Urgent help reqd. SVA Monday 1st.

[marcosman]

Help I need some urgent advice.

   Took the car out for the first time yesterday to get it MOT d and bed things in. Used the wifes satnav to check the speedo and up to 30mph it was accurate. However, after that the speedo reading only went up to just below 40mph irrespective of actual speed.

The setup I have is that I am using the sensor on the front lugs of the propshaft because there are no lobro bolts on the rear drive shafts. The setting is between 3-4 mm as per the manual. Phoned Mark at WF and he said to reduce the gap to 2mm and it would be fine.

Have done this today and the situation is no better.

      Has anyone had this problem and found the answer? I am getting desperate now as my SVA is on mon 1st Oct.

  Any suggestions would be welcombe

[scruffythefirst]

Make the gap bigger, you may find it doesn't start working properly untill you get to 20mph+ but as the sva test doesnt start till 35mph it doesnt matter.  I don't know the westfield mounting but check its secure and not vibrating too much.  Also bear in mind that the front of the propshaft will move a little with engine movement, so your gap stationary might not neccersairliy be the same when moving.  You could always try some magnets on the rear cv joint if you have the push in shafts.

[Barnster]

If you absolutely cannot get it to work consistently and still want to do the SVA, you could try disconnecting the sensor and tell them that the speedo pickup reads from the front wheels and so cannot be measured with their rollers.

I had 3 SVA failures because of sensor problems, ended up getting the factory to sort - they used a reed switch sensor and the front hub nuts.

All I did for the final (passed) SVA was create a printout with road speed column and then another column with indicated speed showing +3%. Never even went near the car but that's all they needed to check.

Obviously get it sorted in the long run.

[marcosman]

Thanks guys for the prompt ideas.

Scruffy what dimension would recommend?

Barnster dont they check the front wheels for a sensor?

I shall try a larger setting first and if no good then i will try a printout. will a standard computer printer be ok?

[kipford]

I had exactly the same problem on my SDV. The sensor is getting confused by the iregularity of the hex head bolts. On mine I made a washer with 10 mm long x 2 mm wide tang. Put this behind one of the propshaft bolts then bent the tang through 90 degrees so it runs axially a couple of mm clear of the bolt head. You then set the sensor to the correct gap over the tang, the sensor is now reading only the tang. You then do you calibrating setting with 1 PULSE per rev instead of 4. This solved all my problems. By the way it was Mark at the factory who suggested it.

[busapower2001]

I did the same as Kipford. Take a large plain washer and cut out (I used a dremel) two almost semi circle sized segments to leave a trapezoidal tang (2mm sounds good, I didn't bother bending it through 90degs as Kipford did).  Make sure you don't remove too much material that you overly weaken the structural integrity of the washer. Place the washer under one of the propshaft bolts such that that tang sticks out radially. Make sure your sensor to tang tip gap is as per the larger Westfield gap setting and then if need be slowly move the sensor inwards before rechecking how the spedo performs - else your lunch the sensor and be goosed for the Monday!

Assuming you fail at SVA because your out by a few mph then ring Mark and he should be able to work out a new pulse code for you to enter such that it will place you within the limits. That's what I did when mine was fractionally out. You don't want to be testing the testers patience with 10 attempts at new pulse codes :-)

[marcosman]

To  megabusa and kipford- Thanks very for your answers to my problem.

Im off tommorrow so I can rig up the sensor .the way you explained. Will let you know the results.

Thanks again , you have raised my hopes from desperation to optomistic!!