VF Parking Brake Issue

[VF300k]

I‘d be taking off the rotors and measuring the diameter of the hand brake shoe (without doing any prior adjustments). They should be around 189.8 mm. You might need to buy a 200mm digital caplier to accurately do the measurement.

If the diameter is way out, I’d be looking to see why, and why both sides are effected. Perhaps the adjusters aren’t working correctly? Are the shoes worn? I’m not familiar with the VF setup, but I’d be checking if the hand brakes are designed to automatically adjust for wear (by seeing if there is an automatic ratchet mechanism).

These pages out of the manual might be helpful…



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This might be a dumb question, but if I Jack up the rear, how do I stop the car rolling forwards? Do I do one side at a time and just keep it in park with the EPB off? (Not that the EPB seems to be doing anything)

I’ve only ever worked on the front, replacing lower control arms on a Subaru and CV boots, always left the handbrake on and car in park and only jacked one side at a time.

 

[chrisp]

This might be a dumb question, but if I Jack up the rear, how do I stop the car rolling forwards? Do I do one side at a time and just keep it in park with the EPB off? (Not that the EPB seems to be doing anything)

I’ve only ever worked on the front, replacing lower control arms on a Subaru and CV boots, always left the handbrake on and car in park and only jacked one side at a time.

Chock the front wheels, and work on a (very close to) level surface. The handbrake needs to be off to get the rotor (which is also the ‘drum’) off. You also want the EPB in the off position to get the correct measurements.

 

[RevNev]

With the rotor on and park brake off, I just remove the rubber grommet to access the hand brake shoe adjuster with a screwdriver and tighten the shoes up as you would with the old drum brake setups until they bind, then back it off a bit until the rotor turns freely. Then the GM diagnostics via GDS2 provides a park brake reset function, activate that and you hear the mechanism functioning several times until reset completion is shown. Park brake then works mint. Electrical issues throw fault codes if there's a problem with the servo mechanism or related modules. park brake switch etc.

The park brake can get out of whack electrically and a reset with GDS2 or a scan tool that has the reset function fixes the issue in most cases.

 

[VF300k]

With the rotor on and park brake off, I just remove the rubber grommet to access the hand brake shoe adjuster with a screwdriver and tighten the shoes up as you would with the old drum brake setups until they bind, then back it off a bit until the rotor turns freely. Then the GM diagnostics via GDS2 provides a park brake reset function, activate that and you hear the mechanism functioning several times until reset completion is shown. Park brake then works mint. Electrical issues throw fault codes if there's a problem with the servo mechanism or related modules. park brake switch etc.

The park brake can get out of whack eclectically and a reset with GDS2 or a scan tool that has the reset function fixes the issue in most cases.

guessing if there's not enough meat on the shoe that the max level of tightening wouldn't do anything?
Basic scan tool should show if it's an electrical issue? what's a decent cheap scanner that can also do the reset? if its the same as the steps as posted earlier from the service manual for the parking adjustment, the hold till it flashes etc could likely get by doing that after adjusting it.

Chock the front wheels, and work on a (very close to) level surface. The handbrake needs to be off to get the rotor (which is also the ‘drum’) off. You also want the EPB in the off position to get the correct measurements.

Yeah level surface isn't something I have much of at this place, quite a steep driveway have actually moved the car to the lawn for now so its not putting all the pressure on the parking pawl as there's no flat spot on the driveway/carport.

If I had too, can I do one side at a time or would that cause problems?, Sorry for the basic as questions, first time I'm looking to get really hands on with maintenance to save on labour costs where I can.

 

[chrisp]

Yeah level surface isn't something I have much of at this place, quite a steep driveway have actually moved the car to the lawn for now so its not putting all the pressure on the parking pawl as there's no flat spot on the driveway/carport.

If I had too, can I do one side at a time or would that cause problems?, Sorry for the basic as questions, first time I'm looking to get really hands on with maintenance to save on labour costs where I can.

Doing one side at a time should be okay, but that won’t overcome the issue of the car potentially rolling. Thinking as I’m typing, I suppose doing it one side at a a time would have the advantage that you can chock three wheels (instead of two). Be careful… don’t put any part of your body that you don’t want to lose under the car, and place the removed wheel under the door sill near where it came off (just in case the car does come down).

 

[VF300k]

Doing one side at a time should be okay, but that won’t overcome the issue of the car potentially rolling. Thinking as I’m typing, I suppose doing it one side at a a time would have the advantage that you can chock three wheels (instead of two). Be careful… don’t put any part of your body that you don’t want to lose under the car, and place the removed wheel under the door sill near where it came off (just in case the car does come down).

Yeah I think being able to chock three wheels and have the wheel and jack stands on the one side at a time would be best, I might not miss an arm/hand but I reckon the missus wouldn't be to happy with me

 

[Skylarking]

You don’t need a diagnostic tool to do the park brake adjuster “disable” and “enable“.

You also don’t need a diagnostic tool to do the park brake calibration.

The manual process is written within the quoted part of post #6 which is an extract I typed from the workshop manual.

As for raising the rear of the car, best do it on flat concrete (middle of a double garage is best) with big wheel chocks on both front wheels and using a jack under the rear diff*. Dont forget safety so always use axle stands

* using the rear diff as a lift point isn’t specified within the workshop manual but many a pro shop have been doing such for years without issue.

PS: on a flat level surface with each front wheels chocked front and back, the car won’t roll anywhere… and if rolling is a concern, raise the car onto 4 axle stands using the cars jacking points…

I’ve welded the heads of 4 scissor jacks onto 4 axle stands for this exact purpose (though I’ve only used it on another brand of car since I haven’t been service the commodore as yet)…

 

[VF300k]

You don’t need a diagnostic tool to do the park brake adjuster “disable” and “enable“.

You also don’t need a diagnostic tool to do the park brake calibration.

The manual process is written within the quoted part of post #6 which is an extract I typed from the workshop manual.

As for raising the rear of the car, best do it on flat concrete (middle of a double garage is best) with big wheel chocks on both front wheels and using a jack under the rear diff*. Dont forget safety so always use axle stands

* using the rear diff as a lift point isn’t specified within the workshop manual but many a pro shop have been doing such for years without issue.

Yeah if the process is the same could likely do without the scan tool for now.

Will likely do the one side at a time, feels slightly safer, do the stands just go near/on the same jacking points or is there somewhere else those should be placed?

 

[Skylarking]

Yeah if the process is the same could likely do without the scan tool for now.

Will likely do the one side at a time, feels slightly safer, do the stands just go near/on the same jacking points or is there somewhere else those should be placed?

Was updating my post as you typed yours.

so look up… don’t look up... look up

 

[RevNev]

guessing if there's not enough meat on the shoe that the max level of tightening wouldn't do anything?
Basic scan tool should show if it's an electrical issue? what's a decent cheap scanner that can also do the reset? if its the same as the steps as posted earlier from the service manual for the parking adjustment, the hold till it flashes etc could likely get by doing that after adjusting it.

Hand brake shoes shouldn't wear much at all in the lifetime of the car as they only contact the drum statically unlike an old drum rear brake's rotational friction. In the event the shoes were excessively worn, they'd likely run out of adjustment.

I don't know of any cheap scan tools that have the park brake reset function, most cheap ones for reading and clearing codes probably don't. Personally, I've only done hand brake resets with the GM diagnostic system.