Speedo Woes

[ALLOA]

I've just completed replacing the dash to my 240 after it's recent engine swap. Everything works fine other than the speedo being erratic. The minute that I take of the speedo register speeds well in excess of what I am actually doing. (Once the car reaches speeds of around 30 mph the needle is at 120!) The car itself is a 'K' reg Torslanda and the donor car was an 'F' reg GLT. The loom and dash are from the 240 GLT so the only original part from the Torslanda is the sender unit on the axle. It is my plan to eventually fit the GLT axle but only after a wirebrush, paint, re-bush etc... Does anybody know if the signal from the Torslanda unit would be sufficiently different to that on the GLT?

I'm aware of the perils of connecting the red and white tacho wire in the wrong place so I can confirm that I've not fried any of the dash pod.

Any ideas?

Regards

S

[Clifford Pope]

No idea, but failing anything else, you could just match either one pair or the other - ie Torslander sender with Torslanda speedo, or the other way round. I assume the speedos are the same size etc, not like the early cars?

[gary austin]

hi doesnt the glt speedo pick up from the rear axle where the rest are different .if you put a normal axle in a glt it wont work the speedo i know that as ive tried that.anyway i have a glt speedo in my garage and lots of other bits and bobs no axles though but ive recently scrapped a glt in fife which i left the back axle on give me a shout and ille find out where it went cheers gary

[ALLOA]

Hi Gary, Thanks for the offer. I'll fit the GLT sender first to the Torslanda axle before trying anything else. On the Torslanda the speedo sender is also in the back axle so, as Clifford says, matching the GLT sender up with the rest of the GLT loom and speedo so should hopefully sort things out.
I like posting these things as people often come back with suggestions that you would never have reached yourself often from their own experiences.

Regards

S

[Ben O Brien]

Up until 86 the speedos were driven by a cable on the gearbox, after 86 they were electronic units on the back axle, When you take off the back plate on the diff you'll see a barrel like unit around the diff assembly with horizontal bars that pass the sender as the wheels rotate, only thing i can think off is that the torslanda may have a different sender assembly with a different amount of grooves or what have you, try making it all the one system, i.e GLt sender with GLT dash or torslanda with torslanda etc. Because you have a different ratio in the GLT axle ity may affect it but not to that extent.

[Clifford Pope]

Ratio doesn't come into it. The sensor picks up the speed of the crown wheel, which is directly coupled to the road wheels. Same wheels = same indicated speed.
Mechanical take-off on the gearbox of course is another matter.