Author Topic: Small journal crank re-grind?  (Read 1194 times)

Offline TimK

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Small journal crank re-grind?
« on: 22.08. 2016 07:18 »
I'm hoping some of the wiser heads out there may be able to offer me some advice.

My 59 Gold Flash has a small journal crank and the drive side big end is heavily grooved, so a re-grind is in order.

The crank is marked +0.030, which I understand is the largest undersize I can go to. But when I gauge the journals they come out at 1.435",

Viking previously posted the below info:

BSA service sheet No. 207, October 1948, re-printed May 1955.

Engine nos. XA7 - 101 to 600; first re-grind 1.4600 to 1.4595, with a
0.065/0.060 face radius both sides. No second re-grind.
Engine nos. XA7 601 upwards and A10 models; three re-grind possibilities.
1.4495 to 1.4500; then 1.4400 to 1.4395; then 1.4300 to 1.4295.
More information from that service sheet; Note that certain engines will be
found to have the left-hand connecting rod drilled to improve lubrication


Does this mean that I can take the journals down to 1.4300 to try and get rid of the scoring?

If I can but that doesn't get rid of the scoring, are there any alternatives? I've heard of journals being built up with weld and then ground to original size - has anyone tried this?

Cheers

Tim
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Tim Kerridge
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Offline KiwiGF

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Re: Small journal crank re-grind?
« Reply #1 on: 22.08. 2016 07:55 »
I reground my SJ crank big end journals to -040 and got the shells from Draganfly, part 67-247.

One more regrind can be done than described in the service sheet.

Hope that helps.

Here is a link to the service sheet , it might also be stored on this forum somewhere.

http://www.bsa-oc.com/wp-content/uploads/bsk-pdf-manager/21_SECTIONA_BSASERVICESHEETNO207.PDF
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New Zealand

1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

1952 Armstrong Siddeley Whitley for rainy days (with wife)

Offline TT John

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Re: Small journal crank re-grind?
« Reply #2 on: 22.08. 2016 08:25 »
I had a small journal crank built up and re conditioned, they did it by welding, not spark erosion, they apparently ridge it with weld then re grind it, I now have a spare crank, original size on the bench but it cost me £300 that was about six years ago, I don't know if I will ever need it but I know its there, if ever I do.
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Offline Rich.

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Re: Small journal crank re-grind?
« Reply #3 on: 22.08. 2016 10:15 »
TT John, I've a small journal crank which is in need of refurb for an early engine that I'm on with. Could please supply details of who and where please.
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Online groily

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Re: Small journal crank re-grind?
« Reply #4 on: 22.08. 2016 13:25 »
http://tandlengineeringbedford.co.uk/ are one lot of people who are always helpful Rich (and Tim for that matter).
Bit of a stretch from N Yorks, but I take my stuff there from France when needed because I have faith in them - they do most things very well and for sensible money. Ads in OBM etc too. I usually speak to Derrick. They have, I think, done quite a few jobs like your one. Materials quality and techniques have got a lot better over the years and I believe they have a good track record on this sort of job, although I haven't yet had a crank built up by them. Worth a call maybe to discuss options?
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Offline Rich.

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Re: Small journal crank re-grind?
« Reply #5 on: 22.08. 2016 14:03 »
Cheers Groily, as we say "distance is no object for a good job" your recommendation is more than enough for me, although been a Yorkshireman, I'll have to shop around. Ho ho!
Rich.
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Offline KiwiGF

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Re: Small journal crank re-grind?
« Reply #6 on: 22.08. 2016 21:17 »
Hi Groily, wouldn't Tim be better off just grinding the crank to -040? Not going to the expense of building it up etc ?  *dunno*

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1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

1952 Armstrong Siddeley Whitley for rainy days (with wife)

Online groily

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Re: Small journal crank re-grind?
« Reply #7 on: 22.08. 2016 22:34 »
Absolutely agree with you. If it will grind, then that's got to be the choice, yes.

Wasn't meaning to suggest going further than that in Tim's case, no way - just wanted to say that I've found T&L are good for all these sorts of things, and are very sympathetic to older machinery.
In the unlucky and unlikely event that Tim's groove, coupled with any ovality, might be more than a single remaining grind can cope with, then bending the ear of people like T&L could be reassuring as they'll have a Plan B.

Also well worth getting the rods checked I reckon - for cracks first off, and for ovality of the big end eye, 'straighth' etc. Like many of us, they polish up OK on the outside  . . . but it's an age thing. "When the maggot gnaws from within, then will the apple rot. . . ."

I'm always a bit of a pessimist with these things to start with, because then I can be happy if the verdict is better than 'terrible'!
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Offline TimK

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Re: Small journal crank re-grind?
« Reply #8 on: 23.08. 2016 09:56 »
Thanks gents,

 I looked on  Draganfly and saw the  +40 shells (thanks KiwiGF) but they were only available on back order, so I checked out Priory Magnetos and they have them as well (and cheaper). The gouge in the journal seems to be less than 10 thou so I'm optimistic about being able to sort it out.

 I can't find anything definitive about the regrind size for +40. Should I just subtract 40 thou from the standard size or is there more to it than that?

 Thanks TTJohn and groily but I think I'll leave the weld and recondition until I've no other alternatives or I win the lottery.
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Offline duTch

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Re: Small journal crank re-grind?
« Reply #9 on: 23.08. 2016 10:24 »

 Basically I reckon D/F suck; go Priory, and when you go to the machinist, don't forget to specify the whatzit radius (0.085"-0.090"?)
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Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Online groily

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Re: Small journal crank re-grind?
« Reply #10 on: 23.08. 2016 10:42 »
Blimey duTch - hope they don't suck too much 'cos I've just ordered a few urgent bits from them after a lump of something rock-like (or a bit of tractor or something) got caught in the rear chain on mine on Saturday. Snapped it clean in half and seriously damaged both sprockets (all not very old either, darn it) blah blah boring.
Luckily no serious consequences for the idiot on board - apart from having to make sheepish call to Herself for a rescue party . . .  That always has consequences, like has to be taken out for a meal and thanked endlessly for a week.
I haven't had trouble before with DF that I can recall - what don't they do right? Is it the bits, or the service?
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Re: Small journal crank re-grind?
« Reply #11 on: 23.08. 2016 12:01 »
As I've said before I have had very little trouble with Draganfly. Lightning Spares, (spit) though were a different matter; good riddance! Burtons recently tried to palm me off with some tat.
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Offline duTch

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Re: Small journal crank re-grind?
« Reply #12 on: 23.08. 2016 22:26 »


 
Quote
what don't they do right? Is it the bits, or the service?

 general attitude, ie; no PR courtesies. Apart from something else, I was sent BSF/WW barrel base studs instead of BSC/WW, and was told " don't send them back" (from Oz,wise call, would've cost more than the item- but it's the principle)

 
Quote
I've just ordered a few urgent bits from them after a lump of something rock-like (or a bit of tractor or something) got caught in the rear chain on mine on Saturday.
  Tractors and bikes don't mix *eek*
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Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Offline KiwiGF

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Re: Small journal crank re-grind?
« Reply #13 on: 24.08. 2016 08:15 »
Thanks gents,

 I looked on  Draganfly and saw the  +40 shells (thanks KiwiGF) but they were only available on back order, so I checked out Priory Magnetos and they have them as well (and cheaper). The gouge in the journal seems to be less than 10 thou so I'm optimistic about being able to sort it out.

 I can't find anything definitive about the regrind size for +40. Should I just subtract 40 thou from the standard size or is there more to it than that?

 Thanks TTJohn and groily but I think I'll leave the weld and recondition until I've no other alternatives or I win the lottery.

Hi Tim, from memory the standard crank is 1.460? If so the -040 undersize would be a journal diameter of 1.420 HOWEVER you should give your rods and shells to the machinest and he will grind the crank to suit so he really has no real need to know the theoretical diameter. The machinest may ask you the clearance you want, if he does the info is the forum somewhere, in the region of 001 from memory.

The depth of gouge on the journal has to be less than 005" as the material (010 of diameter) has to be taken equally from all around the journal.
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1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

1952 Armstrong Siddeley Whitley for rainy days (with wife)

Offline TimK

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Re: Small journal crank re-grind?
« Reply #14 on: 24.08. 2016 08:58 »
Thanks KiwiGF, the damage on the crank is about 5 thou deep and the crank measures out at 1.435 at the moment - which confuses me a bit as at +30 thou I'd expect it to be closer to 1.430. I'll order the +40 shells and if they come out close to 1.420 I should have plenty of metal to play with.
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Tim Kerridge
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