W220 S350 2003 - Front Wheel Bearings replacement, BAS, ESP Pre-safe msgs.
08-18-2018, 11:46 AM
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W220 S350 2003 - Front Wheel Bearings replacement, BAS, ESP Pre-safe msgs.
FRONT WHEELS BEARINGS
SKF 32008 - Inner
SKF LM 12710 - Outer
Lessons learnt on replacing front wheel bearings. I made two big mistakes;
No 1. BIG MISTAKE
I replaced both front wheel bearings at the same time.
No 2. BIG MISTAKE
I did not ‘mic’ the thickness of the stamped metal thickness of the ABS ring, new versus old / current.
Replacing both front wheel bearings at the same time - which in hindsight - is something I should not have done.
Test driving after replacing both bearings, the speedo needle was bouncing between 20 and 60 km/h down my short driveway. Additionally, I was getting BAS, ESP plus Pre-safe ‘Visit workshop’ error messages.
I realised these errors were the result of the bearing change, but at the time, I did not realise what I had done wrong. (Always good to sleep on any problem…..!)
It turned out the ABS ring - which is molded as part of the dust seal - I had assumed to ‘drift'’ flush with the flange of the housing, which resulted in an incorrect air-gap between the ABS ring and ABS sensor.
Since there is no direct access to measure, adjust the air-gap between the ABS sensor and ABS ring (the ABS ring is housed in a metal debris shroud), I just *assumed* the gap would be correct. Gap = 0.5 ~ 1.0 mm.
Removing the brake rotor, I was able - with a light-weight ball peen hammer and thin screwdriver - to gently tap the 'in position' ABS ring ‘backwards’ towards the ABS sensor, thus reducing the air gap.
***Tap EXTEMELY gently as the ABS ring requires minute adjustment!
The way I “guess-timated” the gap, was to slightly loosen the ABS sensor pickup bolt, allowing the ABS sensor to ever so slightly, 'tilt’ forward in its housing, 1.0~2.0 mm deeper into its housing.
Gently pressing down on the ABS sensor, I tapped the ABS ring till it lightly dressed the ABS sensor pickup face. On tightening the ABS sensor bolt, the ABS sensor withdraws again to normal portion, clearing the ABS ring, giving the “guess-timated" air gap.
If you find you have tapped the ABS ring in too far, insert a ±10 mm bolt - or something similar - down the ABS sensor hole and tap the ABS ring ‘back’ into its housing.
FRONT LEFT WHEEL
After “adjusting” the ABS air-gap, I did a test drive = the speedo needle was back to normal!
FRONT RIGHT WHEEL.
After “adjusting” the ABS air-gap, I did another test drive = the ESP, BAS and Pre-safe “Visit workshop” warning messages all cleared!!!!!
It appears as if the Mercedes original part stamped ABS ring may give the correct “spot on” air gap. Perhaps MB use thicker material whereas aftermarket, thinner ABS ring material is used?
(This ring thickness I should have mic’d beforehand….)
I can only put this down to “drifting” the new ABS ring / dust seal flush with the flange, which resulted in an incorrect air gap. Incorrect assumption on my part.
Fortunately, my perseverance paid off as I was about to purchase the iCarsoft to reset the ABS, ESP & Pre-safe warnings... which is now not necessary anymore!
SKF 32008 - Inner
SKF LM 12710 - Outer
Lessons learnt on replacing front wheel bearings. I made two big mistakes;
No 1. BIG MISTAKE
I replaced both front wheel bearings at the same time.
No 2. BIG MISTAKE
I did not ‘mic’ the thickness of the stamped metal thickness of the ABS ring, new versus old / current.
Replacing both front wheel bearings at the same time - which in hindsight - is something I should not have done.
Test driving after replacing both bearings, the speedo needle was bouncing between 20 and 60 km/h down my short driveway. Additionally, I was getting BAS, ESP plus Pre-safe ‘Visit workshop’ error messages.
I realised these errors were the result of the bearing change, but at the time, I did not realise what I had done wrong. (Always good to sleep on any problem…..!)
It turned out the ABS ring - which is molded as part of the dust seal - I had assumed to ‘drift'’ flush with the flange of the housing, which resulted in an incorrect air-gap between the ABS ring and ABS sensor.
Since there is no direct access to measure, adjust the air-gap between the ABS sensor and ABS ring (the ABS ring is housed in a metal debris shroud), I just *assumed* the gap would be correct. Gap = 0.5 ~ 1.0 mm.
Removing the brake rotor, I was able - with a light-weight ball peen hammer and thin screwdriver - to gently tap the 'in position' ABS ring ‘backwards’ towards the ABS sensor, thus reducing the air gap.
***Tap EXTEMELY gently as the ABS ring requires minute adjustment!
The way I “guess-timated” the gap, was to slightly loosen the ABS sensor pickup bolt, allowing the ABS sensor to ever so slightly, 'tilt’ forward in its housing, 1.0~2.0 mm deeper into its housing.
Gently pressing down on the ABS sensor, I tapped the ABS ring till it lightly dressed the ABS sensor pickup face. On tightening the ABS sensor bolt, the ABS sensor withdraws again to normal portion, clearing the ABS ring, giving the “guess-timated" air gap.
If you find you have tapped the ABS ring in too far, insert a ±10 mm bolt - or something similar - down the ABS sensor hole and tap the ABS ring ‘back’ into its housing.
FRONT LEFT WHEEL
After “adjusting” the ABS air-gap, I did a test drive = the speedo needle was back to normal!
FRONT RIGHT WHEEL.
After “adjusting” the ABS air-gap, I did another test drive = the ESP, BAS and Pre-safe “Visit workshop” warning messages all cleared!!!!!
It appears as if the Mercedes original part stamped ABS ring may give the correct “spot on” air gap. Perhaps MB use thicker material whereas aftermarket, thinner ABS ring material is used?
(This ring thickness I should have mic’d beforehand….)
I can only put this down to “drifting” the new ABS ring / dust seal flush with the flange, which resulted in an incorrect air gap. Incorrect assumption on my part.
Fortunately, my perseverance paid off as I was about to purchase the iCarsoft to reset the ABS, ESP & Pre-safe warnings... which is now not necessary anymore!
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biker349 (08-18-2018)
