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+--- Thread: 2 bearing crank in 3 bearing case (/showthread.php?tid=7385)
RE: 2 bearing crank in 3 bearing case - Colin Reed - 13-04-2022
Hi KEITH,
A Couple of things make sure that the oil to the big end journal is clear.
and clean the conrod assemble and check that the bigend with out shells is round if not will need to be resized
last i would recommend not to rebuild B/E journal but to grind all four to ether 10 or 20 th under size depending on what the damaged B/E will clean up at.
Hope that is of some Help
Colin NZ
RE: 2 bearing crank in 3 bearing case - Ruairidh Dunford - 13-04-2022
The crank shown in Marcus’ photos is the type made by IKE.
RE: 2 bearing crank in 3 bearing case - Marcus Ling - 13-04-2022
Hi Ruairdh,
About 2 1/2 years ago I raised a question about IK Engineering as a supplier of A7 crankshafts and at the time no-one seemed to know anything about them and they didn't respond to anyone who tried to contact them. The thread was;
https://www.austinsevenfriends.co.uk/forum/showthread.php?tid=3409&highlight=IK+Engineering
Do you know some more information and are they currently supplying cranks. We assume that Keith's crank dates from 2014 so if that's true they have been supplying them for a number of years and it seems still advertising them. Did they also supply rods to go with them or are they from somewhere else
A real mystery.
Cheers
Marcus
RE: 2 bearing crank in 3 bearing case - Ruairidh Dunford - 13-04-2022
No idea, sorry.
RE: 2 bearing crank in 3 bearing case - Bob Culver - 13-04-2022
As with seat inserts sad tales of failed sprayed crank build ups abound. The usual response is "the process is now improved....."
And maybe not so much now when large radii are normal, but reconditoners were notorious for tightening the radii. If the crank is nitrided it is a pity to grind the radii, although I suppose with the larger crank the fatigue protection is less vital..
RE: 2 bearing crank in 3 bearing case - Henry Harris - 13-04-2022
(12-04-2022, 08:59 AM)Ruairidh Dunford Wrote: I have found that none of the newly made crankshafts I have fitted are symmetrical in this area.
The best that can be achieved is a central position that misses both troughs, statically. Austin cranks are perfectly symmetrical in this area and jets line up on both sides. Even with the asymmetrical positioning on the new cranks, little problem is ever reported, this includes the several hundred I have fitted and makes me think that lubrication at revs come more from mist than a little low pressure oil jet.
All the Austin made 1 5/16" cranks that I have seen have asymmetrical oil troughs.
1 and 4 are at 5 3/8" centres
2 and 3 are at 5 1/8" centres
I don't have a crankcase to hand to check the oil jet centres but I wouldn't be surprised if they were at 5 1/4" centres.
This detail is from the factory drawing of 7th February 1950
RE: 2 bearing crank in 3 bearing case - Ruairidh Dunford - 13-04-2022
Thanks Henry,
I guess my point was that the Austin design is darn sight closer than any of the reproduction ones I have fitted. But as noted above, I am not sure that seems to matter, at least not for 1 5/16”.
I have a similar blueprint - possibly the same source - I noted several variations in the finished cranks and wonder if this was the copy kept in the drawing office and it is the one that went to the shop that had all the final details for production added to it? I would like a copy of that one for sure.
RE: 2 bearing crank in 3 bearing case - Humps - 13-04-2022
A friend who has built a type 59 Bugatti motor virtually from scratch is advising laser welding for the crankshaft build-up. At the moment, this is the way I plan top go.
RE: 2 bearing crank in 3 bearing case - Ruairidh Dunford - 13-04-2022
Sounds good, have you worked out why it has failed, twice, and rectified the problem?
RE: 2 bearing crank in 3 bearing case - Charles P - 13-04-2022
(13-04-2022, 09:42 PM)Humps Wrote: A friend who has built a type 59 Bugatti motor virtually from scratch is advising laser welding for the crankshaft build-up. At the moment, this is the way I plan top go.
Do you know if the crank was nitrided?
The IKE site suggests they were EN40B, a nitriding steel, although the website may not be the most reliable source.
If it is nitrided then laser welding may not be advisable
Charles