Advanced 12 bolt and ABS question

Terms: I just installed a strange 12 bolt, with 4.33 gears. It also has the abs sensor on top of the housing. Car was reprogramed for gear change and correct tire (275/40/17)

Problem: The car brakes normally until under 10 mph. At this time, the abs kicks on on most stops, but not all. Anything above 10 or about there, the car breaks completely perfectly, no ABS comming on, unless you actually lock up the tires, in which case the abs works properly. No ABS codes/lights are thrown, yet the low traction light comes on when the abs comes on as it should

What I have been told: I was told that the abs sensor screws into the top of the housing and gets its reading from a reluctor ring. This sensor should be screwed all the way down, then backed out one full turn so that it doesnt get destroyed by the ring. Possbily it is not screwed in far enough, or slightly too far?

This is another possibility. The 12 bolt was originally on a 99 LS1 Z28. I put in the rear end, yet found that i was missing a spacer of some sort. On the axles, there were the splines, then moving towards the tire, the bearing, then the caliper bracket, then the ending part of the axle (circular).

In order to keep the bushing being crushed, when you bolt the axle tube to the caliper bracket, there should be an aluminum spacer. This spacer was used on my friends new rear however (this was his old rear). Instead, we used 8 washers (4 sets of 2, for a total of less than 1/4 inch depth) to space the bracket away from the bushing, and give the bolts something to push against. Could this some how missaligned the rotor within the caliper, so that when braking both sides of the caliper dont hit the rotor evenly or something to that effect? I would think that since we spaced the bracket out from the axle tube, the rotor should be spaced out that same distance because it, in turn, bolts on through the bracket?

I am just searching for possible answers to the abs problem. As soon as the weather warms up a tad i will re-adjust the depth of the sensor on the top of the housing, but what else could be causing this?

Thank you for taking the time to read, and help,
Jared

Good luck on the Strange ABS sensor.... when I first put mine in, I adjusted the sensor for a specific clearance... I think it was a value recommended by Strange, and I got results similar to yours.... just an instant before the car came to a stop, maybe 5mph, the ABS pulsed once, causing the car to travel about 5-10 feet more than anticipated. I adjusted the sensor a little closer, checking to make sure it wasn't actually contacting the reluctor, and the ABS stopped functioning altogether.....

I just gave up on it, and plan to remove the ABS completely, since I really don't drive the car on the street much any more. I think the Strange ABS option is a huge waste of $300.......

Thanks Fred for the reply.

Tonight i took out the sensor and noticed it had some metal shavings on it. The gears in the rear have only ~100 miles on them so that isnt suprising to me.

Anyways, the sensor must read the reluctor ring magnetically, b/c the sensor is a magnet and attracted the shavings. I cleaned the sensor very well, cleaned the o-ring and the tightening jam-nut. Then installed the ABS sensor unitl it hit the gear, backed it off one full rotation, and tightened the nut.

Since then the ABS has been working correctly, and has not come on at anytime when it shouldnt have. I dont know if it was the shavings, or the incorrect install height, but either way its working! thanks again.

Jared

Good info.... I never checked the sensor after it stopped working. The gears were changed after that, and I'm sure the guy that did them would have noticed any damage to the sensor. I guess I need to pull it out and look for the metal shavings. I have heard the Strange sensors do not have a long life - my Electromotive crank trigger had a similar magnetic pickup, and they recommended replacing it every two years.

I always figured the sensor was a little too far from the reluctor, and as the velocity of the reluctor neared "0" the signal was lost and the ABS unit assumed the rear brakes had locked up. I actually got a depth gauge in there, and measured the depth to the reluctor "tops", then figured the distance the sensor moved in the threads per rotation and set the sensor clearance that way. With the sensor at the recommended depth, it is almost completely out of the threads for the lock nut, like it is a little too short. I guess I should have just pulled the cover off and set it with a feeler gauge.... :rolleyes:.

My thinking now is that I might just sell the entire "ABS" posi unit, and switch to a spool. Then remove the ABS completely. I think I can count on one hand the number of times the ABS actually activated for a reason, and that was typically having one wheel in gravel or having a wheel lift off the pavement after a hard bump.