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I have not used this process on Penton parts but I can give you the lowdown on what shot peening does,
On the surface of any piece of material there are slight imperfections known as stress risers. when a failure occures the crack always starts at a stress riser. Peening or polishing the component reduces or eliminates the stress risers sothere is no place for the crack to start. Peening goes one step further by actually compressing the surface slightly in addition to making it smooth.
You would want to have a magnetic particle inspection process done (most race car guys do this) (magna-flux) and make a metal "fixture" to protect the bearing surfaces from damage during the peening process. there are also cryogenic process that are touted to increase strength but without alloy information I would avoid these processes.  Peening helps reduce catastrophic failure (breakage) and perhaps post peen polishing the leading and trailing edges of the rod may help too..

 

who is your insurance company, if you don't mind me asking?

 

Unfortunatly the only "nice" part of my GS6 is the air box. Everything is bent/broken/rusted/seized. I just got the engine cases back and the crank is stuck in the clutch side. I blasted the right side cases and found holes corroded all the way through. Fortunatly the gears/shift parts look good but I am pretty sure the crank will need reworking. This bike is a disaster but one part at a time and things will take shape soner or later..

 

Jeez man I am blushing.. I have run into a few cyclists here in vintage world..Tell you what. I have been having soo much fun with my Penton and Bull that I keep forgetting to make money and just play with the motos. I got a 77 GS7 and the guys in here have been really helpfull with info and sources for parts.. can't wait to hear it run for the first time.. Ya no problem with tech help..I enjoy helping others make stuff..e-mail me at [email protected] and we will chat.. F

 

if you are trying to just fix the hole I would use epoxy. The reason being is that unless the operator is highly skilled repairing a hole in 1mm thick material is pretty tricky. best case it will be a blob, worse case the welder will end up damaging the material. Avoid brazing unless you can clean both sides of the part because the flux will continue to corrode the steel. (flux is acid) some might say to lap a small piece over the hole but again moisture will collect in the area and the new hole will be bigger than before. If you have a good (really good) TIG guy,(or gal) it can be done with good results.

 

I have done some rust repair with welding and unless the area is pretty good around the hole the area to be repaired will be much bigger than expected. can the piece be removed or replaced?

 

Back in the "old days" (not sure who's) 4130 tubing was first fillet brazed into airframes, racecars, bikes. The tubes were heated red hot, brazed then set by the door to cool in the breeze till they were ready to handle. Later when TIG became the rage, helium was used as an inert gas (rather than argon) and 4130 filler was used. Things started failing and folks figured that the fact that the frame was not heated red hot was leaving stress in the structure, causing the problems. Then in later years softer filler was used, the gas was switched to argon we also found that helium caused an "angular regraining" like safety glass when it fails. So with the new wire, better machines, better gas and cool things like purging and gas lenses the stress releiving just faded away. Some race car guys still do it. To answer the question annealing is in a sense stress revieving. 4130 comes in three grades, Heat treated, normalized and annealed. virtually everyone uses normalized and the need to stress relieve simply does not exist anymore. Thanks for the story on De Costers crash. I got to go to Saddleback for a race in the early 70's and got a signed card with a picture of the "man" layed flat like no man of that day..what a stud!

 

stress relieving is certainly not a bad thing though it sort of went out of fashion when folks started using E70-SX wire for filler instead of 4130. Hey! Ihad a great idea..find someone with a pulse control TIG machine, clean the welds with a wire wheel and just go over them with the pulser on, you can get the texture repaired without risking the tubes.. Frank

 

Thanks much for the information. The frame I have is in very poor condition, several cracks and the down tubes are smashed nearly flat in places. I would be interested in MC5 though I wonder about the frame weight. I was quite surprised at the light weight of the GS6 frame. I have a couple of Maico frames in for repair and the Penton is quite a bit lighter. I would assume the swingarm is the same for both models?
I plan on racing this machine and appreciate the advice. Why don't you send me an e-mail with a phone number so we can get this deal going  "[email protected]"

 

my identity was stolen some years ago..better really cover the bases bro or you will get so burned by those documents left in vehicle

 

Thanks Doc, I drained about a quart of "milk" looking stuff from the crank box so I am sure bearings and seals are needed. My motor guy is pulling it apart this week for a full damage report. I will place an order for parts when the machine begins to take on a more "vertical" stature. Thanks F

 

MIG and TIG welds are "filled" with the same material. usually a 70-80 K tensile material with some additives. Mig is shielded with a mixture of gasses that are not quite completely free of oxygen. TIG uses argon which is usually almost completely free of oxygen so in a direct comparison with the same amount of added material a TIG weld would be better. Specially on 4130.
The only real problem lies in removing the old weld and dealing with the contamination inclusions without further tramatizing the material. If you can remove the old weld without harming the base materials that is a good step. The second problem is the old weld may be full of porosity, slag or some sort of contaminant. TIG will not deal with this junk well. also a TIG weld is much smaller (done properly) and an area may exist outside the area of the TIG weld where the material has been effected my the trauma of the original weld but now is not covered with the new clean TIG weld. I personally do not remove welds and replace them unless they are cracked. (usually tubes fail not welds) for vanity it can be done but there is a good chance that the contaminants will reek havoc and cause the other mantioned problems. If you are committed to this procedure try perging the frame with argon and using a E-70S6 filler the "s" number is for silicon that has a fluxing property. Be shure to run the weld past the end of the stress area in the case of the gusset and be sure to remove as little weld as you can.. Frank

 

Brian, You really shouldn't grind welds out, specially in a structural situation. Because production welds are done so quickly there is usually little gas coverage and the best part of the weld is the envelope or "skin" where the grain structure is not interupted by the shrinkage that takes place during cooling. Also the "tails" or welds that continue beyond the end of a gusset are very important at defusing "stress risers" (areas where stress is focused)
My '77 frame is very thin material and even a slight scratch in a stress area will cause a failure..Frank

 

Thanks John, This message board has already been a huge asset, This would take years without all the information available here. Thanks to everyone!  Frank

 

anyone going to the NY AHRMA MX race this weekend? I don't have a running bike yet but I need to smell some more pre-mix for winter inspiration..F