Honda CB750 Sandcast
The Restoration Shop => Chrome - Anodizing and Other Metal Finish Procedures => Topic started by: Wayne on December 30, 2012, 03:04:21 pm
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Going over my aluminum parts once again while trying to decide on a final finish/technique, whatever you want to call it. My rear flange when removed was caked in grease and road grime etc. I mean it had not seen the light of day in a lot of years. I posted pic's in my restoration thread on what it looked like once I gave it a quick clean up. I decided to remove some of the clear coat and compare how the original and clear coated surfaces differed.
So here we have a shot showing the clear removed exposing a fairly "polished" surface". I have been told that polishers never hit the sandcast production line however, I have no evidence that the P.O. or the original owner removed this hub and polished it themselves and re-cleared it. I know 100% for sure it wasn't the P.O. He would have had me tear it apart and do it for him! ;) (I worked for him when he was riding this bike) The clear was very thin similar to what we see on other aluminum parts.
(http://cb750sandcastonly.com/coppermine/albums/userpics/10001/rear_flange_finish_1.jpg)
Again, this pic shows the clear coat removed and the areas that are polished. It's almost like they went around it with a very large wheel, hitting the face and just catching areas like the boss's for bolts etc. No attempt was made to polish other areas.
(http://cb750sandcastonly.com/coppermine/albums/userpics/10001/rear_flange_finish_2.jpg)
This picture shows where I removed the clear coat on the face and casting area. The casting is clean to say the least. It has the appearance of solder when melted and allowed to drop on the floor. Very shiny and clean, but not polished. I'm having a hard time believing this part and finish are not original to 576.
(http://cb750sandcastonly.com/coppermine/albums/userpics/10001/rear_flange_finish_3.jpg)
Clear coat is still firmly in place over the polished areas after 43 plus years if it is original. I have been doing a LOT of thinking and reading about this lately. We know the original aluminum parts had clear coat on them and yes it chipped off in areas over time. Oil filter cover would be a prime example of an area that's going to get road rash quite quickly. Front of rocker cover is another...fork lowers and the list goes on. I'm going to go over the remaining aluminum parts I have and look for evidence of original finish. I remember one of my fork lowers had a lot of grime and evidence of the original finish underneath. So yes, I'm leaning to a finish with a clear coat over it, just as it came from Honda. Perhaps with the superior products we have today it will stay on much better. 576 will for the most part be a trailer queen as long as I own it anyway! ;)
I'm going to have to get another flange as this one is ruined from the chain guard. The BIG challenge is how to bring that original casting look back. ???
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Hi Wayne,
Looks like we had the same weekend project. I think what you have is original and typical. The polisher hit the areas that could be hit easily and that's it. And I agree on the clearcoat too although the clear coat on my hub seems to be fairly thick. Before you give up on your flange you might want to check out post #388 on my #97 thread.
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Mark
Nice job on your repair. On mine the "step" goes from the good area at 4.30 MM down to 1.60 MM. Looks like I have about a 2.7 MM gouge. :(
(http://cb750sandcastonly.com/smf_forum/index.php?action=dlattach;topic=850.0;attach=1251;image)
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:o Wow, that is excessive. You're right it might be best to try to locate a replacement. On the other hand you've got nothing to lose but I think you're past the point of handwork and you might have to find someone to put in on the lathe. The outside edge does taper down. Yours would just taper down more and when in place may not be that noticeable. I'll keep my eyes open for one. Good luck!
Mark
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Thanks mark. Steve has one but it doesn't have the stampings on the back side that he could see. (mine has "3" and "13") If I shave it down the outside thickness will be 1.45 MM (0.057") at best. I think I'm better off with the replacement and trying to get the finish as close as I can.
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Wayne, could you post some pics of the "3" and the "13" ?
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Wayne, could you post some pics of the "3" and the "13" ?
Ask and thou shall receive! :) The numbers are tiny!
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I'm would think these numbers qualify to go in the "Distinctions" thread... ?
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Would be nice to see what the number progression is through the VIN breakpoints. Some are stamped as per my 576 and some are cast in. Wonder what they mean?
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Good point.
I recall you commented prior, noting cast markings. What vin were cast markings noted ?
Supposition on my part, could the markings be dates ? "3" "13" being March, 13.... ?
We have identified at least 3 types of markings; ink stampings, indented stampings and cast stampings. Some stampings have three sets of numbers, supporting stampings mean day, month, year. Other stampings, if i recall correctly, such as swing arm and oil tanks have two sets of stampings; suggesting day and month stampings, no year. And, other parts on later vins have cast stampings we suggest to be dates of casting...
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This post isn’t exactly about finishing the hub but it kind of fits so I hope you don’t mind Wayne. I looked a little closer at mine. The one from #1553 looks pretty similar to yours. This hub doesn’t have the three center punch marks on it although I think it did have the recall cushions.
(http://cb750sandcastonly.com/coppermine/albums/userpics/10002/DSC09600.JPG)
But here is the odd thing. The one from #97 appears to have what looks like gouges or maybe a better description would be wrinkles. It is on all four posts. Is this damage from road blast or just a poorer quality casting? Has anyone seen that on early flanges? If this is original then I definitely want to keep the look. If it is damage I might want to try to sand it out or maybe use the one from #1553. I did score on some early no hole cushions so maybe it’s not a bad thing to lose the recall history. #97 is way beyond making original but I am striving for correct like it came from the factory.
(http://cb750sandcastonly.com/coppermine/albums/userpics/10002/DSC09577.JPG)
And I checked the numbers. Mine are stamped. Here is #97. It looks like a C and the number 12. Is it maybe a 6? First one with a letter? If this is a date code then I would like to keep it on #97 of course.
(http://cb750sandcastonly.com/coppermine/albums/userpics/10002/DSC09598.JPG)
Here is #1553. It looks like a number 5 and 18. Any more theories?
(http://cb750sandcastonly.com/coppermine/albums/userpics/10002/DSC09597.JPG)
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May 18... ? seems fairly implausible, given one would think vin 97 would have come off the assembly line before the end of March... ? and Wayne's 597 has "3" "13" stampings... ??? Makes me want to pull the rear wheel off 232... :o
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Mark
That damage at first glance to me looks like something got caught up and wrapped around the flange??
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Mark
Your flange from 1553 looks as bad as mine! How were you planning on fixing it? I sent pic's to my welder and didn't even hear back from him! :( I have one coming from Steve however if these things can be repaired with relative transparency I would rather do that. I believe the markings on any piece, as long as they are documented bring value and make the restoration more faithful to the original bike. We know each bike seems to have it's own unique markings. Are there 2 sandcasts truly alike top to bottom? (apart from VIN)
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Are there 2 sandcasts truly alike top to bottom? (apart from VIN)
i would suggest, perhaps the later vin LH horn bikes. Would think alot of the RH horn bikes are the same.
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Are there 2 sandcasts truly alike top to bottom? (apart from VIN)
i would suggest, perhaps the later vin LH horn bikes. Would think alot of the RH horn bikes are the same.
I was thinking right down to the nitty gritty detail Steve, like date stamps and stamps such as these. What are the chances that 2 bikes got components all dated the same, stamped the same, same range of parts if there was a production change and so on. It COULD be a bit mind boggling when you get right down to it no?
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Mark, those marks on your drive flange are from the chain having jumped off the sprocket at some point. Usually down to a stretched drive chain, and a careless owner who didn't adjust it soon enough. It acts as a saw once the chain has jumped off and you try to ride off again.
Regards, Steven
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I think you are right Mr Swan, the early bikes are a bit hit and miss with component parts, whereas as the VIN numbers increased there seems much less in the way of surprises. My 248 has 2 scalloped exhaust spigots and 2 early standard Spigots. I couldn't see the original owner changing 2 of these so I have assumed there was a change afoot with this particular component at about this time
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Agreed Wayne, no two alike.
As fare as the sprocket carrier stampings on #97, if the "5" "18" were May 18, then #97 would not have received that part until at least that date. Given 97 was very likely assembled not long after the completed assembly of #1, kind of hard to imagine the rest of 97 sat around until mid-May wiating for assembly.
The "C" is another confunding stamping.. ?
"5" "18" is from vin 1553..... :-[ OOPS.... misread. my bad. this stamping does make sense for being May 18.
I'd agree w/ Steven V on those marks. They do look like they were made in a rotational line; as Steven suggests, from a jumped chain. Lucky the cases were not broken... :o
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Mark,
regarding the print date my tought is an alfhanumeric classification:
C=March
12-the day of the month.
In this way the date seems to macth with your early vin, as Steve says.
About damage on the flange, i think at external factor (chain?) because the damage is also on the fins, i do not think at poor sandcasting.
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regarding the print date my tought is an alfhanumeric classification:
C=March
12-the day of the month.
That is a plausible theory. Anyone else have numbers?
Your flange from 1553 looks as bad as mine!
Actually it is better than 97 was. The thinnest part of the edge is .140” (3.5mm) so it will clean up nice.
(http://cb750sandcastonly.com/coppermine/albums/userpics/10002/DSC09630.JPG)
Wayne, sorry again for hijacking your thread. Thank you all for the great feedback. I agree that it has to be chain damage. I’m not sure it can be removed and still look decent. So now I have a tough decision to make. Try to clean up the flange from 97 or use the one from 1553. It would sure be nice to see what numbers were on a flange from oh, let’s say like the 2xx range.
Makes me want to pull the rear wheel off 232...
It makes us want you to pull it off too. ;)
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Hijack away Mark. That flange from 1553 will clean up no problem. I wish 576's was anywhere near that good. :(
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Well I bet you can all guess what I decided to do. Try to save the flange for 97. I took some sandpaper to the worst area and it took a while but it will clean up. One down and three to go. Just not today.
(http://cb750sandcastonly.com/coppermine/albums/userpics/10002/DSC09631.JPG)
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Good one ! "It makes us want you to pull it off too."
Bravisimo, Riccardo ! "C" = 3 = March.
Hmm... Mark, now you've dared me.... Ha ! l'd have to do some major moving to get to 232 to remove the rear wheel.