T350 - Speedo Problem

[Blue-Lightning]

I noticed while out in the T350 today that the speedo seems to be very hesitant. While moving in traffic it seemed to just jump between 5, 10,15 and 20 mph while the digital readout went up and down with no problems.

It does the same when traveling at speed (40-60mph), the needle does not go up or down in a continuous motion, but in steps. It almost looks like it is getting stuck.

Is this just a T350 niggle or have I got a problem with the speedo. Any help and advice would be appreciated.

[tail slide]

It's a common problem with any digital speedo, but I've solved it on several cars inc. my T350.

The sensor reads off a serrated steel disc on the offside (I think) of the diff. Often some debris or rust gets in the gap between the sensor and the disc, or the gap's increased by something knocking the sensor - the gap is quite critical.

So I suggest jacking up & having a look, cleaning the disc a bit & testing. If that doesn't work reduce the gap just a fraction by screwing the sensor in with a spanner, and turning the wheel to make sure no part of the serrations actually touches the sensor!

[VARLEYHYD]

Here we go

Speedo Sensor- Adjustment/Removal/replacement (sag v similar all T cars)


Part no. M1889 £100 ish Racing Green TVR

If replacment required use a dealer as they will have it done in a jiffy

To gain access to the Speedo Sensor the car ideally needs to be on a ramp.(jack possibly)
Remove the left NS rear wheel.



The sensor can be seen at the right of the drive shaft, horizontal to the toothed diff output.





View from underneath the car.(exhausts removed on photo)

Clean with WD40 set to 1mm gap

The sensor is best left, complete on the bracket if removed.


View from rear (fuel tank removed)




Alternativley, remove locknuts, follow the blue cable through to the rear inner wheel arch where it enters the body.



The hatch trim top rail and then the left NS trim panel needs to be removed.





Unplug in the inner wheel arch and prise out the wires and sheath from the connector block.

Pull the new sensor wire through, without cutting back the wire.

Remake the connector and re fit the sensor and bracket.
Alternatively cut off at 200mm long from plug then cut back new by 200mm and join with soldered heatshrink joint or sealed connector block.

Check with the ignition on the speedo needle reads zero.

If the needle requires adjustment, select factory settings on POD menu 8; select the mph zero and adjust up or down until the needle is set and save the changes.

Hope this helps

G

[tail slide]

Top advice Graham




PS maybe bump into you at TVRCC Oulton trackday, but it's between events both weekends either side so I may be too frazzled.

[Blue-Lightning]

Thanks for the info Guys.

Graham, I had read through your post on the TVRCC site. If the digital readout also had a problem then I would have thought it was the sensor, however the digital readout seems to be fine and the problem is just with the speedo dial.

Could this still be a sensor problem, or could it be a fault with the display unit.

Graham, how do you manage to keep the Sagaris is such good condition?

Thanks again guys for the replys.

Steve

[VARLEYHYD]

tail slide said:

PS maybe bump into you at TVRCC Oulton trackday

Stopping over at Cadwell monday & tuesday. will be good to catch up, and share some knowledge

I will try and get to Loton Park though

Blue-Lightning said:

Thanks for the info Guys.

Graham, I had read through your post on the TVRCC site. If the digital readout also had a problem then I would have thought it was the sensor, however the digital readout seems to be fine and the problem is just with the speedo dial.

Could this still be a sensor problem, or could it be a fault with the display unit.

Sorry, not looked at this one yet but it is possible the drive on the needle is worn; I think is a gear drive?

I will pull it apart now and have a look! maybe not, as the cars back together after in bits for 5 months being sorted!

Blue-Lightning said:

how do you manage to keep the Sagaris is such good condition?
Steve

You don't really want to know,;
OK
Lots of hours dismantling, improve and perfect, clean, and photo for the
Sagaris Workshop Manual I am doing.

G


G

Edited by VARLEYHYD on Friday 9th May 10:08

[Blue-Lightning]

Thanks for the info Graham

VARLEYHYD said:

Sorry, not looked at this one yet but it is possible the drive on the needle is worn; I think is a gear drive?

So am I right in thinking that the sensor just feeds the digital readout and that there is a seperate drive to the speedo needle.

[VARLEYHYD]

Blue-Lightning said:

Thanks for the info Graham

VARLEYHYD said:

Sorry, not looked at this one yet but it is possible the drive on the needle is worn; I think is a gear drive?

So am I right in thinking that the sensor just feeds the digital readout and that there is a seperate drive to the speedo needle.

It works on a pulse count to the dash pod ecu, so looks like the needle drive.

If the sensor is Ok, the POD is easy to get out just follow my TVRCC WEB link

G

[Blue-Lightning]

Thanks Graham.

Sorry to be a pain, but do you have a larger picture of the jacking points and axle stand positions......are these the same for the T350.

Thanks Steve

[VARLEYHYD]

Blue-Lightning said:

Thanks Graham.

Sorry to be a pain, but do you have a larger picture of the jacking points and axle stand positions......are these the same for the T350.

Thanks Steve

Double click the image

here


G

[earlyriser]

Crikey, Graham, has your car ever been outside? That is one clean chassis.

[VARLEYHYD]

earlyriser said:

Crikey, Graham, has your car ever been outside? That is one clean chassis.

Loves the track and gets wet if it rains, then;

A bit of old fashioned elbow grease, wd40, cotton wool buds, autoglym etc etc etc

It certainly didn't leave the factory like that!!

G