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Help - rear brake caliper piston won't compress

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Help - rear brake caliper piston won't compress

  #1  
Old 04-28-2012, 09:01 AM
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Help - rear brake caliper piston won't compress

Help! I started my rear brake pad replace job yesterday and have not been able to get my piston to compress! I have tried:
1 - c-clamp followed by needle nose pliers
2 - needle nose pliers only (the piston won't go in but will thread out)
3 - piston compression tool (only the dowels don't line up)
I cannot even get the assembly back together with the old pads. Is there anybody who carries the right tool that fits the mini piston holes?
Any other suggestions? I have an undriveable car sitting in my driveway.
 
  #2  
Old 04-28-2012, 10:08 AM
kaneguy
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Are you compressing the piston and turning it (clockwise) at the same time? You can borrow the tool from Autozone or get the tool from Harbor Freight for about $30.
 
  #3  
Old 04-28-2012, 11:01 AM
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Yep, the piston needs to turn while compressing. Its a pain w-out the right tool.

http://www.harborfreight.com/18-piec...kit-97143.html
 
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Old 04-28-2012, 12:47 PM
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Got (multiple tools) still can't find right jig

I got the vise like tool from Auto zone but jigs pegs don't line up with mini piston indentions. I also got the "cube tool" and those pegs won't line up either. With the needle nose, I am turning and pushing but still not getting the piston back in the caliper. If I can't solve this problem, I am going to have tow my car out of the drive way (with no brakes) and take to the shop.
 
  #5  
Old 04-28-2012, 01:40 PM
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The harbourfreight tool does have the block (one size smaller than the most common on that comes with many older tools/rentals).
One thing...you might be able to crack open the caliper bleed valce while twisting and pushing to realese some fluid...making it easier to push...this can be a good idea anyway to get rid of the dirty fluid in it anyway...the fluid in the calipers gets dirty and water logged....and if the calipers are not bleed (even with a pad change) can result in corrosion in the piston...tearing the rubber seals or legging then get gummy), resulting in leaks....and the need to rebuild the caliper.
 
  #6  
Old 04-30-2012, 10:14 PM
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Rear caliper compressed! Success!?

I purchased the Harbor Freight tool for $40 (great store, a place to send my family for Xmas shopping) and the caliper compressed. I also figured out how to attach the rear clips to the caliper (hopefully). After getting the brakes bled and buttoning everything up, drove the car and it stopped and rolled when I wanted it to.
One question: I have done multiple disc brake jobs in the past but I have never felt the disks. After driving for a while and trying the brakes, I noticed the disk were hot to the touch (not blistering but hot). Is that normal?
 
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  #7  
Old 04-30-2012, 10:16 PM
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Thanks!

By the way, thanks for all the help and suggestions. If anyone in the SF Bay Area needs to borrow the caliper compression kit, I'm sure we can work out a deal.
 
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Old 04-30-2012, 11:47 PM
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Yes the disk can get very hot if it use heavily. In fact, if you ever watch a night Nascar race at Bristol raceway where they use the brakes a lot, the disk gets red hot almost yellow. When the brakes gets too hot they start to fade (less stopping power).
 
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Old 05-01-2012, 07:16 AM
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I noticed that the rear disc's appear to be warmer to the touch than the fronts, quite a bit warmer than I would have expected. This was on a new to me car that just had new pads/rotors installed on all 4 corners. Any similar experience's? Any key or typical items that would keep the rear pads from properly retracting? It did diminish after 1k miles, but still a slight difference.
 
  #10  
Old 05-01-2012, 07:43 AM
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The rear disks are solid, where as the fronts are vented. It makes sense that rears don't cool as rapidly as the fronts. The rears do a lot less work though, so I wouldn't worry about overheating them.
 
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Old 05-01-2012, 08:25 AM
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The rears can get very hot for a few reasons; solid disk, small disk diameter, small pad contact area. All this adds up to the rear brakes not being able to dissipate heat very quickly so even though the rear brakes do not work as hard they are not as efficient as the fronts.

To gain a little reassurance, you might want to jack up the rear and spin each tire with the parking brake off just to brake sure the pads/parking brake are not dragging on the rotor too much. A little drag is normal.
 
  #12  
Old 08-07-2017, 07:57 AM
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R53 caliper retraction tool

Originally Posted by sunolmike View Post
I got the vise like tool from Auto zone but jigs pegs don't line up with mini piston indentions. I also got the "cube tool" and those pegs won't line up either. With the needle nose, I am turning and pushing but still not getting the piston back in the caliper. If I can't solve this problem, I am going to have tow my car out of the drive way (with no brakes) and take to the shop.


I'm having this problem too. 2006 R53. Rented tool kit from AZ but nothing in kit fits the piston. http://www.autozone.com/loan-a-tools...set/298604_0_0 Smallest adapter in kit is 1 1/4 inch. Also have cube tools but they don't fit either. Never had this problem with any other car. Damn PIA Mini.


Wished I'd found this out before I disassembled the car. Appears to need an adapter with four pins. http://www.lasertools.co.uk/product/3940 or http://www.lasertools.co.uk/product/3941


Does anyone know another caliper retraction tool kit that has correct adapter to fit??
 
  #13  
Old 08-07-2017, 08:54 AM
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Not done it myself but seems like many people have success with Harbor Freight tool. Worth a look.
 
  #14  
Old 08-07-2017, 10:58 AM
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I have used successfully used the Harbor Freight "Disc Brake Caliper Tool Set", item 40732 on my stock 2006 MCS. There is no adapter with 4 prongs in the kit. I use one of them with 2 prongs. The tool works, but takes a bit of work. I usually fumble around getting things in place (could use 3 hands.) After a few turns it seems to bind and has to be reset. My guess is that the rate the piston screws in is not the same rate that the tool presses it in.

Bottom line. It does work.
 
  #15  
Old 08-07-2017, 11:50 AM
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HF tool gets easier with experience. I've been using it on MINIs since 2004

trick is - if it begins to get 'tight' back off and reset. When it works right the piston does more retracting via the screw motion then is does by the press.

p.s. compare the HF tool to the one Outmotoring sells ...

http://www.outmotoring.com/mini-coop..._tool_set.html

https://www.harborfreight.com/catalo...f&q=brake+tool

both are $50
 

Last edited by Capt_bj; 08-07-2017 at 01:16 PM.
  #16  
Old 08-08-2017, 09:43 AM
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When I did mine 2 years ago, I was not up to speed with the parking brake self-adjust mechanism. It took me some struggle to realize the need to rotate the piston to retract it. I didn't have the needed speciality tool on hand. I just used a C-clamp and a pair of needle nose pliers. C-clamp to lightly compress the piston on the lip, and the pliers to rotate the piston. It took some patience but once I realize gentle does it it was quite easy. In my case the trick was not to crank on the C-clamp but just tighten it lightly as if you crank on the clamp you also make the piston that hard to rotate.

YMMV if you are in rustbelt country.
 
  #17  
Old 08-08-2017, 05:37 PM
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Another Harbor Freight brake tool user here. Wasted far too much time trying to do it with needle nose pliers.
 
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