S1 - Intermittent Speedo

[AdrianR]

1998 Elise S1 - the Stack speedo has started jumping all over the place, going off for a few seconds then springing back to life again. Rev counter unaffected so I suspect either wheel sensor or wiring.

Q - Is there any way to test the sensor apart from replacing it and seeing if the problem goes away?

Thanks.

[AdrianR]

Scuffers said:

it's the sensor, or more to the point, it's spacing to the CV's trigger ring.
it needs to be ~1mm max away, BUT!

this could also be a sign of the wheel bearing wearing out, this le allows the CV joint to move a little in and out of range of the wheel speed sensor.

Thanks - actually that would be OK, as wheel bearing replacement is due anyway (at least one is noisy) plus ball joints and toe links. The car has been minimally maintained for the past few years so need to catch up on the backlog. Now jacked up with undertray off to see what else needs doing.

[AdrianR]

Hub now off. Feels smooth but some grease reside around the seal so will change it anyway. Sensor doesn't want to come out of its mount.

What wears out first? I did quite a few track days when I first got the car and it held up pretty well (normal tyres, no slicks) but I guess worth looking at some bushes and the toe link ends?

Might even get wishbones refinished, as they are starting to rust on the surface. Do people paint these, or get them replated?

• Edit - pressed send and then saw the other suspension refresh thread! **

Ta,
Adrian

Edited by AdrianR on Tuesday 24th March 18:56

[AdrianR]

I couldn't feel any play but there was a definite speed related drone coming from the rear.

OTOH, checking service notes that bearing (NSR) was changed quite a lot of years but not too many miles ago so maybe is sensor after all. Haven't looked at OSR rear properly yet.

Adrian

[AdrianR]

Speedo problem found - broken wire where it pivots round the wishbone.

[AdrianR]

Speedometer needle intermittently flicking back to zero while driving, gradually getting worse until it was dancing about continually. Rev counter and dash otherwise fine.

Makes sense, the wire break was in a tight bend around the inner top wishbone pivot so everytime you go over a bump it would flex. Easy check on the S1 at least without dismantling anything much, just take the wheel off, snip vable ties, ease the wire from the "protective" conduit' and look for nicks in the insulation. Mine fell apart as I did this.

Now tackling the drivers side...someone convince me it isn't a left hand thread on the hub nut - I broke a 3/4 to 1/2 adaptor last night trying to undo it.

AdrianR