ViciousZ

iTrader: (1)

Umm, what grit emery cloth do I need? Thanks.

Kevin Johnson

Be careful.

http://www.federal-mogul.com/speedpr...speed_pro.html

Crankshaft Grinding and Polishing

When refinished, the surface of a crankshaft will develop microscopic peaks which are “tipped” in the direction that the sparks spray during grinding (see the illustration above). If these peaks point toward the oil film area when the engine is running, lubrication is interrupted, and the bearing will show premature wear. It is important that the crankshaft be ground and final polished so that these peaks are tipped opposite the direction that the crank rotates when it is installed in the engine, this is referred to as the “favorable” direction. We recommend grinding the crank in the “favorable” direction, followed by a multi-step polishing process using progressively finer paper. The first polishing operation uses 280 grit paper with the shaft rotating in the reverse direction – this helps to “knock off” some of the raised material left over from grinding. The second polishing process uses 320 grit paper, and the crank should be rotating in the “favorable” direction. A third step polish with a very fine (400 grit) paper is optional, but should again be done in the “favorable” direction. If the thrust surface was contacted during the resizing operation it must also be polished.

Kevin Johnson

Oh, here's something you might be interested in...

http://www.russellw.com/manuals/warn...r_assembly.htm

(b) Never use emery cloth for cleaning and polishing engine parts nor for any other purpose unless particularly specified in this handbook. The use of emery cloth may leave abrasive particles in the engine as well as scratches which may develop into cracks and ultimate failure of part and engine.


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Here's another thought...

http://home.istar.ca/~bigjohn/celica.html

GENERAL INFO ON REPLACING CRANK BEARINGS
The bearings are dependent upon the crank being good. When run for extended mileages, the bearing shells wear down, and the tin based bearing surface disappears, leaving the copper that is lining the shell. If you carry on running, the steel will appear through the copper. When you have two similar metals as a bearing, the tendency is to'pick up' or gall.
Typically, a used crank might have some ovality on the journals. This is more likely on the rod ends than the mains. Ya gotta get those new bearings in fast. If, when you strip the bearings out, you have any journals that have a dull finish, you might have a future prob. If so, try polishing them with super fine emery cloth, known as garnet paper. A really fine wet-and-dry bodywork paper would/might be OK, but you might have to 'kill' the surface by rubbing it over a steel edge of a piece of angle iron or similar - it has to be REAL fine. The goal is to have the journal totally
'chrome'like in appearance. Less than that will be OK, but the judgement is hard to describe without showing it. If the journals are shiny but grooved/lined, leave them
alone, do not try to polish. You should be ok with ovality up to about .001" on the rod journals - any more, it gets dodgy. The trick is to break the thing in like a baby. Try to keep the rpm down to about 3 or 4 grand max, and DO NOT ALLOW THE ENGINE TO LUG IN A HIGH GEAR. It is load that you are trying to keep down, not just revs. This will allow the bearings to wear to the shape of any crank journal imperfections/grooves. Go easy for the first 200 miles or so, and somewhat easy after that, for the next coupla hundred.

ede

well i'm not expert and i don't know any sites to post links to but i'll tell you what's worked for me in the real world and what i've done in the past to the two or three engines i've built with no problems to date. only thing i'd ever put on a crank is crocus cloth, not emery and not garnet, both are too course to suit me. i have used 1500 wet or dry since crocus is hard to find around here. if the crank is very bad or needs ground then i take it to a machine shop, but if the pins and journals measure good i'll chuck it in a lathe and tail stock to hold it, no power, and polish it with crocus.

Kevin Johnson

Many guys (including myself) have used a shoelace to hold the abrasive next to the journal. Wrap a strip around and then loop the lace around once completely but without crossing itself. You should then be able to alternately pull on the ends of the lace to rotate the abrasive strip. The key thing/idea here is to apply an even pressure so you don't take the journal out-of-round. Clean thoroughly. A lathe would be heaven.

RB83L69

I bolt the crank to something so it's absolutely rigid; and use first 600 then 1200 or 1500 then 2000 "wet or dry" sandpaper, cut in a strip to go around the journal; a drop or 2 of ATF as lube; and an old fan belt like Kevin described the shoelace, wrapped around the journal a couple of turns. You can get fine sandpaper like that at Meijer of all places, anywhere that sells auto body & paint supplies, etc.

Emery is WAAAAYYYY too coarse.

laiky

400 grit wet/dry sand paper and real cotton clothsline wrapped around the whole journal soaked with mineral spirits. if you have access to a clean parts washer put the crank in it and put the solvent hose in an oil hole that connects to the journal your polishing. OH yeah and lots of patience