Temp sender thread

[tdafforn]

Hi All,
Quick one, what is the thread of the temp sender?
The sender in my +2 fits into a threaded adapter that then screws into the head?
Cheers
Tim

[bcmc33]

The adapter has the same thread both sides - 3/8" BSP.

[tdafforn]

Thanks, but on mine the sender thread is smaller than the thread in the head and hence has a brass insert (female/male)
Tim

[bcmc33]

I thought that until I removed it from the head. There is a sealing washer between the adapter and head that is 0.95" diameter.

[rgh0]

The Elans and I believe early plus 2 had a mechanical temp sender with the male to male adapter. The later plus 2 ( and twin cam europa) had a female to male adapter for a smaller male screw in electric temp sender.

Unfortunately my plus 2 is not handy currently to measure the thread but the usual major parts supply suspects should know it

cheers
Rohan

[bcmc33]

As far as I am aware both the heater and temperature gauge holes in the head are 3/8" BSP.

And yes, Rohan is correct (as usual), the later +2 variants had an elctrical temperature sender ILO the original capiliary sender. So they probably had a different adapter.

[CBUEB1771]

The electrical water temperature sensor on later +2s is a tapered pipe thread. It goes into the head via a brass adapter/reducer bushing. I am fairly certain it is 1/8 BSTP. This is a vexing size as it is very close to the US 1/8 NPT. The BSTP is 28 threads per inch whereas the NPT is 27 threads per inch. The BSTP also has an included thread angle of 55 degrees compared to 60 degrees for the NPT. The BSTP is also about 0.02" larger on major diameter. In other words it would be very easy to mix these up but damage would ensue. Best to get out the pitch gauges and confirm.

[tdafforn]

Just had a closer look..
The sender seems to be 3/8" diameter and the male part of the adapter is 5/8"..
Question now is, what thread?
Tim

[bcmc33]

Perhaps this helps:

1/8" BSP (29 tpi) is 0.383" major diameter.
3/8" BSP (19 tpi) is 0.650" major diameter.

[tdafforn]

Thats really helpful.
Where do you get that sort of info from?
Tim

[rjaxe]

Apologies for hijacking the thread, but a v. good little booklet which has details of BSP, BA, BSF, Whitworth, UNC, UNF plus much more engineering data tabulated on laminated sheets is called a Zeus Precision booklet. There seems to be loads on sell on E-Bay for a few quid, well worth having.

[bcmc33]

Any mechanical engineer worth his salt would never be more than an armslength away from his Zeus quick reference booklet. However, I retrieved the information from my Engineer?s Handbook which sits on a bookshelf in my home office.

Just to prove my statement, I went into the loft to find my briefcase (been there since retirement), and found the Zeus booklet staring at me as I openned the case. It?s now on the bookshelf ? far more convenient than the big handbook.

[CBUEB1771]

All this has made me go out to the garage at 2315 (GMT+5) to retrieve my Smiths electric water temperature sender, pitch gauges and caliper, it got bl**dy cold out there. The sender is clearly a tapered pipe thread, 27 threads per inch and a major diameter of 0.365 inch at the large end of the taper. So it is 1/8" NPT. I'll post a photo tomorrow. I really expected it to be 1/8" BSPT but it is not, and I really do have an original Smiths part. With all respect to bcmc33, the pitch of 1/8 BSPP and BSPT fittings are both 28 threads per inch, not 29. I agree that the major diameter for 1/8" BSPP is 0.383 inch. Here in the colonies we tend to rely on Machinery's Handbook. Most of the respected fastener and fitting suppliers have dimensional data posted on their websites. I have found these posts to be very reliable and consistent among themselves.

[triumphelan]

A Zeus ,6inch rule & scriber in my breast pocket of my brown coat overall and in the late 50`s ,I was ready for anything the foreman could give me .They are still very much on hand in the top draw of my 50yearold "more& wright tool box "

[rcraven]

You can download an old version of the Zeus tables at http://forums.lr4x4.com/index.php?showtopic=4463, whether legally or not I don't know. A useful and easy to use on line source is
http://www.gewinde-normen.de/en/index.html.
I think most people use the abbreviation BSPT not BSTP.