The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: ellis on 23.07. 2016 17:21
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I know SRM don't advise fitting their pump to a bike with a spin on canister filter. Has any body done this and if so what were the results. Or should I not fit such a high capacity pump with a car type filter. *dunno*
ELLIS
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I was not aware of SRM's recommendation and have fitted their pump and a spin on filter. I wonder of that accounts for the recent onset of wet sumping? I not sure why though?
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Their logic may be that once you stray from standard spec, they don't know what they're guaranteeing.
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As far as I can see, SRM has not included such a warning in the description for the pump in their online shop. You would think that is where the warning would need to be, rather than selling the pump to the unsuspecting filter user. I also have an SRM pump with a spin-on filter and have gone about 1000 miles that way with no apparent trouble and very little wet-sumping. (Just finished a bunch of yard work in 100 deg. F., so too lazy/tired to go looking for the pump install instructions.)
Richard L.
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It seems to me that SRM have some rather bizarre ideas. For example if SRM rebuild an engine for you, the warranty is null and void if you fit a filter of any description. Similarly the same thing applies if you use anything other than straight oil. Whats that all about? Personally I fail to see the logic especially in light of the fact that oil has advanced so much since the days when BSA were still extent. In fact in the later years BSA were in fact actually specifying multi grade engine oil. In the Haynes A10 manual (first published 1973) it says in the acknowledgements section “Our thanks are due to BSA Motorcycles Limited for their assistance” and then goes on to recommend Castrol GTX 20/50. If you by an SRM sump drain kit they supply Allen bolts rather than studs. SRM have a good reputation, but I do not think that they are always right.
John
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S.R.M. Do not recommend fitting an additional oil filter, period. The bike should also be run on straight oil and not multigrade, the engine was designed that way.
Like it or lump it, those are the facts, and I am staggered that people with all the evidence before them choose to ignore them. There is a reason they guarantee their work if you follow their advice, but not doing so invalidates said guarantee.
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It seems to me that SRM have some rather bizarre ideas. For example if SRM rebuild an engine for you, the warranty is null and void if you fit a filter of any description. Similarly the same thing applies if you use anything other than straight oil. Whats that all about? Personally I fail to see the logic especially in light of the fact that oil has advanced so much since the days when BSA were still extent. In fact in the later years BSA were in fact actually specifying multi grade engine oil. In the Haynes A10 manual (first published 1973) it says in the acknowledgements section “Our thanks are due to BSA Motorcycles Limited for their assistance” and then goes on to recommend Castrol GTX 20/50. If you by an SRM sump drain kit they supply Allen bolts rather than studs. SRM have a good reputation, but I do not think that they are always right.
John
Bizarre ideas?........I prefer to call it feedback from building many thousands of engines that have covered millions of miles. Oils may have moved on to keep up with modern engine engineering, an A10 is an old design of engine.
Castrol were back handing anybody and everybody back then to endorse their products, and Haynes are notorious for their mis-information in their manuals anyway.
Straight oils are designed to let go of foreign bodies, multigrades are designed to hold them until they are filtered. Straight oil leaves these foreign bodies in the sludge trap before any damage can be done by them. Multigrade will try to hold on to them, and carry them all the way to the filter which can only be fitted on the return side. That means all the damage is done before it is filtered.
It really is that simple.
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Well, there are a lot of twists to this that threaten to bring on another full-blown oil debate. I'm no oil expert, but I do have a few comments.
As I understand it, oil in the days when our bikes were made did not have limits on the amount of zinc included. Therefore (again as I understand it), flat tappets were well protected against wear. Today, zinc is restricted, so I use Valvoline VR1 Racing Oil, which has about as much zinc of any oil I can buy at the local auto parts store.
As has been recently explained here (so, yet again, "as I understand it"), it is the detergent in motor oil that suspends particles for filtering and not the elements that control viscosity behavior through various ambient temperatures as seen in multi-grade oils.
Finally, if BSA was so concerned about using straight (single-grade) oils, how would that explain what is seen stamped into the top of the oil can in the attached pictures? (That can is a prized possession.)
I am happy to be corrected if wrong but, then, I am going to ask those who are oil gurus to get on the same page with their stories so that us oil novitiates will not be confused.
Richard L.
Adding a close-up (with my daughter accidentally-on-purpose in the background).
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Finally, if BSA was so concerned about using straight (single-grade) oils, how would that explain what is seen stamped into the top of the oil can in the attached pictures? (That can is a prized possession.)
Richard, exactly! Metalflake11, you might find this to be an interesting read http://www.realclassic.co.uk/techfiles/oil030319.html Well actually so might everyone else.
John
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Thanks Richard, I was thinking same, but you put it better than I would've *conf*
Well, there are a lot of twists to this that threaten to bring on another full-blown oil debate. I'm no oil expert, but I do have a few comments. .........
.....>.... I am happy to be corrected if wrong but, then, I am going to ask those who are oil gurus to get on the same page with their stories so that us oil novitiates will not be confused.
Richard L.
...........
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S.R.M. Do not recommend fitting an additional oil filter, period. The bike should also be run on straight oil and not multigrade, the engine was designed that way.
just in an argumentative mood so I would strongly advise against the use of any crank end oil feed, the engine was not designed that way
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On the sludge trap.....does anyone know for certain it was designed to store small metal particles? Anyone actually forensically examined the sludge? *dunno* I thought that (maybe) it was supposed to store the larger particles that could not fit through the big end clearance, that clearance being less than 001 on a good engine.....it seems to me that whatever oil you use those larger particles will have to stay in the sludge trap, until the big ends get sloppy anyway *work*
I run cheapo castrol 20/50 and a "commando" filter on a rebuilt engine, oil changed every 1000 miles ish, filter every other oil change, no problems so far but I've not done 10's of thousands of miles.
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I hated the old american qt cans .....if your spout was not sharp or you didn't whack it in hard enough the first time the can collapsed and the oil went every where
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So SRM are a bit hypocritical with all the mods (roller timing side conversion etc) they sell, and yet insist on mono oil and no filter!
Cheers
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in reply to the original question, i have fitted an srm oil pump and a spin on filter (in the return line). but only done 1000 miles since doing so. the return flow (into the tank) is better than the old original pump, and no wet sumping (i replaced the ball/spring valve in the crankcase too).
i have noticed that if the bike is sitting for a week there's a bit of overhead noise that takes a minute to so to settle down, and I've wondering if this could be due to the increased time it takes for oil to reach there with the longer return path through the filter.
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S.R.M. Do not recommend fitting an additional oil filter, period. The bike should also be run on straight oil and not multigrade, the engine was designed that way.
just in an argumentative mood so I would strongly advise against the use of any crank end oil feed, the engine was not designed that way
*lol* *lol*
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You have a point there Mike.. OTOH the filter sitting full if situated at a reasonable height will give quicker delivery to the rockers perhaps . I moved mine from the toolbox to up under the seat ☺
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Richard is correct, attached are the installation instructions, see lines 2 and 3.
Clive
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hi guys, these are the instructions that I got with the pump. Cant really see the problems that could occur by fitting a filter with the S.R.M. pump as the original pumps seem to work o.k. with them. I am prepared to make my own decision on the issue after reading all the opinions and willing to take the consequences if things go wrong, cheers
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As per marketing of any product you test ,certainly if you giving an implied warranty .
Not recommended just releases liability of your product to any modification outside of your testing regime.
That doesnt mean it wont work or is wrong, it means As a manufacturer i wont be held responsible.
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In the end it is just an oil pump, does the same thing as a stock pump - it pumps oil. Just because its blue and has SRM stamped on it does not change what it does.
I was surprised to see it came with cheesy allen head bolts instead of some nice new studs and nuts. I suppose its easier to slap a pump in with the allens.
I will fit the new pump with studs, so I am sure that will void the warranty. And a decent filter, so its a double whammy to the warranty. *bash*
Lee
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and the allen head bolts were stainless - i would have thought neither necessary or desirable inside an engine. studs would be better but i didn't bother
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What i can conclude from the instructions is that they only advise against fitting any obstruction in the feed line as it says; "The pump demands more oil from the oil tank, and any restriction in the flow will end in disaster"
Maybe I'm missing something here, but I don't see any advise against fitting a filter in the return line?
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What i can conclude from the instructions is that they only advise against fitting any obstruction in the feed line as it says; "The pump demands more oil from the oil tank, and any restriction in the flow will end in disaster"
Maybe I'm missing something here, but I don't see any advise against fitting a filter in the return line?
It says oil lines, not just feed line.
It also says "will be end in disaster," which may have been written by a pirate.
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Finally, if BSA was so concerned about using straight (single-grade) oils, how would that explain what is seen stamped into the top of the oil can in the attached pictures? (That can is a prized possession.)
Richard, exactly! Metalflake11, you might find this to be an interesting read http://www.realclassic.co.uk/techfiles/oil030319.html Well actually so might everyone else.
John
Thanks for that A10, it is indeed an interesting read......It really is a 'pays yer money, takes your choice' situation.
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S.R.M. Do not recommend fitting an additional oil filter, period. The bike should also be run on straight oil and not multigrade, the engine was designed that way.
just in an argumentative mood so I would strongly advise against the use of any crank end oil feed, the engine was not designed that way
OK, I'll rise to the bait!
Isn't an end feed conversion the brainchild of the B.S.A. race department? If so, they did design A10 engines that way. The name Les Mason rings a bell here.
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Isn't an end feed conversion the brainchild of the B.S.A. race department?
so it's a modification, therefore the engine was not designed that way *fight*
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Didn't plunger A10s have a felt filter on the return, in the oil tank?
That might mean they were designed that way too.
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Isn't an end feed conversion the brainchild of the B.S.A. race department?
so it's a modification, therefore the engine was not designed that way *fight*
True!......Telescopic forks are a modification of girder forks, Rear shock absorbers are a modification of plungers, which in turn is a modification of rigids. You need to get back the flat tankers with belt drives, hand gearchanges and solid tyres etc etc.
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OK , but if I take your point all engines should come with a shovel and bucket of coal AND you realise we are all modified monkeys *shh* *smile*
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I'm going back into the sea Bill! *smile*
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Isn't an end feed conversion the brainchild of the B.S.A. race department? If so, they did design A10 engines that way. The name Les Mason rings a bell here.
The crankshaft end feed conversion was indeed a product of the BSA race department. The conversion was pioneered by Les Mason and Chris Vincent whom, no doubt, many of you will remember had great success racing a BSA in sidecar events. Les Mason was the proprietor of Devimead. Les traded from shop in Stafford after BSA closed down in 1972. When Devimead decided to discontinue doing the conversions and retire, SRM took over the "intellectual property" to the timing side bush/bearing job from Devimead some time in the 1980s. In fact if I remember correctly SRM traded for a while as Devimead (Devimead (BSA) Ltd). So, the end feed oil feed conversion can be traced back directly to BSA. BSA of course as we all know did not officially go racing, but they did have a competition department and that was where the development was done. If Bert Hopwood can be believed many developments were vetoed by the BSA managment not on technical merit, but on the grounds of cost. No doubt that explains why the modification was never adopted for over the counter production models.
John
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oil is cheaper than metal *conf*
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On this side of the planet there is no SRM warranty, they didnt fit the product and cannot see how we fitted it or treated it.
Having blown our dough on a high volume high priced item, we have no doubt also flushed the sludge traps so can run the best oil available or whatever we fancy as long as we keep it clean.
Both my A10's run return filters, my B33 doesnt as it doesnt have fragile plain bearings.
Both my A10's also run end fed bearing conversions.
If I'd got my bike rebuilt by SRM I would follow their warranty conditions for the duration of that warranty, but thats never going to apply to me, so I make my own decisions with the best advice I can find from the forum and mates.
I'm probably the only person running both my A10's on Castor but hey thats just so I can readily swap out the motors if I want to.
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RR, so your running Castor so you can drop some methanol in the roady? >:D
Cheers
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I love the smell of castor and methanol in the morning *whistle*
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I love the smell of castor and methanol in the morning *whistle*
Now that surely is the smell of victory.
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To be honest most of the old brit bikes I see dont need a filter the oil does not stay in them long enough to get dirty :)
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Speak for yourself bikerboy. My A10 is leak free so that's why I run a cartridge filter and change the oil annually. Penrite classic light oil 20w-60 with high zinc levels. *good3*
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I think Bikerboy was actually saying A7/A10 owners are more likely to change their oils religiously (twice a year) rather than casting aspersions about prolific leaking as distinct from territorial marking.
If a bike has regular changes so clean fluids and a clean sludge trap then filters are not necessary even though many of us prefer and recommend them.
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Once upon a time in the dim and distant past I was gainfully employed in the buying dept of a local engineering firm, part of my job being to see visiting reps. At the time I was running a vintage bike (not BSA) as well as my Shooting Star, and multi grade oils had not long appeared on the market. (Told you it was a long time ago!) A pal had just changed from Castrol Grand Prix sae 50 to a certain brand of green 20-50, leading to the almost immediate and spectacular demise of his Star Twin's bottom half. This led to shall we say some thought, and when a suitable Oil Company rep appeared, I proceeded to pick his brains. His advice was thus; "Multi-grade oil, say 20-50, is essentially a 20 grade oil with things called VI improvers added. These stop the oil thinning out as much as it would otherwise. Unfortunately, due to the temperatures and pressures in these old engines, the VI improvers rapidly break down, leaving you with basically an SAE20 oil, which the clearances in these old engines are unable to tolerate." His advice was to use a monograde oil, for preferance one formulated for diesel engines, as these operate at much higher loadings than a petrol engine. This I proceeded to do with my A7SS, on which I subsequently covered 90,000 miles in 6 years. The vintage bike got fed something a bit cheaper, being a total loss system. As a matter of interest, I found out some years later that Volkswagen and Porsche made the same recommendation for their air cooled engines. Might answer queries as to SRM's oil spec.
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This is from the 1960 BSA A series Instruction Manual, back when oils where just starting to become a bit multi in grade. What do we see there but a recommendation to use very early Multi-grade oil from Esso?
Glen
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A while back i rebuilt a mini engine for my sins and as part of that the oil pump is considered a consumable and replaced (cheap as chips) as a matter of course, because they suck up unfiltered oil from the sump so wear, the oil is then pressure filtered before it hits the main bearings.
Now if we don't want dirty oil (particularly with multigrades) taking these particles into our mains, the easiest options we have are to firstly keep the oil tank clean as, then to fit a filter on the return line. This does mean crud goes through the return circuit of the pump but is kept away from the mains.
If SRM have a recommendation for monogrades and oil changes, then yes the filter is largely unnecessary.
Trying to avoid the "oil thread" direction, personally I would not run multigrades on any crank I hadn't personally cleaned first, as a switch from a straight 50 to say a 20/50 opens the risk (however remote) of washing through any sludge and trashing the bottom end.
But I do like return line filters as they are better than relying on a bit of gauze.
I guess what we really need is a window in the timing cover so we can still look at that rather expensive blue device pumping the engines lifeblood ;) rather than it being hidden away...
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the following taken from Roland Pike http://beezagent.blogspot.co.nz/2009_02_01_archive.html (http://beezagent.blogspot.co.nz/2009_02_01_archive.html)
"Oil Pumps.The BSA gear type pump is very simple and reliable, at one time we did some tests by simply running a pump on a drill press in a can of oil and measuring the temperature of the oil, we were surprised at how quickly the temperature rose especially as there was not resistance to the flow. On examination of the pump we decided that some oil was being compressed between the two gears, accordingly a small bypass was cut in the cover plate allowing oil to feed back to the inlet side of the pump. Further testing showed practically no heat build up in the oil. Some tests were carried out on A7 (using various viscosity oils, starting with 50 wt and coming down to 40 wt to 30 wt, 20 wt SAE 10 and finally 5 wt. We discovered that normal oil pressure was maintained on the SAE 10 50 wt, 40 wt and 30 wt. At SAE 20 viscosity pressure tended to drop particularly when hot. The engine was stripped at this point to see if the low pressure caused any bearing problems, everything looked pretty good. At SAE 10 wt pressure seemed very low in fact when hot was nil a further examination of the bearings and pistons showed no sign of trouble but the cam followers did not look too happy, starting to score."
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I installed a spin on on a 51 motor.. I reckon it works well...I tapped into the elbow on the infeed to the filter and ran that line to the rockerbox....
my filter is the one that fits a Toyota v8 diesel 2015...and likely a thousand others.
did a bit of investigating, as I was wondering about pressures and whatevers...turns out the filter is supposed to bypass most of the oil on startup...cold oil....and high pressure (and high rpm) ....and really only designed to filter about 20% of the volume....
the reason for the weak bypass is likely the design of a car engine...the oil is directed to (or around ) the filter before it gets to the crank and other shiny bits...where my BSA has it on the return line...
i.m pretty happy with it...this old lump has lasted likely 3 times longer than it was ever designed for.... and likely to be oiling the roads for another 50 years
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Very Big Snip
But I do like return line filters as they are better than relying on a bit of gauze.
I guess what we really need is a window in the timing cover so we can still look at that rather expensive blue device pumping the engines lifeblood ;) rather than it being hidden away...
I had expected substantially better knowledge of the BSA filtering system from you.
The gauze in the sump is there to protect the oil pump.
If it can get through the gauze it will pass through the return side of the pump without damage to the pump.
The gauze in the oil tank outlet is there to protect the pressure side of the oil pump.
If it fits through the gauze it will pass through the oil pump without damaging the oil pump.
The gap between the main shaft & main shaft bush is in the order of 0.0001" to 0.0005", so any particle bigger than that can not get into the bush to do any damage and will pass through the hole in the timing bush into the crank.
The same thing happens at the big end.
Only particles bigger than the clearence between the slippers and the journals can pass into the bearing, the remainder will pass into the FULL FLOW CENTRIFUGAL OIL FILTER , commonly incorrectly termed the sludge trap.
here anything that has a heavier specific gravity than the oil will be flung out of the oil and FORM A SLUDGE in the sludge trap.
Or to put it another way, the sludge trap creates a sludge it does not filter sludge out .
The oil then gets pumped back up to the SETTELING TANK where the output on the top allows volatile contaminats ( like water & fuel ) to exit via the breather. Particles with a lighter Specific Gravity than oil will form a scum on the top of the setteling tank and particles with a heavier specific gravity will drop down below the outlet level.
Eventually the lighter particles will agglomerate ( if you are not using a detergent oil ) into heavier lumps and sink to the bottom of the settleing tank.
Thus each and every part of the 4 level filtering system has a specific job and does that job relatively well when the motor is being used within the design parrameters.
Note, a paper filter mearly filter everything out in one hit, by particle size alone . typically 50 to 120 microns.
However unlike the BSA filters, it does restrict the oil flow which is why it is best put in the return line as the gear pump used by BSA in not a particularly high pressure pump and fairly low volume and never designed to be hooked up to a cartridge filter.
If we have a good think, we will remember many people on this list stating that after fitting the spin on filter, their sludge trap was empty so all the external filter is actually doing s replacing the internal one.
No matter what external filter is fitted, you still need the 2 gauzes to protect the oil pump.
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Fantastically valuable insight, thank you! *yeah*
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hi Trevor, are all multigrade oils (detergent oil), as detergent is the medium that allow water to mix with oil so will allow water(condensation) to get carried around the engine which cant be a good thing, cheers
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The trouble with age (well one of them) is you find yourself starting sentences with " I remember reading somewhere----" which casts some doubt as to the validity of whatever it was you read so --- take this with however many pinches of salt you require.
The first Multi-grade in UK was DucKhams Q 20/40 designed for either or both the Mini engine or Triump motorcycle engines.
The Mini one I don't reckon as that engine had been used in many cars prior to sir Alec's little gem.
I used it in Mini's but didn't find it magically made the yellow grunge in the rocker box disappear at all.
Modern oil is designed to work with Catalytic converters, to do this they lack a component of previous oils that destroys the Cats but was of a benefit to your older engine.
Interesting article here http://www.classiccars4sale.net/classic-car-how-to-guides/feature-articles/a-guide-to-classic-oils (http://www.classiccars4sale.net/classic-car-how-to-guides/feature-articles/a-guide-to-classic-oils)
So for myself I'd use anything for an older engine.
Duckhams BTW was owned by BP who tried to sell it some time ago - don't know who bought it if anyone did
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hi Trevor, are all multigrade oils (detergent oil), as detergent is the medium that allow water to mix with oil so will allow water(condensation) to get carried around the engine which cant be a good thing, cheers
Detergents, in any liquid, water , oil , whatever are nothing more than a molecule that would rather adhere to anything else other than the liquid it has been mixed into.
I am sure we have had this conversation before.
So in a detergent oil the detergent molecules which typically are less dense than the oil molecules attach themselves to anything that is not oil, or themselves.
This firstly makes the "foreign" molecule bigger so it can easily be filtered out and also stops the foreign molecules joining together and sinking to the bottom where they form a sludge.
This is exactly what you don't want to happen in a system that relies on a heavier specific gravity to centrifuge off the foreign molecules but you do want if you are passing your oil through a paper filter.
in oils DETERGENTS ARE DISPERSANTS, the terms are interchangable.
In the kitchen sink the same thing happens.
The detergents wrap around the dirt on your plates and hold the molecules in suspension which is why the water goes cloudy.
In an oil slick, water based detergents grab the non water molecules, mostly the oil and envelope them breaking up the slick.
The difference here is the detergents are heavier than water so the oil + detergent drops to the bottom of the ocean / river.
The detergents have bacteria on one end that breaks down the oil.
In rivers the detergent is lighter than water so it forms a scum on the top which is easily scooped off
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Trevor,
I am certain I must be misreading and/or misunderstnading something you said in the filtering explanation (useful and interesting, indeed). Here is the statement in question:
The same thing happens at the big end.
Only particles bigger than the clearence between the slippers and the journals can pass into the bearing, the remainder will pass into the FULL FLOW CENTRIFUGAL OIL FILTER , commonly incorrectly termed the sludge trap.
I am reading this as somehow saying that the slipper gap is sorting out the particles for removal by the centrifugal system. Isn't it the case that the trap tunnel fills with oil where heavier particles are spun to the outside while the now-filtered oil goes to the slippers via the journal holes toward the centerline? Three possibilites, in order of likelihood: I'm too thick to understand you; I have misread your post and would get it if only set straight; you slightly mis-wrote what you meant to say.
Thanks for clearing this up with having to point out that I am thick, even if I actually got it right.
Richard L.
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...The Mini one I don't reckon as that engine had been used in many cars prior to sir Alec's little gem.
True but sharing the oil with the gearbox was a new idea for UK. Maybe Duckhams was good for that combination.
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Hi All,
...The Mini one I don't reckon as that engine had been used in many cars prior to sir Alec's little gem.
True but sharing the oil with the gearbox was a new idea for UK. Maybe Duckhams was good for that combination.
Thats What I remember being told ?
Duckhams Q20/50 was developed for the combined engine and gearbox
I had a fair few mini's back in the 70's and always ran them on Duckhams
One time the factors pushed me to buy Silkolene 20/50 so I tried a gallon
After about a thousand miles I noticed the hot oil pressure was lower than before
I changed back to Duckhams and all was well again
Some times mini owners would add Wynnes or STP to the oil in a bid to keeep oil pressure up
The additive would coat the needle bearings in the transfer gear, they would then over heat and fail in short order *warn*
John
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True but sharing the oil with the gearbox was a new idea for UK. Maybe Duckhams was good for that combination.
Good point, it did cross my mind when I was typing, also often stated D Q20/40 was for air cooled engines, more theories than you can shake a stick at as they say
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Trevor,
I am certain I must be misreading and/or misunderstnading something you said in the filtering explanation (useful and interesting, indeed). Here is the statement in question:
I am reading this as somehow saying that the slipper gap is sorting out the particles for removal by the centrifugal system. Isn't it the case that the trap tunnel fills with oil where heavier particles are spun to the outside while the now-filtered oil goes to the slippers via the journal holes toward the centerline? Three possibilites, in order of likelihood: I'm too thick to understand you; I have misread your post and would get it if only set straight; you slightly mis-wrote what you meant to say.
Richard L.
Hi Richard, this is how I think it works albeit I think some particles too big to pass through the big ends will inevitably reach the big end before being spun out into the sludge trap? Arguably the big end "clearance gap" is then doing the filtering, or at least some of it, when that happens. The oil feed hole in the journal feeding the big ends is positioned so that centripetal force carrries larger particles away from it, so in a perfect world no large particles would ever reach that far down the oil feed path, but I guess when the engine is rotating slowly or is a stopped particles could make it to the oil hole? I also guess larger particles may be knocking around for some time inside the crank before becoming permanent stuck in the trap?
Sort of related I recently read somewhere on this forum the statement that the small journal crank does not have a sludge trap like the large journal, it's a while since I had my SJ crank apart but I do remember cleaning out some small "pockets" in the crank under the oil feed access screws in the crank, which I at the time thought WERE a sludge trap for particles (they were filled with fairly hard black/grey gunge, anyway).
Maybe someone could confirm or deny the existence of a sludge trap in the SJ crank?
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As regards to the S/J crank there is no tube in the crank but the space between the two screws acts as a sludge trap.
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As regards to the S/J crank there is no tube in the crank but the space between the two screws acts as a sludge trap.
My '55 A10 has no tube.
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As regards to the S/J crank there is no tube in the crank but the space between the two screws acts as a sludge trap.
My '55 A10 has no tube.
I take it that is a small journal crank?
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Trevor,
I am certain I must be misreading and/or misunderstnading something you said in the filtering explanation (useful and interesting, indeed). Here is the statement in question:
I am reading this as somehow saying that the slipper gap is sorting out the particles for removal by the centrifugal system. Isn't it the case that the trap tunnel fills with oil where heavier particles are spun to the outside while the now-filtered oil goes to the slippers via the journal holes toward the centerline? Three possibilites, in order of likelihood: I'm too thick to understand you; I have misread your post and would get it if only set straight; you slightly mis-wrote what you meant to say.
Richard L.
Hi Richard, this is how I think it works albeit I think some particles too big to pass through the big ends will inevitably reach the big end before being spun out into the sludge trap? Arguably the big end "clearance gap" is then doing the filtering, or at least some of it, when that happens. The oil feed hole in the journal feeding the big ends is positioned so that centripetal force carrries larger particles away from it, so in a perfect world no large particles would ever reach that far down the oil feed path, but I guess when the engine is rotating slowly or is a stopped particles could make it to the oil hole? I also guess larger particles may be knocking around for some time inside the crank before becoming permanent stuck in the trap?
Sort of related I recently read somewhere on this forum the statement that the small journal crank does not have a sludge trap like the large journal, it's a while since I had my SJ crank apart but I do remember cleaning out some small "pockets" in the crank under the oil feed access screws in the crank, which I at the time thought WERE a sludge trap for particles (they were filled with fairly hard black/grey gunge, anyway).
Maybe someone could confirm or deny the existence of a sludge trap in the SJ crank?
Have a look a the lubrication diagrams.
The oil passes through the main bearing then into the crank.
The feed hole for the big end is on the inside of the journal and the sludge trap is on the outside.
Drastically heavier particles will be flung into the side of the sludge trap and form a compact sludge.
Lighter particles will flow with the oil but unless they are smaller than the space between the journal and the slippers, they can not get past to do any damage.
That was what I was tying to say if it was not clear.
The space between the journal & the slippers is finner than paper filter you can fit without overloading the pump.
Most of the filters run from 75 to 200 micron but I can't see BSA owners paying $ 45 for a 75 micron filter.
A sludge trap will pull particles out regardless of their size so stuff as fine as 0.01 micron will be pulled out, just so long as it has a higher specific gravity than the oil and a small co-heasive force between it and the oil.
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I run a 1954 Road rocket with a SRM pump and spin off filter.
I use straight sae 40 and dont hang about,
The old pump was original and was U/s and i like filters its not pushing anything bad back into the tank
I fitted a sump plate to allow draining if i lay it up in the winter. but frequent usage it doesn't cause a problem. i do have a anti sumping valve fitted not 100% perfect lets a bit through just like the one in the engine.