P11 oil tank drain plug

Ron L

Ron L

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I'm trying to locate the proper part number or thread form/pitch for the drain plug on the later alloy or steel oil tank on the P11/P11A. The '66-'68 Master parts book only shows P/N 13765 and lists it as fitting "all but P11/P11A". There is no additional listing for a drain plug for P11/P11A. Is this the same plug? From what sparse information I can find, P/N 13765 is 3/8 CEI (26 TPI). Using a thread pitch gauge, the couple plugs I have measure 28 TPI. I don't have confidence in this reading as 28 TPI is hard to read accurately on a simple thread pitch gauge. I have an oil tank plug from a 650 Triumph which is listed a 1/8 BSP (28 TPI), but it will not fully thread into any of the three tanks I have. It threads easily into the tank for the first 1/4", then stops dead. A 3/8 CEI nut will not thread onto the P11 drain plug I have.

Can anyone tell me if P/N 13765 is the correct one for P11/P11A oil tanks? If not what is the correct thread form/pitch? I can make one on my lathe if I know the thread form.
 
Mine is a 69 steel tank P11 Ranger:
1/4 whitworth wrench size at the bolt head.
Pitch is 28
3/8" dia.
Check with Mike Partridge @ Walridge Motors. Should have one. Save you the trouble of making one. Copper washer as well.
 
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CanukNortonNut said:
Mine is a 69 steel tank P11 Ranger:
1/4 whitworth wrench size at the bolt head.
Pitch is 28
3/8" dia.
Check with Mike Partridge @ Walridge Motors. Should have one. Save you the trouble of making one. Copper washer as well.
Click to expand...
Thanks! That confirms what I measure on my two original plugs. The only British thread form in 3/8 X 28 TPI that I have found is 1/8 British Standard Pipe (BSP). My plugs measure 0.375 major diameter for the complete length of thread, so I don't believe they are tapered threads. The new Triumph 650 plug also measures 0.375 major diameter with no taper. The total thread length is virtually the same on the P11 and Triumph plug. However the Triumph plug screws in easily for 3-4 complete turns and then stops. I am hesitant to buy a 1/8" BSP tap to run through the tank threads and risk ruining them. But I am puzzled why the Triumph plug does not fully thread.

I usually go to Mike with a part number, but here there is none. I might wait until Barber and talk to him there. Randy Baxter is usually there also and he might have some insight.

Does anyone have an Atlas tank plug (13765) that they can measure the diameter and thread form?
 
Ron L said:
Does anyone have an Atlas tank plug (13765) that they can measure the diameter and thread form?
Click to expand...

I can measure the diameter and get tpi, but not thread form . Will do tomorrow and report back.

Slick
 
Ron L said:
Thanks! That confirms what I measure on my two original plugs. The only British thread form in 3/8 X 28 TPI that I have found is 1/8 British Standard Pipe (BSP). My plugs measure 0.375 major diameter for the complete length of thread, so I don't believe they are tapered threads. The new Triumph 650 plug also measures 0.375 major diameter with no taper. The total thread length is virtually the same on the P11 and Triumph plug. However the Triumph plug screws in easily for 3-4 complete turns and then stops. I am hesitant to buy a 1/8" BSP tap to run through the tank threads and risk ruining them. But I am puzzled why the Triumph plug does not fully thread.

I usually go to Mike with a part number, but here there is none. I might wait until Barber and talk to him there. Randy Baxter is usually there also and he might have some insight.

Does anyone have an Atlas tank plug (13765) that they can measure the diameter and thread form?
Click to expand...
Hi Ron,
RGM lists 13765 as 1/8 BSP.

13765 search

13765 search search
www.rgmnorton.co.uk
 
I found this stainless fasteners reference on this site. I am not sure who initially did this doc, but it's proven to be indispensable and I've never found one wrong item in the hundreds of bolts I looked up during my N15 project (which had most fasteners present, but in boxes). For this #, I found only an incomplete entry: '13765 PLUG ??? ??? OIL DRAIN', but I found that Andover NM13765 is superseded by 06.7630, which looks to be the part. Looking in the stainless fastener list for 06-7630 to match format (I use a local OCR'ed PDF copy so it's different format) I found it as shown:

P11 oil tank drain plug


Besides Andover, I also use https://www.walridge.com/orderform/ which uses the NN-NNNN (so 06-7630) format. It often provides a picture and useful info. There I find a discrepancy, as Walridge lists it as:

PLUG 3/8 x 26 TPI - CHAINCASE & OILTANK DRAIN PLUG - STAINLESS

Nortons are fun! Not disparaging Walridge as they are always great help, but I think I'd trust the other info.

~Tom
 
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Could somebody with nothing better to do machine one and incorporate a ball valve and hose barb fitting on the other end? That I'd pay $10US for. :)
 
texasSlick said:
I can measure the diameter and get tpi, but not thread form . Will do tomorrow and report back.

Slick
Click to expand...

Okay, this is what I measure on my original Atlas drain plug.

OD = 0.372" (nominally 3/8"). The OD is parallel, not tapered, which suggest the thread form is BSPP
tpi = 28 (I double checked this, definitely NOT 26 tpi
length = 0.400" nominally 7/16"
hex size = 1/4 W

Slick
 
Junglebiker said:
I mentioned this over on FB--has anybody considered a Matchless drain plug?
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Yes, I have. But which Matchless? My problem is there is no part number listed for the P11 tank. Also the P11 tank is peculiar to the model and was not used on any Matchless. The only sources I have for Matchless (AMC) parts is AMC classic spares and the AMC Owners club, both in the UK. The postage for just drain plug is prohibitive and add to that, in the last 4 months two orders of British thread bolts sent via Royal Mail never arrived.

I appreciate those who measured and/or found the thread form of 13765. That leads me to believe it is indeed the same as the P11 plug. I can find one here in the states to confirm the fit. Likely another case of a mistake/misprint in the 66-68 Master Parts book.
 
Ron L said:
Yes, I have. But which Matchless? My problem is there is no part number listed for the P11 tank. Also the P11 tank is peculiar to the model and was not used on any Matchless. The only sources I have for Matchless (AMC) parts is AMC classic spares and the AMC Owners club, both in the UK. The postage for just drain plug is prohibitive and add to that, in the last 4 months two orders of British thread bolts sent via Royal Mail never arrived.

I appreciate those who measured and/or found the thread form of 13765. That leads me to believe it is indeed the same as the P11 plug. I can find one here in the states to confirm the fit. Likely another case of a mistake/misprint in the 66-68 Master Parts book.
Click to expand...

I just assumed G85CS, since that's the frame the original prototype was built in. Is the story about the prototype not having an oil tank drain plug true or just apocryphal? Also I didn't specify which Matchless because again I assumed (maybe incorrectly, I admit) that they probably all used the same drain plug.
 
Ron L said:
But which Matchless? My problem is there is no part number listed for the P11 tank. Also the P11 tank is peculiar to the model and was not used on any Matchless. The only sources I have for Matchless (AMC) parts is AMC classic spares and the AMC Owners club, both in the UK.
Click to expand...

You are in luck. This is the oil tank drain plug of all 1964-69 Matchless heavyweight models (excluding the G85CS which had none). The plug is almost the same as NM13765, the only difference being the length.

01-2019BOLTBSPP1/8"x28x3/8"OIL TANK

- Knut
 
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The small central alloy tank of the G85CS was emptied by disconnecting it, which is an easy task. Mind you, it's a race bike, not built for comfort or easy maintenance.

- Knut
 
Just a tad off topic:

You guys will either get a kick out of this or just chalk it up as "what is wrong with you?'.

I pull all the hot oil out of my oil tank when I do an oil change with a Harbor Freight pneumatic brake fluid bleeder. Takes a lot longer than it would to unscrew that drain plug, but it's nowhere near as messy.

Only place with that Matchless part number is AMC Classic Spares. They are listed for around $3.04 no VAT plus shipping. I found one elsewhere, but it was $9.95 plus shipping.
 
You know, it probably wouldn't be that difficult to copy Harley (gasp!) and make the oil drain a simple arrangement of rubber line hanging down from the tank with a plug at the bottom end retained with a hose clamp. Keeps the bike really clean, and the drain plug can be placed somewhere easy to access. A really neat arrangement might even be to put in the aforementioned hose, put a fitting at the bottom end which the hose clamps onto and which has a threaded drain plug in the bottom. That fitting could be rigidly connected to the frame by means of a fabricated bracket, thus making oil changes an extremely simple, clean, quick, one spanner affair. You could go a step further and put in a ball valve, but personally I don't like draining my oil to be so easy that any curious child might manage it. (I was that kid!)
 
Junglebiker said:
You know, it probably wouldn't be that difficult to copy Harley (gasp!) and make the oil drain a simple arrangement of rubber line hanging down from the tank with a plug at the bottom end retained with a hose clamp. Keeps the bike really clean, and the drain plug can be placed somewhere easy to access. A really neat arrangement might even be to put in the aforementioned hose, put a fitting at the bottom end which the hose clamps onto and which has a threaded drain plug in the bottom. That fitting could be rigidly connected to the frame by means of a fabricated bracket, thus making oil changes an extremely simple, clean, quick, one spanner affair. You could go a step further and put in a ball valve, but personally I don't like draining my oil to be so easy that any curious child might manage it. (I was that kid!)
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If I could get a nipple adapter to go from BSPP to an American standard thread I'd fix that oil tank drain situation in a heartbeat. That BSPP 28 x 3/8 thread is the show stopper.

I don't worry much about kids turning a ball valve, it's the wise guy adults I worry about. ;)

When my spin on filter was on the feed side of the pump, I could drain my oil tank down to the base of the filter inside the tank by removing the hose from the filter housing, and then finish up with the pneumatic brake bleeder. Unfortunately I moved the spin-on to the return side.
 
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O.K. I bought a new 13765 drain plug. Looks identical to the originals. Like the Triumph part, it screwed easily halfway into the tank (all three) then stopped. I then broke down and bought a 1/4 - 28 BSP (parallel) die. Surprisingly, a U.S. supplier and a Milwaukee brand die for less then $15 delivered. I chased the threads of both the Triumph plug and the Norton P/N 13765 plug. Easily ran down the length of both plugs with only slight resistance. Now both plugs screw easily into the tank! My conclusion (opinion) is the plating on the plugs is making the threads slightly out of specification. The die ran down too easily to actually be cutting new thread. I also believe that the correct part number for P11 oil tank plug is 13765, the same as for the Atlas and N15.
 
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