Pistons won't wind back on rear calipers...

PseudoFinn

Active member
Joined
May 21, 2005
Location
Genesee County, Michigan
TDI
Black MKVI Jetta. Premium w/ Nav
So I loaned my TDI to someone... someone who will never be loaned a vehicle again- and they royally screwed my rear brakes up. It took quite a while to remove the calipers, as they were locked up, to replace the rotors. While attempting to wind back the caliper piston... I realized I was not getting anywhere. They would wind, but the booting never compressed, and the piston never went back in, even after maybe 20-30 revolutions, they never seemed to move. Is it possible that the piston was so far extended that they simply will not go back in now? I'm having this problem on both sides. Am I now out 200 dollars for new calipers, or can they be repaired. Am I correct in assuming that when I start turning the piston, it should go right back in without many revolutions?

Please help! My car is now sitting in a parking lot, 30 miles from home!
 

MOGolf

Top Post Dawg
Joined
Jun 27, 2001
Location
underneath something
TDI
2001 Golf GLS TDI Reflex silver, rough road suspension and steel skid plate, 2004 Passat Variant, Candy White, rough road suspension and geared balanced shaft module, and much, much more. 2016 LR RR HSE TD6, 2019 Jaguar I-PACE
What tool are you using for the windback? Does it also put pressure on the piston at the same time?

If it does get pushed out to the extreme limit (e.g. you have no pad material left) it does take an extreme amount of pressure to get it started back in.

There are several people in MI that can help. Can you supply a more specific location for the car?
 

ScorpionBoy

Veteran Member
Joined
Mar 14, 2006
Location
CO
TDI
2003 Jetta TDI
ah. bummer. i haven't had to do rear brakes yet, so i am useless. i do know there are some special tools which are necessary. maybe you need one of those? just wild assed guess, fwiw
 

4Gman

Veteran Member
Joined
Apr 13, 2006
Location
ClaremOnt, CA
TDI
2000 Jetta
Do you have the brake fluid reservoir open?
IF its full, The fluid needs somewhere to go when you push back the piston.
 

PseudoFinn

Active member
Joined
May 21, 2005
Location
Genesee County, Michigan
TDI
Black MKVI Jetta. Premium w/ Nav
4Gman.... I cracked the fluid reservoir. No luck.

MOGolf... The vehicle is currently located in Linden, MI. I didn't realize I would need to apply much pressure at all. This is encouraging. Any idea what kinda tool I would need to get my hands on to get the job done?

Thanks for the SUPER speedy replies, everyone!!
 

wjdell

Top Post Dawg
Joined
May 17, 2006
Location
Central Florida
TDI
06 Jetta TDI DSG PKG 1 17" VV Campy White/Beige
If the piston locked up - you would be wise to replace or rebuild which ever you inclined to do. Kits are cheap but you must prepare cylinder and the piston. If they can be, when you disassemble you know what is required.

Bleed the sys well, if you do not have a work shop manual you should get or borrow.
 

MOGolf

Top Post Dawg
Joined
Jun 27, 2001
Location
underneath something
TDI
2001 Golf GLS TDI Reflex silver, rough road suspension and steel skid plate, 2004 Passat Variant, Candy White, rough road suspension and geared balanced shaft module, and much, much more. 2016 LR RR HSE TD6, 2019 Jaguar I-PACE

jokila

Vendor
Joined
Dec 3, 2004
Location
Houston, Texas
TDI
2003 Jetta GLS, Manual
If there is an Autozone in the area they will charge you $0 to loan you the tool. You do have to pay $35 upfront but you get it back when you return the tool.
 

GoFaster

Moderator at Large
Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
I've done it with the standard cube-shaped tool on a ratchet with a big adjustable woodworker's clamp around the whole deal. Turn a little, squash a little, turn a little, squash a little, etc. It's a whole lot easier with the tool designed for this purpose.
 

ScorpionBoy

Veteran Member
Joined
Mar 14, 2006
Location
CO
TDI
2003 Jetta TDI
rear brakes don't do all that much if you aren't hauling ass. if they aren't totally locked up, drive it home and turn up the stereo so you don't have to listen to the griiiiinding.
 

tditom

Top Post Dawg
Joined
Sep 5, 2001
Location
Jackson, MI
TDI
formerly: 2001 Golf GL, '97 Passat (RIP) '98 NB, '05 B5 sedan
guys, he said the caliper pistons were stuck all the way out. He probably damaged the pads when prying them out. How's he gonna drive it anywhere unless he gets the piston back in to replace the pads?
 

Lug_Nut

TDIClub Enthusiast, Pre-Forum Veteran Member
Joined
Jun 20, 1998
Location
Sterling, Massachusetts. USA
TDI
idi: 1988 Bolens DGT1700H, the other oil burner: 1967 Saab Sonett II two stroke
The piston can in extreme extension situations (pads worn to backing plate for example) be pushed completely off the threaded stud. The piston seal will allow rotation but if it isn't still engaged on the stud, it never retracts.
Press it back until it engages the stud then continue with the twist and push.
A proper tool matches the stud's thread pitch and will significantly reduce the liklihood of damaging the first turn of the thread as the piston is pushed back in contact.
 

dr.zed

Veteran Member
Joined
Jun 8, 2006
MOGolf said:
What tool are you using for the windback? Does it also put pressure on the piston at the same time?

If it does get pushed out to the extreme limit (e.g. you have no pad material left) it does take an extreme amount of pressure to get it started back in.

There are several people in MI that can help. Can you supply a more specific location for the car?
This has happened twice for me. Both times the pad was down to the rivets. You have to wind OUT until the boot literally has no ribs in it. Don't go TOO far out!

Then wind in, then out, then in again. After about 6 times (in the rain, on a gravel driveway... LOL), it WILL go back in. It will take about 15 - 20 full turns to get the piston back in from fully extended.
 

PseudoFinn

Active member
Joined
May 21, 2005
Location
Genesee County, Michigan
TDI
Black MKVI Jetta. Premium w/ Nav
Thanks again everyone for the timely and knowledgable responses. This forum has saved my butt and my nerves. As jokila recommended, I called a local Autozone, they have the tool. I'm on my way out to finish the job now (in the snow... yeah... it's SNOWING@!!). At any rate, thanks everyone for the help, the tips and support here.
 
Last edited:

PseudoFinn

Active member
Joined
May 21, 2005
Location
Genesee County, Michigan
TDI
Black MKVI Jetta. Premium w/ Nav
So now... I have another problem- one of the pistons won't wind back out now. The caliper compresses, then when it releases, it goes too far back out- and the brakes are quite soft at first, and never have quite as much stopping power as they used to. Do I need to wind the piston back out a little bit, or was my bleeding not adequate? I wasn't sure I was really going to need to bleed the brakes, but they were very soft at first pump, would come up on the second pump, but go back to soft after a moment- so we just bled the side that was having a problem- but it didn't help. Air never came out with the fluid.

And the parking brake is nearly useless...
 

jollyGreenGiant

Veteran Member
Joined
Feb 3, 2003
Location
MA
TDI
03 Golf TDI GLS ( my 5th TDI ), 03 Eurovan GLS - VR6 :(
You have to exercise the e-brake repeatedly to get the piston back to it's adjusted operating position. If you haven't already operated the e-brake several times, this is what's needed. If you have done this already and it's not bringing the piston back to position, I question the adjustment of that cable on that end, if that's good too, then I question the actual adjustment mechanism and thus the caliper. The adjustment mechanism might have been damaged in the ordeal...
 

ATX

Veteran Member
Joined
Aug 27, 2006
Location
Austin/San Antonio, TX
TDI
2000 Jetta GLS (Black Leather on Black)
I bet the calipers are fine, but like someone else mentioned...it takes a near a stupid amount of force while turning to get those things turned back where they need to be
 

PseudoFinn

Active member
Joined
May 21, 2005
Location
Genesee County, Michigan
TDI
Black MKVI Jetta. Premium w/ Nav
jolly green- the ebrake adjustment being off sounds to be the must likely diagnosis. Is it possible that it would have changed just by removing it while changing the pads? I've tried backing up and pulling the ebrake a few times and this seemed to have helped a bit.
 

jollyGreenGiant

Veteran Member
Joined
Feb 3, 2003
Location
MA
TDI
03 Golf TDI GLS ( my 5th TDI ), 03 Eurovan GLS - VR6 :(
You need to pull the center console ( armrest ) off, there are two phillips screws that hold it on which are accessible from the back seat. I think the A3's also have two 10mm plastic nuts which are under the shift boot. Pull it right out and then with 2 10mm wrenches, you can adjust the cable. The cable is adjusted properly when the cable is taught and pulls the caliper actuator just barely off it's stop. You'll see what I'm talking about when you get in there and look at it, you can tell if one or both are loose if there is zero tension on the cable with the e-brake in it's relaxed position. The caliper must clamp the pads to the rotor to adjust itself out, if the cable isn't applying full pressure due to reduced throw then you very well may not be able to get the piston to self-adjust.
 
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