ScarboroughSeadog

Howdy folks- my grandfather brought this back from WW2. He said it was from a glider in Sicily. That’s all I know- see the markings. Is it from a Horsa? Or an American glider? Is it from a gunsight? My grandfather is long gone and my Dad is trying to research the gyroscope, without much luck. Grateful for any thoughts! Thanks.

Ruxy- The TB1114-001W senders as now produced are a multi-fit part, which (correctly) span a variety of vehicle set ups from mine (older, less common, military specific) to a range of other classic civvy landrovers (which do have the red mark on the gauge). It would make sense if they are calibrated to by far the most common application (ie the latter). Fortunately I had a repairable 40 year old TB1114-001W which works perfectly- problem solved. Thanks for your help and advice.

I have to say…..I think you’ve nailed it! These senders cover a few different set ups, and hence supply to different gauge decals etc. My particular (dated, less common) set up is an anomaly as far as these senders go. I suspect your explanation will save a fair bit of head scratching for many with this issue- I bet you’re right!

Always good to finish these things off with a conclusion: replaced a faulty fuel gauge, replaced a faulty Lucas switch. All now working perfectly but there is an interesting issue with the senders. I have 3 senders marked TB1114-001W. This is the correct part number. One is brand new, one is say 10 years old, one is say 40 years old. Only the 40 year old one reads correctly (ie empty at empty). The other two newer ones read 1/8th at empty. I can only think the more modern parts have a different resistance scale? Fortunately with a repair made to a snapped spade connection I was able to use the original 40 year old part and all is working perfectly. Bit of a mystery though.

Thanks Ruxy- will try and decipher all this when back in civilisation (away working in the north of Scotland at the moment). My fuel gauge is mounted at 6 o’clock- as you say, as per a late model fitting. Also have the late model oil and temp gauges and transmitters you describe. Haven’t had much time to look at the lightweight, but have now replaced both Lucas switches and have one tank reading perfectly. One tank still not registering empty but suspect that is it’s sender- will replace and see. Expecting that will solve the problem, but will see! Will post a conclusion and findings as soon as I can- but don’t expect that that will be in the next few days.

Just double checking that the Lucas switches are NC? So the circuit is made when the nipple is NOT depressed/activated? If the nipple is depressed by the tap, that breaks the circuit and therefore stops any reading from the tank connected to that switch, correct? I'm thinking if one switch is faulty and remains closed (or partially closed) when activated, that would mean both switches (tanks) are closed (reading) at the same time, which might explain why the gauge reads 1/8 when the tank it should be reading is empty? Does that all make sense? Feels like a bit of a eureka moment, but not in the shed until Sunday eve.....

That said, I’ve owned mine for nearly 25 years and until recently the fuel gauge readings have been spot on. The problem I’ve got is resolvable- just need to figure out the fault.

Thought of that- but the 1/8 reading is at absolute minimum on the sender arm (bent or not), so doesn’t work.

It would be really useful to have a 'print thread' option for reference purposes, which prints the text in a suitable (concise) format without all the banners etc. Is that possible? They have just that on the Lightweight Forum and its very helpful.

New Lucas switch about £30. Mine are over 40 years old so don't mind renewing speculatively. Chain spray probably good preventative idea.

Yes- PRC1789 and 90560612 fitted. Have cleaned the various connections. I'm going to replace the second Lucas switch on the changeover tap. This should be NC (normally closed), but if it has deteriorated and is remaining partially open when not activated, I wonder if that could explain my bogus reading......

Yes, I have a single ammeter on the shunt box- which is located in the rear tub behind the drivers seat. Correct, contract FVE22A/87. First entry on the VHC is 27/11/79. Chassis 95105646A.

Understood- that's the sender I have.

Thanks Clive- my cluster is a later part I think. The gauge fits directly into a common cluster housing.

Thanks- yes correct fuel gauge is PRC1789. It's FFR 20HF63......

How should the earth point shown be correctly earthed? With direct earth from the ‘to fuel tank’ bolt (in addition to the fuel tank connection)?

Late model (1979) 24v models with enclosed cluster gauges can use the 12v sender units- checked this with Blanchards. I have the correct 24v gauge. Thanks for the detailed response which I will try and decipher tomorrow. As you say, mid point on the tank lever is useful anti theft measure, but can catch you out! I did read (on hmvf) the gauge should read empty at the tank lever ‘neutral’ position- hence the query.

Thanks for this detailed response. Looks like the red arrow point is electrically connected to the right bolt (as it appears in the photo). There are 3 earths attached to the cluster securing bolts- perhaps one of them should be connected to the right bolt of the fuel gauge (it hasn’t been for many years- 20, probably). The oil and water temp gauges aren’t earthed directly.

It’s the correct 24V part- direct part number replacement for the old one. It has (and should have I believe) only 2 connections to the gauge itself- the cluster housing is earthed.I’ve just noticed that the gauge reads full when the tank switch is in the middle (selecting neither tank). Pretty sure it should read zero. Any thoughts if that points to a particular fault? pic shows the gauge

Thanks all- and good point ref the compression gland. Will be permanently wired.

This has become a niggle..... Late model (1979) 24V- no voltage regulator on these models. Just replaced fuel gauge and one of the lucas switches and now I have a fuel reading at least. BUT both tanks read 1/8 full when empty (they read full when full). Its not to do with the position of the sender float (which is at the bottom of the tank). The gauge returns to empty when the ignition is switched off. Any thoughts on what the prob could be? Both tanks are well earthed. Thanks

I’ve dissembled the unit and C is clearly earth. A goes to the switch. B goes to the bulb. Any thoughts which is live? Consensus seems to be that B is usually the live pin, but there appear to be different protocols. Any thoughts? I’ll be wiring it permanently to a plug.

Yes- there is a 240v version, stamped as such (like mine)

A very sobering thought! My proposed connection would be permanently made direct to the lamp (same issue with equal length pins though), but many thanks for pointing this out!