Used Speed Sensor from Bell Hill

[ukkid35]

I bought a used speed sensor from BH a few months ago, it was seized in the damaged bracket, but I managed to extricate it an fit it on my car. Sadly still no speedo, I assumed it was the wiring/speedo itself, however I bought a cheap Chinese USB Oscilloscope to help with diagnostics - no signal from the sensor.

I hope they honour whatever waranty was offered, I will report back.

[optimax sniffer]

I think that with the speed sensor it needs to be within a mm or so of the sensor ring. I presume that you have it close enough

[FarmyardPants]

Even closer than that I think. As close as you can get it, basically.

[gerradiuk]

I read here that you can use standard photo copy paper as a gauge for the clearance,If the weather holds out I'll try later today as mine has been acting up.

[Tanguero]

Yes, a piece of copy paper is spot on for the speedo sensor gap. Anything much further than that and you wont get a reliable signal in my experience.

[PuffsBack]

To be honest I think this topic has been overdone a bit in the past. I changed mine back in December and had no real issues with it - yes it has to be close, but these threads give the impression that it has to be microns, its close yes, but I just wound it up to the diff cog, and then backed it out half a turn. Worked first time and easy as pie.

[Zeemax_Mini]

As above, just get it very close but don't lose sleep about the exact gap - as close as you can get without touching! I fitted a brand new sensor which still didn't work on a test drive, got it back up on ramps, moved it half a turn closer and hey presto!

Dom

[ukkid35]

I can just get a cigarette paper in the gap. Is there any way to test them off the car?

[cerbera8]

Had problems with my speedo not working which turned out to be a dodgy earth to the speedo sender. Sender was fine. Setting for sender is apparently 3/4 of a turn back from the cog.

[gerradiuk]

cerbera8 where is the earth for this please, I think this might be my problem.

[cerbera8]

gerradiuk said:

cerbera8 where is the earth for this please, I think this might be my problem.

Hi

John at Sussex TVR sorted it for me so not entirely sure where it goes exactly even though i was there when he worked on it. If you test the continuity between the earth wire that leads to the sensor and a known earth point like the chassis then if this shows open circuit then that should be your problem. He created a new earth from the speedo sensor. He also replaced the connector that connects to the wiring to the speedo head as this was badly corroded, but did not solve the problem on mine.

I would also like to add that mine was intermittant and seemed to come and go when the car was lifted up,and down, making it appear to have been fixed on one occasion until i drove away.... and it stopped..

I also did a bit of investigation on mine and a little clue that it was somewhere in the wiring and not the speedo itself (after john substituted a new sensor) was that the sensor sends a signal to the control box for the doors preventing the doors from being opened at speed. My doors could be opened when i had the speedo problem, but cannot now. Also something i checked was the multiplug behind the helmet holder as the speedo wiring passes through the big 36 way one on it way to the speedo head, didnt solve for me but worth a squirt of wd40 if you are careful.

The wiring diagrams from the tvr site may be useful..

Good luck

Mike

[gerradiuk]

Thanks for that Mike, will have a look at that plug over the weekend & take the sensor off to see if its been rubbing.