Instruments
Speedo
Fuel Gauge
Extra Gauges for Chimaera
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Speedo
Internet Mailing List Jan 97
I've got one of those analogue speedos that makes a loud 'tick' every 10th of a mile. I am told that they were from a dodgy batch
of BL stock that TVR bought and refaced - the tick being caused by the fact that the trip meter was blanked off, but the mechanism
tries to push against a non existent cog every few seconds. The later instruments don't match, so I would have to swap at least
the speedo and tacho together (if they fit the holes in the dash). All in all, it's a bit like driving a very fast grandfather clock.
John Langford
Letter Oct 97
On my car (1994 4.0HC Chimaera) the the mileometer is an electromechanical device that increments every 1/10th mile when a solenoid is pulsed
to click a pawl mechanism. Hence the click. I was told on good authority that this particular instrument originated from a tractor.
There is no trip mileage facility, blanked off or otherwise, and my reason for discovering all this was to add an LCD trip with
a small reset button which works well.
The 1/10 mile pulses are derived from a custom electronic box within the dash. This box converts the output from a gear tooth
speed sensor in the diff, and incidentally also provides a simulated speed sensor signal to the ECU to tell it whether the car is moving
or not. I believe this is used by the ECU to determine whether to adjust the idling speed or not, via the stepper valve. The
simulated signal is not very much like the Rover sensor signal and I suspect that the idling control is unduly inhibited by by
the slightest movement of the car. This may explain idle speed problems; try keeping the car totally stopped for a while and
you should notice the idle speed suddenly correcting itself. If you keep moving, no matter how slowly, it won't.
I suspect that this arrangement was derived for Borg Warner gearboxes and that the earlier Rover units may have the proper speed sensor
and may not have the same idling problems . . .
Mike Gill
Letter Feb 98
Mike's opinion about the cause of the speedo ticking is quite right. If it is ticking, all is okay. In my 94 Griffith the speedo was
working intermittedly and the ticking was not heard. I opened the instrument and found that the solenoid got regular electric pulses
but the small metal plate which is magnetically attracted by the solenoid (this makes the noise) was glueing to it and could not get loose.
There was not enough space between the two parts. I loosened the fixing screws of the solenoid and rearranged it and the problem was solved.
Thomas Hopf
Internet Mailing List Jun 98
The speedo in my Chimaera has had a mind of its own lately. First it was coming on and off every few miles, and has now completely given up. Assuming the 'Sorry Mr Plod but you see my speedo don't work' excuse doesn't go down too well, I'll have to get it fixed.
Is there anything I can check myself to find out where the fault lies, other than take the top of the dash and see if a wire has become loose?
Around the same time, the timing went out a bit, and it often stalls when you put the clutch down to change gear, even at high speeds.
Bit dangerous when it happens changing down for a tight turn as the PAS stops too. Idle at rest is OK though.
Could these too problems be connected, i.e. the computer doesn't know the speed of the car, so isn't adjusting the timing to compensate?
Graham Hay
Internet Mailing List Jun 98
The problem could be a faulty transducer. They get quite hot. Speedos have been known to fail too.
Often they are replaced as a pair no matter which one is faulty, to ensure they are matched.
Exactly the same thing happened to my Griff when the transducer failed. I was told by the dealer that there was some sort of speed related input to
the ECU to stop the revs falling back so much when you change gear on the move, and once this lost the input from the transducer it got confused.
Other people have disputed the existence of this mechanism since. However, all I can say is that, like your car, my car developed the stalling problem
at exactly the same time as the transducer failed, and this problem went away as soon as the transducer was replaced. The timing was unaffected as
far as I could make out though. The problem hasn't re-occurred in the last two years.
Steve Powell
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Fuel Gauge
Internet Mailing List Apr 97
My Chim's petrol gauge keeps dropping to zero (thats not because of the way I drive it) and going back up/down in spasms. Also
when the tank is full it stays at zero for a while (15 miles).
Paul Bland
Internet Mailing List Apr 97
That is symptomatic of a faulty fuel gauge sender where the sender goes off the resistence track when full - hence the zero reading
until you have used about a gallon of fuel and contact is re-made. The ups and downs are caused by this contact making and re-making.
Replacement or adjustment is often the cure.
Steve Heath
Letter Feb 98
My fuel gauge showed empty when there were about 8 gallons in the tank. If the tank was full, it showed 3/4 only.
Here is my solution, but be aware that it is an awkward and dangerous procedure:
1. Open the boot. Loosen the trim on the right upper side of the tank. Unscrew the fuel sender and take it out.
Close the open hole with something! Re-connect the cables and turn the ignition on. Move the white float up and down and look at the fuel gauge.
2. If the needle goes from empty to full then you have to adjust the sender by bending the wire up or down. Hold the sender outside the tank in the same level that it is buit in and arrange the wire so that the float is in its lowest position about 2-3 inches above the lower edge of the tank.
You must be sure that you only bend it up or down, not in another direction, to avoid the float rubbing on the front ofr back wall of the tank.
In most cases that's it and you will have enough petrol for 20 miles when the warning light goes on.
3. If the needle does not reach "empty" or "full" by this procedure, then it's a little bit tricky. You must remove the fuel gauge from the dashboard
and open it. Remove the black or chrome ring and remove the screws at the back. Inside, the pointer is connected to a small coil, which moves in a cage. You can turn this cage to adjust the position of the pointer on the scale. Turn it so that the needle reaches "zero" if the float is completely down
and "full" if it is in the highest position. Secure the position of the cage with a drop of glue and repeat No. 2.
Don't smoke during this procedure!
Thomas Hopf
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Jan 98
The dashboard of the Chimaera models can quite easily be converted to accept extra instruments:
a voltmeter and/or an oil temperature meter.
The voltmeter as fitted in the later Griffith 500 models has exactly the same style as the other instruments in the Chimaera
but there are different colours for dials (magnolia, mint green, yellow black etc.) and for bezzles (black or aluminium).
This gauge can be fitted without any modification and it is available at your local TVR dealer (the supplieris Caerbont
Automotive Instruments).
The oil temperature gauge is not available as such but if you order a water temperature gauge and a water temperature sender
as already fitted to the Chimaera you can have the gauge converted.
Speedy Cables in London specialise in converting and repairing all kinds of gauges and they can modify the TVR gauge
for about 20 pounds (Phone 0171 2269228).
Since the oil temperature seldom goes above 120 degrees (that is in the area of the sump plug where you fit the temp. sender)
the scale as such does not have to be changed but the little water thermometer symbol has to be replaced by an oil
temperature symbol (oil-can with smaller thermometer). For the functioning of the gauge you don't have to do this of
course but it looks very neat.
Where to fit the gauges
First step is to drill the holes in the dash panel. Because the 'wooden' dash panel is in fact a steel plate with a
polyester front with wood motive (indeed, you don't need to be afraid of wood worm attack) you need a special drill to make the holes.
A 2 inch metal drill with adapter is required to drill these holes: you can NOT use a wood circle drill from a DIY shops.
First remove the dashboard top (described else where in the workshop notes) and than determine the position the new gauges.
The best position to drill the holes is left from the speed meter and right from the rev counter.
Make sure to drill the holes on the same level as the existing instruments in the lower level (clock).
Before you drill the holes remove the two upright brackets behind the panel. Most likely the brackets can be left off.
Make sure to position the holes in a way that there is 4 to 6 mm room left between the bezzles and the dashboard upholstery.
The holes must be visible THROUGH the steering wheel.
Use high drill speed to get through the polyester layer without chipping it; reduce the drill speed to get through the metal plate.
The hole pattern of the four centre instrument will now look very much like that of the Griffith instrument panel.
When fitting the instruments in to the holes you may need to enlarge them a bit because the TVR gauges are slightly bigger than
the standard drill. The right hand instruments will NOT interfere with the dash top cover when the holes are drilled correctly.
Before fitting the new instruments it may be worth to reconsider the location of the various gauges.
In order to stay in line with the gauge positions in the Griffith, the WATER temperature gauge should be moved over to the new
position next to the Rev counter and the oil pressure gauge to the new position next to the speedometer.
Wiring up
All connections you need are already present at one of the other gauges except the oil temperature signal wire.
The earth, feed and illumination wires can be extended from any other gauge. The volt gauge does only need these 3 wires.
The water temperature signal wire needs to be extended if the gauge is moved over to the right hand side.
The oil temperature gauge needs a 4th wire which has to be routed to the oil sump plug.
The new water temperature sender unit has to be fitted IN the sump plug. A metalworkshop can drill the plug and cut the correct
thread in it. Use a new plug and prepare the complete unit so it can be easily be swapped with the original plug (at the next oil
change for example)
Make sure the wiring to the sump will not run too close to the exhaust and secure it to the body/chassis with enough straps.
Read out
The benefit of the voltmeter is that it will tell you when the voltage gets too low and your battery may get flat.
When the ignition is switched on it will read approx. 12 volts. Once the engine is running it will read approx 13 to 13.5 volts
and it should not drop below 12 for longer periods.
The oil temperature will not increase as quickly as the water temperature so it gives you a much better indication when
the engine is at the correct operation temperature, ready to accept full load (above 60-80 degrees).
The maximum temperature can however become higher than the water temperature (according to the experts about 10 degrees higher
under normal operation conditions). It should not get higher than 120 degrees measured at the sump plug.
There may be some places in the engine where the temperature will be higher but considering the fact that the sump content is pumped
across the engine several times per minute, you will have a good warning indication when the oil temperature does get too hot.
Bear in mind that this gauge is not replacing the water temperature gauge; the engine may still overheat when the oil
temperature is still relatively low. In general you have to focus on oil temperature when using much engine performance (on the track)
In contrary to the water temperature gauge; this gauge has to be checked more frequently.
Griffith 500
The oil temperature gauge as mentioned above may also be a useful instrument for the Griffith 500 models. Since there is not so much
room in the panel for extra holes it is easier to fit it instead of the clock. In order to obtain access behind the panel both radio and glove
box have to be removed.
Note
Griffith 400/430 and early 500 models have a different supplier (Stewart Warner) for the instruments; they are
not available anymore, neither from TVR nor from SW. These early type instruments can be recognised by the fact that
the are fitted IN the instrument panel rather than ON the panel and have horizontal pointer rather than vertical.
You can of course fit any other 52 mm oil temperature gauge but it will never match the rest of the instruments.
Tom Mogyorossy
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