MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Oiling Tac and Speedo

My dished tac and speedo are in desperate need of oiling I suspect. It's been about 25 years and the gauges bounce around quite a bit.

I have never dived into this aspect before and have some clock oil standing by but was looking for best practices.

First off I know that the needles need to be pried up and off before the face plates can be removed. I am always worried about that sort of technique. Also I suspect that the needles are under some sort of load in order to keep them against the pegs when not operating.

How do I remove them and make sure they go back on at the right place again? I was thinking that I could possibly pry them up just enough to clear the pegs and then take a picture of their resting position. Then when done oiling press them on partially at that location, spin them past the pegs and press them down to the right level.

Also is there a good source that tells you where exactly to put the oil once inside? On clocks generally pivot points but there are some places you don't want oil touching.
Christopher Couper

Chris before you go disassembling the gauges have you cleaned the cables and housings and lubricated them with lithium grease? I would do that first and see if your symptoms still persist.
W A Chasser

Chris -

A watch maker / good watch repair shop can remove the hands in a few seconds. Much safer than buying a tool on eBay or Amazon and trying to do it yourself.

Here are some links that may help:

> Jaeger Chronometric Instruments
http://www.mg-tc.de/articles/JaegerChronometricInstruments.html

> Repairing Jaeger & Smiths Speedometers
https://www.szott.com/lotusinfo/Smith-jaeger_speedo_repair.pdf

> DA220 – TACH & SPEEDO CABLE
https://www.fromtheframeup.com/uploads/TT_DA220_Tach_and_Speedo_Cable_Installation.pdf

> Refurbishing that Odometer
https://www.stovebolt.com/techtips/odometer/index.html

> Speedometer rebuild for GM Art Deco Truck
https://www.stovebolt.com/techtips/gauges/speedometer/index.html

> BBS Thread Title from 15 Oct 2001
TF- Speedometer/Tachometer Cleaning & Lubricating

Lonnie
TF7211
LM Cook

Chris, here are a couple of pictures of a simple hand puller for later TD gauge needles. It is possible to lever the needles off using something like a kitchen fork but this puts a lot of strain on the very small shaft holding the needles.
The two small bolts are 4-40 and the large bolt is 1/4-20. If I remember correctly the small pin which drives off the needle is the shank of a #67 drill (maybe).
Hugh Pite




H.D. Pite

Thanks for the info. I will pour over it.

Bill: I have pulled and lubed the cables. This is why I think they need to be oiled.
Christopher Couper

Sounds like I don't need to take the needles off? Just remove the two screws in the back and the entire assembly is supposed to be able to come out at once?

That would be best for sure.
Christopher Couper

Yes you do not need to remove the dial, at least on a 52' you dont.
I dont seem to have taken pictures.
You can remove the covers and have access. The issue is how to remove the varnished old oil without damaging the dial.

AS I REMEMBER!!!!!!, and it getting bad, I The dial has a smalish pinion gear which on it shaft.

You can remove most of the clockworks without touching this part of the assembly and clean them in a ultrasonic cleaner without going near to the dial and shaft.

BUT I eventually sent mine off for repair. My issues was not jumping around, my odometer was reading 100Times to fast.

Jim B.
JA Benjamin

Chris,

Before you start the fiddle of re-oiling the speedo cable, here is a simple trick that determines whether a fluctuating speedo needle is caused by a sticky cable or if the problem is in the speedo unit itself.

First, start and run the engine for a few minutes. When it is warmed up and idling smoothly, assure yourself that the tachometer needle is indicating smoothly. This indicates that the tac and its cable are working satisfactorily.

Stop the engine. Reach under the dash and undo the speedo cable from behind the speedo unit. Then, undo the tac cable and transfer it across to the speedo unit.

Start the engine and watch the speedo. If it now settles to a steady indication (of engine speed), there is a very good chance that the fluctuating problem is in the speedo cable. On the other hand, if the speedo needle is still fluctuating, the problem is likely to be in the speedo itself, or worst-case, both the speedo and its cable.

So, to confirm if the speedo cable is sticking, connect it to the tachometer and go for a drive. Obviously, if the tac needle is now fluctuating, the speedo cable is at fault.

The same method, in reverse, can be used to check a fluctuating tachometer needle. In this case however, it will be necessary to first ensure that the speedo system is operating smoothly, which means of course that the speedo cable is in the required good condition for checking the tachometer unit.

David
David Padgett

I have a good friend who is a long time clock maker and has serviced a few of mine on occasion. He stopped doing watches many years ago. His advice to me was never oil anything inside the clock as it will only cause problems when it collects and holds dust. The solution is always a good cleaning of the parts. The only thing I would lube would be the worm gears. Just my two cents.
L E D LaVerne

David: Great suggestion. I'll give it a try this weekend.

Both my tac and speedo have been jumping around a bit but it's super easy to make sure the tac cable and gearbox are good.

I was wondering also if I could do the same with a drill? Thinking of putting in a square drive into the chuck and running the speedo and tac with the drill and make sure it does not jump around then.
Christopher Couper

If you do need to remove the pointer, an easy way I learned years ago is to borrow a common table fork from the kitchen. Insert the needle stem between two tines and press down on the fork handle. The tines should easily pry the needle off without the danger of bending the needle. It has worked every time for me.
Lew Palmer

Chris,

The fact that both your tac and speedo are jumping around doesn't really apply to the suggested method, ie. you don't have a properly-working reference to work from.

The drill method works and is a good starting point. Just be careful when positioning the drill, if you are going to apply it from behind the dash.
A small 'Dremel' type drill will be easier to handle.

Good luck
David
David Padgett

David: I have a Dremel and I will use that.

I plan on removing the units from the dash because I am 99% sure it's more than cable lube. I'll do the tac first since it's easier to remove. If it does not jump around with the Dremel then I will try spinning the cable with the dremel from the gearbox at the generator.
Christopher Couper

You need to be able to spin the cable counter clockwise I believe.
L E D LaVerne

As far as I can remember you have to remove the dial to get at the inside of the speedo due to the odometer reset shaft. I use two small espresso spoons, borrowed from the "Government" at 180° apart. Seat the speedo in a roll of gaffer tape to keep it from rocking around. Place a tissue under each spoon so as not to scratch the dial. Lever the needle up at each side with even pressure and the needle pops off. Do this in a clean environment as sometimes the needle goes into orbit.
Wash the spoons and return them to the "Government"

Regards
Declan
Declan Burns

LED I was wondering about that. Hopefully the Dremel is the correct direction. A drill I an reverse.

Declan:
I guess I will see what I see when I pull them out of the case.

Any insight on my first issue about where to remove the needles? I am worried I won't get them on at the proper place if I pull them off. I suspect they have somehow been spring loaded at rest against the pegs.
Christopher Couper

Chris,
Before you remove the needle, lift it over the peg and let it dangle. Mark this position holding the speedo vertical with a piece of tape. This is the mark for re-assembly. Later speedos had a dot printed on the dial for the same reason. It is also a reference point if your sppedo is just a mile or so out so you can fine tune it.
Regards
Declan
Declan Burns

I've taken an old cable and used a 3/8" drill in reverse to test old speedos and tachs. I don't recall any that spin clockwise. My dremmel is not reversing...maybe yours is?
L E D LaVerne

LED and Declan: Just the info I needed. Thanks
Christopher Couper

Any idea where this "dot" was printed? My instruments were rebuilt and refinish decades ago so I don't have any unusual marks that I can see.


Christopher Couper

Chris,

My tac is the same as your's - no 'dot'. I imagine any minor error in indicating rpm is of no real consequence, but obviously not the same for speed indication.

Similarly, there is no dot on my speedo. However, something I have never noticed before, is that the speedo needle when settled against the peg, is pointing to approx 3mph. The 0mph mark cannot be reached by the needle.

A webscan of pictures of a number of the same instrument shows the same thing.

In my case, lifting the needle over the peg, but still touching the underside of the peg, would point to 0mph.

So, perhaps the 0mph mark is in fact, the 'dot'.

David
David Padgett

Chris,

Further to my last note, I've just had a look at my tac which is the same model as your's. However, the scale on mine has the 0rpm mark below the rest stop for the needle, much the same as for my speedo.

I see that your tac doesn't show this. Maybe a result of the refurb you had done? Whatever - not important for a tac, at least.

David

David Padgett

I think it was MGA or MGB when the dot was introduced.
Regards
Declan
Declan Burns

I have just checked an MGA speedo that I have here for repair and it has got the dot.

Regards
Declan
Declan Burns

Yeah. The peg for the speedo is at 4 mph.

Christopher Couper

I finally got a chance to pull both the tac and speedo from the car and run the drill test on them.

The tac came out just fine. With the drill in reverse and a square drive in the cable socket, it came right up to speed, adjusted nicely when I changed the RPM and immediately came to rest when the drill was stopped.

My cable is well lubed and seems to be at the straightest shot it can be. My guess is perhaps the little reduction box but not certain. When I put the tac back in I will try the drill test from the engine side using the cable to eliminate the reduction box and test the cable.

The speedo did not come out as well. While it did increase to a speed it was variable, seemed way to fast and when the drill was stopped it stayed at the level it was at. Only when I took the drill out of the socket did it go back to zero. So something is inhibiting the speedo from working correctly.

At this point I will take any suggestions before I try to break into the speedo works and oil it. Can't think of anything else at the moment.
Christopher Couper

Update: Got to the bottom of my speedo issue. I now know what broke but have no clue why. My tests did not find anything that would indicate why so maybe just a freak event or I fixed the issue by experimenting and oiling. If it does it again I may have to seek professional help.

Here was the issue as seen in the attached picture. Somehow three teeth on the trip odometer are stripped. This is why I had the erratic behavior I suspect. I also remembered that the trip odo did not advance. Not sure about the master one. Running the drill on the component out of the housing I can see the master gear turning and cogging the sprocketed/ratcheted master wheel.

The trip one moves until it gets to the dead place and then nothing happens unless a human comes along to push it past. Doing this the trip odo does advance.

So now I need a new gear. I noticed these are nylon and were probably replaced during the 1994 rebuild. Anyone know of a source?

BTW I did have to take the needle off to get the unit out of the case. And I also had to take the spit pin out of the reset gear so I could push all of this up and free the reset shaft. A real PITA. And when I was pring the split pin off for some reason it shot across the room. I miraculous found it an hour later when I was doing something else. Only the vacuum would have seen that tiny object.

Also I had a hard time getting the needle off it's shaft too. I tried using a plastic fork padded with electrical tape. It was not budging. Then I went for big iron and got an interior panel tool that looked like a Y. Padded that too and pried until I was sure something was going to break. Put my hand over the top to keep it from ejecting since I wanted to just ease it off far enough to clear the post so I could find it's resting place.

Of course that did not work and suddenly it just popped off completely. So now when I put it back together I am going to have to figure out where the resting place should be to put enough tension on the spring to make it return to the post.


Christopher Couper

As was mentioned by many others there really is nothing to oil in the speedo. There is a little grease on the counter shafts and at the main sprocket that drives the counter gears according to an expert.

My other question was about how to preload the needle. Here is the response I received:

"Set it about ¼ inch behind the stop pin, tap on very lightly, then lift carefully over the stop pin to run position."
Christopher Couper

Hugh do you have a needle for a flat faced TD tach?
TRM Maine

WARNING for anyone contemplating cleaning the mechanics of these instruments, DO NOT USE ANY PETROLEUM BASED SOLVENTS.

If you do so you will observe the numerals disappearing from the drums, dont ask me how I know.

Graeme
G Evans

Chris,
The original gears are made of Tufnol. I am expecting some brass replacements here anyday. I have had them made. It might be easier and quicker to get some replacements from Hugh Pite.
Regards
Declan
Declan Burns

Declan. Put a few aside with the rest of the stuff you are collecting for me. Hopefully one day the world will return to normal and we can ship stuff once again. :-)
Christopher Couper

Chris,
I can ship no problem. It just takes ages due to the virus problem but it is going through.
Regards
Declan
Declan Burns

The brass replacement gears that I ordered have just arrived. The quality is good.
Regards
Declan




Declan Burns

Quick update on my speedo. Hugh sent me both a new gear/shaft combo and a new gear. I mounted the new gear onto my original shaft and placing it into the mechanism and turning by hand it bound. Now I think I know why the gear was stripped.

Putting in the new gear/shaft combo worked smoothly.

I lubed the shaft with some bearing grease and reinstalled it into the mechanism. I need new eyes and tinier fingers but I got the job done.

Now I need to put the mechanism back into the case and try it out with the drill in reverse. Hopefully this weekend.

After doing all of this I can appreciate the expertise of those that work on these instruments. Its fine work and there are a few tricks that you need to know to get them apart and assembled again.

In my case I don't trust the shipping world anymore and did not want to sacrifice my perfect speedo to the lost shipping gods. I would rather have a broken speedo than an unmatched one.
Christopher Couper

Update on my speedo. It is all back together again. I was not able to put it in the car but did perform the reverse drill test. All seemed OK and the needle was steady and the trip counter moved appropriately.

Thanks to Hugh for the new trip shaft and gear.

Hope I never have this issue again and have no idea how it happened in the first place.
Christopher Couper

My last post on this thread. This last weekend I was able to put the gauges back in the car and drive it around again. The tachometer worked great and seemed very accurate and steady.

The speedometer also worked very well. My only comment on the speedometer was that every few seconds it would jump about 5 mph and then settle back down again. At this point it's been so long since I had a decent working speedometer I cannot remember if this is normal or not.

None the less I am pleased that both instruments are working satisfactory and seem accurate.
Christopher Couper

This thread was discussed between 10/11/2020 and 18/01/2021

MG TD TF 1500 index

This thread is from the archives. Join the live MG TD TF 1500 BBS now