the sds are for both. interestingly the geen has barium sulphate in it. thats soft. they used to run in industrial engines with the stuff in the oil and didnt even change it. (i might try putting some sand in the oil once i get my ls7 rebuilt.)
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Sizing connecting rod bushings
- Thread starter Cyborg
- Start date
- Replies 96
- Views 13,342
the sds are for both. interestingly the geen has barium sulphate in it. thats soft. they used to run in industrial engines with the stuff in the oil and didnt even change it. (i might try putting some sand in the oil once i get my ls7 rebuilt.)
I wonder if that’s the same stuff they sell for bedding in piston rings.
So another question about installing bushings…. The next job is installing some relatively thin wall sintered bronze bushings into a gear. I stumbled upon this site which talks about using a piloted driver that is .003 larger than the desired ID after insertion. I’ve never heard of this method and wondering if anyone knows where I might find more information. I looked in the Machinery’s Handbook, but haven’t found anything yet.
Oil Impregnated Bronze Bearings
Oil Impregnated Bronze Bearings
Jeff_M_PA
Cast Iron
- Joined
- Oct 31, 2008
- Location
- San Diego, CA
You left out a zero, that should be 0.0003. Seems more reasonable but I would think that number should vary by diameter.
Jeff
Jeff
Thanks for pointing that out. It would seem my reading comprehension isn’t improving with age. I wish I could say it was a typo, but unfortunately it was stupidly.
Interesting concept though any yes you’d think it would vary.
michiganbuck
Diamond
- Joined
- Jun 28, 2012
- Location
- Mt Clemens, Michigan 48035
If not mentioned a little side-to-side clearance is common for heat expansion. The small side to side can be used to assure the there are no tight places as the crank turns in the bearing. You wiggle the rod and turn the crank to be sure that a rub is not there..With a rub the assembly is likely to overheat and seize the bearing and crank.
Yes, this is for the crank end, not the pin end.
Missanglement/error at the pin end can affect the crank end clearance.
Yes, this is for the crank end, not the pin end.
Missanglement/error at the pin end can affect the crank end clearance.
EmGo
Diamond
- Joined
- Apr 14, 2018
Those aren't very picky, you can even just push them in with a vise.
What is picky is the fit of the spindles in the case. They are almost always loose and you really don't want that. Really really don't want. They should be a tight shrink fit. If they aren't, hard chrome and regrind or make oversized ones, bore the cases, whatever.
And that outboard support plate isn't too groovy either. I would probably do something about that.
If you use a steel idler, most of them are not round. Make sure to check backlash in several areas.
That whole valve train is a problem if you upgrade it for performance .... even at Lightning specs, the followers wear a lot, some people have stellited the faces and reground flat, if you put in heavier springs the stock stuff goes away really fast.
You could call Megacycle, San Rafael, Ca, they make new standard replacement cams and know the valve train and its problems already. You're still screwed on lift tho unless you do major surgery to the heads.
And most people remove the compression release stuff ... it has a nasty tendency to come apart in the timing case at high rpm. Oops.
All those little springs in the primary sprocket fail too, and that whole vibration-removal cam thing should just be ditched, make a solid sprocket and use that instead. Save a couple pounds and get reliability, at the cost of smooth cruising.
I wouldn’t try these ones with a vise. They are for a dolls head gearbox (sleeve gear) sintered bronze and very thin wall. I just received 2 new ones and they didn’t survive the trip.
You’re going to have me hiding under my bed. I’ve seen most of the horrors first hand and been told about the others. The cases are new old stock die cast so not so prone to gearbox explosions. They had all new spindles, cams, followers, steady plate, gearbox end cover, oil pump, bearings, etc. The cases were decked. Within .001 over 10 inches, no C3 bearings for the crank. Bearings were lapped to get the correct running clearance. Anyway all good unless I manage to bugger something up.
I have a decent crank within.001 runout, but building a slightly better one. I say slightly better because it’s still all stock except larger pin diameter.
EmGo
Diamond
- Joined
- Apr 14, 2018
You musta bought Apple at $2 a share .... wanna adopt me ?
Nope…. empty nester and plan on keeping it that way.
The cases were bought by my brother almost 50 years ago and then he gave them to me once he realized his clock was about to run out.
They make new ones now along with just about everything else.
partsproduction
Titanium
- Joined
- Aug 22, 2011
- Location
- Oregon coast
Very interesting thread.
Though probably unrelated for several reasons, we make electrical connectors out of Tellurium copper with a 3/4" blind hole for the plugs to push into, blanks are bored conventionally followed by roller burnishing.
The tolerance for the hole is well under .0001 inch using an air gage. Nothing in it is comparable to the OP's need, but we do them for $1.50 per hole (Thousands of holes per year recurrently), but only because our customer gives us a good deal of business.
We bore using conventional boring inserts in the copper, high positive aluminum inserts, the end size of the hole will depend on the burnish rollers though the sizes of the bores must be very close to the same. The wall size of the copper is about .130" so it's pretty forgiving.
The pin it's sized for never turns, there is no lubricant except silver plate, but the point is that the process may work well for volume, though I would expect any microscopic holes would be closed by it, helical grooves prior to burnishing should take care of that. In our process the holes are roller burnished twice, once before and once after silver plating. Believe it or not the dimensions and tolerances are related solely to the feeling of the pin as it is pushed by hand into the finished board by the end user.
Lapping has produced very good results for me on other projects. As for embedding grit my understanding is that the lap material must be softer than what is being lapped or embedding will occur in whichever side is softer.
For lapping gun parts the compound is supposedly garnet and it's said to break down very fast until the particles are too small to further change dimensions.
I don't know about that, some advertisers say whatever will sell, so for me the lap must be softer than the material being lapped.
That bit about making a driver .0003" oversized for sintered bushings is a tip I hope to remember, though I'd be surprised if variables wouldn't change the pilots size for larger or smaller bores. I wonder if that will work with solid bronze bushings?
Though probably unrelated for several reasons, we make electrical connectors out of Tellurium copper with a 3/4" blind hole for the plugs to push into, blanks are bored conventionally followed by roller burnishing.
The tolerance for the hole is well under .0001 inch using an air gage. Nothing in it is comparable to the OP's need, but we do them for $1.50 per hole (Thousands of holes per year recurrently), but only because our customer gives us a good deal of business.
We bore using conventional boring inserts in the copper, high positive aluminum inserts, the end size of the hole will depend on the burnish rollers though the sizes of the bores must be very close to the same. The wall size of the copper is about .130" so it's pretty forgiving.
The pin it's sized for never turns, there is no lubricant except silver plate, but the point is that the process may work well for volume, though I would expect any microscopic holes would be closed by it, helical grooves prior to burnishing should take care of that. In our process the holes are roller burnished twice, once before and once after silver plating. Believe it or not the dimensions and tolerances are related solely to the feeling of the pin as it is pushed by hand into the finished board by the end user.
Lapping has produced very good results for me on other projects. As for embedding grit my understanding is that the lap material must be softer than what is being lapped or embedding will occur in whichever side is softer.
For lapping gun parts the compound is supposedly garnet and it's said to break down very fast until the particles are too small to further change dimensions.
I don't know about that, some advertisers say whatever will sell, so for me the lap must be softer than the material being lapped.
That bit about making a driver .0003" oversized for sintered bushings is a tip I hope to remember, though I'd be surprised if variables wouldn't change the pilots size for larger or smaller bores. I wonder if that will work with solid bronze bushings?
Newman109
Diamond
- Joined
- Sep 4, 2006
There was a tool kit that was sold with a fixture to hold the connecting rods for doing Harley connecting rods in situ after pressing in new bushings. It came with a hand reamer. I borrowed one to use once and never got the hang of it. It left scores inside of the bushings. I gave up and removed the connecting rods and took them to a Harley shop that had a Sunnen Hone. Got a perfect job.
The small end of the connecting rods in a Harley or any other engine is very critical as to fit and finish. Anything less that perfect isn't going to last very long.
It’s only since starting this thread that I discovered what is available in the way of tools for roller burnishing. Interesting subject.
Burnishing Tools | Cogsdill
I have used that TimeSaver lapping compound and it definitely breaks down and can be easily washed away. I trust it and wouldn’t worry about it embedding into the bushing.
As far as whether or not the .0003 over desired clearance works with solid bronze bushings, that’s a good question and was wondering that myself. The only places where I saw mention of that was on the Oilite site and one other site in India that manufactures bushings that sound identical to Oilite.
I made up a pilot that was .0003 over what I was looking for and it ended up with slightly more clearance. Still within the service limit and easy enough to take a bit off the pilot. For a first attempt I was more than happy with the results. IIRC, both sites say “about” .0003, so assume it does vary slightly with diameter.
Anyway….. thanks for your post.
I watched a YouTube video of a fellow replacing and reaming Harley rod bushings without any sort of jig. He just hand bombed an adjustable reamer through there twisting it back and forth. It was one of the most revolting productions I have ever seen. What was really frightening was all the positive comments.
There is a fellow who has a jig for doing Vincent rods. Obviously not the best way to do it ( while still in the engine), but this jig was bolted down to the case and IIRC had a setup to guide the reamer so it was at least parallel to the crank.
If the lap doesn’t work properly on a test bushing, I’ll go visit the fellow with the Sunnen hone. As much as I want to do the work myself, I won’t take any chances on blowing up a bunch or rare parts.
rogertoolmaker
Cast Iron
- Joined
- Jan 3, 2016
Lapping a bearing with lapping compound is a "very poor" idea. The bearing will become charged with lapping compound and lap the journal. Bore the bearing. Allow .0007 per inch of diameter. Hand scraping to fit.
Roger
workin stiff
Banned
- Joined
- Aug 2, 2013
- Location
- stockton ca.
There is absolutely nothing interesting in this thread at all. 3 tenths oil clearance on a pin bushing is fucking stupid unless you are running mineral oil. Who the fuck makes an oil lite pin bushing?
partsproduction
Titanium
- Joined
- Aug 22, 2011
- Location
- Oregon coast
"There is absolutely nothing interesting in this thread at all. 3 tenths oil clearance on a pin bushing is fucking stupid unless you are running mineral oil. Who the fuck makes an oil lite pin bushing?"
Everything I wrote was general as I said, and not pertaining to motorcycle crank pins but to bushings generally. I'm sorry you didn't find it interesting, but I myself will remember it the next time I have to fit a bushing.
I assume pressing a bronze bushing into a steel bore with a shoulder pin .0003" oversized, which is then pressed back out, will result in a slightly smaller clearance than the .0003" as the pressure is removed.
In addition, the surface of the bushing's bore would be hardened and burnished slightly and the microscopic holes closed down so that lubrication is metered at the inner surface.
These are claims also made for roller burnishing IIRC, and an oversize pin is relatively easy and cheap to make compared to a roller burnish.
Everything I wrote was general as I said, and not pertaining to motorcycle crank pins but to bushings generally. I'm sorry you didn't find it interesting, but I myself will remember it the next time I have to fit a bushing.
I assume pressing a bronze bushing into a steel bore with a shoulder pin .0003" oversized, which is then pressed back out, will result in a slightly smaller clearance than the .0003" as the pressure is removed.
In addition, the surface of the bushing's bore would be hardened and burnished slightly and the microscopic holes closed down so that lubrication is metered at the inner surface.
These are claims also made for roller burnishing IIRC, and an oversize pin is relatively easy and cheap to make compared to a roller burnish.
BGL
Hot Rolled
- Joined
- Sep 14, 2010
- Location
- Maryland, USA
I take issue with the 'not a Briggs' reference. We race them enduro karting for 30 minute races at 7,500 rpm on methanol fuel using synthetic oil. They will last up to seven hours total time at an average of 6,500 rpm. They just get tired and occasionally valves need attention. Well unless something breaks, it is stressed well beyond design. We add about 0.0005" clearance on the wristpin for a total of 0.001". with the timesaver lapping compound and water. Soft brush and Dawn detergent for a through cleaning.
Bronze bushings are no issue - use a lapping tool softer [aluminum, lead, copper] than the bronze and cleaning is the key. You must use a fine brush, cloth or ultra-sonic if you have such a luxury. I have done many for a different application with tighter clearance than 0.001"
Bear in mind two things for a wrist pin. it is a rocking motion and a cyclic load, tighter clearance than a spinning shaft. But in this application it is an air cooled engine. Our splash lube oil runs at "chicken fryer" temperature 350F.
I would talk to a vintage motorcycle person.
Bronze bushings are no issue - use a lapping tool softer [aluminum, lead, copper] than the bronze and cleaning is the key. You must use a fine brush, cloth or ultra-sonic if you have such a luxury. I have done many for a different application with tighter clearance than 0.001"
Bear in mind two things for a wrist pin. it is a rocking motion and a cyclic load, tighter clearance than a spinning shaft. But in this application it is an air cooled engine. Our splash lube oil runs at "chicken fryer" temperature 350F.
I would talk to a vintage motorcycle person.
Just to be clear…… there are actually two different bushing discussions taking place. Originally it was a discussion about sizing connecting rod small end bushings. Yes using a Sunnen hone would be the normal process. I don’t have one of those in the shop and prefer not to sublet out work if possible. That’s why I want to explore using a lap instead of the Sunnen hone.
Then (my fault) it went down another rabbit hole about installing Oilite bushings in a motorcycle gearbox sleeve gear. That’s where it got into the discussion about the .0003”. Just to further clarify things, the procedure is to determine what the desired clearance is and then add approximately.0003 to that. So if I wanted .0025 running clearance, the driver would need to be .0028”. I posted this link before and it’s worth reading. Presumably a large company that manufactures Oilite bushings has some experience installing them. It’s on page 3 and it does state that the amount of spring back has to be determined by tests. My first test suggests I need a little less than .0003.
https://www.bearing.co.il/OILITE.pdf
For those that aren’t familiar with Time Saver Lapping Compound, you can read this.
Create Better Component Surface Finishes with Lapping Compounds
In the paragraph on types of lapping, it suggests that a softer lap is not the way to go.
Then (my fault) it went down another rabbit hole about installing Oilite bushings in a motorcycle gearbox sleeve gear. That’s where it got into the discussion about the .0003”. Just to further clarify things, the procedure is to determine what the desired clearance is and then add approximately.0003 to that. So if I wanted .0025 running clearance, the driver would need to be .0028”. I posted this link before and it’s worth reading. Presumably a large company that manufactures Oilite bushings has some experience installing them. It’s on page 3 and it does state that the amount of spring back has to be determined by tests. My first test suggests I need a little less than .0003.
https://www.bearing.co.il/OILITE.pdf
For those that aren’t familiar with Time Saver Lapping Compound, you can read this.
Create Better Component Surface Finishes with Lapping Compounds
In the paragraph on types of lapping, it suggests that a softer lap is not the way to go.
From Newman Tools:
“TIMESAVER COMPOUNDS ABSOLUTELY DO NOT IMBED OR CHARGE INTO ANY METAL SURFACES. Therefore, do not attempt to make a lead, copper or other soft metal lap to lap hard metals, as is done with emery, ground glass, silicon carbide or other similar charging abrasives. The lapping plate should be at least as hard as the surface to be lapped and harder if possible. The softer of the two metals will get the most wear”.
Timesaver Lapping Compound Yellow Label and Green Label Compounds, non imbedding lapping compound, manufactured by Micro Surface - Newman Tools
“TIMESAVER COMPOUNDS ABSOLUTELY DO NOT IMBED OR CHARGE INTO ANY METAL SURFACES. Therefore, do not attempt to make a lead, copper or other soft metal lap to lap hard metals, as is done with emery, ground glass, silicon carbide or other similar charging abrasives. The lapping plate should be at least as hard as the surface to be lapped and harder if possible. The softer of the two metals will get the most wear”.
Timesaver Lapping Compound Yellow Label and Green Label Compounds, non imbedding lapping compound, manufactured by Micro Surface - Newman Tools
