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        General >> Problems >> Rear Disc Brake Piston Retractor Brake Tool
        
(Message started by: Spannerdemon on Apr 16^th, 2006, 10:06pm)

Title: Rear Disc Brake Piston Retractor Brake Tool
Post by Spannerdemon on Apr 16^th, 2006, 10:06pm

I am going to have to replace the discs and pads of my 12v scorpio shortly. parts ordered, and I see that I need a caliper tool to rewind the piston.

I have a couple of domestic sink tap recutting tools sitting idle in my garage which I reckon I could adapt to do this job. They are both good solid tools which will take a fair bit of pressure. Basically I just need to weld a suitable plate with pins on to the end of one of them to match up with the caliper recesses.

Are there four or two pins?

Need to know the size (diameter) of the caliper end, and the distance between the pins (centre to centre).

What sort of force is needed to rewind the caliper please.

Thanks for any help here. :)

I can then get the tool ready for when the parts arrive.

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by sector-9 on Apr 16^th, 2006, 10:11pm

I remember when I was a kid and I was watching my dad bend various G-clamps trying to retract the rear pistons on a Granada. Eventually (after much swearing and bent tools) he gave up and called a friend round. Said friend took a pair of long-nosed pliers to the piston and used them to rotate it as he pushed it back. That's all he used - long nosed pliers engaged in two of the four notches!

Darren

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by Spannerdemon on Apr 16^th, 2006, 10:21pm

Cheers for this Darren.

Not much effort needed to push it back then?? I've got long nosed pliers too!!

I don't really want to buy a tool that I'll maybe only use once, and these two tools that I have are so similar to the caliper removal ones on Ebay etc. I reckon a couple of locknuts on the end of the spindle with a washer welded to them with two pegs would do the same job.

Any more ideas still welcome.

Thank You

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by landbarge on Apr 16^th, 2006, 10:32pm

I invested in a tool from Unipart. Did the job a treat. Considered the Heath Robinson approach but was put right by my very knowlegable mechanic on the force that would be needed to retract the piston.

As you appreciate, the piston is spiral grooved. Even with the god-sent tool a great deal of effort was needed to retract the piston into its housing.

Naturally, once you have done one side the remaining one was completely refitted in under 20 mins; yes I did time myself.

Pay the money to Unipart; the tool can be used on 'other' cars in the future.

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by cossie_al on Apr 16^th, 2006, 10:39pm

I have always managed with long nose pliers.
However,
There is a good chance they will slip and damage the rubber boot

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by Spannerdemon on Apr 16^th, 2006, 10:45pm

I reckon my soon to be adapted tool will do the job pretty well. I have access to a very large and well equipped engineering department where I work, and I'm sure I can make something up from this tool which will be both safe and effective. Just need the caliper/pin measurements if anyone has them.

Thanks.

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by meg on Apr 17^th, 2006, 12:46am

hi pins are 6mm dia ,with centres at 33mm.. if that makes any sense (done with a tape measure,no engineer)sizes taken off sykes pickavant tool (2pin)

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by Simmo on Apr 17^th, 2006, 8:38am

Having just done the job I can only say that whilst I think you could do the job with an adapted tool the long nose pliers method would have been a nightmare. The thread on these units is very fine and it takes long enough to do it with the correct tool. I purchased a 'cube' for use with a 3/8 drive socket set and frankly it was worth every penny of the £6 or so I paid for it. Draper tools do one,which as Landbarge says, fits a variety of vehicles. Good luck whichever route you go.

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by Spannerdemon on Apr 17^th, 2006, 11:04am

Thanks very much for this Simmo.

Just had a look on Ebay and Cube it is!! Hadn't seen these before, so THANKS for that. The other caliper re-wind tools were either silly money, or didn't look man enough for the job.

The low price, £6.00 including postage, and top quality tool maker (Sykes Pickavant), convinced me that I'd rather get the job done as easily as possible, rather than spending half of tomorrow sorting this tool of mine out!!

Excellent result. Brilliant help again from these excellent forums. :D :D :D

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by Spannerdemon on Apr 17^th, 2006, 11:06am

Thanks Meg, but I'm going "cube shaped". Thanks for taking the trouble to take the measurements for me--- which I'll put in my little book anyway!

Never seen this cube tool before, and so cheap that adapting a tool myself isn't really worth all the hassle.

Best regards, and Thanks. :)

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by mr._floppy on Apr 17^th, 2006, 5:49pm

While the long nose pliers trick work when the piston is relatively free to turn, nothing beats the little cube when the piston is a bit sticky.

It's also worth buying the conventional piston retractor for the front calipers too, saves a lot of time.

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by jonnycab on Apr 18^th, 2006, 12:36am

To wind back the callipers I use a large monkey wrench & an old filed down chisel

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by Oliver on Apr 18^th, 2006, 11:10pm

Once you've got the knack of using long nosed pliers it's easy. Just remember to finish with the slots alligned correctly to accept the lug on the back of the new pads.

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by woody1966 on Apr 19^th, 2006, 9:35am

I've just replaced my pads and disks all round and found that the tool used for changing the discs on angle grinders is a perfect fit, not much room to get a good turn on it though....

Title: Re: Rear Disc Brake Piston Retractor Brake Tool
Post by Spannerdemon on Apr 21^st, 2006, 2:46pm

Just completed the job. NO WAY would I consider doing it without a proper tool. The CUBE has been a winner. For just over £6.00 it has now joined the other toolbox essentials. Worth every penny.

Whilst doing it, I tried the long nosed pliers (skidded horribly), and also the Angle grinder key. Fit's but no room to turn it, and it skids too.

If you put "Brake Cube" into Ebay search, you'll no doubt find one.

the ONLY problem i had which was unexpected, was that three of the wheel nuts had a chrome capping on them, and one didn't. The ones 'with' took a 19mm socket, and the one without needed an 18mm.

Didn't have an 18mm so despatched the wife to our accessory shop. While she was away, found a 3/4" one which undid it. Didn't have the heart to tell her.......................

Now a hundred miles or so of careful braking to bed the new pads and discs in.

Then I'll do the front ones. ;D