new abs sensor problem after fitting by pip (Page 1 of 2)



pip
Hello this afternoon I was fitting a new sensor to the front nearside but the old one snapped off so I had to drill it out right at the last bit I had to tap it out as the drill had left a little bit of plastic off the old sensor on the side but I think a bit fell into the bottom of the sensor hole ? anyway I fitted the new sensor went for a drive and the abs fault has gone but when I brake hard it has a grating feeling through the brake .any help much appreciated

Posted 02 Aug 2016, 18:05 #1 

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Duncan
You may have damaged the magnet ring on the bearing. Either that or the debris is meaning the sensor isn't close enough to the ring.
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Posted 02 Aug 2016, 19:04 #2 


pip
Can I get to the debris ? I`m new to diy on the r75 but a quick learner and worked on other cars a bit

Posted 02 Aug 2016, 19:13 #3 

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Duncan
I'm not sure, it's not a problem I've had I just know of people who had the same problem. Often the cure is a new wheel bearing.
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Posted 02 Aug 2016, 19:15 #4 


pip
thanks anyway I`ll have a look tomorrow see if I can get to it.

Posted 02 Aug 2016, 19:17 #5 

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sewerman
If the abs lights off all the time now its probably not the magnetic ring which is part of ghe bearing. When you say grating feeling is it a pulsing or Costa grating? Pulsing under hard breaking is probably the abs doing its job. If it's great in check the pads haven't picked up a bit of the plastic.
Royal Blue Rover 75 CDT Tourer

Posted 02 Aug 2016, 21:02 #6 


pip
Hi sewerman its a real grating actually started juddering a bit when I picked my son up last night so I`ve sent for a replacement hub instead of trying to get the bearing out and a new one back in ,

Posted 03 Aug 2016, 16:18 #7 

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takestock
Sometimes you can sort this by reducing the gap from the sensor to the bearing. try filing the underside of the sensor bracket ( not too much) which will allow the sensor to sit slightly lower in the hole
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Dave....

Posted 04 Aug 2016, 17:49 #8 


pip
Hi I took the sensor out thinking to save it getting stuck in then had to nip out and the grating has gone so its the sensor , I`ll try your idea Dave

Posted 11 Aug 2016, 16:23 #9 

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sewerman
Surely rhis will make it worse bu moving the sensor head further towards the bearing? I'd try the opposite ie packing the sensors out a bit first.
Royal Blue Rover 75 CDT Tourer

Posted 11 Aug 2016, 16:31 #10 


pip
I have been thinking along them lines today as I haven`t had chance to get at it so I`ve got a couple of small washers for the bolt which holds it in I`m going to try that first I think ? if I can make time tomorrow that is ?

Posted 12 Aug 2016, 19:48 #11 

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sewerman
Would also try it without just in case whatever it was has cleared it self, was their signs of were on the sensor were it was catching. I would try that first try also only try 1 washer first as the sensor end needs to be close to the hub ring.
Royal Blue Rover 75 CDT Tourer

Posted 12 Aug 2016, 20:59 #12 


pip
Hi I`ve tried it with just the sensor as it came = like a grating noise but only on the last bit of heavy braking, tried it with 1 small washer = same as then 2 small washers= same as then 3 small washers = same as , then filed the sensor like Dave said = just the same under the last bit of heavy braking a juddery grating feeling , I`m lost now it looks like taking it to my local mechanic I just hate being beat .

Posted 17 Aug 2016, 19:08 #13 

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takestock
It is a known fault that the magnetic ring in the wheel bearing can be damaged when having to drill the old one out. It is also a known fault that if the sensor is replaced and does not seat close enough to the bearing then it cannot correctly "read" the magnetic ring. Hence the need to move the sensor closer. The grating you experience I would assume is the ABS (Antilock Braking System) kicking in as the sensor fails to pick up a signal and assumes the wheel has locked up? Think about it. ;)
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Dave....

Posted 17 Aug 2016, 19:36 #14 

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Arctic
(Trader)
I had the same trouble on my MGZT pulsing of the brakes at very low speed, just as I was going to stop and slowing down for junctions etc, ideally you need to get the car on a T4 (Testbook version 4.Computer Diagnostic System) and it will tell you if it is the sensor or the bearing with the built magnetic ring.

Mine turned out to be the OS rear bearing.

Posted 18 Aug 2016, 08:56 #15 

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Bermudan 75
My car has this problem on occasions, does a normal system check on the T4 pick this up or is it a specific diagnostic check?

Mike
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Posted 18 Aug 2016, 13:42 #16 

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squire
I'm interested too, as I have similar problems, mine clears start up check, light goes out, but ABS kicks in at low speeds, after about 2-10 miles, sometimes even further ABS fault flags up, also occasionally brake fault flags up! Switch off engine and everything resets. Problem is thought to be offside rear but bearing been changed twice along with sensor.
Martyn

Posted 18 Aug 2016, 18:08 #17 


pip
Im at a bit of a loss now I had tried everything said to me on here but no joy so I took it to my local mechanic I gave them another front hub I had with no damage to the magnetic ring , when I went back they had changed the hub saying I had damaged the magnet on the original one but when they tested the car it is doing exactly the same ? they have told me they ran a diagnostic and it came up with the drivers side needs a new sensor ? I brought the car home as he is going away for the weekend, this morning I put my laptop with TOAF downloaded on to it and all the abs sensors showed no errors but I think it is worse now than it was ? fed up aint the word, forgot to add theres no warning light on the dash

Posted 20 Aug 2016, 18:15 #18 


pip
Sorry its been a while I have been so busy so I thought I`d update it , I had a new sensor fitted to the drivers side front but it was just the same so I took it to big russ and t4`d it which it was showing front drivers side so I had another hub put on that side as well as the one I`d had put on the passenger side both with new sensors outcome = just the same juddering under braking then I remembered something Arctic had said on his reply so I got a new rear hub and fitted it myself to the offside after cleaning up a rather rusty backplate Finally its cured I was nearly at my wits end and going to trade the car in but as I said previously I hate being beaten so I just kept going but it just goes to show a T4 session doesn`t always show the problem ?

Posted 01 Nov 2016, 14:57 #19 

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Colvert
That must be a relief. Anyhow, all's well that ends well.

Posted 01 Nov 2016, 17:47 #20 


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