Really confused. Bloody threads/fittings

[bitsilly]

Right, I have a Serc oil cooler and was supplied aeroquip fittings to fit it. However they do not fit. Using my thread gauge, the comb that fits the serc thread says 7/16 or 14 (its a whitworth gauge). So I would now describe the thread as Whitworth 14 or BSP 7/16 thread. Is that right?

I cannot fathom using the gauge at all. Take -6 fitings, the catalogue says they are BSP 3/8 but my gauge measures the thread perfectly as 5/16.

I guess I wont get much feedback on this so while youre here, to put it another way, how do you connect a serc oil cooler with 7/16 thread and o/d 22.5mm fittings to -10 hose?

This is why people buy kits isn't it!:boohoo:

[Dutch Paul]

Originally Posted by bitsilly

Right, I have a Serc oil cooler and was supplied aeroquip fittings to fit it. However they do not fit. Using my thread gauge, the comb that fits the serc thread says 7/16 or 14 (its a whitworth gauge). So I would now describe the thread as Whitworth 14 or BSP 7/16 thread. Is that right?

I cannot fathom using the gauge at all. Take -6 fitings, the catalogue says they are BSP 3/8 but my gauge measures the thread perfectly as 5/16.

I guess I wont get much feedback on this so while youre here, to put it another way, how do you connect a serc oil cooler with 7/16 thread and o/d 22.5mm fittings to -10 hose?

This is why people buy kits isn't it!:boohoo:

Bitsilly (is that your real name??)

There are dozens of different threads about.
The easiest way, to save any confusion, is to find your nearest hydraulic type supplier and take all your parts to them. They should be able to sort you out.

[bitsilly]

Good answer!

Bitsilly was as a result of having a tuned John Eales 4.6 RV8 engine in a Westfield Seight. Just haven't figured out how to change my name yet! It's actually Ed!

[wilf]

Ed - the dash-6, 8 10, etc thread are very different from anything else. They were invented for hydraulic couplings on helicopters!

So - if you have a cooler that has a "dash" size fitting, you need the same on the pipes, and all the measuring in the world won't help.

The "dash" fittings refer to the ID of the pipes, a -12 is 3/4", -16 is 1" etc.

Every size up in 4s is another 1/4" pipe ID.

For help, look up "think auto" - Mocal suppliers, they will sort you out.

[Keith1968]

I was a designer for a forklift company many years ago so built up some good knowledge of fittings in my head, although I can't say I'm remembering so well now...but here goes and apologies for any mistakes......

As Wilf says the dash 6 number is the pipe size in 16ths of an inch, so no 6 is 6/16ths or 3/8 dia, no 4 is 4/16th's, no 8 is 8/16ths or 1/2" and so forth.

These is a standard "english" hydraulic fitting nomenclature, not just helicopters but anything hydraulic.

The "english" standard thread form for hydraulic are either JIC (your pipe fitter will say something like "no 6 JIC mate..") but which is actually a UNF thread form, or the other type is usually BSP.

Whitworth was never a pressure thread.

Just to confuse the issue further, a UNF thread form will have a -dash extension after the number which anotates the thread per inch, not pipe size.

What I think you 'might' need is a BSP to JIC adaptor to go into the cooler, then a JIC to JIC hose then another adaptor to go into the engine.

Of course whatn you should REALLY go for is metric face seal adaptors instead which are far far superior and universally used nowdays. Ask a local hydraulic van man to make up for your car.

Hope that helps.

[V8bassman]

Must clear up a couple of things.

The BSP threadform developed out of the old Whitworth thread and the two are to all intents and purposes one and the same. The number 14 refers to the number of threads per inch, and is 14 on 1/2", 5/8" and 3/4" BSP threads, so your oil cooler thread will be one of these. I suspect it will be 1/2"BSP as this is very common on oil coolers. To check, measure the outside diameter of the thread, If it is indeed 1/2"BSP, it will measure 21mm or thereabouts depending on the tolerances to which the thread has been turned. It is a common misconception that BSP thread size refers to the actual diameter of the thread. In fact the size quoted actually refers to the inside diameter of the pipe on which the thread has been turned. So if the 1/2" is actually the nominal bore of the pipe, the thread turned on the outside of the pipe will be 1/2"BSP (British Standard Pipe thread).

JIC is actually an american thread form (JIC stands for Joint International Conference) and is identical in thread diameter and pitch to SAE and UNF, the only difference being the angle of the cone seat on the fitting which forms the metal to metal seal. JIC / UNF is a very common threadform on Goodridge / Aeroquip type hose fittings.

As far as hydraulic hoses are concerned, nowadays there is a bewildering variety of threadforms around, and many OEM manufacturers produce their own threads to try and prevent the likes of me supplying a much more economically acceptable alternative to their products. Doesnt stop me though, I can usually get around the problem somehow. However, by far and away the most common thread we deal with here is still the good old BSP.

Hope this helps.

[bitsilly]

Thanks gents, I really didn't expect to get any coherent answers!
I rang Mocal with a view to explaining but their phones were on the blink so they sounded like Daleks on helium. I possibly need a different size cooler and won't be able to fit adaptors (space) so I'll buy a compatible cooler to the fittings I have. Then I'll contact FluidAir to keep it in the family!
I hate walking away without understanding but I guess this one is best left to the experts, neither can I afford the infinite number of gauges etc needed.

[wilf]

Ed - this is one of those cases where you need to buy all the parts for that "bit" in one go, from one supplier. Then the onus for it all to fit is upon them, and you don't need to acquire in-depth specialist knowledge.

[mylesdw]

Originally Posted by V8bassman

Must clear up a couple of things....
Hope this helps.

Expert input is what really makes these forums, thanks Dave.

Would I be right in thinking that JIC and AN fittings are interchangeable; it seems to work OK but is that by luck or by design?

[V8bassman]

Originally Posted by mylesdw

Expert input is what really makes these forums, thanks Dave.

Would I be right in thinking that JIC and AN fittings are interchangeable; it seems to work OK but is that by luck or by design?

Myles, the AN thread is a US Military (Army/Navy hence AN) thread with the same dimensions and 37deg flare as JIC but the Military will not actually confirm that the two are interchangeable 'due to specialised military requirements'. Which means in other words you shouldnt have any problems !