February 2000 Tech Feature www.virtualindian.org   
    Home / Features / Flywheels / Part 4
    Flywheel Workshop 4
   By Cotten   
Now we really open the door for adamant opinions with the Preparation stage. This is perhaps the most important sequence of steps, as all subsequent Inspection and Assembly depends upon its thoroughness. (Machining usually leads to more Prep.) 

I think we all will agree (except for the EPA and environmental groups) that a preliminary solvent wash is in order. Here in Illinois the cheapest practical solvent is mineral spirits, available sometimes as cheap as $2 a gallon. My equipment is simple: My vessel is an old double laundry tub on wheels, with rounded bottoms and spigots so I can regularly decant to wipe out sediment. The metal lid is hinged with a fusible link to please my evil insurance company. Aside from a turkey baster, deep-fry baskets, and a variety of brushes, only the air compressor adds any efficiency. My water scrub station is similar, although I use a siphon gun to steam off 
abrasives, detergents and the like. 

Here's where will shall diverge in dogma: Almost everything I prep gets run through a blast cabinet at some time or another. I have a 'coarse' cabinet with Aluminum oxide or the mineral media called "Starblast", and a second one with the next-to-finest grade of beads. (I look forward to affording some of those cheap plastic table top cabinents for walnut hulls, steel shot, etc.) Often pieces will be treated in both. It goes without saying that judicious choices are to be made with each piece to be blasted, such as masking, etc. We all know of the hazards here from embedded and trapped abrasives. I firmly believe that cleansing is possible as long as every trace of gummy carbon has been removed. Ferrous materials will not imbed grit, assuming proper pressures, however Aluminum does readily with aggressive abrasives like the AlO2 or silica. External surfaces are Adalox brushed at my shop (a soft nylon impregnated with AlO2, not steel, see top picture on this page) while internal areas are vigorously water-scrubbed and then encapsulated with Glyptal (a solvent resistant bakeable enamel available in quarts from Eastman ). One cannot emphasise attention to scrubbing at this point. Most motorcases will be scrubbed several times, depending upon the sequence of prep, machining, re-prep, thread chasing, honing, prep for assembly, etc. I obtain the most professional results by even blasting out the oil passages as opposed to masking: it is the gum retained that most often retains the abrasive, and no masking is 'tight' enough. 

I think I'll let you all explode with dissention at this point. 

From: "Marc Gunderson" <indian@beachaccess.com.au> 
Hi Cotten & others, I too blast every part for inspection purposes and to make everything clean for the assembly part. I use a Degreaser which is a hydrocarbon that has a detergent additive to clean parts. I then hose off the parts with water and thoroughly air blow dry them. 

One thing I learned years ago about reconditioning engines is that you need to clean the parts properly before assembly. Something like Kerosene or Petrol/ Gasoline is not good enough to remove all the dirt and grime. 
A detergent type cleaner is the only way for final cleaning. Kerosene etc. is good for initial cleaning to remove oil , etc. 
After finish honing cylinders, I clean the bores with a Caustic/ alkaline type commercial cleaner to ensure all the impregnated honing grit is removed. Any really dirty ferrous parts I boil in a Caustic solution to remove the bad bits. Just like a small hot tank you see at Engine 
Detergent molecules actually enclose the dirt particle and remove it. If your not sure about all this, it would be best to go and find some books on this topic or engine reconditioning books and see what they say. 

PREPARATION 2nd installment: equipment 

My blast cabinets are undistinguished; a cabinet is a cabinet, plumbing is as expected, etc. I do, however, use an intermediate 5 gal vaccuum canister as a cyclone before dust is hosed to a 16 ga vacs fitted with gargantuan 10"x16" filters bought from a salvage house. Separate vacuum systems are used for each cabinet. The lights are shock resistant floodlamps, and I buy the expensive (!) carbide tips for the aluminum oxide. My first gloves were sewn from raincoats, but cheap ones are occasionally available from outfits like Harbor Freight. 

The pressure-washing (Hot!) stall is adjacent, and SimpleGreen has proven to be the most cost-effective surfactant. 

The Adalox (impregnated nylon) brush I mentioned is a 16" wheel pulleyed down slow. This is a safe brush that will not burnish the soft case surfaces, yet gives a bright cleanliness as opposed to the dull mill profile that will collect fingerprints and other dirt. Small 1/4"shank versions of these are available at retail outlets. I use a nominal 2" bore brush for a final plateau finish on the rod races after honing. A similar brush is used on finished wristpin bushings or to gently crosshatch serviceable installed bushings. At this point, the Prep and Machining stages overlap, but microfinishes are important. 

Mounted wheels are effective on the ferrous hardware. All that is needed is a half-horse (or bigger!) motor mounted on a benchtop with a hardware store arbor to hold wheels, probably from the same store. Here, the peening action of a stiff wire wheel concieveably affects the 'skin' of forgings much as shotblasting. Rods should be 'polished' lengthwise for this reason.  
I set up a 'buffing mule', or bench with two overhanging 2' long horizonal spindles pulleyed to motors beneath. The spindles are merely 1/2" threaded rod with self-aligning pillow blocks from the tractor supply store. The pulleys and blocks are spaced with nuts, as are the rack of four varied wheels each; One is filled with wire wheels from knotted to extra fine, while the other has a selection from flapsanders to sisal to muslin. The end spaces allow for quick swaps from the wall stock of wheels, and footswitches speed up work and add a safety feature. (Mine were accepted by the insurance suits by hinging Lexan shields that also extend the bench top). Note to those who may use this notion: Slant your bench back towards a wall, so all of your hardware won't vibrate onto the floor. 

Accessory appliances for prep work are infinite in variation, but blasting and wheeldressing account for the bulk of mechanical cleaning processes in my commercial circumstance. Chemical processes include not only the detergent and solvent scrubs, but paint strippers, carb digestives, even baking soda or acid etches may the order for unique circumstances. (Here in Illinois, the early black-top paving was tarred pea-gravel called 'bitumenous', and its removal from headfins can be a tedious surgery.) 

The unsung workhorse behind all of the prep equipment is the air compressor: Too big still isn't enough. 
Let's chew on this for a while before I spew Inpection. 

From: "Moen" <moen@get2net.dk> 
When blasting/cleaning, my experience is that the cleaning stage can not be over-emphasized. Cleaning internally blasted aluminum really calls for near-insane application of the scrubbing brush. I use hot water & dish washing soap, and a small collection of pipe cleaners & gun bore brushes for oilways, and I spend hours on it! 
As you say, grit won't embed in steel the same way, and I have little reservation about blasting steel parts. It goes without saying that thorough(!) cleaning is still in order for those. 
I guess I like the "new" look resulting from a good blast as much as the next guy, but I actually prefer degreasing and brushing with solvent, and brushing exteriors with a brass wire brush on "working bikes".  

From: indianjohn <johnmarg@pilot.infi.net> 
The Glyptol is a good idea even with new cases. It tends to seal any porosity that may exist in the castings. Indian used it, or something similar, on their cases for just that purpose (the red you see inside of many Indian engines). 
From: Keith <Packardv8@aol.com> 
YA,  and i've seen it flaked off real bad too!!!!! I dont use it.  I've seen alot of cases that show absolutly no trace of any having ever been applied. 

From: "Cotten" <Liberty@npoint.net> 
Not to worry, Keith, The original factory coating I believe to be "Gasoila" which is soluble with alcohols. Any alcohols in the vehicles gasoline will end up in lesser quantities in the oil, just as the moisture from combustion will. Glyptal is an enamel that, if properly applied to a prepped surface, is quite durable in hot oil. I have had success with a green epoxy also, judging by its excellent condition when opened again for overhaul years later. Remember, my primary reason for using it is to encapsulate abrasives left even after dedicated scrubbing. 

From: Keith <Packardv8@aol.com> 
YA! Thats the stuff (Gasoila) I've seen peeled off. 

From: "Moen" <moen@get2net.dk> 
I think Loctite makes a sealer for porous castings too.  

Blast cabs & wire wheel rack 

Click for full size 
Air compressor: Too 
big is not enough... 



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