Speedometer Advice Needed

[Bob Moseley (RIP)]

Hi all
I am currently restoring an instrument cluster for an Australian 2pdr Anti-Tank Carrier. This is the first one of these I have done and I noticed that the speedometer face was different. All Ford Blitz and Carrier speedometers I have restored to date have all had the gear change quadrants on the face. In this case those quadrants are not there. Given that these 2pdr Carriers were a one off 200 batch in 1942, I need to know whether they all had this type of face. So if anyone has access to a 2pdr Carrier with original instrumentation, I would like to know.

I've attached a scan of the face, didn't scan too well, with a comparison of the standard face as I know it. The 2pdr face is mounted on a Stewart Warner speedometer head Part No. 97050.

Bob

[Ken Hughes]

Bob i am led to believe that nz carriers do not have the gear change segments,I do stand to be corrected by those more in the know,but this is what i am led to believe after discussion with a fellow with a nz carrier with your type of speedo face,and comparing it to my 13cab ford truck type with the gear change segments.
he says that the ones like yours are very rear here in nz!
Maybe Tony Smith will know?

[cliff]

Bob I have one photo of a restored one which shows the instrument panel and it is the same as yours with the segments for gear changes.

[Bob Moseley (RIP)]

Hi all
I have just received an image from another 2pdr Carrier and this also shows the non-quadrant face. I'll contact some other owners who don't subscribe here for further confirmation. However it looks like new artwork coming up.
Bob

[Tony Smith]

This speedo is sourced from an NZ built LP2a, and does not have the gear change segments on it. I could sell it on e-bay as an original, rare 2pdr part and retire!

[Tony Smith]

The rear side showing the original wiring and speedo mechanism, also a Stewart Warner type. Wiring terminals are of a different style to the usual Ford type found on Blitzes and MCP's.

Interestingly, note that while no fuel gauge is provided on Aust and NZ carriers (as fuel level is checked with a dipper stick), that the hole in the panel is filled with a dummy gauge ie the body of the gauge has no electrical innards, but has terminals and a gauge face that's blank

[Tony Smith]

Only done 476 miles, still running it in!

[Bob Moseley (RIP)]

Hi all
Using the old adage "If all else fails, read the Manual", I did and it explained why the gear change quadrants are not present on the 2pdr speedometer faces.

[Bob Moseley (RIP)]

Here is the image I mentioned earlier, thanks Darian, off an original instrument cluster. However looking at the mileage and speaking with the owner, it appears the speedometer was rebuilt utilising the original face but mounted onto a truck or car speedometer head. Whilst this looks good the speedometer head would contain the incorrect gearing. Another difference between this one and a standard Carrier is that the headlight toggle switch is a Ring Grip one as opposed to the small brass toggle switch.

Tony, thanks for your images, especially the wiring side. The panel I'm restoring at the moment needs to be re-wired and I'll compare yours with what I have. I'm now quite comfortable that this is the correct speedometer face for the 2pdr Carrier.

Thanks for the input but keep commenting.

Bob

[Tony Smith]

Originally posted by Bob Moseley
..... However, it appears the speedometer was rebuilt utilising the original face but mounted onto a truck or car speedometer head. Whilst this looks good the speedometer head would contain the incorrect gearing.
Thanks for the input but keep commenting.

Bob

Bob, the variations in the "gearing" (eg 3 to 18, 3 to 21 and 5 to 18) are all contained on the rear output of the gearbox, not within the speedo instrument. All Ford speedos, both Waltham and Stewart Warner, have the same internal ratios, as I understand do most US Speedos of the period (incl Jeep, GMC, Dodge, etc Military styles). I think the standard figure is 2000 turns of the cable to an indicated mile. So if the CABLE turns at 2000rpm, the speedo indicates 60mph and the odometer adds 1 mile per min. The different driving and driven gear ratios on the Speedometer output of the gearbox are an attempt to match the rotation of the Differential and wheels (or track!) per mile to the 2000 turns per mile of the speedo.

If this is not clear, I could do some math examples to explain.

Let's assume that our Carrier is trundling along nicely in a straight line at 2000rpm engine speed in 4th gear (1:1 ratio). We will say it has a 5.83 to 1 diff and 35 tooth drive sprocket. Carrier track has a 1.75" pitch. In a 1 min period, the crankshaft will rotate 2000 times, the gearbox output shaft will also rotate 2000 times (1:1 ratio), while the axle shafts will rotate 343 times (5.83:1 diff). If the drive sprocket turns 343 times and moves 35 links per rotation, that is 12005 links per minute at 1.75inches, or about 1750 feet. 1 mile = 5280 ft, so in 1 min our carrier has travelled about 1/3mile, or does a speed of 20mph.

How do we get the speedo to show this? The gearbox output shaft is turning at 2000rpm. With a speedo drive gear of 18 teeth and a driven gear of 3 teeth, the speedo cable will be turning at 666rpm. As the Speedo requires 2000 turns for a mile, 666prm will show 1/3 of a mile a minute, or 20mph! We're on the money, and ready to take on the speed cameras!

[Bob Moseley (RIP)]

Hi Tony
I was just going with the information contained in the Workshop Manual. The speedometer I am restoring actually has the number 5 scripted on the rear housing. I'll post an image of that. In the meantime I've highlighted the area of the Manual from where I obtained this information.
Bob

[Tony Smith]

And I was pointing out that the different ratios referred to in the manual are all in the gearbox at the Speedo cable output, and NOT in the Speedometer. All Speedos are the same "speed". You won't have any problems with the "mismatched" speedo that you foresee.

[Bob Moseley (RIP)]

Tony
What is your interpretation of a "speedo head" and where do you consider it is?. I always thought the "speedo head" was the body of the speedometer containing the speedometer drive gear and odometer.
Bob

[Grant Bowker]

Originally posted by Tony Smith
All Speedos are the same "speed".

Silly me, I thought the Speedo was an Australian invention, some wearers being fast, some beautiful and a very few both.

[Tony Smith]

Originally posted by Bob Moseley
Tony
What is your interpretation of a "speedo head" and where do you consider it is?. I always thought the "speedo head" was the body of the speedometer containing the speedometer drive gear and odometer.
Bob

It's apparent that whoever wrote the manuals considered the "Speedo head" to be the connection joint of the speedo system to the transmission, using the term "head" to mean point of connection in the same way as in "Beachhead, "Railhead" or "Borehead". It depends which way you look at it. From one direction, the "head" is the end of the system, from the other it is the first point of contact.

[Max Hedges]

found this in a box the other day, any ideas what it fits
Max

[Bob Moseley (RIP)]

Hi Tony - I'm afraid I disagree with you regarding your interpretation of a speedo head and that all speedos being the same speed. Below is a definition of a speedometer that contains the words speedometer head.

The mechanical analog speedometer is driven by a cable housed in a casing and connected to a gear at the transmission. This gear is designed for the particular vehicle model, considering the vehicle's tire size and rear axle ratio. In most cases, the speedometer is designed to convert 1001 revolutions of the drive cable into registering 1 mi on the odometer, which records distance traveled by the vehicle. The speed-indicating portion of the speedometer operates on the magnetic principle. In the speedometer head, the drive cable attaches to a revolving permanent magnet that rotates at the same speed as the cable. Floating on bearings between the upper frame and the revolving permanent magnet is a nonmagnetic movable speed cup. The magnet revolves within the speed cup, producing a rotating magnetic field. The magnetic field is constant, and the amount of speed cup movement is at all times in proportion to the speed of the magnet rotation. A pointer, attached to the speed cup spindle, indicates the speed on the speedometer dial.

I've also posted the image of the rear of a 2pdr speedometer showing the number 5 that the manual states is on the speedometers specificall designed for the 2pdr. If all speedos are the same why bother with the number 5 and the explanation in the manual.

Bob

[Tony Smith]

I'm not making up the definition for the phrase "Speedo head", some bloke did that in the 40's when he wrote the manual. Disagree if you wish, but crack open the Speedo instrument and show us a picture of the gears inside that you say will be in the combinations of 3/18, 5/18 and 3/21. A deener to a quid they won't be there!

[Pedr]

Firstly, I'd like to thank Bob for this thread. Once again a serious thread that one can sink one's teeth into. It has lead to some serious research in the past couple of days.

With regard to the speedometer face.

I have gone away and looked in my original wartime production photodatabase. All photos were taken in SAR Islington. ( Down the end of my street ). All photos were taken 20/6/1941. This album is manufacture and assembly of carriers at SAR. They are early number hulls (i.e. around hull number 1500. They show a number of component sub assemblies, one being the complete instrument panel.

This photo shows that the gear change quadrants have been blanked out. It appears that they have been covered with a black ( or some other dark colour, darker than the brown colour of the face ) semi circle that has had a rectangular shape removed for the odometer.

This lead me to wonder how common this was, as I have chosen an early face speedometer ( brown / maroon with inverted triangular numerals, as opposed to the grey one with square numerals ), mine too has the gear speed quadrants marked on the face. So now is this correct or not?

I visited the Carn collection and looked at some of the original carrier instrument panels on the shelf and those in carriers. Apart from stirring up a different hornet's nests for us, Darian and I found a face that these quadrants had quite visibly been painted out. Darian ( not me with my eyesight ) could still read the screen printed numbers under the black paint. The broken glass on the instrument cluster meant that we were definately able to clearly see the gauge face.

....continued next post

[Pedr]

In this photo it is very obvious that the gear change speed quadrants have been covered ( I believe possibly with some kind of sticker, as between 52 and 58 miles an hour there is a much darker band that looks like it may be a shadow ). This Instrument cluster is from a standard early model carrier.

[Pedr]

I now believe that all carriers had the gear speed change quadrants blacked out by some means, and that this appears to have been done in all carriers.

A couple of other things.

1. Fuel gauge.

It appeared to us (Darian and myself ) that the cluster that Tony Smith has posted images here of; still have the fuel gauge need affixed, even though there is no scale printed on the gauge face nor electrical connection fitted.

Once again, close inspection of the photos show that this may be the case on these gauges also.

Can you confirm or otherwise if your cluster has a needle in the dummy fuel gauge Tony?

[Pedr]

Here's another wartime photo from my collection.

It shows:

A ) A needle on a blank face where the fuel guage would normally have been.

B ) A painted patch over the gear speed change quadrant between 0 and 26 miles an hour.

C ) A "Ring-Grip" brand switch for the headlights.

D ) The patch covering the original idea for the position of the horn button. On the Instrument panel.

[Pedr]

This cluster is in a carrier restored in WA sold originally to Reg Chapman then on to Don Vallis.

Black paint to 26 miles obvious.

[Pedr]

2300hrs local. will continue this tomorrow night.

Pedr

[Dale Law]

Hello Bob & Tony,

I have read the thread and all the information is very good and interesting. I myself, own a CMP as well as own and restore classical cars, my prize car being a 1958 Ford Fairlane 500 Skyliner known as a "Retractable Hardtop".

In most car shows we have "Concourse Judging". I am not sure what you have down there for "Army Truck" shows but I am not aware of any concourse type judging shows for MVs.

I think worry about the "ratio" in any of the gearing is really "splitting hairs". That is like stating whether you have a Timken, SKF, NTN, etc. bearing instead what may be written in the Manual. So in reality, who is really going to dismantle to see if you have the correct make.

Also, during the war, I am sure they were not worried if the speedometer was out a few mphs. If you are in a convoy, you have to follow the vehicle in front you and not staring at the speedo to see if they are going the correct "speed".

In conclusion, we should all be happy that we have such vehicles around to enjoy and cherish. I don't think the public is going to be anal or know the difference whether any MV vehicle is going 18 or 20 mph down the road. I don't think we have to worry about getting a speeding ticket at any speed.

Regards,
Dale

[Tony Smith]

Originally posted by Pedr
It appeared to us (Darian and myself ) that the cluster that Tony Smith has posted images here of; still have the fuel gauge need affixed, even though there is no scale printed on the gauge face nor electrical connection fitted.

Once again, close inspection of the photos show that this may be the case on these gauges also.

Can you confirm or otherwise if your cluster has a needle in the dummy fuel gauge Tony?

Yes it does have a needle, and while the gauge face is blank, it is not completely black, but rather has the pinstripe around the gauge face perimeter and a King Seely part number.

[Tony Smith]

Originally posted by Bob Moseley
Tony
What is your interpretation of a "speedo head" and where do you consider it is?.
Bob

Originally posted by Tony Smith
It's apparent that whoever wrote the manuals considered the "Speedo head" to be the connection joint of the speedo system to the transmission,..

I think I have found why the Author of the manuals was misled as to the location of these gears. In the Ford Australia Carrier Parts Book, the Speedo driven and Drive gears are listed in the Speedometer section, where they belong NUMERICALLY, listed below the part number for the actual Instrument cluster, but PHYSICALLY they are located on the back of the gearbox. A Technical Writer who is not intimately familiar with the arrangement of the Carrier may assume from this placement in the parts list that these gears form a part of the Instrument cluster.

[Lynn Eades]

Thanks guys. This has been a most enjoyable thread. It has some "meat" in it, (not the swimmers)
I, and no doubt, many others have learnt from the sharing of your knowledge. Thanks again

[cletrac (RIP)]

With all this discussion of speedos I thought I might as well show this one and see if anyone else knows what it's off. I do because I took it off.

[Tony Smith]

It's off a Ford Civvy or MCP truck with an Eaton 2-speed rear axle. The little attachment off the rear of the speedo alters the ratios when the axle ratio is changed.