Christian S. Hansen
Post Number: 296
|Posted on Friday, 01 July, 2016 - 07:16 pm: |
Re: 1966 SS MPW Coupe CRX2541
Has anyone determined a substitute oil pressure switch (dash warning light)?
Once removed, the "probably" original switch has "4432 3-5 M6" stamped around the circular body and "England" moulded into the plastic portion. The current part # at both Flying Spaces and Introcar is UE44823P and the design is different, with a large hex drive around the body, whereas the original 44323-5 has a round body and a smaller hex portion just above the threads. The similarity of the numbers is curious and while the UE44823 is not that expensive (about $25 plus shipping), there must be a readily available and less costly (about $10?) substitute from local auto parts stores, but I have had no luck finding it.
Once determined, that info can be added to Brian's resouorce compliation. Anyone been there, done that?
Post Number: 467
|Posted on Friday, 01 July, 2016 - 07:58 pm: |
I believe there's a Tee One article recommending Bob Chapman's (Melbourne) one. It doesn't leak like the original. Bob manufactures and remanufactures parts. His front brake discs are an improvement also - one piece not 2.
I have his sender on my car and it's all good. His prices are usually reasonable too - about what you'd pay for any other car.
Post Number: 9
|Posted on Saturday, 02 July, 2016 - 07:43 am: |
The RR shadow oil pressure switch looks all the world like a unipart gps126 which is a kind of standard oil pressure switch. 1/8-27 thread 10psi blade terminal.
That switch has been used on many different kinds of car. I personally have one on my mini and one on my lotus (though disconnected because it is a 907 engine) They drop to ground at around 10 psi.
If you see the light while you are driving it's really bad, you should stop driving and figure out what is going on or risk really bad and expensive things happening.
If it comes on at idle, it is not good, but if it goes away when driving you can probably drive home without destroying anything.
Here is a link to something that should work, though as I mentioned I really don't know what the OEM pressure rating is.
For a little extra entertainment at the parts counter, I would suggest cross referencing the switch and finding the saddest or most obscure thing that ever ran a gps 126( like a tractor, airport tug, or some Peugeot product) and ask for oil pressure switch for that.
I have a lucas sob 103 I pulled from my mini and replaced with a 126 sitting in my shed and a RR silver shadow sitting in my driveway, If there aren't too many mosquitos out tonight maybe i'll answer this definitively.
Post Number: 24
|Posted on Sunday, 03 July, 2016 - 01:34 pm: |
Ross The sender is of a mini an is not a 1/8-27 thread it is 26-NPT. 1/8 BSP will half fit down the hole will work but not wright.
Christian S. Hansen
Post Number: 299
|Posted on Sunday, 03 July, 2016 - 02:24 pm: |
Do I infer correctly that the proper threading is 26-NPT? If so, I will continue the search with that as a requirement. Thanks for that clarification.
Post Number: 14
|Posted on Sunday, 03 July, 2016 - 03:29 pm: |
Good to know.
The thing I took out was probably and OEM unit (located on the oil filter mount) but it was definitely a LUCAS unit and definitely stamped 103.
It had a tapered thread (bspt or npt) so I threw in a GPS126
I didn't put a straight threaded sender in a taper hole or vis versa. I'm not a animal,... well, sort of as I don't honor the difference between British Standard Pipe Taper and National Pipe Taper. 1/8 in tapered threads are so close they are all but completely interchangeable.
Few sizes are truly interchangable, but like M6 and 10-32 bolts, 1/8 taper fittings are the same in practice.
I didn't get a chance to pull the sender on the RR last night, but if you know what thread you have and a pressure you want, here's Wells' list.
Christian S. Hansen
Post Number: 300
|Posted on Sunday, 03 July, 2016 - 05:40 pm: |
Philip...As a novice here, I did some unilateral research and suspect a typo in your thread, and that you meant "28" not "26"? Apparently the 1/8-27 NPT has a tapered thread and 27 threads per inch. The 1/8-28 BSP has a straight thread and due to its straight OD being about that located half way down the decreasing taper of the NPT, not only are the threads not properly engaging, it will stop at that half way point there the ID of the NPT taper is less that the OD of the straight threads of the BSP. Hence, I surmise that the proper thread for the sender should be the 1/8-27 NPT, which is confirmed when I measure the sender I removed.
Ross...Thanks for that link. I will scan down the list and hope to find one with the proper thread and that triggers at about 7-10 pounds.
Update: Scanned the list, looked at images, and found nothing similar in 1/8-27 NPT...only NPTF, which I understand is different in that it seals by a slight crushing of the treads instead of having to use teflon tape or other sealant on the threads. I suppose that's OK. PS117 seems like it will work, even though the design differs from the original and needs a special socket to install. It will be the fall-back option. There were some references to BSPT, which I presume is a tapered version of the BSP, but the threads per inch will still be a bit off with that one...28 versus 27.
Christian S. Hansen
Post Number: 301
|Posted on Sunday, 03 July, 2016 - 07:10 pm: |
Curiouser and Curioser...Alice in Wonderland?...
I began to wonder why a British car would use US pipe sizes rather than BSP and now doubt the conclusion that the threads are 1/8-27 NPT. Anyone know for sure?
I had no real luck simply counting the threads. That would have been too easy. I concluded it was NPT simply on the basis of the major OD of the tapered section which is .406 and reducing down to .386 over the length of the threaded portion. BSP straight threads apparently have a consistent OD of .383 and NPT has an OD of about .390 midway on the taper...so based on those diameters, the NPT seemed to be the better fit, as the .380 BSP straight thread diameter seemed to be too small to match. What could go wrong?
Here is where it gets interesting. The OEM part number for the switch is UE44823R and I wondered what the "R" stood for, and as it turns out, that is apparently the designation of the "tapered" BSP fitting...the BSPT! So that leads one to conclude that the OEM part is indeed BSPT, not NPT.
Here's the kicker: The part number on the "original" switch removed from the car had the designation of "M6" on it, and one reference source noted that the "corresponding" pipe thread for the 1/8-28 BSPT (the "R" designation) is M6!! Further, the OD given for M6 (presumably measured midway on the tapered portion of the threads) is .400 which dovetails with measurements from the switch removed from the car perfectly. This seems to add up. The proper thread for the RR is the British thread...BSPT, designated "R" as on the OEM current replacement, and "M6" as on the original part. Am I catching on here, and a proper substitute part should be the 1/8-28 BSPT?? Looks that way. Were it not for the interest of finding the "workaround" for Brian's "compilation", I would be inclined to simply buy the switch from Flying Spares...but instead I succumbed to the challenge of finding the substitute. Silly me!