V8S Speedo Transducer

[v8s4me]

The original part with 20 teeth seems to be unobtainable so I'm looking at options. Rimmers stock a 22 tooth unit designed for a 3.09:1 final drive. The V8S has a 3.36:1 final drive (according to SH). So can one of you technical boffins out there tell me what the net effect will be? Eg will the speedo under or over read? Another issue is the type of pulse the transducer sends to the speedo. I've been told the TVR unit is 8 phase, but some are 4 phase. Rimmers have no information on this. The part number quoted by Rimmers is DRC8016A.

Any suggestions? Thanks in advance.

[phillpot]

with 22 teeth it will presumably take longer to turn than 20 teeth so will under read, speedo will show slower than actual speed?


2 is 10% of twenty so by about 10% ?


One could no doubt do some far more accurate calculations using the two final drive ratios but I can't be ar*ed

[Oldred_V8S]

Joe

There is a company out there that makes a conversion box for this purpose.

http://www.jaycar.co.uk/productView.asp?ID=AA0376&...

If the Rimmer unit throws out 8 pulses, this may be the best option, though I am sure there is a converter that can adapt 4 to 8 pulses.

Edited to add:
There is a cheaper one on the bay of pigs £19.99
http://www.ebay.co.uk/itm/SPEEDO-TRANSDUCER-22-TEE...

This is turning into a minefield:

Rover SD1 speed transducers

Speedo transducer; 1982 onwards (electronic speedo). 2 pin connector

3500 (20 teeth, orange) 3.08:1 axle ratio.

2600/2300 (23 teeth, black) 3.45:1 axle ratio.

2000/2400TD (22 teeth, red) 3.09:1 axle ratio.

Edited by Oldred_V8S on Wednesday 8th July 09:57

[v8s4me]

Oldred_V8S said:

..If the Rimmer unit throws out 8 pulses, this may be the best option, though I am sure there is a converter that can adapt 4 to 8 pulses...

Is it definite that the V8S unit is 8 pulse then?

Oldred_V8S said:

..There is a cheaper one on the bay of pigs £19.99
http://www.ebay.co.uk/itm/SPEEDO-TRANSDUCER-22-TEE...

I'm exchanging messages with this guy to see if the little white label offers any clues as whether it is 4 or 8 pulse. If it is the correct number then this will do for now and I'll work out how to compensate for the incorrect reading. But I do need a definitive answer on whether we have a 4 or 8 pulse unit fitted.

Oldred_V8S said:

..
Rover SD1 speed transducers

Speedo transducer; 1982 onwards (electronic speedo). 2 pin connector

3500 (20 teeth, orange) 3.08:1 axle ratio.

2600/2300 (23 teeth, black) 3.45:1 axle ratio.

2000/2400TD (22 teeth, red) 3.09:1 axle ratio.

..

As you say, a minefield. Rimmers also list DRC8172U as a 20 tooth alternative but that is for a diff ratio of 3.08:1 and ours are 3.36:1. The connector on this one is wrong but that's an easy fix. None of the Rimmer parts are for a diff near to ours so whatever we fit will be a compromise.

I've sent my knackered unit to (not very)Speedycables today to see if they can do anything with it. I'll keep you posted.

Looking back through my history file this will be the 4th or 5th transducer so this is clearly a problem area, on mine anyway. I suppose being so close to the exhaust it just cooks.

[tinks v8S]

I got a new one and was wrong when I was doing 40 I was going at 80 got used to it for a while until I found one was told you can have them calibrated to correct pulse

[v8s4me]

Hi Tinks. Did you keep the invoice for the correct one? And if so, does it give a part number or any other info to identify it?

Cheers

[tinks v8S]

No invoice ask Heath @ x works they swapped for me have invoice for slow one

Edited by tinks v8S on Wednesday 8th July 22:12

[v8s4me]

tinks v8S said:

... have invoice for slow one....

What was the part number of the slow one? Then I'll know what the wrong part is. Thanks

[Barkychoc]

I've got one stuck in a drawer in my father's garage that came off my old V8S. I pulled the wires out of it when I removed the engine and gearbox - I forgot to remove the connector. It is repairable (I'll do it) if someone can tell me which way round the wires go.

I'm going to be clearing out a few bits and bobs I accumulated.

[v8s4me]

Hi Chris - Any help?



If you mean the wires to the unit I can take a photo this evening of the one that's on mine at the moment. If you can fix it I'll buy it off you.

[Barkychoc]

Yes that's the bugger.

I have a bit of terminal in mine that I think I can solder on to - but I don't know which wire goes which side - I think if you look hard there is some small text on the white plastic part just saying patent pending or something useless - the wire colours in relation to the text is what I'm after.
It is a square wave output (I had one on an oscilloscope ages ago) so theoretically it may not matter.

I can have a go at fixing it and send it to you free of charge if you want - if it works you can send me some beer tokens, preferably lots of them!

[Oldred_V8S]

Barkychoc said:

Yes that's the bugger.

I have a bit of terminal in mine that I think I can solder on to - but I don't know which wire goes which side - I think if you look hard there is some small text on the white plastic part just saying patent pending or something useless - the wire colours in relation to the text is what I'm after.
It is a square wave output (I had one on an oscilloscope ages ago) so theoretically it may not matter.

I can have a go at fixing it and send it to you free of charge if you want - if it works you can send me some beer tokens, preferably lots of them!

Chris

Not that I suspect you need it but I found this doc on the web. Nothing majorly exciting but...

Transducer repair

[v8s4me]

Chris - does this help?



You can just make out "Made in UK" at the top. There is also a small rebate on the inside of the moulding which should help orientate the wires.

The unit is now with Speedycables so I can't actually look at it for you.

As you can probably tell from the pictures I tried to repair mine but every time I got to a piece of wire I though I could solder to it snapped off.

Do you happen to know if I'll be able to change the units over without dropping the exhaust?

Given Tinks' post above about the wrong unit reading half road speed, does that mean we have an 8 pulse unit in our 'box?

Edited by v8s4me on Thursday 9th July 22:13

[Barkychoc]

Has the green wire got a bit of brown stripe on it? If so that gives me what I need.

[SJS357]

Hi Joe
After our email conversation it got me looking into it a bit.
Spoke with a few people about its and now DG are getting some made.

Question: Where did you get the ration 3.36: 1 from. ?

Simon.

This is mine (apparently)

[v8s4me]

SJS357 said:

...Question: Where did you get the ration 3.36: 1 from. ?

The Steve Heath manual, page 221 (2nd Edition).

[v8s4me]

SJS357 said:

..........Spoke with a few people about its and now DG are getting some made.....

Interesting...TVR Parts told me they couldn't get the internals to have more made up.

[v8s4me]

SJS357 said:

..This is mine (apparently)

Good to get the pulse rate confirmed. Thanks

[phillpot]

v8s4me said:

SJS357 said:

...Question: Where did you get the ration 3.36: 1 from. ?

The Steve Heath manual, page 221 (2nd Edition).

A couple of sales brochures I have agree with 3.36:1 for the V8s.

v8s4me said:

Good to get the pulse rate confirmed.

Think your pulse rate will need confirming by the time you get this one sorted

[SJS357]

Apparently, the guys who are making them for DG are the original manufacturers of the sensors for TVR Ltd
So they should know there beans. (Hopefully)

Seems the Diff ratio & Sensor ratio are different (gearbox)

They may have publishing the diff ratio, tyre size alternatives, speeds etc as shown in SH book.
But there seems no point in publishing/advertising the sensor ratio.