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Rear Speed Sensor Removal

stuttgartmetal

Well-known member
Joined
23 Feb 2009
Messages
2,519
Well after soaking the Allen bolt for two day I put an long Allen key on it, and it unscrewed !

But the sensor is in there solid.

How do you get the sensor put ?
 

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This is a really difficult job. Although the sensor body is plastic the aluminium will have oxidised and swollen jamming it in. Try some pipe grips on the metal collar (not much room) heat and pentrating oil. See if it will twist a bit.
I ended up drilling most of it out. A small drill into the copper wiring around the magnetic core. Once the core is out with yards of fine copper wire penetrate the end of the sensor with a large wood screw and use that to pull out the rest. Drilling with a Dremmel will help due to it's small body size.
I bought a special reamer to clean out the hole afterwards they are made just for that purpose. A set from Machine Mart is not too expensive in fact cheaper than an individual one on ebay. Clean out the threads in the retaining bolt hole as well and fit with Molykote or similar do not use copper anti-seize.
There is a write up on Rennlist perhaps 944 forum.
Be careful not to drill too far into the sensor housing and damage the sensor wheel, refer to the new sensor.
If all fails then you have to remove the hub and hammer it out from inside.
Slow and steady, being a Dentist I have access to some lovely little picks and chisels which helped. They did not go back to the surgery I hasten to add.
https://rennlist.com/forums/996-forum/585004-replacing-wheel-speed-sensor.html
 
And onwards we go.......
 

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The magnetic core is very brittle and may snap so work around it removing the copper wire then you're just left with the plastic outer which you can carefully collapse with fine chisels or a dremmel cutter avoiding the aluminium. I use a rose head bur in the dremmel to score the inner surface and then a tiny chisel to fold it in. Once free the wood screw should pull it out. The housing will need a good clean out with the reamer if you can get one otherwise the new sensor will not go in easily to the full depth.
 
Straight to Machine Mart for a Draper punch and chisel set.
£9
I bought a Chinese Dremel copy for £25 off eBay last year.
That came in useful. Toptip: if you do buy a copy Dremel, buy the genuine Dremel accessories.

This is where I am now.
I've ordered a new sensor from Matt at Type911 in Beckenham.
 

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Congratulations on a job well done that many would baulk at. I recently acquired 4 Dremmels with all the attachments invaluable stuff. I even used one on my own tooth at Daytona after a traumatic experience with some beef jerky not something I would recommend.
 
Endoman said:
Congratulations on a job well done that many would baulk at. I recently acquired 4 Dremmels with all the attachments invaluable stuff. I even used one on my own tooth at Daytona after a traumatic experience with some beef jerky not something I would recommend.

Did I just read that a dentist used a Dremmel on his own tooth?!? :floor:

All those years of kitchen roll / electrical tape knuckle repairs are forgiven :grin: :thumb:

:bandit:
 
One of those jobs that require a bit of focus and patience.
The rears are easier to access, and because the bolts situated east/west there's less chance of it filling with water and corroding.
Having the tools when you do jobs like this is the key.
A multimeter to check resistance diagnoses the sensor's functionality.
Plenty of wd40 on the Allen bolt. A good Allen key set which needs to be seated properly. Take care to really clean the bolt out before torque is applied to it. I snapped the head off the sensor, and drilled it out. The dremel tool with a remote handset. I drilled out the white plastic first, which I did with plenty of light so you can see what you're doing.
A needle punch folded the drilled sensor in on itself.
I got access by removing the caliper, disc and backplate, which I had recently fitted up after a refurb.

I'm hoping this will replacement will extinguish the ABD and ABS light.
Just waiting for a sensor now, before I can conclude the operation.
 

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Funny just done this over the wknd as well ,as my nsr was faulty .
bloody nightmare . Ns bolt snapped and sensor was also seized , had to drill both out .my cars a 95, Make sure you don't have the old type part number sensors as you will have to change both rears to the new senors. There's is a technical Bulitn about floating on the web .the osr was a little bit easier as learnt my lession and used a lot of heat . :thumb:
 
axlefoley said:
Make sure you don't have the old type part number sensors as you will have to change both rears to the new senors. There's is a technical Bulitn about floating on the web:



I'm all ears
Could you expand your comment so I can get my head round it ......
 
Thankfully not applicable as the car is a 96.
But massively interesting.
Thanks for the pdf.
 
Hi, just to add my 2pence on this, on the steel bodied ones I usually snap the top off then use a blowtorch (with the surrounding area tin foiled off) to soften the plastic surrounding the core, then pull that out. Then using a small sharp screwdriver and hammer (or similar), collapse the tube in on itself. Then just pull it out. Drilling is a super PITA because the core is super hard. It's still a crappy job though.

Berni
 
£120 later.

And on.......
 

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This is a tricky job, however Halfords is your friend. For as much as they get slagged off, their professional tools are awesome. Ok, not Snapon but still have a lifetime guarantee and good for non pros.

Order of play

ABD and ABS lights do not extinguish on start up, or flash on when driving.

Check your battery connectors, especially the positive additional connector
Clean the two or three relays found under the bonnet on the left of the spare.
Uncluttered the cover nearest the inner flitch or arch whatever you know it as.

Check your lights don't go out still

Next

Jack up
Axle stands
Front and rear
Find the sensor
Click the block out of the plastic cylinder
Unplug the sensor
Set your multimeter (7.99 eBay) to omega (resistance) and the reading shoul be 1400-1600 ohms. If it's not recording a resistance when measuring across the sensor contacts, the sensor is fubarred. You may have one not working or a number of them.


Soak the bolt holding the sensor in place with Ed 40. I soaked mine hourly for 2 days. Clean the bolt and firmly seat a 5mm Allen key.
Get this bolt out cleanly and your golden.
Muller the bolt and you enter a world of pain.

Cut the lead off the sensor
Break the cover off
With a Dremell (£25chinese copy eBay) still out the plastic carefully so not to damage the aluminium which the very very expensive Porsche suspension is made out of. Using a fine punch, fold the core in on itself

Clean the hole out
Use a new bolt
Refit new sensor


It's 90% sensor problems that trigger the light.
The aluminium oxidises, and crush the sensor.
That's why they're difficult to remove.
The key to removal is getting the retaining bolt out.
 

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