?? Splitting a Beezer 650 (or Tri for that matter) ain't much of anything... Lets you clean out the sludge trap while yer in there too. Bet I could have one apart and back together before you could make a special wrench.

 

How would you ensure proper torque on the nuts with such a special wrench? Calibrated wrists?? This isn't like you Ratch!

 

Cheers fellas,

 

Rj

 

No , splitting the cases is not a big deal but it more than doubles the time required to replace the shells. Some customers didn't want to pay the long buck and just wanted to get running again. Made a lot of people very happy to turn over a new set of bearings, in at 8:00, riding at noon.

Torquing is a snap, just a matter of calculating the added distance, no big deal at all.

[Guest ratchethack]

Wot Gary said. Calculating for an extension on the torque wrench couldn't be easier. For me, going after big-ends was a matter of balancing effort against perception of degree of real need. The bottom-end wasn't rattly, but as I recall, I thought it was starting to show an "inclination". I already had the barrels off for application of a new coat of high-temp paint after a top end job. Splitting the cases meant engine out for complete dismantling -- too far past the original scope of the mission. I put many tens of thousands of most memorable miles on 'er after that without a thought of the bottom-end.

[DeBenGuzzi]

about those points, they are more like a badge of honor, Todd, Pete, Greg, Edge, and Zebulon(I'm sure some others) already have one in my book for their contributions. Its like the opposite of Bodge points. they're like little congretional medal of honor for Guzzi's on the guzzi board well as nice as that can be on a message forum in cyberspace ,

"but they lokka re al nicea" -borat