Hi all,

I poseted this on a more generic forum, and they suggested I ask here, so here I am. I haven't yet had a chance to try their suggestions (was well after nightfall when I read their replies), but I'll incorperate them into my query to get your opinoin on the matter too.

Basically, the old speedo gear in my auto lost a couple of teeth somewhere along the way, and in the last week completely stopped spinning. I lost my speedo entirely, and the transmission locked itself in limp mode because it figured it was an electrical fault.

After finding the gear damage (I figured it was the sensor), I bought a replacement from my local dealer, fit it to the replacement speedo sensor I'd removed from a spare BW35 (prepared this sensor before I found the gear damage, and it moved more freely than the one I removed so I figured I'd install it) and everything seemed peachy.

Next morning, however, and every morning since, as well as the evenings on my way home from work (ie when the engine is cold) the speedo will waver - it almost never reaches the actual speed I'm travelling, but quite often drops back to zero for small periods. It's almost like a worn speedo cable, save for the fact it's electronic. After the car has had a chance to warm up, however (around 10 minutes of highway driving), the speedo will return to normal operation (sometimes I have to encourage it by restarting the engine) and will stay that way so long as I don't leave the car sit for extended periods.

One theory suggested has been that there is a poor connection somewhere, but would this be along the cable or perhaps inside the sensor itself? Also I was wondering if maybe the transmission needs to be "re-taught" and this time lapse is giving it a chance to take on some failsafe settings that are pretty close to what they should be. The fact that it comes good suggests the sensor itself is not 100% faulty, and if I can help it I'd rather not have to get under the car and switch it out again.

As a worse case scenario I still have the original sensor, as well as access to a complete BW40 inside a nearly complete '86 LTD, so if it sounds like the sensor is actually faulty I do have some options.

Thanks in advance for your help.

Cheers,
Jon.

1 question why a BMW sensor?? are they the same? if so mm sounds dodge i would replace with a FORD unit or aftermarket spare,

aslo the DRIVE gear inside the gearbox sounds liek it has beenn stripped and needs replacing
the gearbox extensionhousing will need to come off, so remove drivesahaft and the tne housing 4 bolts so it pretty easy

I would guess that the gear is not locked to the replacement sensors shaft correctly or the sensor is faulty (probably the latter) The original gear could have been stripped if the sensor bearings are siezed or in the process of siezing. I think a replacement sensor would be best.
Cheers
TW.

You didn't possibly push the sensor too far into the housing?

There is a metal 'elbow' on there to hold the sensor a certain distance out of the housing. But I have seen instances where the mounting bolt was tightened too much and the arm had bent, allowing the sensor to slip a little more into the housing.

It would just touch the gear and slip off, giving that wavering look and sometimes the speedo dropping to zero...

The gearbox I scavenged the replacement from was a Borg Warner - more specifically a BW35 originally from an '85 XF Sedan - so the sensor is a much a Ford part as I'm going to be able to get.

I did pull up the bolt holding the sensor in fairly tight - tight enough so it didn't feel like it was going to come loose, but not too tight as it was tedious to put any decent pressure on the spanner where it was. I will, however, remove the sensor and check to see if the bracket has been bent in the process. I'll hunt around for a replacement sensor as well, just in case this is also causing a problem.

Thanks for your input on the situation. Earliest I'll be able to try anything is Sunday (damned work!), but I'll keep you informed as to how it goes. If anything else comes to mind, please don't hesitate to let me know.

Cheers,
Jon.

[quote="Disco Frank"]1 question why a BMW sensor??

LOL... someones trippin

yer just re read it BW..... F**k prescription drugs...