Balancing pistons. Can I grind away this ridge?
#1
Burning Brakes
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What purpose does this ridge serve? Does it do anything like scoop oil onto the pin or is it for balancing and can be safely removed to lighten the piston?
#3
Burning Brakes
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I just need to remove a few grammes to balance the set. I need at most 2.5g gone from the heaviest piston/pin combo. I'm planning to use a Dremel tool.
#6
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Thanks.
I thought the rods and the pistons were balanced separately? A few random hits from a google search:
I thought the rods and the pistons were balanced separately? A few random hits from a google search:
I paid $175 to have an engine balanced about eight years ago. The pistons were put on a lathe and the metal machined out of the skirt area up high. The rods were done on each end and the crank was actually balanced on each journal.
This is done by weighing each piston on a sensitive digital scale to determine the lightest one in a set. The other pistons are then lightened to match that weight by milling or grinding metal off a non-stressed area such as the wrist pin boss. The degree of precision to which the pistons are balanced will vary from one engine builder to another, and depends to some extent on the application. But generally speaking pistons are balanced to within plus or minus 0.5 grams of one another.
Last edited by bebbetufs; 02-15-2014 at 07:45 AM.
#7
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I prefer to balance the parts separately. that way you can mix and match rods and pistons. that can come in handy if you have to replace anything later.
Lightening the whole skirt has some risk - you should not take any material out of the thrust areas.
The tab you are pointing to is a good place to start - but do not take any more material off once it flush.
Lightening the whole skirt has some risk - you should not take any material out of the thrust areas.
The tab you are pointing to is a good place to start - but do not take any more material off once it flush.
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#8
Burning Brakes
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Thanks Chris.
Unfortunately I am in too much of a hurry
Today I balanced the set by taking material out of the trust areas because that's what they did to my other set when I sent them away for balancing (Opel tuner). I did however cover as much area as possible to minimize loss in one area. After grinding I hand sanded and polished as best as I could by hand to hopefully reduce the amount of stress risers.
Here are some photos.
What do you think? Hopefully I won't have to buy yet another set of pistons.
Unfortunately I am in too much of a hurry
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Here are some photos.
What do you think? Hopefully I won't have to buy yet another set of pistons.
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You will be fine - the pistons have a very deep skirt so the small amount of weakening at the very bottom will no be a problem.
#10
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Thanks. I think I've confused "thrust area" with "pin boss".
I've removed most of the material from the surface of the piston pin bosses. 1mm at the most. I had to re-chamfer the oiling holes to restore the original chamfer, but some of the chamfer was still left.
I've removed most of the material from the surface of the piston pin bosses. 1mm at the most. I had to re-chamfer the oiling holes to restore the original chamfer, but some of the chamfer was still left.
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if you look at the pistons you should see where the skirt is lower that the rest of the piston - those are the thrust areas.