1007 crank broken

Hi , last week we dismantled my friend and I, his 1007 engine, after a sudden knocking noise during a track days practice, and making it short , we found the timing side bearing damaged , and a tiny crack in the relevant crank cheek... no good ! we stopped working in the shed and go up to have some beers! I sent an email to Steve , and he does'nt have any crank available as spare ( he had enough spares to build two 1007 engines, and that's it), so back to the beers......! the day after , (no beers!) back to the shed we started thinking how to use the 1007 remaining parts ( which are all exclusives : pistons, cases, barrel) and fitting a 89mm std crank , and we roughly calculate that we had to machine down something (head, barrel case) with 4mm, but yesterday my buddy call me to say he had made a mock up and with 1007 (83mm bore) piston and 89mm crank there are allready 0.5mm protruding above the jugs....! the squish depth of the 1007 head beeing 2mm, something is either wrong or not logical ( to my mind!!), I cannot check myself ready now ( 5hours drive from him).
Then however , as we are both short of cash and cannot afford a billet new steel crank ,we have to make a steel flywheel to use the std cdo crank we had , which steel is the best to use , 4340 ? I had found a guy selling slice of that specs 180mm dia, and 25mm or 50 mm width, my friend is a retired tool maker from aerospace and can do it or at least try to do .........! any thoughts ??

4340 would be plenty adequate for the flywheel. I would say even a milder steel will be plenty adequate for the flywheel when considering the OEM stock flywheel was cast iron.

If it were me, I would beg, borrow or steal to get a solid billet crank made for 1,007cc capacity. There is no replacement for displacement. Is your friend up to the task of making one himself?

I just saw a complete 1,007cc Steve Maney race motor on EBay. Maybe you could purchase that motor and fund it by parting out your 1,007cc.

Exactly where was the crack on the crank. If it were the rod journal, had the crank be ground undersize?

Hi dance, thanks for your reply, about steel specs, about billet cranks I had asked to Falicon and M.A.P, no way, even Triumph ones are on short list ! and my buddy tho competent cannot make a full billet one, just the flywheel and we could "copy" the full circle one as per the german guy
http://www.britishclassicbikes.de/index.php/produkte/norton-produkte
the crack is going from the cheek journals to the side of hat cheek , tiny but lethal !! and yes the it had been ground once due to a rod failure few years ago , and I had read the post ( just yesterday , too late ) https://www.accessnorton.com/Norton...and-high-compression.23016/page-2#post-341098

Moldex crankshafts can make you just about anything. They have made various solid billet Norton cranks for me and others in the past.

Moldexcrankshaft.com


There’s also Ro-Dy Machining in Plymouth, Michigan here that does billet cranks for Norton’s, BSA and others. I have heard very good things about them.

860 N Holbrook St.
Plymouth, MI 48170
(734) 459-9335

They run an add in the following link:
VFT.org

It sounds like the one cheek of your crank is kaput!

Have you considered just having the one cheek remanufactured or maybe a new pair of cheeks?

Why not just use the flywheel from the 1007 crank, fitted to the stock 89 mm stroke drive and timing side halves that you are planning to use? You might have to bore the bolt and stud holes in the halves out from 5/16" to 3/8" to match the flywheel, but that's not a very complicated procedure.

Ken

Ring Mick Hemmings for a billet crank, he can get them made any stroke and configuration, rods too

Hi Ken, the 1007 flywheel bolt's holes are not on the same PCD than the std cdo ones , a needs to be plugged and redrill we had thought of that , but that will make new holes pretty close of old plugged ones and so not very safe to our mind !about a new crank billet we ( or least he is a bit short on cash , me too ...!) and we want to use what we had , but I will ask ( I am just the spanner monkey and the english speaking guy , tho seeley owner too !) to Mick , and why not to Moldex and others , but I guess that will be in the 2500 USD range ( and we had the import tax of 25% ...so UK could be a far better option ).

Hi,
I have a company here in Belgium that make billet cranks and less cheaper
PM me if intrested
Yves

marinatlas said:

Hi Ken, the 1007 flywheel bolt's holes are not on the same PCD than the std cdo ones , a needs to be plugged and redrill we had thought of that , but that will make new holes pretty close of old plugged ones and so not very safe to our mind !about a new crank billet we ( or least he is a bit short on cash , me too ...!) and we want to use what we had , but I will ask ( I am just the spanner monkey and the english speaking guy , tho seeley owner too !) to Mick , and why not to Moldex and others , but I guess that will be in the 2500 USD range ( and we had the import tax of 25% ...so UK could be a far better option ).

Click to expand...

Interesting. Steve started out in the crank business by making steel flywheels for stock cranks, so I assumed that when he started making all three parts, he used the same bolt pattern, except for fitting the larger 3/8" diameter fasteners he uses. Sounds like that was not a correct assumption. I have several of his crankshafts, and have had a couple of them apart, including a 1007, but never thought to check the bolt pattern. I'll look more carefully on the next one to see what the difference is.

Ken

Marinatlas, I realise you are primarily focused on moving forward with your engine build currently, but I’m also very interested in the root cause of this failure (as I’m sure you are, as understanding and eliminating this is the ONLY way to ensure it does not repeat).

If I have read your post correctly, the crank had an earlier re grind due to rod failure. Is your hypothesis that the failure is due to:

1) not having it re nitrided afterwards?
2) the stress relieving radius not being re ground correctly?
3) stress induced by the earlier rod failure?
4) Or is it due to an inherent lack of strength in the crank design?

Hi Eddie (?), that's an interesting point, first it's not my bike , so I do not have all the infos regarding the past , but I am very close with it's owner and followed him on most (but not all) of his sessions, the engine is a full 1007 kit from the right person , head stage 3, only deviation is BSA type camfollowers (as JS), don't remenber which carbs are on ...! the first failure was a rod ( steel one ) but drive side one ( I hope I remenberb but willcheck by phone later on)! ), so newsteel rod and regrind ( locally)and no re nitriding (quite sure of that), quality of radii not known, oil is Castrol R 40, I dismantled the engine with the owner on the last failure and everything was OK : head, piston, barrel, rods. After going on the dismantling the timing cover some bits of the outer cage of the timing FAg bearing were found inside the cover , but seems Ok (visualy and externally , so not yet put apart,then parting out the rods show nice bearing shells on drive side , and just slightly worn (not scored ) timing one, the drive side bearing was visually perfect , but not the timing one (as we guessed!!), then we found that crack (tiny too!) on the timing journal going to the cheek , so we asked ourselves who make the egg the hen or the hen make the egg !!!! for me if oil supply problem it's more often the left/drive which failed first , but......? when yesterday I read thoroughly this previous post
https://www.accessnorton.com/Norton...and-high-compression.23016/page-2#post-341098
I thought it could be the root cause, no re nitriding.........!
Steve told me he will retire soon , but have two years more to work , and so will not supply anymore some 1007 cranks (or just a cheek), as he got just enough spares to build two new engines .....
That bike had previously a 920 with std crank , and on the same track years ago the flywheel exploded through the cases so my friend went to a full 1007!

Hey marinatlas,

Any chance you could post some good photos of the crack?

I realise I’ll get lambasted for heresy here... but... have you considered cutting out the crack and welding?

You could also get the journals welded, ground to original size and nitrided?

Interesting about Steve wanting to retire. Let’s just hope Chris Bushell doesn’t buy the business!

Your words about limited spares for the 1007 make me glad I stuck with 920 for my project !

Hi eddie, no way about the photos , the crank is 5 hours drive from me (near Paris) and I am near St Malo ( Britanny!), just got the owner on phone right now , and as said he's short of cash ( we are both retired now, and we bought all our bikes and parts when at work...!) so , my advise , keep on working!!
my other buddy ( Dan Parker) in Blighty, is the one who sells currently his Seeley's fleet on the bay , due to job problems and others ...so same issue , for him no dosh in the pocket must sell some bikes for living , he even fancy to buy a house down here in small Brittany as they far cheaper than in Uk ..! so at the end about that engine my Paris friend will make a steel flywheel for his std 89mm cdo crank (spare one on the shelf!)and put it in the 1007, ending with 83x89 (around 962 cc), a cheap way of keeping on tracking.......

Well, I have 2 young kids, a wife, and a shed full of bikes, and therefore, zero foreseeable retirement options...!

Anyhow, 83x89 and 962cc sounds like it just might be a very nice motor!

Dave Nourish always told me that he preferred his 88.5 stroke motors to the 93 stroke even if it sacrificed cc's. He reckoned they had similar bottom end torque but were more flexible as they had a wider effective powerband to play with.

Don't know whether it would fit the remaining parts you plan to re-use, but there is a brand new Jim Schmidt's one piece billet crank for sale on the french Motos Classiques Anglaises web site. Price looks quite appealing!

PM me if needed.

Laurent