MG-Rover.org Forums banner

1 - 20 of 25 Posts

·
Registered
Joined
·
434 Posts
Discussion Starter · #1 ·
Hello guys!

Hoping someone can help me witht he speedo on mt 420, Was driving home at 8:30 this morning after a LONG night shift.
got on A50 dual carrige way doing 70, after a minute or so, I looked back at the speedo to see it on 0.

Was one of those double take moments, firstly didn;t realise importance of it saying 0, but soon realised I was still driving down daul carrige way in 5th gear, 3000 revs.


I've tried a search and gone all the way though epsilons 18 pager on the T series, but I can't find any information on where to find the speedo on the gearbox.

Is it likely to be the speedo?
Should I just swap it out?


Any advice would be great!

Thanks.
 

·
Registered
Joined
·
194 Posts
hi you dond say what year your 420 is but if its a 96 on it will have an electric speed sensor on the tp of the gearbox if you lookdown the back of the engine kind of in the middle you should see it. it has a multy plug with 3 wires to it... i have a spare speedo drive and sensor.. if you find yours fulty drop me a pm..
 

·
Registered
Joined
·
2,153 Posts
Speedo transducer is a very loose push fit ....it could have come out ...

basically there is a plastic gear on the diff that drives a plastic worm .......the plastic worm has a sensor head attached . (push fit ) that pics up the revolutions and translates it to voltage that is sent to the speedo.

location ......here .

it's directly below the LPG filter (1 foot) I've just fitted....on the top of the gearbox.




other reasons speedo can pack up ...
1. diff bearings have packed up
2. plastic drive gear has stripped because of above .

3 alternator not charging ....rectifier in back of alternator fault. ........in that case you will have a few other faults ...........like a flat battery and not being able to start the car ..


all the best.mark
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #4 ·
"3 alternator not charging ....rectifier in back of alternator fault. ........in that case you will have a few other faults ...........like a flat battery and not being able to start the car .."

I stil have rev counter, so wouln't that mean alternator is fine (has not long beenr eplaced but could be loose earth i suppose)
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #5 ·
I have cheked the connecter and gave it some WD40, but that seemed fine anyway.

Although the switch itself seems to be a little loose.
I was able to twist it with my hand clockwise - didn't seem to tighten up at all. Should it? How does it connect?
 

·
Registered
Joined
·
2,153 Posts
they are loose ..push fit
that's why they can jump out and come undone ...

take nut off lower half of sensor......take out lower half and inspect drive for it ..look for worn away plastic gears
whilst you are there check gearbox oil level ...if the oils gone ...then i think your gearbox may be gone also.

try to see by if there is any sideways play in the drive shafts....that is play front to back of the car direction ..and up from the floor to bonnet direction.

NOTE there will be play from the direction of the box to the wheels.

if there is loads of oil leaking from were the drive shaft goes into the box .yore probably too late.!!!
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #10 ·
UPDATE!

have got replacement part from rover breakers - told them it was for a 420 gsi s reg.
asked will it fit - he replied yes, there all the same on rover 400's.

I was uncertain but took it anyway...

the replacment is 2 inches shorter than the original one!
GREAT.


anyway, at least I know it is the "drive" part (with the plastic gearing on) that is at fault. The gearing itself is fine, just the spindle seems off center and jammed.

ill try and see if I can free it up, but does this part come to pieces easily?

Also, on the bit that came out of the gearbox itself, it seems to have some "sand grains" over it, within the oil. Is this bad news for the gearbox?

Finally! How can I check the oil in gearbox?
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #11 · (Edited)
Heres a picture of the unit.

Ive taken the plastic rod from inside the metal tube(the metal tube seems to be stuck in place - by design???

ive take the cog off too - the cog and the plactic rod both fit together (but upto each other neatly), but are not supposed to as far as I can see (don't think it was one bit but broke - as both the end of the cog and end of the plasic rod are both smooth.

Anyone got any ideas?
(pics are different)
[img=http://img124.imageshack.us/img124/2460/dsc00445zi1.th.jpg]







I've come to the conclusion that this has snapped, but the motion if it rubbing has worn the ends smooth.
Think I'll araldite it together as a temporary fix!
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #15 ·
Yes, theres a metal tube that runs the was through the unit.
within there the cog has a spindle that run right the way up the center of the tube - and forms into the square that the speedo sensor connected into.

on mine the cog and spindle had snapped.
after aroldyteing them together and leaving 24 hours, it worked untill i got upto 20mph, and then broke!

Have a replacment on the way hopefully!
Untill then ill carry on using my phone with gps receiver for speedo!
 

·
Premium Member
mg_zt_t
Joined
·
21,915 Posts
don't know

if i had mine in bits i could confirm

mgjohn where are you !

all the best.mark
come to think of it isnt that little gear meant to be joined onto the shaft somehow

all the best.mark
Handled numerous PG1 speedometer drives. Never known that little pinion (cog) to be separated from its shaft....
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #17 ·
Handled numerous PG1 speedometer drives. Never known that little pinion (cog) to be separated from its shaft....
was in this case.

had sheared off, and then obviously as the cog was still in motoin, had rubbed on the now "none" moving part and formed a smooth edge on both pieces.

After roughing both ends up and "glueing" them together, it lasted for 20mph.

Although I've just this second been handed the part that a member off here sent me, so hopefully ill have speedo working tomorrow morning, right after I pick the car up form my mates, got taxi home after gettign rather drunk!!
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #18 ·
Just to add, I think this may off happened (Pinoin, seperating from shaft) because the metal spindle is off center, meaning as it turns ts stiffer as it passes one half than the other.

maybe a cause of excess heat and wear...
 

·
Registered
Joined
·
66 Posts
Something else

Hi my speedo has similar probs. But in the winter when its very cold it works fine for about 10 to 15 mins. then it just drops to 0 and stays there until its cold again.

Chcecked the sender thingy and ti seem to be fine , no wear or damage and if you put iron filings on the sensor you can se them dance around so the magnet inside is turning. any other ideas how to fix mine?

Sally
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #20 ·
Mine is now working.

Mick - check will be in the podt soon! Thanks!

Altough this has shown up that my speedo is out my 6mph at 30
(my speedo says im doing 30mpg, but satnav (two independent sat navs) report me to be doing 24mph!

as far as I know, standard wheels/tyre sizes.


My cruise control is working now also though! :D
 
1 - 20 of 25 Posts
Top