1932 Model 9a - General Questions

Started by Ian Roberts, April 27, 2024, 10:26:14 AM

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singleminded

Hi. You'll really enjoy the 9A. I have a '32 one.
with regard to the gland nut on the Gearbox selector shaft some gearboxes do not have the adjustable nut, mostly i have found that the clamp up style lever (type B) cannot be adjusted.

Daniel

Congrats to your 9a. I agree with the previous comments. For the gearbox of my 32 Model 9 I use Castrol 9038/1 semi grease.

Regards
Dani
Visit my Homepage www.underground-motors.ch

Rick Parkington

#4
I'd agree with Thomas on this. You may find a thinner oil in the primary,  eg SAE20 helps prevent clutch slip as is can squeeze out between the plates faster. The gland seal on the gearchange can be a source of leaks, it's a felt seal under a nut and in theory tightening the nut squashes the felt onto the shaft to make the seal, obviously this won't work if the washer's not thick enough to need squashing. Felt seals should be soaked in melted tallow, sounds medieval but it's readily available because it's used for getting cable through long plastic conduit. Autohose supply felt in suitably thick sheets if needed. 
   
The problem with the gauge is as Thomas says, it doesn't really mean much in itself. The 9A oiling system directs oil to  the pressure indicator - the plunger in a chrome housing by the pump. This plunger blocks the oil coming out of the pump to prevent wet sumping while standing (in theory, in practice oil can still track across the pump to the return side and drain down the scavenge pipe into the crankcase). Upon starting,  pressure lifts this plunger and the rod on the end pokes out of the housing to show it's pumping. It's initial movement opens the feed to the rocker box and gauge. It that was an open outlet, there would be no pressure and the plunger would open no further, but in the rocker box elbow there is a ball and spring to create back-pressure, recorded on the gauge. That back pressure causes the pump to push the plunger out further, opening a second oilway to the big end. Because a roller big end has little back pressure, the plunger spring is now stronger than the oil flow and closes again until pressure builds up anew and the process repeats.
What really counts is movement of the plunger - you need to  make sure it coms all the way out to feed the big end not just halfway. Problems can arise here when a random new spring or copious sealing washers have been fitted and if you ever have the cover off I'd advocate checking how far it comes out to open the rocker feed and big end feed and making a note so you can check when it's running. The trouble with pressure is that it measures restriction rather than flow, if you fitted a strong spring in the rocker box elbow valve, you'd get huge pressure reading - but no oil! Similarly zero on he gauge could mean all the oil is going to the big end - or there's no ball valve in the elbow to show pressure on the gauge but ALL the oil is going up there!  So it's a balance. On SAE 40 I think my gauge used to read 20 psi hot and 40 cold on the no.2 oil tank tap setting.
Hope this makes sense!
Cheers Rick

klaudius

Quote from: Ian Roberts on April 27, 2024, 10:26:14 AMHi
Being new to the Sunbeam marque, I have several basic questions to start with.
The bike is currently being re-commissioned.
Work completed by previous owner - new piston/re bore - new valve guides springs valves

1/. Expected oil pressure at the oil pressure gauge
    Cold start and running
2/. Type of engine oil (make and grade)
    Type of gearbox oil (make and grade)
    Type of primary chain case oil (make and grade)

Thanks for your input.

Regards Ian R

Thomas

Welcome to the Beamers, Ian!

1. The oil gauges of different machines do not deliver the same absolute values. It is the individual relative one, which counts. When being cold the gauge will go to the stop. Only when the motor becomes warm it will give you a value (mine is at around 30 lbs/sq. inch) and only when reaching a stable value the motor is on running temperature. In fact, I use it as a temperature indicator.

2. Any mono grade oil is fine. I use Castrol XXL 40 and it is ok at 10 and 35°C (tested in the Alps). Grade 50 and 30 are also ok but then I would adapt them to the season. I have a grease lubricated gearbox (no oil). There is a dynamic crankshaft seal which stops oil floating from the sump into the primary case. Hence, I believe that one can use the same oil as for the motor. At least I do that.

Cheers, Thomas
1946 BSA C11
1937 Sunbeam Model 9
... and a scratched Hyundai
(MSCR member)

Ian Roberts

Hi
Being new to the Sunbeam marque, I have several basic questions to start with.
The bike is currently being re-commissioned.
Work completed by previous owner - new piston/re bore - new valve guides springs valves

1/. Expected oil pressure at the oil pressure gauge
    Cold start and running
2/. Type of engine oil (make and grade)
    Type of gearbox oil (make and grade)
    Type of primary chain case oil (make and grade)

Thanks for your input.

Regards Ian R