Author Topic: Sludge Trap Plugs  (Read 1034 times)

Offline rowan.bradley

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Sludge Trap Plugs
« on: 12.11. 2017 15:30 »
What is the timing side of the crankshaft supposed to look like? On mine, the drive side has a plug like I expected, but the timing side has a hole, which seems to be threaded, and have punch marks around the edge, but no plug. Should BOTH sides have a plug? Are the plugs the same as each other?

Don't forget that this bike has not been driven for about 45 years, so the plug may have been taken out by me or by someone else at some time in the distant past. It doesn't have to have come out while the bike was being used.

If I fit the hex socket plugs, I hear that I need to rebalance the crankshaft. Is this something that I can do myself, or does it need specialist equipment? If it's possible to do in the average garage, are there any instructions anywhere? If I need to have it done professionally, who offers this service?

Thanks - Rowan


Current bike: 1958 A10 Super Rocket (in bits), purchased in 1967.
Previous bikes: M21

Online RichardL

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Re: Sludge Trap Plugs
« Reply #1 on: 12.11. 2017 15:45 »
Rowan,

Without two plugs you have no engine, as no oil will get to the rod bearings. The dimples are intended as anti-loosening measures. On your model, the plugs are different from eachother, with different shapes on the inside for centering and stabilizing the sludge-trap tube that fits inside the crankshaft by running through the journals.

Old plugs are removed by carefully, and with a light touch, drilling away the dimples and working out the plug by the screwdriver slot, which ofter doesn't work, or by a variety of other extraction methods. In my opinion, for casual riding, rebalancing just because of the difference in plug shapes seems unnecessary. Others are more expert and may hve different opinions, but, to me, the sludge that will form in the trap represents a greater source of potential imbalance.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Online bsa-bill

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Re: Sludge Trap Plugs
« Reply #2 on: 12.11. 2017 15:49 »
I would echo Richards remarks, put hex plugs in both my A10s and did not rebalance the crank
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online JulianS

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Re: Sludge Trap Plugs
« Reply #3 on: 12.11. 2017 16:36 »
I would go to an expert should you want to rebalance the engine - someone who would do a dynamic balancing job and has the equipment and experience to do a proper job on a motorbike engine.

I dont think it worth doing or necessary just because you change the sludge trap plugs, but if you are doing a full engine rebuild on the bike it is worth considering. Had my A10 done by SRM and a nice job it was. Had a Starfire done by Basset Down Balancing again a nice job.

Online Rex

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Re: Sludge Trap Plugs
« Reply #4 on: 12.11. 2017 16:37 »
Nor me, and both plugs are the same.

Online RichardL

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Re: Sludge Trap Plugs
« Reply #5 on: 12.11. 2017 17:05 »
Nor me, and both plugs are the same.

Rex,

Maybe your's are, but these are not:

http://shop.srmclassicbikes.com/product/large-journal-hexagon-sludge-trap-plugs-pair-a10-a65

Yes, I had to go to SRM to be sure before posting my reply to Rowan.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Online Greybeard

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Re: Sludge Trap Plugs
« Reply #6 on: 12.11. 2017 18:47 »
Nor me, and both plugs are the same.

Rex,

Maybe your's are, but these are not:

http://shop.srmclassicbikes.com/product/large-journal-hexagon-sludge-trap-plugs-pair-a10-a65

Yes, I had to go to SRM to be sure before posting my reply to Rowan.

Richard L.

I haven't looked to see what bike Rowan has but the Plunger doesn't have a sludge tube and the plugs are the same.

Offline rowan.bradley

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Re: Sludge Trap Plugs
« Reply #7 on: 12.11. 2017 19:05 »
Mine is a swinging arm Super Rocket.

Can someone please explain the difference between "large journal" and "small journal"? What are the diameters of each (assuming that it is the diameter that is different) and when did they start the Large Journal?

Thanks - Rowan


Current bike: 1958 A10 Super Rocket (in bits), purchased in 1967.
Previous bikes: M21

Online JulianS

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Re: Sludge Trap Plugs
« Reply #8 on: 12.11. 2017 19:21 »
Large journal means the big end diameter.

large journal crank photo below, note the radial bolts holding the flywheel on, small journal did not have radial bolts. This type used from 1957. There was an earlier large journal crank which was a bit different.

The early type large journal was introduced with the Road Rocket in 1954.

The standard A10 used a small journal until the DA10 series when in got the large jurnal as the photo. The Road Rocket got it from engine CA10R 5051  the Super Rocket from CA10R 4650. I previously posted the parts bulletin with this information.

Online Rex

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Re: Sludge Trap Plugs
« Reply #9 on: 12.11. 2017 20:42 »
Rex,
Maybe your's are, but these are not:

Yep, they're later ones than mine, and those have the "pip" which, if I recall, later Nortons had too.

Offline mikeb

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Re: Sludge Trap Plugs
« Reply #10 on: 12.11. 2017 21:32 »
Quote
Can someone please explain the difference between "large journal" and "small journal"?
you can measure the journals - you'll need a micrometer. large journal is somewhere between 1".6465 and  1".6865 depending on how ground it is. i think small journal diameter is 1.46" abouts.

if removing the sludge trap plugs some threads say whack them with an impact driver etc. don't do that as you can crack the crank. use drills, heat, extractors. mine were not easy. took ages and help.

the hex ones are the way to go.

EDIT:
a super rocket should be Large journal:
STD".........................1".687 - 1".6865
010"......................... 1".677 - 1".6765
020"......................... 1".667 - 1".6665
030"......................... 1".657 - 1".6565
040"......................... 1".647 - 1".6465

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Offline rowan.bradley

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Re: Sludge Trap Plugs
« Reply #11 on: 13.11. 2017 10:45 »
Which of those two SRM plugs goes in which side?

In order to remove the sludge trap, do I need to take out both plugs? If not, which one needs to be removed?

How does one get the sludge trap out of the crank?

Thanks - Rowan


Current bike: 1958 A10 Super Rocket (in bits), purchased in 1967.
Previous bikes: M21

Online duTch

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Re: Sludge Trap Plugs
« Reply #12 on: 13.11. 2017 11:00 »

 The tube is held in place by the flywheel bolt directly over the journal- from memory it may be a bit different from the other two, being longer and has a locating tip....but maybe I made that last bit up because it sounds plausible..... *conf2*.

 It should be obvious which is which when yo remove them...I think the one with the stub is to locate the 'dumb-end'...but I'm sure someone will correct me on that
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
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Online JulianS

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Re: Sludge Trap Plugs
« Reply #13 on: 13.11. 2017 11:26 »
This may help.

The plain end at the timing side. Note the oilway from main bearing and make sure you do not screw the plug in too far and block it.

The trap is held by the extended centre bolt.

The three flywheel bolts are quite highly stressed.

I had one sheer off from fatigue and wreck a crankcase. Very expensive.

Worth replacing them for peace of mind

Offline rowan.bradley

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Re: Sludge Trap Plugs
« Reply #14 on: 13.11. 2017 11:27 »
you can measure the journals - you'll need a micrometer. large journal is somewhere between 1".6465 and  1".6865 depending on how ground it is. i think small journal diameter is 1.46" abouts.

EDIT:
a super rocket should be Large journal:
STD".........................1".687 - 1".6865
010"......................... 1".677 - 1".6765
020"......................... 1".667 - 1".6665
030"......................... 1".657 - 1".6565
040"......................... 1".647 - 1".6465
Thanks for that information. Mine are 1.6575" (measured with my not very accurate metric vernier), which says they are large journal reground to -0.030".

Rowan


Current bike: 1958 A10 Super Rocket (in bits), purchased in 1967.
Previous bikes: M21