Discussion
Since buying my car I've always felt the speedo was over-reading by about 20%?
A check with GPS today confirmed my suspicions were almost spot-on. The speedo in the car was changed a couple of years ago when the old one packed up and presumably I have different style clocks as they are the later black with silver rims type with digital odometer rather than analogue. Car is a '95 500 btw.
Are there different types of sender fitted to the diff that I can change to sort this out or is this type of speedo adjustable with a screwdriver? Alternatively, should I take this up with the dealer that carried out the speedo change?
I can live with the inconvenience, it's the mileage piling on that worries me!
A check with GPS today confirmed my suspicions were almost spot-on. The speedo in the car was changed a couple of years ago when the old one packed up and presumably I have different style clocks as they are the later black with silver rims type with digital odometer rather than analogue. Car is a '95 500 btw.
Are there different types of sender fitted to the diff that I can change to sort this out or is this type of speedo adjustable with a screwdriver? Alternatively, should I take this up with the dealer that carried out the speedo change?
I can live with the inconvenience, it's the mileage piling on that worries me!
Edited by griffit on Wednesday 4th April 11:51
griffit said:
Anybody?
The cars have two types of speedo senders dependant on what gear box you have.
The rover boxed cars have a sender in place of the cable speedo drive. either 4 pulse or 8 and not repairable/adjustable.
T5 cars have a sensor mountes near the diff, either sensing the driveshaft or prop shaft revolving. This is adjustable , but if you are getting a reading then I would guess its working ok.
Speedy cable can recalibrate some speedos.
I have a T5 box so potentially the sender is adjustable? How do you go about adjusting the sender though, I don't recall much in the bible about adjustments when I looked?
I think I saw speedy cable mentioned in the archive somewhere. Am I right in thinking they can make a little box that has X input and Y output to sort things out? I'd prefer this to be a last resort if the sensor isn't adjustable.
I think I saw speedy cable mentioned in the archive somewhere. Am I right in thinking they can make a little box that has X input and Y output to sort things out? I'd prefer this to be a last resort if the sensor isn't adjustable.
antonyj said:
The cars have two types of speedo senders dependant on what gear box you have.
The rover boxed cars have a sender in place of the cable speedo drive. either 4 pulse or 8 and not repairable/adjustable.
The rover boxed cars have a sender in place of the cable speedo drive. either 4 pulse or 8 and not repairable/adjustable.
Only the pre-cats I believe. Susequent catted cars used the LT77 to drive the ECU, and the speedo from the front of the GKN/Propshaft. Early black rimmed speedos (ETB) have an adjustment screw on the speedo ~ tales of axle stands & adjusting are on here somewhere
antonyj said:
T5 cars have a sensor mountes near the diff, either sensing the driveshaft or prop shaft revolving. This is adjustable , but if you are getting a reading then I would guess its working ok.
Speedy cable can recalibrate some speedos.
Depends on the Diff, BTR on the driveshaft, GKN on the propshaft flanges. There are Xover cars with T5 box & GKN diffs?? The later T5 & CAI dials use the signal splitter box of magic.
Its a bit of a minefield, and your profile says your car is 95 which doesnt help. Which Gearbox, diff & instruments does your car have? In addition due to TVR build planning/process the changeovers dont always seem to be as clear cut as you would expect.
Dave
spend said:
antonyj said:
The cars have two types of speedo senders dependant on what gear box you have.
The rover boxed cars have a sender in place of the cable speedo drive. either 4 pulse or 8 and not repairable/adjustable.
The rover boxed cars have a sender in place of the cable speedo drive. either 4 pulse or 8 and not repairable/adjustable.
Only the pre-cats I believe. Susequent catted cars used the LT77 to drive the ECU, and the speedo from the front of the GKN/Propshaft. Early black rimmed speedos (ETB) have an adjustment screw on the speedo ~ tales of axle stands & adjusting are on here somewhere
antonyj said:
T5 cars have a sensor mountes near the diff, either sensing the driveshaft or prop shaft revolving. This is adjustable , but if you are getting a reading then I would guess its working ok.
Speedy cable can recalibrate some speedos.
Depends on the Diff, BTR on the driveshaft, GKN on the propshaft flanges. There are Xover cars with T5 box & GKN diffs?? The later T5 & CAI dials use the signal splitter box of magic.
Its a bit of a minefield, and your profile says your car is 95 which doesnt help. Which Gearbox, diff & instruments does your car have? In addition due to TVR build planning/process the changeovers dont always seem to be as clear cut as you would expect.
Dave
Car is a 95 serp with a T5 box. I'm afraid I've not been up close and personal with the diff to know which type I've got.
The clocks are currently the type in the photo below but with black faces. Digital odometer instead of analogue. Replaced in December 2004 as I recall.
[pic] http://cgi.ebay.co.uk/ws/eBayISAPI.dl [/pic]
Does this help at all or do I need to check the diff too?
ETA: Currently running 245/45 16's on the rear.
Edited by griffit on Wednesday 4th April 13:30
griffit said:
[The clocks are currently the type in the photo below but with black faces. Digital odometer instead of analogue. Replaced in December 2004 as I recall.
That might be your problem as SH mentioned, sounds plausible that ETB clocks were replaced with CAI ones... Check the diff & where the sender is.
Seasider said:
What does the Sensor tell the ECU ?? When my sensor packed up it didn't appear to make any difference to how the car ran !!
Tells the ECU if the car is moving & stops the stepper accelerating for you
- just saves a bit of fuel.. Dave
Seasider said:
What does the Sensor tell the ECU ?? When my sensor packed up it didn't appear to make any difference to how the car ran !!
It tells the ECU when to control the idle i.e. the car is at a standstill. If it doesn't see this then when you lift off, the ECU can think oh we are stopped I'll get my mate the stepper motor to control the idle. Unfortunately his big brother the engine still wants to turn over and confusion rains. Bad lumpy running/idle can result.
shpub said:
That sounds like the wrong speedo for the car so it is being fed more pulses than it would expect. I suspect that it isn't adjustable and the only way to solve the problemn is to get it recalibrated.
Is there a not a different sender per speedo type to overcome this problem? How else did TVR get around this when the speedos changed?
richb said:
griffit said:
. Digital odometer instead of analogue.
When you say digital odometer instead of analogue, presumably you don't mean digital as in LCD but digits rotated electronically? 
I can't think what an analogue odometer would be like?I have a little LCD screen showing the current mileage... but still not trip counter! How hard could it have been to incorporate one?! I would consider that digital and the rolling numbers to be analogue?
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