Balancing pistons

Regular Jo · Post by **Regular Jo** » Fri Jul 26, 2002 8:48 am

Anyone ever balance there own pistons? I know of a few people but I really want to do this myself. Made enough mistakes in life ,one more wont hurt. Any pic..what size drill bit? Any experienced help would be great.

Marty · Post by **Marty** » Fri Jul 26, 2002 8:53 am

I do but I dont use a drill bit. I use an endmill in a mill and remove from underneath the crown.

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Marty Staggs
www.staggsracing.com

Post by **Marc** » Fri Jul 26, 2002 8:59 am

Hopefully you can achieve a good balance without having to remove material from anywhere but the balance pads that most pistons have for that purpose. Avoid removing material from the underside of the pin boss if you can, and don't leave any sharp edges that could be stress risers. I normally use a rotary file on a high-speed handheld grinder. If you have a gram scale it should be a piece of cake, otherwise you'll need to rig up a balance and cross-check them all. Don't forget that the wristpin weights may vary so they need to be kept with their pistons (and a little pin juggling may save some time too). Normally rings and wristpin clips won't vary in weight enough to matter unless you're extremely anal. Anything within a couple grams is adequate (Stock Porsche spec is 5) so don't panic if you go a hair too far on one.

rich2481 · Post by **rich2481** » Fri Jul 26, 2002 9:35 am

There have been tech articles in Hot vw and Vw trends about it, at least in the 80;s when I subscribe regularly.

lesd · Post by **lesd** » Fri Jul 26, 2002 10:45 am

Marc, I have a digital scale that reads to the nearest gram. Is that good enough to do pistons? ( all to within 1 gram of each other) ?
Thanks
-Les

Regular Jo · Post by **Regular Jo** » Fri Jul 26, 2002 3:32 pm

What type of end mill bit. I have access to a drill press so I can buy the bit.

Marty · Post by **Marty** » Fri Jul 26, 2002 4:34 pm

4 flute with 1/2" diameter is what I use. 1 gram is fine. I sure have not seen "balance pads" on VW pistons.

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Marty Staggs
www.staggsracing.com

rajay · Post by **rajay** » Sat Jul 27, 2002 12:36 pm

QUALITY SCALE SALE ENDS AUGUST 2, 2002..www.discountscales.com..OHAUS MODEL #CS2000..$60...2000grams..1gram increment..weigh your pistons,lifters,rods..(.1GRAM INCREMENT SCALES ALSO AVAILABLE)

rajay · Post by **rajay** » Thu Aug 01, 2002 9:58 am

SCALE SALE ENDS TOMORROW...www.discountscales.com

Post by **Marc** » Thu Aug 01, 2002 10:02 am

<BLOCKQUOTE>quote:<HR>Originally posted by Marty:
I sure have not seen "balance pads" on VW pistons.

<HR></BLOCKQUOTE>

Gee, now I'm worried...I wonder what I've been grinding away all these years?

Marty · Post by **Marty** » Thu Aug 01, 2002 1:20 pm

<BLOCKQUOTE>quote:<HR>Originally posted by Marc:
Gee, now I'm worried...I wonder what I've been grinding away all these years?<HR></BLOCKQUOTE>

Beats me.
Wrist pin boss? LOL

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Marty Staggs
www.staggsracing.com

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Thu Aug 01, 2002 8:56 pm

On a mahle piston thats not a balance pad, it is an indicator of the direction the piston should be installed. After thoyusand of miles the arrow gets carboned away and they want a definite way for the installer to install the piston.

I do just like Marty and use a 4 flute endmill under the crown. I have been seeing Mahle sets way out on my balancer lately, as much as 20 grams between 4 pistons.....that much of a variance means unboxing 5 sets and tossing them into sets acording to closer weight out of the box.

My spec is .5 grams per 4 pistons more than that and you can feel it..Balancing is important..

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Jake Raby
Raby's Aircooled Technology
www.aircooledtechnology.com

Johnny T · Post by **Johnny T** » Fri Aug 02, 2002 1:51 am

Jake Raby, You are the King! Anal has met it's match in this case! *L* .5 grams per set? Would buying P/C's from GBE be better then since you get POTL P/C's? Or do you do all the machining to get POTL's yourself? BTW when I move back to Tennessee next year I am coming to see you!

John

Post by **Marc** » Fri Aug 02, 2002 5:19 am

The hard part, of course, is making sure that the EXACT same amount of oil clings to each piston & enters each wristpin and that the EXACT same amount of carbon builds up on each piston. Otherwise you can feel it....

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Fri Aug 02, 2002 6:20 am

A sense of sarcasm in the air....Great!

if the engine is built correctly and ran hard enough there won't be any carbon buildup on the pistons!!lol

Yes, there is a .2 gram per inch of bore equation to correct for oil on the pistons backside on my bobweight card. The recip factor is also based uopn weights of the rod bearings being used and even the oil that is displaced by the rod bearings, based upon the crankshaft clearances....this is no exaggeration, just the reason my CNC balancer cost 30K...

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Jake Raby
Raby's Aircooled Technology
www.aircooledtechnology.com