Re: speedometer

[tonygoodall]

If you turn a cable or twisted string round, the twists still go in the same direction, so what's the reason for a 'one way only' installation? Tony TC 9825

> From: "Forstner, Peter" peter@mg-tc.de> > Reply-To: peter@mg-tc.de > Date: Wed, 24 Jul 2002 11:14:53 +0200 > To: "'PCamp@pearsons-enfield.co.uk'" PCamp@pearsons-enfield.co.uk> > Cc: mg-tabc@yahoogroups.com > Subject: RE: [mg-tabc] speedmeter > > Paul, > This year I replaced the tacho cable and both ends are equal. So you can > install it in both directions. But only one direction is OK! > > Perhaps both ends of the speedo cable are different. I don't know. > > Regards > Peter > TC6325 > > Paul > TC3348 > ----- Original Message ----- > If you turn a cable or twisted string round, the twists stikk go the same

way, so whats the reason for a 'one way only ' installation?

[Eladdedrok@aol.com]

I have a question about the design of the speedometer used on the MG TC cars. I understand it is different than the mechanical types used on American cars as they are magnetic and the TC is a chronometric design. Will someone tell me just what chronometric is or means. Don't want to tear mine down to find out and find I have fouled up something. Dale TC 9749 Catlin,Il USA [Non-text portions of this message have been removed]

[Terry Sanders]

All TC's had chronometric speedometers and tachometers. They were used until part way through the TD production. Carl Cederstrand (Cederstrand@earthlink.net) wrote a great paper on how they work. They are based on a clock movement......what ever you do, don't disassemble it......leave that to the experts of which there are few these days. John Marks in UK being foremost. Terry in Oakland Eladdedrok@aol.com wrote: I have a question about the design of the speedometer used on the MG TC cars. I understand it is different than the mechanical types used on American cars as they are magnetic and the TC is a chronometric design. Will someone tell me just what chronometric is or means. Don't want to tear mine down to find out and find I have fouled up something. Dale TC 9749 Catlin,Il USA [Non-text portions of this message have been removed] Yahoo! Groups Links [Non-text portions of this message have been removed]

[Forstner, Peter]

Dale, I learned the function of chronometrical instruments from Carl Cederstrand's article. Now I try to explain with some words how chronometrical instruments work. This instrument obviously is the mechanical implementation of a modern digital system. A camshaft forces the execution of a little "program". Imagine an internal "virtual pointer", equal to the pointer on top of the dial face, but is hidden behind the dial face. 1) Reset "virtual pointer". After the reset the "virtual pointer" points to 0 RPM. 2) Start to count the number of revs for a defined time period. Here the interregnal clock is necessary to give a defined time period. Counting is done with the internal "virtual pointer". During this process the "virtual pointer" turns from 0 RPM to the actual RPM value (but you can't see it from outside). 3) Copy the position of the "virtual pointer" to the RPM pointer you can see on top of the dial face. This is the moment where the pointer of the instrument jumps! 4) Restart with step 1. The following functional blocks are in the instrument: - Internal clock to define the counting time period. - A counter, which is a bunch of cog wheels. You can start (cog wheels engaged) and stop (cog wheels dis-engaged) the counter. - And there is a camshaft with hair springs controlling the sequence of tasks to do the measurement. If you have experience with repairing / maintaining clocks, you also can maintain this chronometrical instrument. Hope it helps Peter Forstner Germany - Munich peter@mg-tc.de> -----Original Message----- From: Eladdedrok@aol.com [mailto:Eladdedrok@aol.com] Sent: Monday, 05 April, 2004 00:12 To: mg-tabc@yahoogroups.com Subject: [mg-tabc] Speedometer I have a question about the design of the speedometer used on the MG TC cars. I understand it is different than the mechanical types used on American cars as they are magnetic and the TC is a chronometric design. Will someone tell me just what chronometric is or means. Don't want to tear mine down to find out and find I have fouled up something. Dale TC 9749 Catlin,Il USA [Non-text portions of this message have been removed] Yahoo! Groups Links

[Graham Knight]

Dear All, I have a TA with an XPAW engine and TC gearbox. The original engine was swapped out before I owned the car and I think the back axle was changed at the same time. I have now changed the cw and pinion for one of Roger Furneax's 37/8 ones and I want to get the speedometer showing something vaguely correct. I have a few questions: Is the TA speedometer the same as the TC one as far as the relationship between cable RPM and speed shown is concerned? If not, how can I tell which one I have? What is the recommended way of getting the speedometer to show a correct reading with new cw & pinion? Is some sort of gearbox available (in the UK preferably) to put in the drive? Many thanks. Graham

[Paroor]

Hi Graham, Last year I bought a Pocket PC with navigation system. This can be used by pedestrians, for motorcycles and cars. They are sold here now a days for less than 300 including road maps of Europe. Road maps are expensive. I use this navigation system to control the speedometer of TC. The navigation shows the actual speed of the vehicle while driving. In my opinion it is correct with minimum tolerance. Compared to my Mercedes speedometer there is only +- 2 kM/h difference. May be you can borrow one navigation system from some one. Drive constant at 30 MPH for while and watch the Navigation system as well as the speedometer in the MG. Repeat this with 50 MPH and 60MPH. Mark the 30,50 and 60 point with some colour tape. This will give you some temporary help to get a feeling of the car at various speed we use in our traffic. There is some reason to drive around with the TC for distance. May be then you can get the speedometer modified for the present differential set up. Madhu -----Urspr ngliche Nachricht----- Von: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com]Im Auftrag von Graham Knight Gesendet: Samstag, 16. Dezember 2006 11:30 An: mg-tabc@yahoogroups.com Betreff: [mg-tabc] Speedometer Dear All, I have a TA with an XPAW engine and TC gearbox. The original engine was swapped out before I owned the car and I think the back axle was changed at the same time. I have now changed the cw and pinion for one of Roger Furneax's 37/8 ones and I want to get the speedometer showing something vaguely correct. I have a few questions: Is the TA speedometer the same as the TC one as far as the relationship between cable RPM and speed shown is concerned? If not, how can I tell which one I have? What is the recommended way of getting the speedometer to show a correct reading with new cw & pinion? Is some sort of gearbox available (in the UK preferably) to put in the drive? Many thanks. Graham [Non-text portions of this message have been removed]

[murray arundell]

Hi Madhu, I too use a GPS to check my speed in the TC. Its interesting to note that your Benz is showing only a 2km variation. In my case the Garmin indicates that my MG-F is doing 50kph when its indicating 60kph. My BMW motorcycle has a similar variation Cheers Murray Arundell _____ From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] On Behalf Of Paroor Sent: Thursday, 21 December 2006 6:18 pm To: Graham Knight; mg-tabc@yahoogroups.com Subject: AW: [mg-tabc] Speedometer Hi Graham, Last year I bought a Pocket PC with navigation system. This can be used by pedestrians, for motorcycles and cars. They are sold here now a days for less than 300 including road maps of Europe. Road maps are expensive. I use this navigation system to control the speedometer of TC. The navigation shows the actual speed of the vehicle while driving. In my opinion it is correct with minimum tolerance. Compared to my Mercedes speedometer there is only +- 2 kM/h difference. May be you can borrow one navigation system from some one. Drive constant at 30 MPH for while and watch the Navigation system as well as the speedometer in the MG. Repeat this with 50 MPH and 60MPH. Mark the 30,50 and 60 point with some colour tape. This will give you some temporary help to get a feeling of the car at various speed we use in our traffic. There is some reason to drive around with the TC for distance. May be then you can get the speedometer modified for the present differential set up. Madhu -----Urspr ngliche Nachricht----- Von: mg-tabc@yahoogroups .com [mailto:mg-tabc@yahoogroups .com]Im Auftrag von Graham Knight Gesendet: Samstag, 16. Dezember 2006 11:30 An: mg-tabc@yahoogroups .com Betreff: [mg-tabc] Speedometer Dear All, I have a TA with an XPAW engine and TC gearbox. The original engine was swapped out before I owned the car and I think the back axle was changed at the same time. I have now changed the cw and pinion for one of Roger Furneax's 37/8 ones and I want to get the speedometer showing something vaguely correct. I have a few questions: Is the TA speedometer the same as the TC one as far as the relationship between cable RPM and speed shown is concerned? If not, how can I tell which one I have? What is the recommended way of getting the speedometer to show a correct reading with new cw & pinion? Is some sort of gearbox available (in the UK preferably) to put in the drive? Many thanks. Graham [Non-text portions of this message have been removed] [Non-text portions of this message have been removed]

[Paroor]

Dear Murray Arundell, I think there are 24 satellites there for GPS assistance. The older model navigation systems can handle only seven of them ? The next generation was able to handle 12 or so. But the new ones can handle up to 18 satellites or more at a time. So they are also in a position to measure the height as well if it is programmed for that feature. Speed can me measured best in our "straight Autobahn" in Germany. The software and the road maps had a lot bugs in the initial stage but now they had modified sever times and it is getting better every time. Early models never had city pin code. But now it is standard in every software. In Germany for example there are many Bad Soden. TCM (Traffic message channel ) is also getting better. Why not up date your software ? Soon the European system " Kopernikus" will be commissioned. But their service will be charged. madhu 65812, Bad Soden, Germany [Non-text portions of this message have been removed]

[Fred Renner]

Dear Listers My tc speedo made a bizarre move today and I'm looking for hints as to its maladay! And a solution. The instruments were restored by John Marks about 20 years ago.So here's what happened...going about 45/50mph the needle went to the 100 mark ,stayed there a few miles and made its way back to zero where it has stayed except when it made that move to 100 again and now seems to be stuck at zero again.The odometer still tracks correctly so I think that tells me the cable is okay.For sure Mr. Marks can't repair it since he is retired! Short of sending the unit to Nisonger, does anyone have a clue as to what happened. As always thanks for any help. Fred Renner # 4970

[Bjorn Klingenberg]

Fred, The problem most likely is the cable. I just went through a long process of identifying this as my problem for the same symptoms you describe. An inherent problem with the original installation is that the cable coming out of the transmission makes a sharp 180 degree turn and then makes it across the bell housing for another sharp turn through the firewall. I made some adjustments to the routing and now enjoy a perfectly smooth speedo operation. If you like, I'll send you some photos of my cable routing. Bjorn TC7773

----- Original Message ----- From: Fred Renner To: mg-tabc@yahoogroups.com Sent: Saturday, April 10, 2010 4:31 PM Subject: [mg-tabc] speedometer Dear Listers My tc speedo made a bizarre move today and I'm looking for hints as to its maladay! And a solution. The instruments were restored by John Marks about 20 years ago.So here's what happened...going about 45/50mph the needle went to the 100 mark ,stayed there a few miles and made its way back to zero where it has stayed except when it made that move to 100 again and now seems to be stuck at zero again.The odometer still tracks correctly so I think that tells me the cable is okay.For sure Mr. Marks can't repair it since he is retired! Short of sending the unit to Nisonger, does anyone have a clue as to what happened. As always thanks for any help. Fred Renner # 4970 [Non-text portions of this message have been removed]