Wet sumping while running

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Groily
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Re: Wet sumping while running

Post by Groily »

3BA: major dia 4.1mm, minor 3.22mm. Pitch of 0.72mm or 34.79 threads per inch. Thread angle 47.5°

Thread angle is important on critical fasteners. Many things can be bodged (60°UNC up many a 55°BSW hole of same tpi and vice versa, and games can be played with small metric screws up BA and other small 55° or 60° 'imperial' holes, along with that old favourite of 1/4" BSF up 60°1/4" BSC holes and vice versa . . . . Seen so often that it's just a sigh of resignation).

But for an oil pump end plate, a decent fix is needed.

3BA is a tricky size these days in terms of buying nuts and bolts - the even sizes are easier. The same goes for helicoil inserts for thread repairs in the odd BA sizes. It may therefore be an option to take out a damaged thread to the smallest next size in another series, or to a size that will take a helicoil in some other series if BA's not available (and there's enough meat), and go that way.
The butchery of forcing the wrong thing up a tired female thread is just a recipe for future problems.

To the list of BA fasteners should be added all the timing cover screws on twins, at 2BA. And what a pain they can be too.
Plus the electrical bits (mags and dynamos), where they are a good choice.

My favourite data charts are attached. I'm sure I've attached it before, but no harm done by repetition. Captured from a now defunct website. From it, you can work out a zillion 'hybrid' workarounds which pass the test of engineering acceptability even if they are off makers' spec. And save money sometimes.
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56G80S
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Re: Wet sumping while running

Post by 56G80S »

Clive is spot on regarding 3BA as I recall but memory is fallible. The bolt hole had already been botched and was at 2BA. The standard little bolt doesn't usually use all of the thread available but already cut, so you may be luckier than me in regard to using a 3BA bolt and turning it into a stud. I got a too long 2BA bolt, cleaned out the hole very thoroughly, screwed it in fingers only and marked the depth. Then used the end of a small screwdriver to check that total depth of the hole as a check one the hole depth, don't know why I didn't use the end on the vernier. This allowed a comparison with the depth of thread just as a guide. Measured the depth of the pump plate, disregarding the counterbore in it for the standard bolt, and subtracted that from the available thread depth, allowing a mm or so for safety to avoid bottoming out and marked that.

Cut the head off 2BA bolt, locked two nuts together on the intended stud, screwed it into the hole with high strength Loctite. Enlarged the hole in the plate correspondingly.

Worked for me. I didn't have the facilities or the contacts to get the hole drilled and re-tapped further oversize but more importantly, there doesn't seem to be much meat between the hole for the bolt and the bore of the pump in the crankcase.

Johnny B
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cfaber
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Re: Wet sumping while running

Post by cfaber »

Groily wrote: Sat Jan 21, 2023 6:40 pm 3BA: major dia 4.1mm, minor 3.22mm. Pitch of 0.72mm or 34.79 threads per inch. Thread angle 47.5°

Thread angle is important on critical fasteners. Many things can be bodged (60°UNC up many a 55°BSW hole of same tpi and vice versa, and games can be played with small metric screws up BA and other small 55° or 60° 'imperial' holes, along with that old favourite of 1/4" BSF up 60°1/4" BSC holes and vice versa . . . . Seen so often that it's just a sigh of resignation).

But for an oil pump end plate, a decent fix is needed.

3BA is a tricky size these days in terms of buying nuts and bolts - the even sizes are easier. The same goes for helicoil inserts for thread repairs in the odd BA sizes. It may therefore be an option to take out a damaged thread to the smallest next size in another series, or to a size that will take a helicoil in some other series if BA's not available (and there's enough meat), and go that way.
The butchery of forcing the wrong thing up a tired female thread is just a recipe for future problems.
It seems some sources of 3BA helicoils do exist, AFAIK the new bore size will need to be 4.3mm, cut with <mystery tap, TBD>, I'll measure to see how much space I have to work with, with this screw. I think in some ways I'm lucky that it's on the crank case side.

Has anyone tried this yet?
Groily wrote: Sat Jan 21, 2023 6:40 pm To the list of BA fasteners should be added all the timing cover screws on twins, at 2BA. And what a pain they can be too.
Plus the electrical bits (mags and dynamos), where they are a good choice.

My favourite data charts are attached. I'm sure I've attached it before, but no harm done by repetition. Captured from a now defunct website. From it, you can work out a zillion 'hybrid' workarounds which pass the test of engineering acceptability even if they are off makers' spec. And save money sometimes.
Thank you! this is really useful. I've reached out to a few suppliers here and over there to see if I can track down any helicoils, once I understand my options I'll figure out what's next.
:beer:
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Re: Wet sumping while running

Post by cfaber »

56G80S wrote: Sat Jan 21, 2023 6:47 pm Clive is spot on regarding 3BA as I recall but memory is fallible. The bolt hole had already been botched and was at 2BA. The standard little bolt doesn't usually use all of the thread available but already cut, so you may be luckier than me in regard to using a 3BA bolt and turning it into a stud. I got a too long 2BA bolt, cleaned out the hole very thoroughly, screwed it in fingers only and marked the depth. Then used the end of a small screwdriver to check that total depth of the hole as a check one the hole depth, don't know why I didn't use the end on the vernier. This allowed a comparison with the depth of thread just as a guide. Measured the depth of the pump plate, disregarding the counterbore in it for the standard bolt, and subtracted that from the available thread depth, allowing a mm or so for safety to avoid bottoming out and marked that.

Cut the head off 2BA bolt, locked two nuts together on the intended stud, screwed it into the hole with high strength Loctite. Enlarged the hole in the plate correspondingly.

Worked for me. I didn't have the facilities or the contacts to get the hole drilled and re-tapped further oversize but more importantly, there doesn't seem to be much meat between the hole for the bolt and the bore of the pump in the crankcase.

Johnny B
Thankfully in my case these appear to be original and non bodge jobs. In fact, there are no bodge jobs on this bike :D, the only one that it came with was a cigarette lighter on the head lamp which I erased.
Fix it until it's broken!

Otherwise how will
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Groily
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Re: Wet sumping while running

Post by Groily »

Just in case it's useful . . . the tapping drill in my Uni-Thread 3BA insert kit is marked a nominal 4.3mm - so could be you're spot on for a standard 3BA result if you can find the necessary.
The tap in the kit isn't marked with any dimensions but is stamped
OSG UK
3BA W/1
FAC1246851


The plain shank of one 4.3mm drill I just measured - which has been in a chuck or three over the years - came out at 0.167", a fraction under at c. 4.25mm.

I don't know if other thread repair kits use exactly the same dimensions for the drill and the tap as their insert wire gauges may differ marginally, but the 3BA Uni-Thread repair kit is what I use regularly as it's the stock thread for many British magneto HT pick-up screws, which are often in a sad state.

https://uni-thread.com/tr_ba_inserts.php
Seems they still list 3 and other odd sizes. High price compared to 0 2 & 4 because the tooling for the less common sizes was made in Germany for them specially I think. Or that's what they told me when I last ordered up 3 and 5 BA sets
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Re: Wet sumping while running

Post by cfaber »

Groily wrote: Sun Jan 22, 2023 8:28 am Just in case it's useful . . . the tapping drill in my Uni-Thread 3BA insert kit is marked a nominal 4.3mm - so could be you're spot on for a standard 3BA result if you can find the necessary.
The tap in the kit isn't marked with any dimensions but is stamped
OSG UK
3BA W/1
FAC1246851


The plain shank of one 4.3mm drill I just measured - which has been in a chuck or three over the years - came out at 0.167", a fraction under at c. 4.25mm.

I don't know if other thread repair kits use exactly the same dimensions for the drill and the tap as their insert wire gauges may differ marginally, but the 3BA Uni-Thread repair kit is what I use regularly as it's the stock thread for many British magneto HT pick-up screws, which are often in a sad state.

https://uni-thread.com/tr_ba_inserts.php
Seems they still list 3 and other odd sizes. High price compared to 0 2 & 4 because the tooling for the less common sizes was made in Germany for them specially I think. Or that's what they told me when I last ordered up 3 and 5 BA sets
Thanks this was very useful. I ordered a set, and boy oh boy was it not cheap. But I want this fixed correctly and I'm not going to bodge in some incorrect thread and bolt combination.

Though if i had to take this plate off more than once, I would probably think about converting it to studs (as matchless probably should have done when they built the motor in the first place)
Fix it until it's broken!

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Groily
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Re: Wet sumping while running

Post by Groily »

I feel your $£€ pain. I have felt it myself living outside the UK. But you do get a good few inserts in a set, which is a plus I suppose - should you ever need another one. Not sure if they offer different lengths of insert - didn't look that far - but with any luck you'll be able to do a neat job.
I so agree with you about studs and nuts. I am still reeling from recently fighting with the corroded bolts (with undersized heads for the M8 shanks what's worse) used by a certain Japanese manufacturer to attach the flanges that hold the 4 header pipes onto the front of the cylinder head on one of mine. It's all very well doing things at a factory when everything is new and shiny - but it would be good if they'd spare a thought for Joe Blow a few years down the road just occasionally! And, as with the Matchless, we don't want to be taking fasteners in and out of aluminium on a regular basis . . .
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cfaber
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Re: Wet sumping while running

Post by cfaber »

Groily wrote: Tue Jan 24, 2023 4:18 pm I feel your $£€ pain. I have felt it myself living outside the UK. But you do get a good few inserts in a set, which is a plus I suppose - should you ever need another one. Not sure if they offer different lengths of insert - didn't look that far - but with any luck you'll be able to do a neat job.
Yeah, after I pull the motor. I'll fixture it up on my mill and make sure the new hole goes exactly where I want it. I hope I won't need to use the 3BA inserts again, but it's always nice to have that in your back pocket in the event that they're needed for something
Groily wrote: Tue Jan 24, 2023 4:18 pm I so agree with you about studs and nuts. I am still reeling from recently fighting with the corroded bolts (with undersized heads for the M8 shanks what's worse) used by a certain Japanese manufacturer to attach the flanges that hold the 4 header pipes onto the front of the cylinder head on one of mine. It's all very well doing things at a factory when everything is new and shiny - but it would be good if they'd spare a thought for Joe Blow a few years down the road just occasionally! And, as with the Matchless, we don't want to be taking fasteners in and out of aluminium on a regular basis . . .
Been there a few times, you should see my nice collection of helicoils, drills, taps and insertion tools for this very reason..

In general, you don't want to remove fasteners from aluminum more than a few times, I guess they never expected to have people removing these frequently, however it becomes necessary with bikes as old as these =) At least there's good viable solutions to fixing these now-a-days :D
Fix it until it's broken!

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Re: Wet sumping while running

Post by cfaber »

So I haven't given up on this yet. I'm still waiting for the helicoil kit to arrive so I can get started. But it seems to have been held up in customs since January =/
Fix it until it's broken!

Otherwise how will
anything get done?
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