speedo

stuthegasman · Post by **stuthegasman** » Wed Aug 15, 2007 8:25 pm

Here's a puzzler for you i'm hoping someone might be able to shed some pearls of wisdome on... the speedo suddenly stopped working on my mk1 coupe removed the instrument cluster pulled speedo cable out of back of clocks moved car backwards and forwards inner cable rotated as it is should forward and backwards, used a slow speed power screwdriver to drive the speedo head which worked fine read about 10mph so that seems ok held the end of the inner cable gently whilst it was rotating to make sure it wasn't the gearbox drive slipping no problems there either so what the heck is going on there does not seem to be any excess play in the cable and seperately the cable and the speedo head work but put them together and nothing happens not even a flicker am I missing something here coz it's driving me mad..

cheers
stu

Uncle Frank · Post by **Uncle Frank** » Wed Aug 15, 2007 8:30 pm

Sounds like the nylon worm gear on the speedo drive is slipping on the shaft, try replacing the easy one first, if you are really unlucky it could be the one on the gearbox output shaft, which means a gearbox strip

JIM73 · Post by **JIM73** » Wed Aug 15, 2007 8:31 pm

bit strange mate !!! i would physically check the nylon drive though , ive had lots of them go on me !!! :?

stuthegasman · Post by **stuthegasman** » Wed Aug 15, 2007 8:33 pm

thanks Frank and Jim but I can hold the rotating inner cable quite tightly with a pair of long nosed pliers and the cable still rotates it does not appear to be slipping which is what is puzzling me is the nylon drive bolted to the gearbox itself ??
stu

JIM73 · Post by **JIM73** » Wed Aug 15, 2007 8:39 pm

yep ! just one bolt and it normally slides out !!!

Uncle Frank · Post by **Uncle Frank** » Wed Aug 15, 2007 8:40 pm

Hi Stu, if you grab a copy of a workshop manual you will see the speedo drive is held in with a Y shaped clamp, held in place with a 7/16 bolt, over the end of the cable, undo this clamp and you can take out the nylon drive to inspect it, it does sound as if this is where your problem is, but of course i may be wrong, maybe someone else has come across this problem as well??

stuthegasman · Post by **stuthegasman** » Wed Aug 15, 2007 8:42 pm

if it is the nylon drive where can I get one ??

Uncle Frank · Post by **Uncle Frank** » Wed Aug 15, 2007 8:46 pm

I would put a wanted post on the forum, someone will have a spare, or you could try one of the triumph specialists such as John Kipping or TD Fitchett

.

JIM73 · Post by **JIM73** » Wed Aug 15, 2007 8:48 pm

normally from a scrapper !! im not sure if you can buy new or not !!!

stuthegasman · Post by **stuthegasman** » Wed Aug 15, 2007 10:41 pm

http://www.rimmerbros.co.uk/cgi-bin/rim ... te/gearbox
could that be what I need possibly ??
stu

madmart · Post by **madmart** » Thu Aug 16, 2007 4:26 am

hi, whats the back of the speedo like where the cable goes in?
the nylon bit with the square hole sometimes wears out.
my tc was like it and a previous owner had wrapped some electrical tape round the end of the cable and jammed it in to cure it!

stuthegasman · Post by **stuthegasman** » Thu Aug 16, 2007 8:16 am

that might just be the problem as I can't remember seeing a nylon piece so it might have worn away cheers i'll have another look tonight after work and let you know
stu

norway_triumph · Post by **norway_triumph** » Fri Aug 17, 2007 7:03 am

the orange nylon drive for the 1800 (think it was 26 teeth) - but i can look up that. can be obtained fron the mgb-hive as a drive for a us-speg mgb GT . i bought one some 6 months ago. if your car is a 1800 and the drive is worn let me know and i'll dig out the links, parts# etc.
- i think even the 1700 nylon drive is the same as the 1800 one.
i don't know what the white 1300 nylon drive compares to but you should even be able to use a 1800 drive but you will get an error-reading speedo that you'l have to compensate for

Kilroy · Post by **Kilroy** » Fri Aug 17, 2007 10:37 am

Stu

I had a problem with one of my cars - the speedo would not work at all below a certain speed, and then it underread quite considerably once it got going.
I changed the inner cable, but no improvement.
I checked the drive unit on the transmission, but could not find a problem.
I then decided to change the entire speedo cable (outer), and in doing so, discovered that the ferrule at the top (speedo) end had migrated a little off the actual outer cable.
This was indeed the problem.
The new outer fixed it and now it is perfect.
Eyeball both ends of the outer cable very carefully.
HTH.
Kilroy

Post by **MarinaCoupe** » Fri Aug 17, 2007 6:01 pm

Marina all with 4.1:1 back axle (e.g. 1.3s saloons/coupes 7cwt/440 vans & pickups) - 22G 1785 - 23 teeth - Triumph equivalent - Part No. 219006

Marina all with 3.63:1 back axle (e.g. 1.8 & 1.7) - 22G 1784 - 20 teeth - Triumph equivalent - Part No. 219004

Marina 10cwt/575 van/pickup with 4.55:1 back axle - 22G 2019 - 25 teeth - no Triumph equivalent