sensor removal

Taz's Master · 01-12-2004, 03:50 AM

I'm trying to remove my speed and referance sensors. The first was stiff, but came out. The second is more difficult. I've used PB Blaster, but the only way I can twist it is by using a 7/8 combination wrench, I can't budge it with my hand. Am I missing anything, or is there a technique someone has used that would help?

VINMAN · 01-12-2004, 04:01 AM

They can be a ***** to get out , they get some corrosion in there. If you can, take off the bracket they are mounted in. I ended up breaking one trying to twist it out.

Taz's Master · 01-13-2004, 03:25 AM

I am a little concerned about getting the proper clearance if I remove the bracket. Is setting the bracket up properly as straightforward as simply gluing the .8mm washer to the sensor and tightening everything, then removing the washer?

Dark Skies · 04:13 AM

Quote:

Originally posted by Taz's Master
I am a little concerned about getting the proper clearance if I remove the bracket. Is setting the bracket up properly as straightforward as simply gluing the .8mm washer to the sensor and tightening everything, then removing the washer?

It's supposed to be but ... when I did this I forgot to take into account the raised section in the middle of the bottom of the sensor - a dimple hammered out by the magnet inside. Consequently the outer area of the sensor was correctly gapped but not the middle that protruded through the hole in the middle of the washer. Subsequently I trashed a new sensor on the flywheel. It made me very angry.

If your sensor is flat it's okay to do the washer trick.

If not - work out how much the area in the middle is raised by and add it to the .8mm washer to compensate. Ie. If the dimple is .1mm then add a .9mm washer to allow for this.

If you are replacing the sensor anyway you might want to use the old one to make up a tool for spot on fuss-free gapping.

Here's the link:

DIY speed sensor adjustment tool

Taz's Master · 01-13-2004, 06:23 AM

Thanks for your responses Vinman and Dark Skies. Dark Skies I'd done a search and read your link, but this is for a clutch job and hopefully a replacement sensor isn't necessary. One question: It is cold here, down in the teens, and less (I suppose this may be why the sensor is so tight, the contraction of the aluminum may be greater than that of the plastic of the sensor, making the hole tighter), will my clearance be adequate when my engine reaches opperating temp?

Dark Skies · 01-13-2004, 06:34 AM

Quote:

Originally posted by Taz's Master
It is cold here, down in the teens, and less (I suppose this may be why the sensor is so tight, the contraction of the aluminum may be greater than that of the plastic of the sensor, making the hole tighter), will my clearance be adequate when my engine reaches opperating temp?

The short answer is I don't know.

The long answer is I really don't know but suspect it is more to do with corrosion of the alloy bracket. The powdery white oxide is probably causing the tightness.

As for the clearance ... .8mm is the only figure given in the Porsche manual so I'm sure you'll be fine with that anywhere in the world outside of the frozen tundras of Siberia - where your metal would shatter anyhow.

VINMAN · 01-13-2004, 10:07 AM

I agree with Dark Skies, its the corrosion, not the temp, thats holding the sensor in. when you finally get it out, you will see how much gets in there. I've seen them where they had to be knocked out with a hammer. When you put them back in, use a light coat of NO-OX or Never Seize on the inside of the bracket.

Taz's Master · 01-24-2004, 10:23 AM

My bracket is held on with bolts other than typical 6-point bolt heads, I'm assuming allen bolts. This little aspect of the car's construction is not endearing the vehicle to me. Any clue as to the size of the allen bolt, and any hints as to how best to remove them so that I can get the sensor out? I am very frustrated now, as I cannot see how I will be able to reach the bolts with either the proper allen head socket, or one of the L-shaped keys.

Dark Skies · 01-24-2004, 02:13 PM

Quote:

Originally posted by Taz's Master
My bracket is held on with bolts other than typical 6-point bolt heads, I'm assuming allen bolts. This little aspect of the car's construction is not endearing the vehicle to me. Any clue as to the size of the allen bolt, and any hints as to how best to remove them so that I can get the sensor out? I am very frustrated now, as I cannot see how I will be able to reach the bolts with either the proper allen head socket, or one of the L-shaped keys.

If memory serves the cap head screws require an M5 allen key.

What you need is a quarter inch drive socket set - preferably with one of those woven wire flexi-drive extensions (so you can reach in amongst all those obstructions) plus a range of allen key sockets. Not expensive and it'll prove very useful around the car.

Taz's Master · 01-25-2004, 04:40 AM

Dark Skies, I realise that this thread isn't as much fun as the hp debates, but you have my sincere gratitude for continuing to provide advice. You too Vinman, the last couple of weeks it was tough to work on the car. Single digits outside temps and I had internal temps over 100, but now I get to go back at it.

speedracing944 · speedracing944's Garage

I had the same problem with my clutch replacement. The sensors were the biggest pita. I spent 1 full week trying to get them out. I sprayed penetrating oil on them and then wiggled them back and forth while pulling up on them. When they would slide up a little I would spray them again and push them back down. I would then continuue the process. Everytime I wiggled them they would get closer to comming out so I kept at it. At one point I was so frusterated I called the dealership asking "what the ***k". Paitence is the key to succsessful removal without damage. good luck to you and may the force be with you.

Dark Skies · 01-25-2004, 06:45 AM

Quote:

Originally posted by Taz's Master
Dark Skies, I realise that this thread isn't as much fun as the hp debates, but you have my sincere gratitude for continuing to provide advice. You too Vinman, the last couple of weeks it was tough to work on the car. Single digits outside temps and I had internal temps over 100, but now I get to go back at it.

You're more than welcome. Plenty of folk here have helped me out in the past and all I'm doing is, hopefully, putting something back by way of return.

Having re-read your post and my response I realized that my advice was slightly out in that I was referring to the M6 cap heads holding the sensors in their place. I nipped out to check on my own car, as I suspected that the bracket retaining screws were probably M8s. Sure enough they are so you'll be needing an M6 allen key fitting with a 1/4 drive socket to deal with these.

1/4 sockets sets are pretty reasonably priced so it's well worth getting the most comprehensive set you can afford as they're invaluable for dealing with the really tight spots. The more so because of the range of other 1/4 inch based extension tools that are compatible with this size drive. I regularly find the fittings of extendable wratchet screw-driver kits will work with my socket kit.

Taz's Master · 01-26-2004, 01:01 PM

OK, the bracket bolts are out (M6 by the way), the sensor is still in the bracket. I cannot move the bracket away far enough from the bellhousing to clear the pivot tit. I can pry on it with a screwdriver (but I'm afraid to apply more pressure), and the bracket is free and loose, but I can't clear the tit (I'm assuming that the sensor is preventing the necessary front to back movement). Any suggestions?

Taz's Master · 09:23 PM

I have removed 2 bolts, and the rear sensor is still in the bracket. It is very loose and I can move it 1/8"+ from the bellhousing, but I cannot get it all the way off of the pivot, although the other end moves far enough away to be able to clear that distance. It feels hung up on the end closest to the fender (as opposed to the center of the car). Is there anything that I need to do that I've overlooked? The pivot and locking bolts are completely out, but the bracket won't come off the pivot tit, and I've pried pretty hard (to the point where I'm messing up the metal on the bracket and the bellhousing). Is there something else that needs to be removed to free up the bracket?

Dark Skies · 02:58 AM

As I recall the bracket has an enlarged hole (about 10mm) which fits over a metal dowelling. The other hole in the bracket is slotted to allow for adjustment. When I removed mine the flywheel sensor had been destroyed (it had clouted the teeth and subsequently been disembowelled). Obviously this gave me the necessary clearance to remove the bracket with the remains of this sensor still in place - although I've only just realized this since you've pointed out the problem.

If there really isn't any extra clearance to move the bracket then I would suggest loosening the bellhousing bolts a few turns (you're going to do the clutch anyhow so no biggie) to see if you can get some extra movement rearwards.

VINMAN · 01-27-2004, 04:17 AM

Whatever you do dont try to pry the bracket , they break real easy

(trust me I know) . If both bolts are out you should be able to lift it straight up.

robm-951 · 01-27-2004, 04:36 AM

If you are pulling the sensors for a clutch job, the bracket & the remaining sensor will come away from the pivot dowel in the block when you pull the bellhousing away. Does that make sense? In other words, the sensor and bracket are now free to move with the bellhousing.

Also for resetting the sensor gap, I did something a little different than the washer setup on the clutch job I just did. Once I had the flywheel mounted, I slipped a sensor back into the bracket with the bellhousing still off. Then while under the car, I could use a feeler gauge and very easily adjust the sensor gap (the bracket bolts are very accessable from underneath with the bellhousing removed). Once set, I pulled the sensor back out and continued the re-assembly process.

Rob

Taz's Master · 01-27-2004, 01:27 PM

Guys, I really appreciate your help.

Vinman, there is a pivot that the bracket fits over that is the thickness of the bracket, I cannot move the bracket far enough towards the firewall to clear that tit or whatever its correct term is.

By the way, the design of the bracket is total BS. The sensors are not sold as a matched pair, so they are obviously built to a tolerance so that if the bracket is set for one they are both properly clearanced. So, the bracket could be built to the proper height to clearance the sensors, rather than be made adjustable, then it could bolt straight down to the bellhousing and lift straight up. I am convinced that the design was to make positioning the sensors a daunting challenge for the backyard mechanic, and take more time (and thus create a higher charge) for the factory service department.

Dark Skies · 01-27-2004, 04:35 PM

Quote:

Originally posted by Taz's Master
I am convinced that the design was to make positioning the sensors a daunting challenge for the backyard mechanic, and take more time (and thus create a higher charge) for the factory service department.

Scout around the board and scrap yards - I'm sure you'll find a faulty sensor you can make a setting tool from. After that it is the easiest thing in the world to set. Trust me - I'm a lawyer.

VINMAN · 01-28-2004, 04:05 AM

Quote:

Originally posted by Taz's Master
Guys, I really appreciate your help.

Vinman, there is a pivot that the bracket fits over that is the thickness of the bracket, I cannot move the bracket far enough towards the firewall to clear that tit or whatever its correct term is.

Did you try to tilt the back of the motor down a bit?, thats what i had to do. It should give you enough clearance then.