Gt6 mk3

[Dolomitejohn]

Hi all

Couple of questions you may be able to help with. 

Spedo just stopped working. I guess cable or drive at g box end. Which is most likely? 

And vibrations from rear end. Guess uv joints. Easy to change? 

 Thanks all. 

John 

[johny]

you've got to start with the easiest checks first:

disconnect cable at speedo and check its turning when the back wheels are driven. And if you get the rear of the car in the air check prop and half shaft u/js and prop sliding joint play.

Then move onto the more difficult stuff.....

[Colin Lindsay]

9 minutes ago, Dolomitejohn said:

Spedo just stopped working. I guess cable or drive at g box end. Which is most likely? 

Either end. It's most likely, unless it's broken completely, that the inner cable has slipped backwards out of the speedo. Which end can you personally gain easier access to? You can either get at it from the rear of the speedo, and pull the inner cable out slightly with pliers, or else go to the gearbox drive end and push the inner cable inwards so that it comes out of the other end and into the speedo. Have a look at the condition as heavily frayed wires mean a new cable.

Clues as to the vibration? it could be anything from a wheel imbalance to a bent axle so try to explain how it sounds or feels.

[dougbgt6]

Speedo: As Colin says, could be either end.  Gearbox end is a tunnel off job, speedo end needs the triple jointed wrist. You can undo the speedo clamps and pull it forward enough to see down the back, so you can get your hand on it via the centre facia panel. I would favour the tunnel, tedious but less frustrating than the hand behind the dash.

UV joints are fairly easy as are prop shaft UVs , but vibration could be anything.

Doug 

[Dolomitejohn]

Hi doug and all. 

Just removed Spedo cable from rear of speedo. Pulled the inner cable out and hey presto its snapped at gearbox end. 

Does the tunnel have to come out to access the cable at gearbox end or is it accessible from under the car? 

Cheers all. 

John 

[Pete Lewis]

Amd while youe at the geabox end please remove the angle  drive make sure there is a 7/16" plain washer fitted  to space the drive

Away from the pinion drive  housing.

You are most unlikely to get  cable off from underside unless you have double jointed   8" fingers with a torch on the  end !!!

While  the tunnel is off good time to add big holes to  access the gearbox filler  and the  speedo cable .to  ease future jobs.

if you feel,you need to lubricate the new cable its best to  use graphite dust not overly available

You can  wet and dry a pencil , john will advise  you can get grit in the flakes  

A light smear of grease not much the spriral wound cable can transfer it into the head 

If a cable has wrong inner protrusion you can with grips wind the spiral outer  this  will  grow or shorten the outer quite easily

Pete

Edited July 4, 2019 by Pete Lewis

[Dolomitejohn]

Not sure I have an angled drive. It does not have overdrive (sadly). 

Does that make job possible from below? 

John 

[Clive]

Sadly not. The chassis rails and gearbox mounting plate all get in the way. 

So limber up, H frame out and tunnel out. As Pete says, generous access holes are a good idea for the future. As is a good deal when refitting the tunnel. (Some like a thick circa 6mm? foam seal. In the past I have tried oiling the metal panels, and using silicone on the actual tunnel, hoping it would create a "perfect" seal that would not stick to the metal. Didn't quite work... )

[Dolomitejohn]

Hi Clive. 

Thanks. I have only just fitted the tunnel and h frame along with new seal, reflective sound insulation and new dash parcel shelves and lower vents. Arghhhh

Not sure I want to cut holes in my nice new plastic tunnel...... 

Oh well.... A nice job for the weekend... 

John 

[johny]

I still think its easier to get to the speedo end (it certainly was on my Vitesse but maybe that has more room behind the dash) but if you are going to remove the tunnel again it will give a chance to have a look over the gearbox if you didnt do that recently. Theres checking all bolt tightenesses, gearbox rubber mount condition, oil level, gearlever linkage, bleed clutch etc 

[dougbgt6]

John,

Here is a picture of my tunnel, I've put it on here several times  before. I installed some recessed lighting in one of my ceilings (didn't like it much) and re-used the tool I bought from B & Q to drill the holes. I bought a giant grommet off fleabay and used black sealant to keep it in. THEN I checked the gearbox oil. No change in level since the last time I checked 5 years ago.  Did I need to do it, I suppose so. I haven't done one for the speedo cable, the current one is 45 years old an still going.

 

Doug

[Pete Lewis]

On a local 13/60  cut hole in tunnel and ran cable inside under  the  carpet  there  was a reason which if  i  remember  was to 

Get a std  cable to fit on a overdrive conversion  when ever when everywhere was shut

Pete

[Buggy]

I also have a problem with the speedo on a GT6 Mk3,i removed the speedo but coudnt get the inner cable to move at all,so i removed the Tunnel,and speedo cable at other end same thing stuck solid,ordered new cable,however the angle drive off the gearbox is loose and sloopy at the end that fixes to the cable,if i remove the drive from the gearbox(is it a screw fitting??)that roughed up knurnled  fixture,??it appears to have a grub screw in it,any ideas?? help

[Pete Lewis]

the knurled nut on the angle drive is just!! screwed onto the speedo output drive on the gearbox

they do get gorrilla hands wreck them          its a fine thread easy gets crossed 

on refitting the drive add a 7/16 washer between  the angle and the gearbox to prevent pre loading and failing the angle drive ....common problem  the washer is a BL tech fix

pete