[Vwdiesel] 3M bristle disc use? Re: prepping block for head gasket tips

[James Hansen]

I have the radial discs as well, they are too abrasive for gasket prep.
They CUT more like a grinding disc.  They are handy as all heck for 
paint prep and minor grinding when welding, especially sheet metal work, 
and cleaning up surfaces prior to welding, but highly NOT recommended as 
a gasket surface prep.
The bristle discs are an abrasive impregnated plastic of some sort, 
almost like a cratex product, but more flexible, and not as agressive.
You just let them float along, not a lot of pressure needed, but 
increasing pressure seems to just wear the disc faster.

On an oil pan or valve cover gasketry, I use the bristle disc before 
washing the pan out.  You do have to take care not to tear off the outer 
edge bristles, but I'll use an older one with short bristles to do that, 
so they don't break off as easily.
-james

brian gochnauer wrote:
> James,
> 
> Have you (or anyone) tried the radial disc, looks like it would have more
> flexible uses like oil pan gaskets.?
> Kinda pricey, how long do they last ?
> http://www.sjdiscounttools.com/mmm7544.html
> 
> 
> 
> 
> On 1/19/09, Will Taygan <william at taygan.com> wrote:
>> On those bristle discs, how much pressure do you use?  I'm also assuming
>> you use it so the bristles are all touching the block at the same time,
>> and not on an edge.
>>
>> P.S. I've got an angle grinder, a dremel, and a drill, but no die
>> grinder.  Probably have to use the drill, hmmm...
>>
>>
>> Thanks,
>>
>> Will.
>>
>>
>> On Sun, 2009-01-18 at 00:01 -0600, James Hansen wrote:
>>> Will, I use these on every gasket surface, especially when using MLM or
>>> steel shim head gaskets on my race car motors.
>>>
>>> http://www.sjdiscounttools.com/3m7528.html
>>>
>>> I just googled 3M roloc bristle disc, so you could see  a picture, no
>>> recommendation whatsoever for these guys, but the price seems good.
>>> You'll prep maybe 5 blocks with one disc, so try to find one from a
>>> supplier such as acklands that breaks up cases and sells them
>> individually.
>>> They are EXTREMELY good surface prep, use with a die grinder (best is a
>>> 90 degree one) and a roloc backing pad to match.
>>> You want the white (v.fine) pad, it makes a very good gasket mating
>>> surface for most aanything, is very slow to cut on steel, mostly
>>> polishes, and is designed to surface prep aluminum, so it cuts very slow
>>> on steel.
>>>
>>> Turn the crank so all the pistons are down a bit, stuff an oil saturated
>>> rag in each hole to catch cooties, and keep them from going past the
>>> piston crown to the top ring.  After polishing, clean clean clean.
>>> run a tap down the head bolt holes, vacuum the holes out, blow them out,
>>> such them out with a soda straw, ANYTHING to get them completely
>>> perfectly clean or you can crack the block when the bolt encounters some
>>> foreign material.  Ounce of prevention saves a pound of "Oh shit!"
>>> -james
>> -snip-
>>
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