13 replies to this topic

[cristiano1968]

hi im in the process of rebuilding my 998cc engine   

ive measured all the places on the crankshaft and they are all within the tolerances 

i used a micrometer i did scratch it a tiny  bit with the micrometer   i ll post a pic 

anyway my question is 

does it have to be polished or can i put it back in without  being polished?

[slidehammer]

without seeing a picture, unless you were hitting it with the micrometer it should be absolutely fine.

[cristiano1968]

Ok I'll get a picture uploaded tomorrow ??

[Cooperman]

There are two things to consider when refitting a crankshaft:
The journal diameters and the surface finish.
If the journal sizes are all within tolerance the surfaces must be completely smooth and free of marks, ridges and scratches.
It is often possible to have a crank micro-polished rather than reground.

Edited by Cooperman, 17 September 2020 - 09:33 PM.

[cristiano1968]

The journal diameters or all within tolerance

[cristiano1968]

I can run my finger nail over all the scratches
They are not deep scratches finger nail slides over them.
Or have in ruined it.
Or well a polish at the machine shop do any good?

Attached Files

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•  20200918_003639.jpg   45.6K   5 downloads

[cristiano1968]

Or as cooper man said get it micro polished?

[Spider]

Or as cooper man said get it micro polished?

 

A  Polish would be in order I'd also suggest here.

[mini13]

It should be fairly hard to damage a crank with a mic, looking at the pics I would jet a strip of 2000 grade W&D and give it a quick polish with some wd40 and see how it looked then.

[cristiano1968]

you think i should leave it for the machine shop?

[Cooperman]

As 'Mini13' says, get a strip of Wet & Dry about 10" long and 1/2" wide, put some WD40 or othr thin oil (3-in-1) and pull the wet & dry across the journals, making sure you do the entire circumference. Use a new strip of W & D on each journal, doing the worst-looking ones first. If they polish-up fairly easily you will be good to install. If they don't you will need a crank re-grind to the next size down and, obviously, a new set of bearings smaller than the size you have.

[drydavel7]

I use 400 grit paper to clean up journals if needed. This is usually the finish left after a machine shop polish. A strip of production paper against the back of an old cambelt Works well.

[cristiano1968]

Ok cooper man
I'll get some wet and dry and give it a go.
Thanks

[cristiano1968]

Ok drydavel7
I'll give 400 a go