classic motorcycle forum
Motorcycle Discussions => British Bikes => Topic started by: henry_norton on September 29, 2008, 02:16:24 PM
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I'm trying to find some information on the optional bronze head Triumph fitted to their pre war Tiger 100s. Has anyone on the forum got any pictures they could post or even a link to a picture on the web?
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As far as I know the bronze head is exactly the same as the standard iron heads (except for the casting material of course), possibly with the exception of the casting number adjacent to the spark plug holes being different.
There was a bronze head on ebay a few months ago for circa £2000. Prior to that the last genuine one I saw up close was on 1939 T100 reg No HDH 364 (featured on the cover of Classic Motorcycle in 1984ish) which I believe was sold to Holland approx 12 years ago. As with all rare parts these days, there are fake bronze heads out there which are basically iron heads with varying shades of gold/bronze paint applied.
If you are looking for one good luck !!. I've been looking for a sensibly priced one for the last 6 years.
I've been told that they had a habit of cracking when they were new between the bolt holes especially the centre holding down bolts and were then replaced with the standard iron head.
I'll see if I can find a photo and post.
Regards,
Martin
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Thanks Martin, £2,000 !!!! That's just about what my 65 Bonnie's worth.... It's not surprising less scrupulous people are painting up iron heads gold, but pretty outrageous none the less. Anyway, thanks for the reply - I'd still like to see a picture if you've got one but, like yourself, I think two grand is a bit steep, even for a cool (and cooler running) bit of kit like that.
Best of luck in your search. HN
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If you find one and take your special bronze magnet with you it would be easy enough to establish it's credentials!
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Bronze magnet!!!! Is that otherwise known as a pen knife to scrape away the bronze coloured Humbrol enamel? ;)
If I was laying out £2,000 I'd probably want it sent off to a lab for analysis......
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I can sell you a 'bronze magnet'. It works equally well with any non-ferrous metal. Ten quid to you.
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Thanks for the offer - I've never heard of a magnet that sticks to non ferrous metals except induction coils. That's definitely something for another type of forum though....
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Henry
Think about it. A standard magnet will stick to a cast iron head, painted or not. No need for a penknife etc. My spoof (bronze)magnets, wil stick to any ferrous metal and will NOT stick to non-ferrous metals. Hence a 'bronze magnet' will stick to a pretend bronze head and not to a proper bronze head. They don't stick to wood either!!!!! (If I used smileys there would be guffawing one here). Cheers.
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Hah!! You could make a million with that idea mate!!! ;D ;D ;D
Maybe the fakers out there should put away the bronze paint for the moment and get out the wood chizels. How else are they going to beat this new magnet technology??? ;D
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Well, after 18 months I've now had the chance to put that theory to the test and it works !!!
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What? Bronze magnets?
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Yes Bronze magnets, they work perfectly, you should give Draper or Machine Mart a call and sell them the idea !!
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Hi All,
I just discovered this forum and topic and thought I'd reply. I owned a 1939 tiger 100 with the bronze head for many years. I bought it for 325 quid in the late seventies when I was an art student and sold it around the end of the nineties if memory serves. This may not be correct, but when I did the first rebuild and went to buy new valves, guides and springs I was told that the exhaust valves were of the larger, post-war type and guess this could be the difference between the bronze and iron heads. The bike had been raced after the war at Brands Hatch and came with what I was told was a McCandless swinging arm conversion, twin carbs and a finned rear brake hub and drilled sprocket from its racing days. Also 9.5-1 pistons which made it fly until in my ignorance I punched a hole in one using too low grade petrol. I kept it running in many guises with little or no money, but it was incredibly reliable, my only transport, taking me through many winters, snow and all, and even a tour round France. I sold it when I left the country for some years to guy who said he wanted to race it, but I never kept up with him and haven't been to the vintage races for many,many years. Not a huge amount to add to the sum of knowledge on bronze heads, but a rather pleasant nostalgia trip for me. Cheers
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Speaking of bronze heads, coincidentley there are 2 of them for matchy singles on Oz ebay at the moment, one starting at $2,000!!
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Hi All,
I just discovered this forum and topic and thought I'd reply. I owned a 1939 tiger 100 with the bronze head for many years. I bought it for 325 quid in the late seventies when I was an art student and sold it around the end of the nineties if memory serves. This may not be correct, but when I did the first rebuild and went to buy new valves, guides and springs I was told that the exhaust valves were of the larger, post-war type and guess this could be the difference between the bronze and iron heads. The bike had been raced after the war at Brands Hatch and came with what I was told was a McCandless swinging arm conversion, twin carbs and a finned rear brake hub and drilled sprocket from its racing days. Also 9.5-1 pistons which made it fly until in my ignorance I punched a hole in one using too low grade petrol. I kept it running in many guises with little or no money, but it was incredibly reliable, my only transport, taking me through many winters, snow and all, and even a tour round France. I sold it when I left the country for some years to guy who said he wanted to race it, but I never kept up with him and haven't been to the vintage races for many,many years. Not a huge amount to add to the sum of knowledge on bronze heads, but a rather pleasant nostalgia trip for me. Cheers
Hello Alianco, the bronze head I have has larger inlet valves and the exhaust valves are standard, haven't run it yet but will probably have to tinker to get it running right. I have a picture of a T100 with Mc Candless rear springing and a bronze head which was for sale a few years back, but don't know how to post pictures on here, any help appreciated ?
Regards,
Martin
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Hi Martin, I'm sure you're right about the valves, it was thirty years ago. I'd be interested to see the picture you have, but like you I can't see how to attach a photo or I would put up one of mine in its last guise. Maybe someone more computerate could advise.
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Open an account with photobucket or similar, free of charge, download the picture and copy the image code on here, the picture will appear as below. .
(http://i690.photobucket.com/albums/vv261/Trifield/HPIM0950.jpg)
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Here's how you attach a picture. Reply to the post as you would normally, and at the bottom left of the screen you will see an "Addditional Options" button. Press this, and you will find the attachments option.
Cheers
Nigel
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Here (I hope, following Nigel's instructions) is my Tiger 100 with bronze head and McCandless swinging arm conversion. The seat was from a cossack since their industrial rubber ones were more comfy and didn't disolve like the pattern ones after a year. The two-into-one was stainless for all weather riding and no garage and the brooklands can was just a bit of fun. The purists may well have a heart attack, but it was year round transport and apart from poor brakes, dull lighting and a rather flexible, bolt-up frame it was a great bike. Cheers.
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Many Thanks Nigel,
Alianco,
Here's the pictures of the one I saw for sale.
Kind Regards,
Martin
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Hi Martin, Yep, that's my bike, FBP 627. So it didn't end up as a vintage racer after all. Pity, I rather liked the idea of someone thrashing it around the track. I certainly would never have the bottle to do it. Apart from the pipes, silencers and seat it looks pretty much as when I sold it. If you look closely at the rear shocks you will see a bright ring below the spring. When the old ones went west I could only afford a special offer pair for a much lighter bike and it virtually bottomed out so I turned up two, thick aluminium blanks to pre-compress the springs. They must be over twenty years old now. Can you remember where you saw it for sale? I'd love to know what happened to it.
Cheers
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Alianco, I'll PM you the email address of the seller so you can contact him direct. Kind Regards, Martin.
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Thanks Martin. I emailed him and it turns out he swapped it with a mate in the UK for a Vincent in bits. Who knows, I may even get to have another go on it.
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Hi Alianco, An interesting story about the bronze head tiger you had. Great story, particularly about your travels and the Post war Brands Hatch history. I often look at this site and enjoy the comments about `is it or isn`t it a bronze one. Please don`t scrape heads with a pen knife, particularly if the owner is in the near vicinity!!!!!. I can help you with some of the history. It was indeed swapped for a dismantled HRD Vincent, a series A Comet that was accidently discovered in a municipal dump at Hayes in Middlesex,found 2000, cost £40 and swapped two and a half years ago. I am very pleased to inform you that FBP 627 is alive, taxed and MOT`d and well cared for up in the Chiltern Hills. Please leave message as i am very interested in any historical details of this machine. You may well be able to sit and ride this bike again if we can arrange it. I will try to post photo of what it looks like now and i have a copy picture of it with siamese ex/p and Brooklands can that was passed onto me. Regards, Biggles
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I have just had my bronze 39 T100 cylinder head vapour blasted and it looks stunning , it's removed all the old staining and burnt on oil .
The bronze heads were originally painted black when fitted in 39 but after what it cost me there is no way it's going back to black !
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Have to question the statement that Bronze heads were painted black originally. I've seen pictures of original bronze headed bikes with no sign of paint on the heads ? Also Bronze heads were claimed to aid cooling due to the better heat dissipation properties of bronze, so painting them would surely defeat the object ? Heads and cylinders weren't originally gloss finished as they are now or powder coated, and I don't see how cyclinder blacking would adhere to the bronze ? What original documentary evidence is there to support the theory the head were painted ?
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Bronze would be fairly easily chemically blacked though, using a sulphur compound like artists use for bronzes. This would prevent them corroding to a green finish in any humidity, and assist heat loss.
Although they do look spectacular in freshly cleaned finish.
There is also several things they could be dipped in to preserve the bronze looking finish - period photos may well show how they looked in b&w photos, which would give a clue.
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I have spoken to someone who has owned two bronze heads for a 39 T100 and he said both were black or black paint stuck between the fins .
My bronze head also needed the old paint removed from between the fins before i could have it vapour blasted . I have seen the racer T100 in the picture you have posted and know it was an original bike ordered with a bronze head in 1940 but it would have been pulled down and cleaned up a few times in its racing life ?
I am not 100% sure that they were painted black but i think they must have been , i think the people who paid their £5 in 39/40 would be just as keen to show it off as i am and maybe most were polished up for looks .
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I think pride of ownership here is ignoring basic physics. The bronze head was an interim step between the cast iron head to aluminium alloy as we have today. It only existed because it could get rid of heat a little bit better than cast iron. If it was black it worked even better. Polishing it reduces its ability to shed heat. Dark surfaces radiate heat much more than shiny surfaces.
The theory behind the bronze head was that better cooling meant that when running on petrol you could raise the compression ratio higher than was possible with a cast iron head. All things being equal, a higher compression ratio gives more power.
Obviously if you blackened the head you maximized its ability to shed heat so the compression ratio could even be a little higher.
If you want to take advantage of the reason the bronze head exists, blacken it. If you just want show what you have keep it shiny but only run the standard compression ratio.
Cheers,
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Hi , Yes that's all correct Even though i am sure they were black from the factory this is the one thing i will be happy to be "wrong" .
My bike is used for ride outs and sunny days and is not used for classic racing , as i dont need to squeeze the last drop of power from it i am more than happy with my "blingy" head . Horses for courses as they say .
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Bronze head fitted to 1939 T100
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If you've also fitted bronze valve guides, ensure the rocker oiling supply works and you get oil lubricating the valve stems, otherwise the valves stick............
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Hello Martin , After asking a few different people i went with the cast iron guides rather than the bronze ones , time will tell if that was the right thing to do but three out of the four i asked told me to go with the iron guides .
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Yeah, I toyed with the idea of iron guides which would have been "self lubricating" but opted for bronze so I didn't get differentials in the expansion and contraction properties of the two materials. Had to upgrade my oiling system though as a result.
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The expansion rate of cast iron is faster than bronze so at least they will stay tight in the head , also i think you could buy the bronze head from Triumph with cast iron guides ready fitted for £7.4s in 1939 .
My bike had covered over 78,000 miles in it's long life and although it was well worn out this was done with the standard oiling system to the top end so with the low thousand miles i have planed for it i am sure it will be fine , fingers crossed !
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The expansion rate of cast iron is faster than bronze ...
I doubt that....
Cheers
Andy
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Cast Iron 5.8 microinch/Deg F
Phosphor Bronze 9.9 microinch/Deg F
As per http://www.engineeringtoolbox.com/thermal-expansion-metals-d_859.html
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Sorry esometisse and bomber i got that arse about face and got that so wrong . I will have to take it for a spin and listen out for the guides going up and down with the valves !
Hopefully they will be tight enough to stay tight but now i am worried :(
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Picture from "front on" now it's up and running sweetly
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1939 Triumph Tiger 100 fitted with bronze head ( title of a short youtube clip now posted online if it is of interest to any readers )
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Bronze cylinder head for a 1939 Tiger 100 on ebay now .
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It's a very rare Bronze head too as it was made in 1946 , one of a special small batch made by Birco in Birmingham for Triumph as spares for pre war T100 privateer racing bikes, hence why it has the post war part no cast into the head E2258 albeit on the other side to the iron heads being made at the time.
Well worth a punt at it's current price....be interesting to see what it finally goes for.
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It's a very rare Bronze head too as it was made in 1946 , one of a special small batch made by Birco in Birmingham for Triumph as spares for pre war T100 privateer racing bikes, hence why it has the post war part no cast into the head E2258 albeit on the other side to the iron heads being made at the time.
Well worth a punt at it's current price....be interesting to see what it finally goes for.
Wow ! never knew anything about post war bronze heads ! My bronze head has E 1454 B cast into it , the same number that is cast into the iron heads .
All the bronze heads i have seen have this number ,that is until i spotted this one on ebay .
Thank you for the info Martin
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No worries.
The only reason I know this is one of the bronze heads I have is a Post War one and I had the details confirmed by Hughie Hancox when he was alive. So now someone has posted the question of its rarity on ebay for all to see...I'm interested to see how much it goes for :)
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I saw that on ebay's latest posting about the head and thought you had posted that up .
I have a picture of a restored 39 Tiger 100 that came out of H H workshops with Speed twin exhausts on it , he stated that " they were not fitted with the removable end caps until 1940 " so he was not always 100% correct but this info about the head rings true .
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No I didn't post it up, I thought you did !
My head is slightly different from the current head on ebay as mine has the internal oilways as well as the external oil drains fitted so it could be fitted to either 39/40 or 46 bikes.
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sold for £3,2030 !!!!!!!!!! the bronze head on ebay .
That's a lot of money , it did come with some rough 1946 Speed Twin crankcases but i'm sure that did not add a great deal to the value .
Even if it was cast for Triumph by Burco in 1946 and is rare i cannot see it being worth more than a genuine bronze head made by Triumph in 1939/40 ?
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That's a chunk of money, but then again, my mate was moaning a while back about an Inter tank going for £500 odd and an Excelsior Manxman engine going for £1400 recently, so I suppose when we're buying rare parts for high-end bikes we're all going to have to get used to paying top-dollar.
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Runesika,
Triumph didn't cast the heads in 1939 either...they were cast by Birco on behalf of Triumph as was this 1946 head. I'm sure Rob Stockdale could confirm this if you ask him.
Just goes to show there's a lot of people out there with more money than sense !
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Runesika,
Triumph didn't cast the heads in 1939 either...they were cast by Birco on behalf of Triumph as was this 1946 head. I'm sure Rob Stockdale could confirm this if you ask him.
Just goes to show there's a lot of people out there with more money than sense !
Hi Martin ,
Oh i see what you mean now . So do you know if Birco cast both the bronze and the iron heads for Triumph ?
Martin , you talk like you have a bronze head spare , are you now booking a safety deposit box !!!!!!!!!!!!
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Warning !
Bronze head on eBay with 1946 crankcases AGAIN .
Seller in Scotland, 0 % feed back .
Seen it before with same old pictures , I'm 99.9% sure it's a con so buyers beware!
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Be wary of anything for sale in Scotland, doubly so if it's supposedly in the Isles, as it seems to be a favourite of the Nigerian scammers..
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Scammers use Scotland as its remote and the last thing they want is "pay on collection" even if it shows as an option .
Worth saying you want to collect and wait for the excuses as too why they need to send it .