Author Topic: Broken case  (Read 706 times)

Offline Superflash

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Broken case
« on: 28.01. 2020 10:35 »
Hey y'all. Have a conundrum on my hands. The piston set arrived today so I pulled the motor apart after doing a dry run. After splitting the cases I noticed a crack around one of the oil pump stud holes. Gave it a tap and a big chunk fell out. Now, these aren't matched cases. So...is it ok to use or should I get a new timing case....or, there's another option. One of the suppliers here has got a matched pair of std A10 cases. Just means I'll park the SF case.....
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Online BSA_54A10

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Re: Broken case
« Reply #1 on: 28.01. 2020 11:22 »
Clean it up.
weld a lump of metal there the reface &  redrill the hole.
Bike Beesa
Trevor

Offline Swarfcut

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Re: Broken case
« Reply #2 on: 28.01. 2020 12:05 »
Yes, build up the case with weld to restore the pump mating suface, but in fact there looks to be enough material for the gasket to give an oil tight joint, but this is marginal.
 You may find there is sufficient depth of metal to extend the stud hole deeper, and make a longer custom stud. Original threads... Case Thread is 1/4 Whit, nut end 1/4 Cycle.  As mis -matched cases,only the drive side carries any true identity, so the basic choice is to use the matched A10 cases (easy), swap the timing side case or repair existing, both entail more work but easy success really depends on how well the castings line up, as regards sump plate, gearbox mount and cylinder base faces.
  Line boring just the blind camshaft bush is the cheap way of sorting that area, then a custom timing side bush line bored to match the drive side case is the usual trick.

Swarfy.

Online RichardL

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Re: Broken case
« Reply #3 on: 28.01. 2020 12:20 »
I had a similar issue at my sump plate. You can see a picture of the weld here:

https://www.a7a10.net/forum/index.php?topic=14370.msg119450#msg119450

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Offline Greybeard

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Re: Broken case
« Reply #4 on: 28.01. 2020 12:52 »
Would that have been caused by not using a washer on the nose of the pump?

Offline Swarfcut

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Re: Broken case
« Reply #5 on: 28.01. 2020 17:01 »
   GB     Unlikely.  Accidentally dropping the case on the oil pump stud is more probable. A tight on the studs oilpump is usually down to bent or bowed studs. The result of a missing washer will distort a pump body, but not fracture a sound casting. Always the possibility of some fella forcing a stud down an oil filled blind hole, and hydraulic pressure fracturing the casting. However the stud needs to go to the bottom of the hole to get maximum support from the soft alloy case. Too short a stud puts the load just on the first few threads.

Swarfy

Online KiwiGF

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Re: Broken case
« Reply #6 on: 28.01. 2020 20:17 »
Hey y'all. Have a conundrum on my hands. The piston set arrived today so I pulled the motor apart after doing a dry run. After splitting the cases I noticed a crack around one of the oil pump stud holes. Gave it a tap and a big chunk fell out. Now, these aren't matched cases. So...is it ok to use or should I get a new timing case....or, there's another option. One of the suppliers here has got a matched pair of std A10 cases. Just means I'll park the SF case.....

JB weld “plastic metal” will fix that, instead of welding, it’s amazing stuff, it looks like there is enough thread left in the case anyway, so no need to rely on a thread cut in the JB weld.
New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts

Offline Superflash

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Re: Broken case
« Reply #7 on: 29.01. 2020 00:06 »
Well I've had a good look with a torch and magnifying glass. The missing bit stopped before it reached the thread, so I'm thinking that there shouldn't be any issues with getting the stud fixed in. My only worry was the potential for oil to seep past the washer and gasket even though the top stud hole is quite a bit apart from the oil passages, (unlike the bottom stud hole which is almost in line with the oil holes). I had bought a set of pump studs with the idea of doing up an old pump that I had picked up. After reading a thread on here about the SRM pumps, I forked out the dosh and bought one of them instead of using the old one. As you know, they supply allen bolts to fix the pump in with, but I'm thinking, if I use the std studs instead, then I could build up the mating surface with some of that plastic steel that KiwiGF suggested.
Even though the cases aren't matching, they do seem to bolt up together quite well. Again, used a magnifying glass right around the seam looking for dips or bumps, and couldn't see any. The sump plate plopped straight on no problems, and the cases go together quite snuggly with a bit of encouragement with a rubber mallet...is that usual, or should they just more or less plop together as well? Cheers
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Online KiwiGF

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Re: Broken case
« Reply #8 on: 29.01. 2020 07:57 »
Well I've had a good look with a torch and magnifying glass. The missing bit stopped before it reached the thread, so I'm thinking that there shouldn't be any issues with getting the stud fixed in. My only worry was the potential for oil to seep past the washer and gasket even though the top stud hole is quite a bit apart from the oil passages, (unlike the bottom stud hole which is almost in line with the oil holes). I had bought a set of pump studs with the idea of doing up an old pump that I had picked up. After reading a thread on here about the SRM pumps, I forked out the dosh and bought one of them instead of using the old one. As you know, they supply allen bolts to fix the pump in with, but I'm thinking, if I use the std studs instead, then I could build up the mating surface with some of that plastic steel that KiwiGF suggested.
Even though the cases aren't matching, they do seem to bolt up together quite well. Again, used a magnifying glass right around the seam looking for dips or bumps, and couldn't see any. The sump plate plopped straight on no problems, and the cases go together quite snuggly with a bit of encouragement with a rubber mallet...is that usual, or should they just more or less plop together as well? Cheers

It’s encouraging the sump mating faces “match” but I don’t think there is any option but to check the camshaft bushes are aligned, and of course the mains. My engineer reckoned the mains generally align but not the cam shaft.
New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts

Offline Swarfcut

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Re: Broken case
« Reply #9 on: 29.01. 2020 08:56 »
 Superflash,  The thread starts at the joint face, not halfway down the hole, so looks to have been a pulled thread at some stage. The front stud is shorter.....possibly put in this hole by mistake, (maybe?) and without a full length of supporting thread the load was too much.

 SRM use cap screws, but the stud arrangement is better for soft castings, as the alloy thread is undisturbed no matter how many times the pump is on and off.

 If the camshaft turns freely, any cases are a good reasonable match. So try the cam first to get an idea. The cases usually require a light tap here and there to get them square to align. Camshaft binding (check its not bowed by trying it in the matched cases or turn between centres) means bushes and line boring. All three bushes...expensive, cheap way, just the one as I suggested earlier.

Swarfy

Offline Superflash

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Re: Broken case
« Reply #10 on: 29.01. 2020 10:11 »
Hi Swarfy. Well just tried putting the cam in as you suggested. Solid as a rock... not even interested in turning. I think at this stage given I've only got the drive side case that is genuine SF, I'm going to wrap it up and stash it away. As I  mentioned Mike's classics have a matched pair of plunger cases so will put all the internals into them. Over time I'll revisit the whole SF thing and do the job properly. Once I've paid the credit card off... *eek* Cheers.
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Offline berger

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Re: Broken case
« Reply #11 on: 29.01. 2020 11:37 »
the cases should come together without tapping / bashing them they just glide down the studs if they are matching cases and a hand clap on the cases seats them. matching cases that don't glide together have studs that over the years have been stressed a little and end up a tiny bit out of line.

Offline Swarfcut

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Re: Broken case
« Reply #12 on: 29.01. 2020 21:16 »
  A couple of things to look for when chasing plunger crankcases. 

      If you are lucky to have a choice, go for cases from the BA engine number series. These cases have a proper crankshaft oilseal on the drive side and an oil feed from the PRV to the camshaft trough. These features were an improvement over the earlier design, but whether they make any real difference.......

 Matching cases have identical numbers stamped in the crankcase halves, on the front just below the dynamo cradle. If out and about looking at cases, take the camshaft to check it turns without binding.

 Swarfy.


Offline Superflash

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Re: Broken case
« Reply #13 on: 29.01. 2020 21:58 »
Hi. The ones he has are stamped ZA10 6603. Cheers
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Offline Swarfcut

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Re: Broken case
« Reply #14 on: 30.01. 2020 08:55 »
Hi, That number dates from 1951-'52, and are the early design. They use a slightly different crankshaft primary drive sleeve, with a scroll edge. Over time whether by rationalisation, design, or substitution, early engines without a seal are found with a smooth edged drive sleeve, according to findings by Forum members, so any sleeve you have will fit.

 Design and part applications for the drive sleeve, oil slinger and later  oilseal are all covered extensively within previous forum posts.  There is no difference in the basic crankcase castings for A7 or A10 variants.

 The condition of the anti drain ball valve in the oilway between pump and timing side bush is often overlooked, as is the integrity, operation and oil tightness of the sump pick up pipe.  Problems with either can only be fixed by splitting the cases, once more extensively covered on the Forum so plenty of information available to consider.

 Cheers, Swarfy.