Wind back tool for front brakes

[Robbo12]

Hi, I am thinking of changing my front pads on my superb MK3, could anyone tell me if I need a tool that screws and pushes the pistons back in, or do they just push back.

Thanks for any advice.

[john999boy]

I believe the wind back tool is only required for the rear brakes.

[D402]

Both the front and rears push straight back, but, for the rears, you have to use a diagnostic tool to electrically retract the electric park brake mechanism first.

[varooom]

2 minutes ago, D402 said:

Both the front and rears push straight back, but, for the rears, you have to use a diagnostic tool to electrically retract the electric park brake mechanism first.

I was then going to post, exactly this. 🤝

 

[Robbo12]

Thanks for the advice great help.

[Carlston]

You can get a disc brake spreader tool on ebay/amazon.

 

This is a very popular design which is sold under various brand names and also unbranded. They are probably all made in the same factory in China and are available from just over £8 including postage.

 

The tool enables you to push the front brake caliper piston back before removing the old front brake pads.

 

https://www.ebay.co.uk/sch/i.html?_from=R40&_nkw=disc+brake+spreader+tool&_sacat=0&_sop=15&rt=nc&LH_ItemCondition=3

 

Edited 12 September, 2022 by Carlston

[Ootohere]

Everyday a school day.

For years i have done it wrong because i remove the old pads then use the tool to push back the pistons to allow in the thicker new pads. 

Edited 12 September, 2022 by roottoot

[Carlston]

39 minutes ago, roottoot said:

Everyday a school day.

For years i have done it wrong because a remove the old pads then use the tool to push back the pistons. 

 

As long as you can do the job without damaging anything.

 

Using a wind back tool on a brake caliper piston that is not designed to be rotated could damage the outer dust seal. Although an adaptor would be used with the wind back tool, unless the adaptor's bearings are incredibly smooth (not likely with cheap Chinese tools) this would create a twisting force on the brake caliper piston and rotate the piston possibly damaging or stressing the outer dust seal.

 

A damaged brake caliper piston seal will let in water and cause the piston to seize, resulting in the need for an expensive brake caliper rebuild or replacement.

 

Very common "piston wind back tool" set probably all made in the same Chinese factory

 

 

Edited 12 September, 2022 by Carlston

[Ootohere]

On your bike.

You said the tool enables you to push back the front brake caliper piston before removing the old front brake pads. 

 

I hope you are not a Mechanic or Tech training anyone because they might listen to you. 

[Carlston]

11 minutes ago, roottoot said:

You said the tool enables you to push back the front brake caliper piston before removing the old front brake pads.

 

It does. Where is the discrepancy?

 

[varooom]

7 minutes ago, Carlston said:

 

It does. Where is the discrepancy?

 

He is meaning you said to push back piston before removing pads

 

He is saying most remove pads before pushing back piston.

 

 

Edited 12 September, 2022 by varooom
Image added

[Ootohere]

@CarlstonIf the OP is changing brake pads with the caliper on and the disc fitted are you prising the pads / calipers back with  screwdriver to get the tool in with the pads still fitted?

[Carlston]

8 minutes ago, roottoot said:

@CarlstonIf the OP is changing brake pads with the caliper on and the disc fitted are you prising the pads / calipers back with  screwdriver to get the tool in with the pads still fitted?

 

See this youtube video starting at 2 minutes 16 seconds, where the autodoc mechanic uses a wind back tool with an adaptor. It looks like he has taken my advice about being careful not to rotate the piston, because he has left the piston side brake pad in place while he pushes the piston back.

thi

Edited 12 September, 2022 by Carlston

[D402]

It's fine to push the piston back with or without the old pads still in place, it's also fine if the front pistons rotate while you're doing it. The rears, however, must be pushed straight back without rotating because this could damage the electric park brake mechanism.

 

I use a g-clamp on cars and motorcycles, and a screwdriver between the old pads on pushbikes.

[Robbo12]

Thanks again everyone don't think I'll have any problems now, good advice from you all.

[ApertureS]

Just something to add from my experience. 

 

I completely get that the service manual shows pushing the piston back with no pads. In this situation its completely fine. There are 2 situations where it is not fine though.

 

1. Multi piston calipers. Youll be there all day fighting the pistons back, just leave the pads in and push back on them.

2. Ceramic pistons - Some expensive calipers have pistons made of a ceramic material - if you even try to push back straight on the piston youll crack it and they aint cheap.... Use the pads, make sure its completely square and push away. 

[Whenwillilearn]

Hi

 

I just recently replaced my front pads and discs to cross drilled brembos. Bought a piston wind back tool from euro carparts and utilised the old pad as a spacer to make up the gap when the piston was being pushed back in. I would recommend a push back tool, after a few years of use and road grime the piston will not push back in easy without some direct constant force applied.

 

Changed the discs on the front also. Easy tap off with a copper mallet. MOT advisory due to rust on the inside face of the discs. Now i have quiet braking again.

 

Changed the rear pads. The rear piston will not retract enough to replace pads when park brake is 'off'. As you are all aware its electronic thus i removed the small electrical actuator from the caliper. Then would the piston back in by turning the shaft now exposed by removing the actuator. 

 

A simple job and £££ saved by avoiding dealer prices. 

 

VCDS or ODB needed to wind in those rear calipers and put into service mode. 😂 Not needed.

[ApertureS]

16 minutes ago, Whenwillilearn said:

Hi

 

I just recently replaced my front pads and discs to cross drilled brembos. Bought a piston wind back tool from euro carparts and utilised the old pad as a spacer to make up the gap when the piston was being pushed back in. I would recommend a push back tool, after a few years of use and road grime the piston will not push back in easy without some direct constant force applied.

 

Changed the discs on the front also. Easy tap off with a copper mallet. MOT advisory due to rust on the inside face of the discs. Now i have quiet braking again.

 

Changed the rear pads. The rear piston will not retract enough to replace pads when park brake is 'off'. As you are all aware its electronic thus i removed the small electrical actuator from the caliper. Then would the piston back in by turning the shaft now exposed by removing the actuator. 

 

A simple job and £££ saved by avoiding dealer prices. 

 

VCDS or ODB needed to wind in those rear calipers and put into service mode. 😂 Not needed.

As much as the diy method of removing the motor is ‘fine’ it’s really not.

 

when you use a diagnostic tool it winds the caliper off fully and clears the learnt values.

when you reenable the handbrake after change it doesn’t just wind it on. It monitors current draw from the motors and winds the calipers on and off multiple times, this is to allow the car to learn the new values and prevent the motor from either not tightening enough or over tightening and causing premature failure of the motor or it’s housing. Yes it happens a lot, you’ll see cracks appear around the 2 bolts holding the motor on.

 

I personally don’t recommend using the manual windback method but everyone is entitled to do it as they wish, just it’s good to know all the facts first 

[Whenwillilearn]

8 minutes ago, ApertureS said:

As much as the diy method of removing the motor is ‘fine’ it’s really not.

 

when you use a diagnostic tool it winds the caliper off fully and clears the learnt values.

when you reenable the handbrake after change it doesn’t just wind it on. It monitors current draw from the motors and winds the calipers on and off multiple times, this is to allow the car to learn the new values and prevent the motor from either not tightening enough or over tightening and causing premature failure of the motor or it’s housing. Yes it happens a lot, you’ll see cracks appear around the 2 bolts holding the motor on.

 

I personally don’t recommend using the manual windback method but everyone is entitled to do it as they wish, just it’s good to know all the facts first 

Good comments. 

 

When the motors were re-attached and the handbrake engaged the park brake was engaging and disengaging multiple times before finally engaging. This was the moment the car adjusted its memory for the new pads and set its new piston on and off position.

 

The rear brake motor will always be learning. The pads will wear over time, hence the motors have to account for this by stroking the piston further as the pads wear. In your case as described the ECU will always monitor the current until the pistons dead head and motor current increases as a result. The dead head current will not change fundamentally unless the motor is failing (perhaps a ground fault), its the same motor, the same load, the same power supply. The difference is the motor run time for a change in piston stroke.

 

 

 

 

 

 

 

[Robbo12]

Thanks for the advice everyone I'm going to attempt to change the front pads and discs next week and will let you know how it goes. I now have the push back tool and thinking of getting Pagid Brake Discs and Pads. Do you recommend any different?  Don't think I would be brave enough to change the back pads due to the electric hand brake.

[Whenwillilearn]

Cross drilled discs look nice through the wheels if that floats your boat. I paired them with pagid pads. Good braking performance and quiet. The originals that i removed were always a little noisy, probably due to them rusting on the inside disc face. 

[Robbo12]

Just a quick update I have managed to change my front Disc's and pads with no issues, thanks for all the advice you all gave me. Would be nice to change back pads but it will probably be issues releasing the electric brake.