Just been out for a nice ride on my '59 A10, going really well but a weep from the breather. Got down on the ground to look and noticed some corrosion on the frame bottom tube. The more I looked the more rust streaks which I found odd as I had sanded and repainted this frame last year. Scraped the tube and soon opened up a hole about 3/8" dia and its obvious the frame is heavily corroded inside. Started the engine and a steady stream of rust flakes fell out the frame so my conclusion is its scrap. Pity as its a matching numbers bike.
I've never had a frame do this before, I've had the bike about 2 years and while there were signs it had been stored in a damp location, externally the frame looked fine. Riding it and the vibration seems to have exposed the problem.
I'll be posting for a replacement frame in the wanted section and trawling e-bay. Anyone else had this happen?BSA_reduced.jpg
Before scraping the frame it may be possible to cut ot the rusted part and let in a new piece.
I would be up for that but what concerns me is how widespread the cracks in the paint are and rust streaks. This is a frame that was painted about a year ago and showed nothing so I'm thinking the internal corrosion is widespread. Its also under the side stand bracket.
frame_hole_2.jpg
If it were mine I would try to find a damaged frame.I would get some spigots made and remove some of the frame and fit in another piece. A B series frame would do as a donor as well.
Seen a lot coroded frames, but not like this :(
Me neither!
At least you found it before it collapsed under you!
Hi,
Is this a clamp on stand? I think I can make out the remains of sleeve for a brazed side stand lug.
As standard, half of the clamp was attached to the frame and if the clamp became loose it could wear through the frame.
Dave.
I got underneath after the ride to look for the oil leak. When i wiped the frame I noticed the paint was lifting in many places. At first I thought stone chips but each one was coming though from inside, that hole is the one I dug into but there were many over the whole length on the bottom tubes. I ran the engine to monitor the breather (it is breathing too hard, that's another story) and a steady stream of rust flakes fell out the hole and made a little pile.
I'm sure the frame is toast but I've been riding BSA's a since 1971 and I never seen anything like this.
it used to be common on cb750 frames, the bottom rails had 1/8 drain holes that clog up and cause internal corrosion. its a red ticket mot failure as any light prang could be a disaster.
While clearing the work space to strip the bike I remembered the only time I'd seen corrosion like this was a car that had been by the coast all its life. Surface paint was fine but all the body was paper thin and corroded from inside. That got me thinking and the bike came with the buff log book:
Plymouth
Plymouth
Plymouth
Plymouth
Headcorn
Forfar
Montrose
Dundee
So its spent most of its life by the sea. Well at least that explains it. I think the condensation is salty and the air is always damp.
Got the frame off (or rest of bike off frame...) here's what its like underneath.
frame_hole_3a.jpg
Hi,
Is the other side the same?
Dave.
I wouldn't put my trust in anything from that frame.
I don't trust it. It does appear to be only on one side but there is evidence near where the side loop joins the top tube. OK its the same side but its high up. Thing is I sanded and sprayed this frame about 12 months ago and this wasn't visible. I'll cut it up when I get time, I'll need to keep the head-stock and number for when I negotiate with the DVLA at some stage. Its a decent bike and nice to ride so I'm looking for a good frame.
DVLA have tightened up a lot in recent years so I'd be careful about what you tell them. What some may advise is to try and get a frame with a V5C, build the rest of the bike into that & notify DVLA about the engine change. Or even without a V5C but then you'd have to build the bike up and get it certified by the BSAOC.
I don't envy you.
Is it not worth contacting a frame builder to quote repair / replacement tube , ,not sure if tery mèed is still going he has built some fantastic bsa frames ,its amazing what skill they have
Yes, though prior to that I'd get it media blasted to assess the extent of the damage, as those holes don't look to be feather-edged through corrosion.
A repair could be a whole lot easier than dealing with the DVLA, particularly so if you're going to start cutting off head stocks.
What the pictures don't show is the huge amount of delamination inside or the volume of rust flakes that fell out. I know the rust is many times the volume of good steel but I would not feel comfortable unless I had drilled quite a lot of holes or had some NDT done.
I drive an old Land Rover where chassis are regularly replaced, yes it gives the DVLA kittens but they get over it. I can get a frame from a parts dealer with a receipt and build the bike up and get back on the road. Then I can notify the DVLA and ask which route they prefer, change the reg or change the frame no. All I need is a dating cert if they want the reg changed and if the frame is linked to a reg that's not been cancelled then its just a small admin fee. Its common practice with the Land Rovers to cut off the dumb iron with the chassis number on and retain it for reference along with the purchase receipt for the replacement.
Its all just really annoying, the bike has never ran so well and I was looking forward to more riding. I've got a Matchless too so I can get out but its a low geared 350 so its not the same. I just got that all dated and registered so I'm up on the DVLA processes.
terry mead is still working on frames so no problem having it repaired.
he charges very reasonable as well.highly recommended. electric car dvla finally thinks it understands the offside rule and cant stop blowing the whistle.
I'm finding frames that are solid but have a bit of crush damage to the down tubes, probably from a chair or crash bars. If I have to go with one of those I'll give Terry a call. I'be be happier with that type of repair where I know all the metal is good than my frame where I have a lot of doubts. The other problem with my frame is that it will be hard to stop further corrosion inside now its taken hold.
I believe that some powder coaters and other places clean frames by dipping them in something horribly corrosive. Some frames have places where such liquid can get inside the tubes. I don't think they do anything about rinsing or neutralising anything that has got inside. It would be interesting to know if this frame had ever been dipped.
That's a good point and could be an explanation. It had corroded though at the top too where that tube joins the main top tube which would be odd for condensation so you may be on to something. I did a weld repair but it was odd and left a nagging doubt.
Quote from: Tigerfeet on 16 Aug, 2025, 20:07 I believe that some powder coaters and other places clean frames by dipping them in something horribly corrosive. Some frames have places where such liquid can get inside the tubes. I don't think they do anything about rinsing or neutralising anything that has got inside. It would be interesting to know if this frame had ever been dipped.
I've never known powder-coaters to use anything other than blasting media of some kind. Quick, cheap and very effective.
Platers, now, they like to dip things in 'orrible solutions..
If you are still looking at a replacement frame, new rules from DVLA mean you should be able to retain your VRN .... see https://www.gov.uk/vehicle-registration/repairs-restorations. It seems they will let you stamp the old frame number on the replacement frame (but need to overstamp old one with "-----") - but you need to check with them first (I sugggest). This was only released on 26th August, so not "bedded in" yet. If you do try this, please let us know how DVLA respond.
Yes I'm watching that very carefully. My interpretation is the same as yours, its both good and bad timing: its good because i have a frame and can stamp it, but its bad because it went to the poweder coaters un-stamped because I wasn't sure what the new rules were in detail. Now they have explained in more detail so I'll stamp it later and put a thin coat of paint over.
Two steps forward, one back.....