Pfc. Parts

I thought I'd share my method for dealing with front brake sensor replacement on the '85 928 (in pictures). I didn't take a lot of pictures but I think you'll get the idea.

On '86 and later models Porsche had the wisdom to use cabling similar to the pre-'86 rear sensors; specifically, they put a junction in the wheel well so it wouldn't be necessary to remove the engine in order to replace the front brake sensors (just a joke. Sort of).

On the '85 the sensor coupling is inside the engine bay, meaning you have to figure out how to thread the new cable through a bulkhead then find the junction somewhere near the smog pump (passenger's side) or under the master cylinder (driver's side). It's ugly as far as I can tell. I took one look at it and decided there had to be a better way. At this point I was unaware Porsche had fixed the problem in later models. I'm sure this is one reason most '85 and earlier owners have abandoned the factory brake wear sensors in favor of cutting them off and duct taping the wire to the bulkhead.

I'll describe my approach and follow with pictures. I haven't mastered the art of interleaving text with pictures using the Rennlist interface. Please bear with me.

What I did was buy two new stock '85 front wear sensors, cut the spade lugs off after determining the length necessary to put a solid junction on the brake line support bracket in the wheel well, then cut the existing cable just above that bracket. I then used three successively larger gauges of heat shrink tubing and a matched pair of male and female insulated spade/lug connectors to form a junction.

First I slid the three shrink wrap sections, about 4" each, in successively larger sizes from 1/4", 3/8" and 5/8". Then I crimped 18-22 gauge female quick disconnects to the existing cable (after stripping a little insulation from them of course) and shrunk the 1/4" tubing over the existing cable, butting up against the base of the connectors. Then slid the 3/8" over the base of the connectors and shrunk it, leaving the 5/8" tubing alone for now.

I repeated this process using male connectors on the replacement connector cable, which had been cut to the required length. If you're careful you can shrink the 3/8" tubing in a way that lays the connectors flat together and makes the whole thing much easier to connect and disconnect. Be careful with this, it's important (see photo #1).

Once the connectors where shrunk on both cables I filled them with silicone grease (any grease would probably be fine, I used the grease you buy at electronics stores). Then I slid the final layer of 5/8" tube over both sides of the connection and shrunk it.

Finally, I used a cable tie to secure the connection to the brake line bracket, placing the connectors above the bracket to isolate them from stress caused by turning the wheels. Special points go to people who notice the finished cable in photo #2 has the connection *below* the brake line bracket; yes you're right! I took it apart and did it again but I didn't take a picture.

What I got looks to be a reasonably weather tight connection. I think it's probably much easier than using the factory part on any 928s built before '86.

NOTE: I placed the female connectors on the existing cable (pointing down) and male on the replacement cable because the insulating shrouds on the connectors are better oriented to resist water intrusion I think. Just an opinion.

OTR18WHEELER

I have a pair of sensors waiting to be installed when I do the front brakes, I will keep this in consideration, although I'm no purist, the zip ties should be black.

The Forgotten On

A true purist knows they are the almost clear opaque ones

Sorry, couldn't resist.

hinchcliffe

Or you could save the time/money and just tie the ends together and check your pads often. Of course I'm a track rat so I'm changing brakes all the time......

dr bob

For those playing along at home, every set of pads I've seen has needed some dressing with a small file to open up the little cutouts for the sensors. The metal backing plates for the pads are stanped and the cutout isn't dressed well. Then it's painted for corrosion protection. The cutout needs the paint cleaned out, and the little flashings cleaned off before the sensors go in. This little bit of detailing allows you to later remove the used but working sensors intact, and goes a long way towards getting either new or used sensors safely installed in the pads without breaking them.

I helped a guest replace pads on his car here one time, and he/we managed to trash a couple new sensor sets before I realized how poorly the pad backing plate was finished. Since then, every set of pads gets a few minutes of attention with the jeweler's files so the sensors fit correctly.

Pfc. Parts

You might also want to look at the '86 & later part and see if there's a "more compatible" way to retrofit the part to older cars. I'd already bought all the connectors and stuff to make a homebrew version so I never really looked at the newer part.

Pfc. Parts

I agree, and I went with this idea myself for years while the car was just driven on the street (which is why I know about the duct tape approach), but I took fresh pads to the track last November and wore them to metal in two days so I decided to put the sensors back in. I should have checked them each day but didn't. I had no idea how fast a track can eat brake pads.