British-Cars.org

Welcome to the DMR Site for British Car Information.

Recommendations

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 - Speedometer problem

I have a 1953 MGTD and am having a problem with the speedometer.
When the car is in motion the speeedometer needle goes up to the presumed normal speed, but then jumps around - ranging from 10 mph below or above the expected speed.
I took the speedometer out and connected an electric drill to the back and it holds a given speed very smoothly - indicating to me the speeedometer is fine.
I took the cable out and it looks OK, but feels jerky if you run the car and hold your fingers over the dashboard end of the cable.
Any suggestions?
Should I try a new cable?

Many thanks,
Bill in Ann Arbor, Michigan
W Chandler

The inner cable is sort of a wound wire, that can bind or wrap up, then releases, then binds, etc. That can cause the bounce. Make sure there are no sharp bends in the housing, and you can also remove the inner cable and lubricate it well. Even then, these speedos tend to bounce. Search the archives as well- lots written in the past about this. George
George Butz

I think, from the number of postings, that it is a common problem...mine also bounces. I took off the transmission end to slide out the inner cable and found that I couldn't slide it out...seemed to be capped in such a way as it couldn't slide?
Noticed Moss sells an 'original' style and a repro.....could the repro inner cable be non-removable, or did i miss something?
gblawson(gordon- TD27667)

I think there is a circlip on the original cables you can remove and slide it out- that said, it has been a long time since I have done that. Not sure about replacement. If present, the clip is on the instrument end and you would have to remove that first? George
George Butz

The circlip is indeed up at the head end of the cable. It can be removed, rebent and replaced after the cable is lubed. I've tried every lube known to man... from graphite powder (messy in a plastic bag) to lithium grease (messy as I smeared it on) and I still have a slight bounce. I think our cable takes a few too many turns as it wanders its way into the head of the speedometer. Try to keep any turns as large of a radius as possible.

warmly,
dave
Dave Braun

...yes, i found the circlip at the speedometer end, but not at the bottom end...just the inner cable going through a brass cap that seemed pretty solid....(and covered with oil).....anyway.... think I will check its routing first.....It does seem like a pretty common problem....
gblawson(gordon- TD27667)

I had the identical problem, and a new cable solved it.
Edward
E.B. Wesson

My 1952 TD just came back from a 338 kilometer. trip, about 212 miles,yesterday. The same thing happened to my needle (wavering) from 80K to 95K, 50-59 MPH, with a relatively new cable, made in UK. On reading the archives it says to use graphite, I'll try that later. The tachometer was spot on.
On a second note, 22-23C, about 72-74F outside temperature, my oil pressure on starting sits at 62lbs., after 20 minutes, when warm around town, it sits at 52-55lbs. On the highway when running for about an hour or so at 4000-4300 on a very twisty/hilly second grade highway with a 5.125 it sits at 42lbs. with water temperature at 82C, about 180F, When idling after this the oil pressure sits at 22-23lbs. Is this normal under these conditions? AND, this was the first time I have driven a TD this length of time or other sports car in 18 years, "IT WAS GREAT".
Cheers,
Barry
C B Ryley

Barry. On oil pressures and water temps - if it helps, during normal summer running (ambient temp: mid-70s F) my oil pressure starts at 55 psi, and drops to 40 when hot (20 psi on idle). Water temperature when running is 75 - 80C but you'll see surges on the temperature gauge when you've driven the car hard - they're quite rapid and I found them a bit alarming at first.

BTW, there's heaps of info and discussion on both topics in the archives.

On speedo cables, I had a similar problem until I straightened-out the cable run, which the PO had routed to take an over-tight turn. I don't know if it might help in your case but it's worth looking at.

- Tom.
Tom Bennett - 53TD 24232

Thanks Tom. Your information was just what I was interested in.

I had read quite a bit in the archives, but basically just wanted some feedback as to how most other TD's operated under Summer conditions.
I will check the routing of my speedo cable.
And, read the archives some more.

Have a Great Summer.

Barry
C B Ryley

Bill, I've always had a bit of fluctuation in my speedo needle. It bumps about 1-1 1/2 mph above and below the correct speed. I've tried everything. It's a matter of fixing it with
the gentlest bends possible. I found that I can alter the movement (and noise) by reaching behind the dash and moving the cable between the instrument and the firewall. This large unsupported run seems to be the culprit. I have tried to find the path of least resistance and loosely cable-tied it to the harness and brackets. Don't cinch the ties too tight, as that will defeat the purpose.
Steven Tobias

hello. Re: cable rout. I have routed the cable from tranny orwardand up thr6uethroughthe frontpart of the floorboard inside the firewall and over to the speedo, suported on several places You need perhaps
shorten tha cable. And another thing, The square end of the cable can be too long
shorten it a bit and do not tighten it too much on the speedo
Thoralf. Norway TD 4490
Thoralf Sorensen (TD4490)

My brand new NOS cable had a circlip on the transmission end, which I left off. The clip is in the glove box now in case I ever need it!
I have found that all speedometers need TLC and a few drops of light oil in the right places INSIDE the unit.
It's easy to take the speedometer out and disassemble, clean and lubricate all moving parts. It also gives you the opportunity to clean the lens on the inside, also the face. Don't use anything stronger than windex on the face.
chuck
cj schmit

Thank you all for your comments.

I bought a replacement cable from Moss Motors and it works perfectly! The needle moves as smooth and steady as can be.
I bought the "replacement" type, not the "original" type.
This was a perfect fix for the price of about $40.

Bill from Ann Arbor
W Chandler

This thread was discussed between 15/08/2011 and 24/08/2011

MG TD TF 1500 index

This thread is from the archives. Join this live forum now