Question with regard to the transfer box i need clarification on type of thread thats on the so called drain plug hole as i read different things , I know its a 1/2 inch hole but I read in places on the net in different forums thats its a NPT and in others it BSPT one is for you guys in the USA and the other is British the main difference is the angle of the tread that is different 1 is 55 degrees the other is 60. which one is it ?

I am from the UK / England are the cars threads different in different parts of the world ie USA and UK?

also just as important , is the thread on the transfer box Tapered and so creating a seal with the then tapered plug?

i am after this info as i am going to fit a 1 way valve to allow easy filling of oil but until I know 100% for sure what type of fitting it is and whether its a tapered fitting im stuck.

all help and advise is appreciated.

 

Ashcapri28, it is my understanding that the drain plug is a standard 1/2" NPT fitting. I created a rig that you can put into that hole and I used a 1/2" NPT adapter with no issues.

Yes, the plug is tapered, but the use of a little bit of sealing compound would be advisable.

Please keep in mind that I am in the US and if there are different drain plugs for different markets, that might be why you are getting conflicting answers. If in doubt, you will have to pull the plug and then put a thread gauge on the plug to get an idea of what the thread angle is. Both an NPT and BSPT use 14 TPI for a 1/2" fitting. So, the only way to really tell the difference is to hold the metric and ASE thread gauges against the plug and see if you can spot a slight difference in the thread angle. Once should fit really tight and the other you will see a bit more light between the thread gauge and the plug.

I deal with a lot of different fittings and plugs at work. There is a lot of good information inside this booklet (https://www.swagelok.com/downloads/w...n/MS-13-77.pdf). This will go into more info than you probably want to know.

 

Man, that is really a handy PDF, Thermo. Thanks for sharing.

 

Alfadude, if you like that one, get your hands on what is called a "machinist's Handbook". It is about 5-6" thick normally and anything and everything you can imagine is written in that book when it comes to metals, fittings, and the like. Used to have to have a lot of that info ready at the tip of the tongue when I was helping to build/operate/repair submarines.

 

"It is about 5-6" thick normally"????? Is that what she said? Sorry, I couldn't resist. That popped in my head when I read it.

That machinist's handbook I'm sure would come in very...er....handy....but I don't know that I would have the patience to read through it. Scanning that PDF is about all the attention span I seem to have these days............

 

Alfa, is that why we have to pump twice, to give the full 6 inches? Sorry, you threw me down the gutter and had to go just that one step further. Or the other one is being a tuna can man. May not go deep, but you will be remembered for the stretch marks.

 

I also deal with various types of fittings. My employer (VW) gave all of its maintenance men a Fluid Connector ID guide by Parker. It can fit in your hand and includes thread pitch gages, descriptions and a caliper to measure ID and OD. It may be available at Parker.com. Hope this helps.

 

tnzman09, I work with swaglok and Parker stuff a lot. I do all the instrumentation stuff at a nuclear power plant. So, the fittings is a vital part of what I do. Knowing what goes where makes a big difference. Having a fitting let loose on the wrong system makes for a bad, bad day. Nothing like stumbling out of a cloud of steam.

 

Thermo as always you are correct. I have also worked in high pressure/temperature propulsion plants where small mistakes can be deadly. Even low pressure systems with poorly fitting connections can be disastrous. Matching fluid fittings is no small matter, so of course, one should use all means possible to find the correct fittings. Best regards.