Protocol to cold weld races in worn bores

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Hobot

Hobot

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Seeking hand holding on vital details to epoxy races in bores without the race seating in piling up epoxy to foul the race track or prevent full race seating or cold weld in any shims too.

Also seek method to use epoxy to prevent worn bores in the first place, when there may not be any room for epoxy and want to keep it that way when operating engine and tranny into heated elastic strains. Epoxy is famously strong in shear but not so much as an adhesive, unless surfaces textured to bind by shear resistance. One could drill a notch or 3 in bore rim then grind off a bit of back of race to match up, seat race then dribble in just enough thickened epoxy to set up and lock in place. May put a wire in the space to back up even more. To remove I think just drill out a bit then use enough heat to soften epoxy and remove as usual or weld a rod on count to 30 and remove. I wonder what size notch is safe in the race? I wonder how many 'nail downs' should be created? I wonder what epoxy is appropriate?
 
Chewing gum is probably going to be as effective.
Or best Arkansas billy goats pee would probably be as good too ?
tell us how they go ?!
No reputable bike shop would be seen dead using either of these though...

Tell us more of this though - what bike, and what bearings. ?
How worn are the housings. ?
It is possible to copper plate the outer of the bearings, to make them oversize over stock.

Or, at a pinch, the housings may be able to be machined out slightly oversize, and shimstock brass sheeting - or beercans - used to take up the difference.
This is still hillbilly engineering at its finest though.

A good shop could probably have them welded up, and machined back to stock.
Cost a $bit$ though, especially keeping them aligned...
 
there is a million different Loctite grades, some specific for this purpose, it works well and can handle hi temperatures.
 
I get the feeling this is just another posting by steve to keep up his ratings...or should i say rantings? as Donald states there is many grades of "glue" that will do a "so.So " job. Reclaiming a bearing bore is by re-maching and pressing a sleeve in...any other method ,goe's under the heading....Exceptable bodge.
 
I have been thwarted in my atempts to repair spun bearing recepticles in the past by some of the same means you propose. What it comes down to is that there has to be enough compression fit, whether by press-fit (transmission bearings) or crush force (rod big ends) to be above the yield force anticipated during normal use. Especially in the case of aluminum surrounding steel (almost everything in our Norton engines/transmissions), nothing we can do can overcome the force of expanding aluminum vs. steel vs. temp. If the aluminum doesn't already have enough tesile stress against the steel shell of the bearing, it will pull itself and any adhesive loose once the temperature begins to rise. What we're left with is to either have the bearing pocket machined oversize then sleeved back to new, or welded and machined.
 
Didn't we all read Jim Comstocks recent mention here that bearings fitted with loc-tite in good housings showed no sign of it having been there later on - when the motor was subsequently opened.

In a worn housing, sounds like a recipe for a short life, possibly with some extra undesireable consequences ??
 
BTW, that crack about goats pee wasn't that far of the mark, in some respects and circumstances?

Nortons had problems in the 1930s with cranks slipping and becoming mis-aligned (single cylinder cranks, that is, think large circular flywheels).
The solution was, literally, found to be sal-ammoniac, applied to the crankpin journals at crank building time.
Instant rust bond between steel components, no more misaligned cranks....
 
+1 on neater_potater's post.

I have had some experience refurbishing the trunnions on jet engine turbine blades. these were chrome plated, then precision ground back to specified tolerances. bearing bores could be similarly treated, but the bores must be precision machined back to tolerance with particular attention given to maintaining concentricity. chrome may not be the metal of choice for plating a bore...it is very hard and difficult to machine. Copper or nickel may be preferable, but then there is the issue of some metals do not plate well over others. Better to get a knowledgeable plater's input before proceeding.

locktite would be my method of choice in a non-severe load application. I once took out the radial play in my old pickup's steering column with locktite, being very careful not to get the stuff into the bearing! in this example, the radial load and rotational loads are minimal, and concentricity of little concern.

Welding, then machining back to specs, is a good option if the part is stress relief annealed after welding.
 
Hard-chrome on the OD of the bearing race can work OK if the housing isn't worn off-centre.Copper plate might work too,but it could wear more on a main bearing.A main bearing will always be a loose fit and rolling around when the engine is hot.
 
Of course this is just for my own ratings and nothing useful for me or anyone else. You've been warned off!

Years before Jim reported Never Finding Loctite left in crank bearing bores I read the reports of others with same findings. Fine for pick up truck suspension and maybe smaller engines, just not inside my Norton engines or transmissions. If you believe in shoe eves go ahead and use locitic with rabbit foot applied.

Chemicals corrosion method is wonderful to trap similar material flat faces together or bind a shaft like swing arm spindle in bores but not gonna cut it in Al bore expanding with heat and shaft flex so it'd act more like abrasive to open bores more.

The plating method is a long time standard. I had it done by copper to make up undersize crank ends in Peel project as chrome wouldn't stick to the nirtide surface pollution. As reported its a touchy and expensive procedure so not cost effective. The thin shim material would also be too tricky for me to attempt and hard to fine tune its dimensions in swelling conditions.

There are ways to stake races by brute force that distorts the bore and the race some and by tricky drill and tap the seam between soft Al and hardend steel then put in set screw and hope it stays put. Its about the gold standard we've seen examples of here but easy to mess up and for sure not a DIY method with bench grinder and hand drill. I've races traped by radial aimmed set screw in shaft slots or bearing dimples in my old lawn mower but don't think there is access to do so in our cases.
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So how much notch in Al bore and steel race to put something in w/o tapping threads, like epoxy or low melt metal that melts above operating temps enough it'd stay firm till a hick heats it over that to install or remove?
 
I don't think any of the repair methods short of boring and resleeving will work. Not sure if you can even chrome bearing races without flash over to the bearing surface even with proper masking...plus would be expensive and may not work.

Shimming, glueing, Locktite and Set screws all sound bad to me. How do you get the set screw method to not shift the bearing off center if the bore is larger than the bearing? Even a thou or two is too much IMO.
 
hobot said:
Of course this is just for my own ratings and nothing useful for me or anyone else. You've been warned off!

Years before Jim reported Never Finding Loctite left in crank bearing bores I read the reports of others with same findings. Fine for pick up truck suspension and maybe smaller engines, just not inside my Norton engines or transmissions. If you believe in shoe eves go ahead and use locitic with rabbit foot applied.

Chemicals corrosion method is wonderful to trap similar material flat faces together or bind a shaft like swing arm spindle in bores but not gonna cut it in Al bore expanding with heat and shaft flex so it'd act more like abrasive to open bores more.

The plating method is a long time standard. I had it done by copper to make up undersize crank ends in Peel project as chrome wouldn't stick to the nirtide surface pollution. As reported its a touchy and expensive procedure so not cost effective. The thin shim material would also be too tricky for me to attempt and hard to fine tune its dimensions in swelling conditions.

There are ways to stake races by brute force that distorts the bore and the race some and by tricky drill and tap the seam between soft Al and hardend steel then put in set screw and hope it stays put. Its about the gold standard we've seen examples of here but easy to mess up and for sure not a DIY method with bench grinder and hand drill. I've races traped by radial aimmed set screw in shaft slots or bearing dimples in my old lawn mower but don't think there is access to do so in our cases.
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So how much notch in Al bore and steel race to put something in w/o tapping threads, like epoxy or low melt metal that melts above operating temps enough it'd stay firm till a hick heats it over that to install or remove?
Click to expand...


Well on my gearbox I used Devcon, after very carefully cleaning the bearing and bore I warmed the Al housing and put a very thin smear of Devcon on both surfaces and slid them together, pretty much guess work on not putting too much on, a bit like gasket sealants where less is more idea. At least on the gearbox with a roller bearing you can make sure none is where it shouldnt be. Then I pegged both bearings with a counter sunk cap screw so they cant move even if they wanted to. Cant report on success yet though as its still sitting under the TV in the lounge with no wheels
 
Wasn't there a post, long ago, showing a pin between the race and bore? IIRC, a hole was milled with the bearing in place , half in the bore, half in the race, of the same diameter as the pin. It was probably a Comstock fix.
 
Shimming, glueing, Locktite and Set screws all sound bad to me. How do you get the set screw method to not shift the bearing off center if the bore is larger than the bearing? Even a thou or two is too much IMO.
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Yes on concern about distorting the race with the side ways set screw method, unless a dimple in the race? If so how much a dimple?

As to the shim method, I think the bad bores get sort of oval shaped, so would think a rebore to re-round and match the shim stock would be needed. Kind of tricky machining to me but may be routine to machinist.

Set screw that split the seam of race and bore is a great way to go, though most tricky to do I'd think and don't know how long that fine fit could be repeated.

Devcon sounds like over kill in tranny and wonder how it lets go when needed but appreciate the shop wisdom description and success to keep the glue contained. Oh ugh, here's its spec sheet which lists service temperature -40f to 200F. Hm leaves out crank case use if so.
http://www.devcon.com/prodfiles/pdfs/fam_tds_175.pdf

J B W 500-600f hi temp takes days to really harden well but even after it gets a bit soft-compliant though still shear resistanct nearing 400f. I think this allows some thermal expansion with the parts its bonding. Trixie's cases sealed with it fine but that a low stress job. Maybe the Iron Putty could be rolled to a sliver then stuffed in to lock in place with crude notches instead of threaded set screw - ugh that could back out itself.
 
hobot said:
As to the shim method, I think the bad bores get sort of oval shaped, so would think a rebore to re-round and match the shim stock would be needed. Kind of tricky machining to me but may be routine to machinist.
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Most machinists would not use this method, because shimming is really only a temporary fix. In a press fit situation you create additional surfaces that can easily let loose with shimming. It's also difficult to get shims to hold tightly...never the same as the original fit because the shims will move during press. Just not a good fix.

hobot said:
Set screw that split the seam of race and bore is a great way to go, though most tricky to do I'd think and don't know how long that fine fit could be repeated.
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Very difficult to machine a hole half in a hard material and half in a soft material. Cutting each part separately in a mill would likely work, but then what holds the bearing in? The set screws? If you add some sort of epoxy it may work but is this really a good fix for the long term? Could it loosen up again? You also could move the bearing to one side more...just doesn't seem proper to me.

hobot said:
J B W 500-600f hi temp takes days to really harden well but even after it gets a bit soft-compliant though still shear resistanct nearing 400f. I think this allows some thermal expansion with the parts its bonding. Trixie's cases sealed with it fine but that a low stress job. Maybe the Iron Putty could be rolled to a sliver then stuffed in to lock in place with crude notches instead of threaded set screw - ugh that could back out itself.
Click to expand...

JB Weld is difficult to get proper mix to get the highest strength and cure. Still too much chance it will come loose again.

Making a proper sleeve is still the best approach IMO.
 
Remember this fix Steve ?

Protocol to cold weld races in worn bores
 
dennisgb said:
I don't think any of the repair methods short of boring and resleeving will work. Not sure if you can even chrome bearing races without flash over to the bearing surface even with proper masking...plus would be expensive and may not work.

Shimming, glueing, Locktite and Set screws all sound bad to me. How do you get the set screw method to not shift the bearing off center if the bore is larger than the bearing? Even a thou or two is too much IMO.
Click to expand...

Hard chroming is a tried and tested method, but is very expensive as you need someone with a universal grinding machine to accurately take the outside diameter back to the shaft size. It is only used on much worn crankshafts for instance.
 
Oh yes indeed fredful that image is front and center in my mind as best way I can conceive, set screw holds a sleeve in so not so tricky to replace and match or machine threads on each new race. Would also not have to wait on epoxy set up to run or hassle on removal. Will ask Ken about doing this for Peel's Maney cases and local shop to recover an over raced Qualfe shell's bores. The photo reveals what amount to remove form outer race too. Still would be neat if I could just bench grinder small notches and fill with a melt out epoxy or metal to do it at home. I must face time and again, like many others, this ain't a cheap or easy hobby to maintain and any short cut too soon pays back with you know what.
 
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