Jump to content

Speedometer cable question


Recommended Posts

Ok evening all , I have searched this topic and read lots of detail ... My speedo has stopped working I have un done the cable from the speedo and whilst it looks ok it does not rotate when driving , so I have read the inner can be replaced ? , I have removed the inner very easily , the end that goes into the overdrive looks square and not damaged , I was expecting it to be damaged , it's a 1965 tr4a with OD so I expect an angle drive , could this be damaged ? Before I buy a new cable and strip the car down to replace , any obvious checks advise ? Finally it's rh drive the cable I removed measures 67.5" ... Moss and revington quote different cable lengths ... Any ideas ...

Link to post
Share on other sites

It's unlikely that the gearbox end is broken, so how square is square on the ends of the inner cable? I can think of two possible answers:

The square end at the gearbox is not quite square enough to avoid slipping within the drive

The outer cable has for some reason been stretched, & the inner is now not quite long enough to reach the square drive tube in the gearbox.

 

I would test it by pushing the inner back in as far as you can, twisting it as you go, when (if) it engauge's with the drive it should no longer be turnable.

at any rate you should be able to feel when it either engauges, or tries to engauge with the drive. if you cant feel the differance from when it is nearly all in, & all in then it suggests that the outer has stretched.

 

Bob.

Link to post
Share on other sites

Hi Sperry,

fit the inner back into the outer and go for a test drive with the cable disconnected.

Does the inner cable rotate when driving.

Grab hold of the inner - does it stop rotating - if yes then suspect the angle drive. If no then angle drive is OK.

 

The square hole in the gauge is apprx 1/2" deep. The square end on the cable is often apprx 1/4".

Have the edges of the square cable been round off.

It may be possible to tap the collet further down the cable that gives the protrusion of the square end.

 

Have you tested the gauge. Connect a small diy craft drill motor to the gauge and using about 100rpm see what the gauge does.

 

Roger

Link to post
Share on other sites

Ok thanks for the replies , both square ends appear to be in good condition , not rounded at all . When I slide the inner back, it rotates freely and then I can feel it engage in the angle drive and is then solid . I have been messing about all day I cannot get it to spin round when Iam out in the car driving .... Suspect angle drive ? Is this a big job to change ?

Link to post
Share on other sites

Hi Sperry,

to remove your angle drive -

remove drivers seat

On the offside of the tunnel rear of the 'H' support there 'may' be a panel you can take off. This will expose the angle drive.

If you are lucky the angle drive will simply unscrew (Ho Ho Ho).

 

With the angle drive in your hand you should be able to turn the input drive and see the output rotate.

 

If it doesn't then the flexible drive may be sheared . If you prise the back off the drive you will see how it is built. I used a spitfire speedo inner cable for the square end.

 

Roger

Link to post
Share on other sites

I Had exactly this issue15+ years ago, took the cover off the side of the gearbox as Roger describes & saw end hand popped off angle drive and the drive gear was missing...luckily I found the gear resting on the chassis. I put it back, but the end-cap was missing, it was about the size of a 1P coin, so I spread a 1P with a bit of planishing, dished it with a centre punch, then fitted it like a core plug.

It's still there today...

Link to post
Share on other sites

Yes, but-- Sperry sais that when he pushes the inner cable all the way back in, he then cannot turn it - so it's not a case of a gear falling out,

or the flexible drive breaking, more a case of something has jammed.

 

Bob.

Link to post
Share on other sites

I was reading up on angle drives over the weekend in preparation for fitting my OD gearbox. It appears that it's important that a spacing washer is fitted between the angle drive and the gearbox/OD. It not, it can lead to premature failure of the angle drive. Might be worth a check if you have to remove it. There's some useful info on the Moss website:

 

http://www.moss-europe.co.uk/graphics/uk/instructions/021-511_120694_980-411_INST.pdf

 

Steve

Link to post
Share on other sites

This is a 4A speedo cable from an OD transmission, the inner wire is 67.25 in long, the outer is 66.75 in long, so there is only 1/2in of wire "sticking-out".

The outer coating of this cable is not original its been restored with Raychem heat-shrink tube.

 

This is the speedo end, I have withdrawn it so you can the the plastic part that keeps it in the right place.

This is a tight fit on the wire:

https://flic.kr/p/oqoLpn

 

This is the gear-box end. There is no plastic part and the right-angled drive goes up inside the nut.

https://flic.kr/p/o8U7yD

 

This is an original right-angle drive. Note the fancy brass work:

https://flic.kr/p/oomVmY

https://flic.kr/p/oqnfeS

 

There is a bit too much grease around here for a final fit.

Grease can work up into the speedo head and gum it up.

 

This shows the fit to the cable, much as you would see looking down onto the overdrive:

https://flic.kr/p/o8U3kj

 

The plastic collar sets up about 1/8in of end-float on the inner-wire.

Edited by AlanT
Link to post
Share on other sites

I was reading up on angle drives over the weekend in preparation for fitting my OD gearbox. It appears that it's important that a spacing washer is fitted between the angle drive and the gearbox/OD. It not, it can lead to premature failure of the angle drive. Might be worth a check if you have to remove it. There's some useful info on the Moss website:

 

http://www.moss-europe.co.uk/graphics/uk/instructions/021-511_120694_980-411_INST.pdf

 

Steve

Hi Steve,

 

From your Avatar I presume you own a TR4.

 

TR4's were never fitted with angle drives, the cable went straight from the overdrive up to the speedo.

 

Regards, Richard

Link to post
Share on other sites

Sperry

 

You may find the cable relatively intact , and the angle drive is pretty strong.

 

Put the cable in the back of the speedo and turn it to see if the speedo needle reacts. Make sure the cable has a good square end.

 

On my 4a the speedo input shaft had partially seized I broke a new cable within a week. Not sure where I found it but somewhere on the web is an article relating to dismantle and reassembly of this particular speedo unit. The shaft needs freeing off and greasing as it seizes in the speedo casing if this turns out to be your problem.

Link to post
Share on other sites

sperry does but Steve Priest doesn't :)

Thanks Richard. Yes, mine is a 4. My replacement box is from a 4A and came with an original angle drive. I realise I can do without it but did wonder if it might result in a more direct/relaxed routing of the speedo cable. I guess all will be revealed when I get around to fitting it.

 

Cheers

Steve

Link to post
Share on other sites
  • 2 weeks later...

Alan with relation to the angle drive and speedo question I origional ly posted ... Today I removed the angle drive , stand alone it looks fine , turn the input from the OD you can see the female speedo end turning , put the speedo cable in , if you turn the OD input it doesn't turn however if you turn the speedo cable the male OD end spins ... Any ideas ?

Link to post
Share on other sites

Hi Roger, looking at the exposed picture of your gearbox, I can on the dash you have small panel with 2 red and 2 green lights, courisity has gotten the better of me and I'm interested to know what they are for?

 

Mark

Link to post
Share on other sites

Hi Roger, looking at the exposed picture of your gearbox, I can on the dash you have small panel with 2 red and 2 green lights, courisity has gotten the better of me and I'm interested to know what they are for?

 

Mark

 

 

I think it's a ILS (instrument landing system) from one of BAs jets. It tells Roger how to get home from the pub. up/down, or left/right. ;)

 

Cheers

 

Graeme

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.