Author Topic: Am I going to regret not buying this crank?  (Read 2027 times)

Online Greybeard

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Am I going to regret not buying this crank?
« on: 09.12. 2015 19:01 »
Stated as a standard crank
http://goo.gl/Bh93Pz

Offline RichardL

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Re: Am I going to regret not buying this crank?
« Reply #1 on: 09.12. 2015 19:59 »
It is a chunk of change but, then again, it has two or three grinds left on it. I suppose it depends on how bad you need it. MB-Transits is a member here, maybe he would consider a member discount.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online Greybeard

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Re: Am I going to regret not buying this crank?
« Reply #2 on: 09.12. 2015 20:21 »
I don't need it at the moment but you can bet your life that when/if I do need one they will be double the price!

Offline Rocket Racer

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Re: Am I going to regret not buying this crank?
« Reply #3 on: 09.12. 2015 20:35 »
Personally I'd only be looking for a crank if I was worried about how worn my engine was and also knew it was already well undersize. Or it was apart and I knew it was beyond redemption
A std crank would be nice but is your existing crank that bad it will need replacement next time the motor comes down?
That's a lot of money for something you might not ever need.
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Re: Am I going to regret not buying this crank?
« Reply #4 on: 09.12. 2015 20:52 »
Don't worry, I'm not buying it.  *smile*

Offline RichardL

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Re: Am I going to regret not buying this crank?
« Reply #5 on: 09.12. 2015 21:29 »
In the case of my machine shop, I thoroughly believe them whey they say they can build-up with a high-quality weld when (no "if" while I can ride) I need it. So, short of breaking it in half, I, too, must pass on it.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline TT John

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Re: Am I going to regret not buying this crank?
« Reply #6 on: 10.12. 2015 10:05 »
I had to replace a crank just after I did a rebuild on my 57 Golden Flash but I had my old one rebuilt up with weld and then ground to the original size, they did a fantastic job but it cost me £300, that is a small journal one, which is now waiting in stock, hopefully I won't need it but you never know. *wink2*

Offline nimrod650

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Re: Am I going to regret not buying this crank?
« Reply #7 on: 11.12. 2015 18:55 »
regarding building up with weld dont they metal spray anymore

Online morris

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Re: Am I going to regret not buying this crank?
« Reply #8 on: 11.12. 2015 20:20 »
regarding building up with weld dont they metal spray anymore

Basically talking about the same thing here because "metal spray" can be regarded as a form of welding:
https://en.wikipedia.org/wiki/Thermal_spraying
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Offline jachenbach

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Re: Am I going to regret not buying this crank?
« Reply #9 on: 12.12. 2015 00:00 »
Seems awfully expensive to me. I sold 2 or 3 spares last winter and don't think I got more than $250 US for any of them. And I thought that was a lot.

Online mikeb

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Re: Am I going to regret not buying this crank?
« Reply #10 on: 12.12. 2015 03:07 »
if you look at the second pic (of the timing side end) or the first pic and zoom in... looks like the shells are in place protecting the  main journals but those journals don't appear to have much of a radius. i'm no expert but if that's true it's likely been metal sprayed already....?  *eek* I think I'd want to view a better photo for that $$$
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Offline coater87

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Re: Am I going to regret not buying this crank?
« Reply #11 on: 12.12. 2015 14:53 »
if you look at the second pic (of the timing side end) or the first pic and zoom in... looks like the shells are in place protecting the  main journals but those journals don't appear to have much of a radius. i'm no expert but if that's true it's likely been metal sprayed already....?  *eek* I think I'd want to view a better photo for that $$$

 If you look even closer, it looks like there might be some inclusions in the same picture. If that crank was here in the states, I would say we are nuts and thats at standard. Being its across the pond, I am going with more than likely a built-up crank.

 You guys over their were much more prolific at rebuilding and keeping vehicles. Over here people just seemed to buy new or trade up. Once it needed a complete rebuild, it was parked or junked.
Central Wisconsin in the U.S.

Offline RichardL

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Re: Am I going to regret not buying this crank?
« Reply #12 on: 12.12. 2015 15:56 »
Well guys, as I said, MB Transits is a member here, so you could try sending a PM (or a question through eBay) if you are interested. For my way of thinking, and for that money, I go by the old saying: "better the devil you know than the devil you don't know," which would lead me to a genuine weld-up and regrind. i don't know how much that would actually cost, but I doubt it's close to $700.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline nimrod650

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Re: Am I going to regret not buying this crank?
« Reply #13 on: 12.12. 2015 16:33 »
you can see by the prices why they buy a nice a10 and break it for parts

Offline BSA_54A10

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Re: Am I going to regret not buying this crank?
« Reply #14 on: 16.12. 2015 21:59 »
The crank represents 40% to 60% of the entire manufacturing cost of the engine which is why so many companies use the same crank on several different capacity engines.
Before you ask, 40 % for malleable iron or steel casting
And 60% for a forging.
Cast cranks are a tad heavy for motorcycles and do not generally get used in high stress engines.

Over time the interstitial defects within the metal itself migrate and it looses strength.
Thus it is a good idea to get them carbonitrided when you pull them out.

BSA cranks are somewhat over engineered so can get ground down a lot further than most would believe.
We had a memebr with an imported A 65 where the crank main was at - 0,15" , yes 150 thou undersized and he rode it like that for a year or so, no problems till he decided to tear it down and saw what was in there.

Metal spraying and welding are totally different processes despite what an ill-informed Wikki ego posted.

Welding is just that, the molten weld metal builds up a molten weld pool on the surface of the crank, thus changing its grain structure if the crank was forged and the grain size if the crank was cast.

Metal spraying splatters the very hot but still solid  surface of the crank with tiny droplets of molten metal which diffuse into the solid crank a very short distance, It does not change the grain structure of the crank unless done too hot or too slow ( to long ) and allows grains to reform and thus get bigger ( weaker ).

Each process has its pros & cons and they are not just 2 different ways of doing the same thing.
Some applications don't care but a lot of times one will be better suited than the other.
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