Jump to content

Speedometer cable question


Recommended Posts

Hi Mark,

I was having an 'invention moment' a while ago and needed to know what was happening.

The red leds mimic the stop lights - if the stop light filament fails for whatever reason the led will not illuminate when the pedal is pressed.

The green leds indicate what the overdrive is doing - I was playing with some OD logic devices and needed to know what the circuit was doing.

 

The panel is now redundant and thje ash tray re-inserted. However I have kept the stop light indicator and hidden the leds.

I have gone back to the normal OD switch - far better than silly logic circuits.

 

Roger

Link to post
Share on other sites
  • 7 years later...

Great info on this page, tho I am 8 years down the road.....seems everyone has angle drive.  What about the Tr4 without?  The cable goes straight in the gearbox but my new one only barely enters the pinion.  How far is is supposed to go in gearbox?  My broken cable was in for about 1" and snapped.   I pulled out with skinny needle nose and thought the new cable would go right back in.  Not.   Also. the Speedometer is now a tad difficult to get in and it seems drive cable is a little long sticking out (by probably the amount lost at gearbox).  I have a hard time screwing both end caps in with the tension on cable.   Finally, would the pinion gear at gearbox have seized breaking original cable and making it hard to line up the new cable properly to go all the way in, assuming its squared off inside and you cant put square peg in the round hole.   Any ideas and I would be more than greatful!  Cheers.

 

Edited by tr4head
Link to post
Share on other sites
9 hours ago, tr4head said:

Great info on this page, tho I am 8 years down the road.....seems everyone has angle drive.  What about the Tr4 without?  The cable goes straight in the gearbox but my new one only barely enters the pinion.  How far is is supposed to go in gearbox?  My broken cable was in for about 1" and snapped.   I pulled out with skinny needle nose and thought the new cable would go right back in.  Not.   Also. the Speedometer is now a tad difficult to get in and it seems drive cable is a little long sticking out (by probably the amount lost at gearbox).  I have a hard time screwing both end caps in with the tension on cable.   Finally, would the pinion gear at gearbox have seized breaking original cable and making it hard to line up the new cable properly to go all the way in, assuming its squared off inside and you cant put square peg in the round hole.   Any ideas and I would be more than greatful!  Cheers.

 

The gearbox end of the cable needs to be free to slide right in, the inner cable is secured in position by the collar at the speedo end, which as you have said is sticking out too far to get the nut on.

I would suggest that there is still some remains in the speedo drive hole of the old cable, although I have also come across new cables being slightly too big, requiring a light touch with some emery paper to clean up the square on the end.

The speedo drive unit can be removed if it is easier to work on the bench to see whats in there stopping the cable entering.

Ralph

Link to post
Share on other sites

I had same issue with the gearbox end of the cable, required a bit of light filing before it fitted neatly into the drive unit, when I made initial enquiries with TRGB (who supplied the cable), they admitted that occasionally they have to do this on cars they are working on

David

Link to post
Share on other sites

I had a similar problem.

Re-calibrated and reconditioned speedo stopped working. Checked cable and it was perfect, so I checked the angle drive. The remains of the square end was stuck (brazed) in the angle drive with a few wisps of cable remaining. The new cable had been inserted and tightened as a friction fit and it actually worked for 7000 miles.

We (John Morrison and I) decided to ditch the angle drive and a longer cable was purchased and a hole in the chassis was relieved slightly to allow the cable and nut to pass through. It works and no pesky angle drive to worry about

Andy

Link to post
Share on other sites
  • 1 year later...
On 5/6/2022 at 10:10 AM, qkingston said:

I had same issue with the gearbox end of the cable, required a bit of light filing before it fitted neatly into the drive unit, when I made initial enquiries with TRGB (who supplied the cable), they admitted that occasionally they have to do this on cars they are working on

David

On the run up to Glamis my speedo stopped working (after 1500 miles of no issues). after checking nothing was obviously loose, I disconnected the speedo end and drove a short distance, the inner cable was not turning. I removed the gearbox tunnel access plate and disconnected the cable and re-connected the speedo end, the speedo needle moved when I turned the inner cable from the gearbox end. I unscrewed the Rt Angle drive and reconnected the cable; turning the Rt angle drive shaft, no movement on the speedo needle. Oddly however, when turning the rt angle drive on its own, I can see the output shaft turning. I purchased the repro Rt angle drive from TR Shop during the rebuild. I'm guessing the Rt angle drive is kaput, any other suggestions?

Regards

David

DSC_0121.JPG

Link to post
Share on other sites
1 hour ago, qkingston said:

On the run up to Glamis my speedo stopped working (after 1500 miles of no issues). after checking nothing was obviously loose, I disconnected the speedo end and drove a short distance, the inner cable was not turning. I removed the gearbox tunnel access plate and disconnected the cable and re-connected the speedo end, the speedo needle moved when I turned the inner cable from the gearbox end. I unscrewed the Rt Angle drive and reconnected the cable; turning the Rt angle drive shaft, no movement on the speedo needle. Oddly however, when turning the rt angle drive on its own, I can see the output shaft turning. I purchased the repro Rt angle drive from TR Shop during the rebuild. I'm guessing the Rt angle drive is kaput, any other suggestions?

Regards

David

DSC_0121.JPG

I fit these as the current repros are poor.

https://www.speedograph-richfield.com/shop/angle-drives/rgb-2401-series

Stuart.

Link to post
Share on other sites

I recently fitted an angle drive  supplied byTR Shop. It lasted 300 miles!!! Failing as I was leaving the Eurotunnel on my way to TRCH@50, just what you want at the start of a 1000 mile road trip, grrrrr.

I have ordered a new one from Spedograph Richfield but so far it's been on the way for two weeks! I am beginning to think that a working speedo is not meant to be.

George 

Link to post
Share on other sites

It's pretty poor if they are only lasting that long, I'll get one of those ordered from Speedograph Richfield tomorrow; Stuart I assume you've had no problems with them?

David

Link to post
Share on other sites
16 hours ago, qkingston said:

It's pretty poor if they are only lasting that long, I'll get one of those ordered from Speedograph Richfield tomorrow; Stuart I assume you've had no problems with them?

David

Nope fit and forget. You will find its a bit more bulky than standard so adjustment sometimes needs to be made to the cover plate but not always

Stuart.

Link to post
Share on other sites

TR4A. My mileometor works fine but the speedo goes all over the place and is never consistent. I can be doing any speed on the dial in a 30 zone. I'm using the tacho to ensure compliance with speed limits after checking it against an app. Also the tripmeter won't reset. If the mileometer is working does that mean a duff speedo?

 

Les

Link to post
Share on other sites

It means  worn bearings on the spinning magnet part of the speedo, or a build up of dirt on the magnet / alloy disc.

Fixable if you are brave enough !

Bob

Link to post
Share on other sites
35 minutes ago, Les Millington said:

Thanks guys, the latter I think, bravery is disappearing with age.

 

Les

Les - how about going the whole hog and replacing all your instruments with a set of these magnolia faced ones! They have all been fully reconditioned and a bargain at £475 for the whole set.

I do have quite a few other small OE instruments for sale which likewise have been fully reconditioned as original with black faces and white lettering  - PM if interested for more details - unfortunately no speedos or rev counters

Cheers Rich

 

 

IMG_0882 (1).jpg

IMG_0883 (2).jpg

IMG_0884 (2).jpg

IMG_0885 (1).jpg

IMG_0886 (1).jpg

Link to post
Share on other sites
13 hours ago, Lebro said:

It means  worn bearings on the spinning magnet part of the speedo, or a build up of dirt on the magnet / alloy disc.

Fixable if you are brave enough !

Bob

This is exactly what is happening on my speedo (TR4 1964): the cable is fine, cable ends too. Yet when driving, the speedo wobbles up and down; for example at 40km/hr it oscillates between 30 and 50 :)/

Where do I find a view of those magnets, or an exploded schematic?

Sending to the UK for repair would be the very last option due to Brexit EU vs Uk transport/taxes/duties/... issues (my car is located in the South of France).

Link to post
Share on other sites

I don't have a diagram, but it's not hard to take the innards out of the casing. 

Remove speedo from car

twist the chrome bezell off, & catch the glass, & the metal rim below it.

unscrew the trip reset knob.

slacken the 2 screws on the rear, & being prepared to catch the dial as it releases, remove the two rear screws.

All then will be revealed. the magnet is a big slab of steel which spins as you turn the input cable. small particles of ferrous material can find their way onto the magnet, & if they are big enough, or, if the magnet is wobbling about (loose bearings) they can touch the alloy disk which is under the magnet, & is connected to the needle.

Hope that helps

Bob

Edited by Lebro
Link to post
Share on other sites

I just found this video: magnetic speedometer disassemby

Not for the faint-hearted :)

 

EDIT: I contacted the creator of that video, a gentleman in Gloucester, http://magnetic-speedometer-repair.com/

I probably will send the meter to him, after our holiday season here when I can miss the meter for several weeks.

Edited by earckens
clarification
Link to post
Share on other sites

I have the same problem with a wavering Speedometer at about the 40-50Mph point. I have tried to investigate it, if I spin the cable with a drill, at the gearbox end of the cable, the speedo needle appears to be stable. So I guess this means the speedo, cable and cable routing are OK and the problem is with the gearbox.

I have also checked the dimension of the cable square end verses the size of hole in gearbox drive and there shouldn't be any way it can be slipping.

So then I gave up....

Link to post
Share on other sites

Hi Rich

 

I've already got a list of 'essential'  upgrades/improvements without you tempting me:rolleyes: Not sure about white, I'll have to ask herself, having done over 7,000 miles in the last couple of years, only about 100 have been without my wife, she gets a good shout.

Link to post
Share on other sites
6 hours ago, gloide69 said:

I have the same problem with a wavering Speedometer at about the 40-50Mph point. I have tried to investigate it, if I spin the cable with a drill, at the gearbox end of the cable, the speedo needle appears to be stable. So I guess this means the speedo, cable and cable routing are OK and the problem is with the gearbox.

I have also checked the dimension of the cable square end verses the size of hole in gearbox drive and there shouldn't be any way it can be slipping.

So then I gave up....

Interesting, I had not done this test. I guess I'll have to ask my wife to watch the speedo while I am driving the drill :).

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.