Monaro 'graunch' and 'Low Traction', you know the one

[SturdyHSV]

I was of the mind it might be ABS related, hence the noise, the feel in the brake pedal etc, but why the TCS light? I'm not sure. Although it is just a 'low traction' warning, maybe if the ABS triggers it fires the warning too?

[bigwheel]

SturdyHSV said:

I was of the mind it might be ABS related, hence the noise, the feel in the brake pedal etc, but why the TCS light? I'm not sure. Although it is just a 'low traction' warning, maybe if the ABS triggers it fires the warning too?

[SturdyHSV]

Interestingly, the Yanks think it's shimming required on the rear wheel speed sensors... Don't see how that would have caused me an issue when stationary though

http://www.ls1gto.com/forums/archive/index.php/t-1...

[bigwheel]

SturdyHSV said:

Interestingly, the Yanks think it's shimming required on the rear wheel speed sensors... Don't see how that would have caused me an issue when stationary though

http://www.ls1gto.com/forums/archive/index.php/t-1...

This looks like the solution. Insufficient air gap at the rear ABS sensors. GM Technical Service Bulletin states the rear ABS air gap must be between 1.5mm and 2.0mm. Get yer feeler gauges out.
I was talking to a mechanic acquaintance about this today and he says it's widely known across the car world (he had to shim his BMW
sensors to get rid of Low Traction warnings).

All is explained in the LS1GTO forum thread with a good photo-link of the sensor in position.

I tried my local friendly Vauxhall dealer for GM p/n 90278359 rear ABS sensor shim (it's a generic part among several other models eg. Omega) but is discontinued and no longer in stock, UNLESS, someone can find otherwise
The shim is 0.5mm and pear-shaped with a small hole (bolt) and large hole (sensor).

[paul450]

bigwheel said:

This looks like the solution. Insufficient air gap at the rear ABS sensors. GM Technical Service Bulletin states the rear ABS air gap must be between 1.5mm and 2.0mm. Get yer feeler gauges out.
I was talking to a mechanic acquaintance about this today and he says it's widely known across the car world (he had to shim his BMW
sensors to get rid of Low Traction warnings).

All is explained in the LS1GTO forum thread with a good photo-link of the sensor in position.

I tried my local friendly Vauxhall dealer for GM p/n 90278359 rear ABS sensor shim (it's a generic part among several other models eg. Omega) but is discontinued and no longer in stock, UNLESS, someone can find otherwise
The shim is 0.5mm and pear-shaped with a small hole (bolt) and large hole (sensor).

ron have you tried asking simon (the part from another car fits) expert

[Major Monaro]

Looks like you've found the answer. Good stuff

[bigwheel]

paul450 said:

ron have you tried asking simon (the part from another car fits) expert

Mmmm. No I haven't.

Err, Simon, GM p/n 90278359 might cross ref. with Opel p/n 530804

[L2VXR]

If someone can put some accurate measurements to a sketch I could knock something up in stainless
or confirm they are like this generic sensor

[SturdyHSV]

First Google result...?

http://www.autovaux.co.uk/product/90278359-shim.as...

Continuing on...

http://www.partsbase.org/parts/gen-90278359/

Which leads to:

http://www.partsbase.org/parts/ope-530804/

[bigwheel]

I emailed these people who promptly replied they were unable to supply.
Even though the GM part number was in their PDF list of part numbers.
www.vauxhall-car-parts.co.uk
01562 731442

I suppose what I'm trying to say is just because a p/n is listed by an independant parts supplier, it doesn't mean that they can supply!

Edited by bigwheel on Tuesday 24th November 21:17

[bigwheel]

SturdyHSV said:

First Google result...?

http://www.autovaux.co.uk/product/90278359-shim.as...

Continuing on...

http://www.partsbase.org/parts/gen-90278359/

Which leads to:

http://www.partsbase.org/parts/ope-530804/

Partsbase.org seems to be a cross reference database who don't supply parts.
I'll phone Autovaux to see if they can actually supply.

[bigwheel]

L2VXR said:

If someone can put some accurate measurements to a sketch I could knock something up in stainless
or confirm they are like this generic sensor

The diameters on your drawing of the generic sensor (18mm) and the bolt hole (between 6mm and 7mm) are as measured by the American who improvised with copper washers. Gauge of metal used is about 0.5mm.

http://www.ls2gto.com/forums/attachment.php?attach...

[L2VXR]

bigwheel said:

The diameters on your drawing of the generic sensor (18mm) and the bolt hole (between 6mm and 7mm) are as measured by the American who improvised with copper washers. Gauge of metal used is about 0.5mm.

http://www.ls2gto.com/forums/attachment.php?attach...

I'll see what I can do tomorrow

[bigwheel]

L2VXR said:

I'll see what I can do tomorrow

[L2VXR]

bigwheel said:

pm sent

[Yanayaya]

I've just taken a copy of the workshop message from the LS1GTO forums so it's in this thread:

TCS - Low Traction Indicator ON With No Wheel Slip
Subject:
Low Traction Indicator Illumination with no Wheel Slip (Shim Wheel Speed Sensor)

1. 06-05-25-005 - (12/19/2006)

Models:
2004-2006 Pontiac GTO

Condition

Some customers may comment that the low traction indicator may be illuminated with no wheel slip.

Cause

This condition may be caused by an insufficient air gap between the rear wheel speed sensors and the reluctor.

Correction

Check the air gap measurement between the reluctor and the speed sensors on both rear wheels. Adjust with a shim if required.
1. Check the air gap between the reluctor and the sensor on both of the rear wheel speed sensors. The air gap must be 1.5 mm (0.059 in) to 2.0 mm (0.079 in).

^ If the air gap is within specification and the customer concern is still present, refer to the appropriate diagnostics in SI.

^ If the air gap is less than 1.5 mm (0.059 in), a shim, P/N 90278359, must be used to achieve the correct air gap spacing.

1. Remove the speed sensor. Refer to Rear Wheel Speed Sensor Replacement in SI.

2. Install the shim.

3. Install the speed sensor. Refer to Rear Wheel Speed Sensor Replacement in SI.

2. Verify that the customer concern has been resolved.

[bigwheel]

Well I got underneath and using feeler gauges checked the airgap for the rear ABS sensors and found n/s 0.762mm(0.30") and o/s 0.996mm(0.039").
Considering the air gap needs to be between 1.5mm(0.059") and 2.0mm(0.079"), I'm going to need one or two 0.5mm gauge shims in each sensor.
The measurements on this drawing are OK apart from the distance between hole centres being 20mm and not 22mm as in the drawing.
http://thumbsnap.com/8btQjJux

While I was there, I removed the allen screw on each sensor to see how easy they are to remove. Both sensors are refusing to budge. I tried tapping the lobe either way to rotate it but with both the sensor and mounting hole being alloy, I didn't want to damage things. There's no corrosion anywhere.

I'm open to advice as to how to get them out.

This photo is from the American forum.
http://www.ls1gto.com/forums/attachment.php?attach...

Edited by bigwheel on Sunday 6th December 22:46

[bigwheel]

Had another go at removing the rear ABS sensors to install the shims. Doused with release oil.

With the Allen screw out, got a large shifter around the sensor lobe shape and tried rotating the sensor. Looking through the screw hole I can see that this end of the sensor is loose and trying to twist very slightly. The seized part seems to be at the other end of the sensor where the air gap is, close to the drive-shaft reluctor.

With the size of shifter I'm using, I could quite easily snap the alloy diff housing lug if I lean on it too hard.
Putting some heat on the seized area would be the next move, except the electrical nature of the seized ABS sensor precludes that idea.

What is the fit here like? Is it keyed? Is it an interference fit? Non-metallic?

Edited by bigwheel on Saturday 13th February 23:30

[MyM8V8]

bigwheel said:

Had another go at removing the rear ABS sensors to install the shims. Doused with release oil.

With the Allen screw out, got a large shifter around the sensor lobe shape and tried rotating the sensor. Looking through the screw hole I can see that this end of the sensor is loose and trying to twist very slightly. The seized part seems to be at the other end of the sensor where the air gap is, close to the drive-shaft reluctor.

With the size of shifter I'm using, I could quite easily snap the alloy diff housing lug if I lean on it too hard.
Putting some heat on the seized area would be the next move, except the electrical nature of the seized ABS sensor precludes that idea.

What is the fit here like? Is it keyed? Is it an interference fit? Non-metallic?

Edited by bigwheel on Saturday 13th February 23:30

You will snap it off. Its a parallel fit into the housing but it doesn't need much swelling of the ally (caused by salty roads) to make it seize completely. I've never managed to get one out successfully. Only thing I can think of is to take the plate off and try and get it to a hydraulic press and try that???

Hope others here may have more successful outcomes to discuss.

[bigwheel]

MyM8V8 said:

You will snap it off. Its a parallel fit into the housing but it doesn't need much swelling of the ally (caused by salty roads) to make it seize completely. I've never managed to get one out successfully. Only thing I can think of is to take the plate off and try and get it to a hydraulic press and try that???

Hope others here may have more successful outcomes to discuss.

Thanks for replying.
By "parallel fit" do you mean the sensor won't rotate in the housing and will only slide straight in or out?
I've already tried gently prising a screwdriver in the air-gap between the reluctor and the sensor tip but backed-off for fear of damaging the sensor tip as I don't know if it's non-metallic.

I sorn it through the salty months and as a very low miler the diff area is pristine.

I can't think how the housing area could be supported on the "anvil" of a press.

Edited by bigwheel on Tuesday 16th February 00:33