Zahnflankenspiel Ölpumpe (metrisch)

Begonnen von Taz, 27 März 2021, 13:37:46

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Taz

Hi zusammen.

Ich greife eine Frage von Chris aus Großbritannien auf, der folgendes Problem hat.

R27 mit 10mm Ölpumpe, Meßmethode nach Abbildung 103 aus dem Werkstatthandbuch von BMW wie hier im Forum verfügbar.

Nach dieser lag das Zahnflankenspiel weit über der Toleranz des Werkstatthandbuchs...da sind 5/100 mm max angegeben, seine Pumpe hat mit den Bestandszahnrädern 17/100 mm Spiel.

Er hat dann einen neuen Satz Zahnräder gekauft, damit ist das Spiel aber nur unwesentlich auf 15/100 mm gesunken...die Bohrungen im Pumpengehäuse sind seiner Ansicht nach nicht eingelaufen, seinen Aussagen zufolge kein spürbares Spiel.

Jetzt die Frage aller Fragen: was tun...Messung mit Hinweisen aus der Gemeinde wiederholen, alle Zahnräder (inkl Pumpe) wegschmeißen und neue kaufen, auf andere Weise (z.B. Ventildeckel runter, Pumpe mit Bohrmaschine antreiben und Ölfluß bewerten) einschätzen, einbauen und fahren (weil der Wert hiesigen Erfahrungen zufolge nicht kritisch ist) oder .... ?

Ich bitte um Meinungen, Kommentare, Diskussionen...

Viele Grüße, Ute
Ich hab noch nie einen Sarkasmus vorgetäuscht


auf Tour:

Zipfelreise (2019)
Cymru "Radnor Revivals" (2016)
Alba "Isle of Skye" (2013)
Austria Großglocknerhochalpenstrasse (2012)
Alba "Spittal of Glenshee" (2011)

Taz


Ich hab noch nie einen Sarkasmus vorgetäuscht


auf Tour:

Zipfelreise (2019)
Cymru "Radnor Revivals" (2016)
Alba "Isle of Skye" (2013)
Austria Großglocknerhochalpenstrasse (2012)
Alba "Spittal of Glenshee" (2011)

rolf

siehe mi geschreibsel zu "neu ist besser...da neu"::::neu ist eben nur Nachbau und mitnichten besser....s. 17/100 Spiel zu 15/100 Spiel....müsste doch eigentlich auf 5/100 Spiel runter gehen
ich habe noch nie eine Ölpumpe gehabt die 5/100 Spiel hatte....die hatten alle mehr....und blieben problemlos drin und pumpten ihr Öl ebenso Problemlos.

ChrisR27

Hi Ute & Rolf,
I'm replying to Ute's message in the 'R27 Adventure' thread, all oil pump information now here.
Thank you for the link to the table, I didn't think to look there.
2000 ml/min @ 7500rpm, that must be engine speed so an oil pump (drill) speed of 833rpm. I plan to try some tests today so will let you know how I get on.
Regards,
Chris.

Taz

Hallo Rolf.

Vielen Dank für Deine Info...im Grunde läufts also darauf hinaus, daß die Dinger sauber und unbeschädigt sein sollten, das Zahnflankenspiel ist in der Praxis weit weniger kritisch als es die engen Toleranzen von BMW erscheinen lassen.

Liebe Grüße, Ute
Ich hab noch nie einen Sarkasmus vorgetäuscht


auf Tour:

Zipfelreise (2019)
Cymru "Radnor Revivals" (2016)
Alba "Isle of Skye" (2013)
Austria Großglocknerhochalpenstrasse (2012)
Alba "Spittal of Glenshee" (2011)

berndr253

Hab für Manfred vor langer Zeit mal eine vergrößerte Pumpe nachgearbeitet, die einfach keinen /Durchfluss brachte. Ursache war hier, dass sich die Räder im Lauf der Zeit in die "Grundplatte" eingearbeitet hatten.
Nach dem Überfräsen der ausgearbeiteten Fläche hatte die Pumpe eine mehr als zufriedenstellende Leistung

Bernd
Leben und Leben lassen

Taz

Hallo Bernd.

Danke...das Axialspiel scheint also wirklich deutlich wichtiger zu sein..und es ist erfreulicherweise ein lösbares Problerm, im Gegensatz zum Zahnflankenspiel.

Liebe Grüße, Ute
Ich hab noch nie einen Sarkasmus vorgetäuscht


auf Tour:

Zipfelreise (2019)
Cymru "Radnor Revivals" (2016)
Alba "Isle of Skye" (2013)
Austria Großglocknerhochalpenstrasse (2012)
Alba "Spittal of Glenshee" (2011)

4Taktix

Bei der im Bild gezeigten "Messmethode" und der Zahnform der Pumpenzähne kommt es entscheidend auf die Position der Zähne zueinander an.
Eigentlich bräuchte man sehr schmale Fühlerblätter ( 3 mm ) und müsste probieren, ab welcher Stärke sich die Räder nicht mehr durchdrehen lassen.
Nur dann ist eine valide Aussage zum Flankenspiel möglich.

Gruß,
Sascha
Think outside the box !

berndr253

Einfach mal testen - ich war überrascht wie stark sich das Spiel der Stirnseiten der Räder zu der "Bodenplatte" ausgewirkt hat

Grusz

Bernd
Leben und Leben lassen

cledrera

ZitatI plan to try some tests today so will let you know how I get on.

Hi Chris,
many thanks in advance.

Clemens
Du bist im Recht; nun sieh zu, wie du da wieder heraus kommst. (v. Chamisso)
Lieber Einzylinder als zwei Fallschirme (v. mir)

Krottenkopp

Zitat von: ChrisR27 am 28 März 2021, 09:26:49
Hi Ute & Rolf,
I'm replying to Ute's message in the 'R27 Adventure' thread, all oil pump information now here.
Thank you for the link to the table, I didn't think to look there.
2000 ml/min @ 7500rpm, that must be engine speed so an oil pump (drill) speed of 833rpm. I plan to try some tests today so will let you know how I get on.
Regards,
Chris.
The cam is turning just with the half rpm as the crank does.
So 7500 rpm at the crank is 3750 rpm at the cam, and with the gearwheel with 9 geartooth 416,something rpm will be enough...


Gruß Heiko/2
Gruß Heiko/2

Taz

Hallo Heiko.

Vielen Dank für die Korrektur des Übersetzungsfaktors...stimmt, die Ölpumpenwelle dreht sich nur mit 1/18 der Kurbelwellendrehzahl.

Viele Grüße, Ute
Ich hab noch nie einen Sarkasmus vorgetäuscht


auf Tour:

Zipfelreise (2019)
Cymru "Radnor Revivals" (2016)
Alba "Isle of Skye" (2013)
Austria Großglocknerhochalpenstrasse (2012)
Alba "Spittal of Glenshee" (2011)

ChrisR27

Hi everyone,
My R27 engine is on the bench so I can easily turn the engine by hand and look into the oil pump drive shaft hole. On my engine 9 rotations of the crankshaft = 1  rotation of the oil pump shaft, I'm not sure why we have a difference of opinion here? For me the oil pump runs at 1/9 of the crankshaft speed so at the BMW test speed of 7200rpm the oil pump is rotating at 800rpm. (If I am making a silly mistake, sorry, please correct me). What we don't know from the BMW test figure is the viscosity of the oil, also, if the BMW test used an 'engine' with lots of horsepower the drive could be a calibrated 800rpm, I can't achieve this.

I made a tool where I could bolt the oil pump to the tool and have an output connected to a hose, the hose was then routed to a measuring jug. My battery drill was checked for speed while pumping oil using a tachometer at the start and end of the 1 minute test. The battery is quite old so the drill slows down slightly during use. The starting speed was 700rpm, the finishing speed 680rpm, I think we can assume an average of 690rpm. In one minute the oil pump pumped 1400ml of oil, when I changed the gears to the new set the volume pumped was the same, 1400ml. Sorry, I can't seem to insert a picture? The difference in backlash between the old gears (0.18mm) and new gears (0.15mm) was very small, even so I was surprised the amount of oil pumped was the same.

My test speed was 690rpm/800rpm*100%, so 86.25% of the BMW test speed, so the relative flow rate for may pump is 1400/0.865 = 1618ml/min.

Given we don't know the viscosity of the oil in the BMW test, and it is quite cool here in my garage, maybe that's not such a big difference? It would be really good to repeat the test with a known good, 2000ml/min pump of course but we don't have that luxury.

Hopefully this all makes sense and if I have made an error please correct me, I won't be offended! Also, if someone can tell me how to insert a picture I post a picture of the test.

Regards,
Chris.











ChrisR27

The picture did attach after all but it's upside down, what a fool.......

Krottenkopp

#13
Zitat von: ChrisR27 am 29 März 2021, 19:52:26
Hi everyone,
My R27 engine is on the bench so I can easily turn the engine by hand and look into the oil pump drive shaft hole. On my engine 9 rotations of the crankshaft = 1  rotation of the oil pump shaft, I'm not sure why we have a difference of opinion here? For me the oil pump runs at 1/9 of the crankshaft speed ...
Regards,
Chris.

As I wrote before, the oil pump is driven by the CAMSHAFT , not by the CRANKSHAFT !
The ratio of the CRANKSHAFT to the CAMSHAFT is 2:1
The ratio of the CAMSHAFT to the OIL PUMP SHAFT is 9:1

So your ratio in total is 18:1


I painted a picture for you...




Gruß Heiko/2
Gruß Heiko/2

Krottenkopp

Sorry,
I was just outside to open the lid from the Oil Pump Shaft, and you're right, it's turning as you told.
I don't know exactly why in the moment because I had just the flashlight of my cellphone with me...
Sometimes it is the different between theory and practice...


Gruß Heiko/2
Gruß Heiko/2

Krottenkopp

My mistake was the worm of the worm gear at the camshaft.
In my memories I thought that it is a single worm, but it is not, it is a multi started worm. (2 starts)


Gruß Heiko/2
Gruß Heiko/2

4Taktix

Hi Chris,
the point is highly likely that your comparison doesn't consider any resistance and also the cold oil.
The hotter the oil gets, the lower the viscosity. ( and the easier it slips through small gaps )
I'd make a calibrated orifice, let's say 2 or 3 mm, put it into the outlet-hose, then repeat the comparison with hot oil ( ~ 80 °Celsius / ~ 180 °F ).
I'm certain that the hotter the oil and the smaller the orifice, the more obvious the difference will be.

Cheers,
Sascha
Think outside the box !

ChrisR27

Hi Sascha,
The problem is I want to get the bike back together and go for a ride so don't want to do much more testing, I don't think the bike has been on the road for 20 or 30 years so I'm like an excited child!
We don't know the grade of the original BMW test oil, or the temperature, so comparing against the 2000ml/min is difficult. My test did use a multigrade oil, SAE 10/40 semi synthetic, so is probably very different to the 1960s BMW test oil. I also don't know if the BMW test was to an open outlet or through a restriction, in real life we don't even know the 'resistance' of the R27 oil ways. It might be that the effective lubrication is adequate at 1618ml/min, maybe even much less? I wish I could find a way to know for sure. At the moment all we can do is compare against the 2000ml/min, that's the best we have. I do have an oil pressure gauge that I was going to connect to the test rig but when I took it out the needle was damaged.
1618ml of oil in a jug does seem like a lot of oil in 1 minute, especially when the sump capacity is only 1250ml, some of the oil must pass through the pump twice every minute. I might be worrying about nothing?

I will try one more test with the oil heated up to see if the amount pumped in one minute increases. This is a good idea to compare flow rate against viscosity. I'll get back to you.

Regards,
Chris.

Taz

Hello Chris.

there's the scientific approach you are following now...and as almost all parameters of the original test are at least vague you can continue with may-bes and could-have-beens...or you could stick to the rather down to earth approach Rolf has drafted...make sure that the lateral clearance (which according to a number of mature members around here is much more important) is small enough and then have some fun down in the South...

Just my 2pc, Ute
Ich hab noch nie einen Sarkasmus vorgetäuscht


auf Tour:

Zipfelreise (2019)
Cymru "Radnor Revivals" (2016)
Alba "Isle of Skye" (2013)
Austria Großglocknerhochalpenstrasse (2012)
Alba "Spittal of Glenshee" (2011)

rolf

Chris....bullshit!
you don´t have any vaLUES....so what would you compare?? lOST OF TIME

4Taktix

Zitatso I'm like an excited child!
if you would have told us first of all  ;D
Seriously - don't stick too much to the BMW-test and to the absolute volume per time.
And against your assumption the volume will decrease, the hotter the oil !
Also these kind of pump isn't really designed to build up significant pressure, as Roller-bearings don't require pressure literally.
They just have to be 'lubricated' sufficiently, so to speak.
The idea behind the test rig is more to find out, which pump/wheels/components work best, in relation/comparison.
If you're keen to take a ride rather tomorrow then next week, I'd just hone/grind the pump-lid as best as you can, take the new wheels and put it together.
Then make an auxilliary shaft ( mild ~ 6mm steel bar with one end hammered flat, so it fits diagonal into the quare pump connection sleeve ),
chuck it to your Battery-drill and turn it clockwise and check, if both rocker-shafts were supplied and spill some oil.
You can also choose a 'thicker' oil - 20/50 to be on the safe side, if it comes to a longer tour. Possibly during warm weather with baggage and hilly terrain.
This is quite common for 'aged' engines with some miles on the hunch. Due to extended play and the viscosity thing.

Good luck.
Sascha

Think outside the box !

ChrisR27

Sorry Rolf, which bits do you think are bullshit, maybe all of it? All I'm trying to do is get a better understanding of the pump. I was told the clearance between the oil pump gears was critical and mine were very worn compared the the BMW specification. So I spent about 90 Euros on new gears and this may have been a waste of money if the gear clearance isn't the important factor.

Anyway, here's a bit more bullshit to keep the thread running.

As Sascha suggested I repeated the test with oil at approximately 70C, I used the same test set up as before. The result changed from 1400ml/min to 1550ml/min but the drill ran slightly quicker at an average of 700rpm. Using the formula as before this equates to 1771ml/min, an additional 153ml/min.

This is just more information, I'm not drawing any conclusions.

Regards,
Chris.







rolf.soler

#22
Zitat von: ChrisR27 am 30 März 2021, 17:56:24
I might be worrying about nothing?
exactly  :)
Your test shows that the oil pump pumps oil.
That is all I would need to know. And maybe that the cogwheels are not rattling around in the housing.
I guess hardly anybody knows many ml/min are actually flowing, and the amount passing through the tiny holes is surely smaller than with a free outlet. Oil pump meter would not help, this type of pump is not a pressure pump.
There are pages and pages about tyre pressure, octane in fuel SAE oil grades etc., but nothing about pump flow. That indicates that it is not a problem, else we would see epic discussions and adventure stories and repair videos.
So my advice: put t together, put it in and stop testing, if you don't want to miss riding it this spring
But please no synthetic or even semi-synthetic oil in any place. The more synthetic, the more likely is potential (!) aggression to non ferrous metals (copper, brass, bronze). The engine is maybe the only place that contains none of these (except if you have high quality bearings with brass cages like I do..) Even so, it's a good habit to NOT use synthetic oil anywhere.
Pure mineral oil (15-40, 20-50 or monograde 30 / 40 are best and cheaper

ChrisR27

Thank you Rolf, useful advice on oil selection.
One final piece of information, I removed the wear on the pump body using fine emery paper on a surface plate and the flow increased from 1550ml in one minute to 1650ml. With the correction for drill speed this takes me to 1886ml/min, an increase of 115ml/min or 6.5%.
As suggested all I can really do is establish relative increases in oil flow for changes made to my pump. Changing the gear wheels made no noticeable increase in oil flow, removing wear from the pump body did make a improvement. If I had known this when I started the engine rebuild I would not have bought the pump gears.
As far as there being no information on pump flow testing suggesting there are no problems you may well be correct. However I am very happy to know my pump is now working as close to 100% as possible, and that I have made an improvement and understand where, and how, the improvement was made. If BMW were happy with the standard oil pump on the R27 why did they change to 15mm gear wheels? BMW must have thought there was an issue with the 10mm oil pump, maybe as the pump wears and the rate of flow decreases there is a resulting increase in engine wear? As the 15mm gears wear the reduction in oil flow is, perhaps, insignificant.
Kind regards,
Chris.

4Taktix

I assume this is due to the shorter conrod on R27.
It has the shortest rod (120 mm) compared to R26 ( 125mm ) and R25/xx ( 136mm ).
This results in higher side load on the piston and therefore BMW made 2 little oil-bores in the barrel skirt. ( R26 = one bore, R25/xx no bore in skirt )
This adds lubrication for the piston sidewalls.
These additional bore(s) require to be supplied sufficiently, which again made a bigger pump reasonable.
Last not least this is probably also due to cooling purpose, as R27 in stock is intended for the highest rpm-rates of all 250cc models, resulting in highest engine temperatures relatively. Gearbox ratios, wheelsize, Oilvolume all remained equal to the predecessor model R26, so they did no other measure to compensate higher temperatures.
For me, these two are plausible and obvious reasons, allthough I can't supply a black on white proof for that.

Cheers,
Sascha
Think outside the box !

berndr253

Some years ago I made some tests with the oil pump of a R25 and found out, that the temperature of the oil had no significant influence towards the throughput.
Even with an oil-filter (paper) on the "succing-side" and with used oil the pump did its work.

Bernd
Leben und Leben lassen

rolf.soler

I agree basically, especially concerning the R27 and the reasons why it is more temperature sensitive . On the other hand, the R27's built with the 10 mm oil pump (til > 1963 at least) are still up and running...certainly some got a blocked piston, but probably not more than the R26 and older models. If everything else is correct (ignition timing, gas mixture) the standard pump is sufficient
I got a 15 mm pump some years ago and put it in my R27. I had an oil temperature gauge already before the change, and the max. temperatures on long distance tours in full summer were about 5° lower with the larger pump. There is an effect, no doubt. But as I said, even with the 10 mm pump a reasonably maintained R27 will do. Tuned engines are a different matter of course

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