# Caliper rebuild? 337/20th. Yes or No



## hootyburra (Feb 19, 2007)

UPDATE 5-31
I found these kits I just need to know if they will work? 
http://www.rockauto.com/catalog/moreinfo.php?pk=878358
This would be the rear ^ Is the dust boot included? 

There are 2 kits for the front? 
http://www.rockauto.com/catalog/moreinfo.php?pk=314360
http://www.rockauto.com/catalog/moreinfo.php?pk=878476



I found this boot kit
http://www.rockauto.com/catalog/moreinfo.php?pk=110377

I am searching under the TT quattro because I read here they are the same. 
http://forums.vwvortex.com/showthread.php?846180-The-brakes-of-the-MK4-platform-OEM-and-Upgrades 
___________________________
Changing the rear pads today I discovered the boot was ripped and full of dirt. 
The piston was also a pita to retract, bent the handle on the tool. 
Seeing how expensive these calipers are, would it be advised to rebuild it? 
I found the kits on ECS and a few walkthroughs on google, nothing specific to VW. 

Has anyone rebuilt one, if so is it recommended?

Edit. 

http://www.ecstuning.com/Volkswagen-337_20AE--1.8T/Search/Caliper_Rebuild/ES1596/
Found this for the rears. No boot though...

I have also found the fronts are the 11.3" same as the 225 TT's but not painted. ... IS there a kit for these?


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## hootyburra (Feb 19, 2007)

I found the rebuild kits on ECS and various links/videos to give a general idea on doing it, seems pretty straight forward. The only thing I can't find is the boot


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## hootyburra (Feb 19, 2007)

:screwy:


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## hootyburra (Feb 19, 2007)

anyone rebuild a caliper?


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## germancarnut51 (Mar 23, 2008)

Which tool did you use to try to retract the pistons?

Were the brake pads worn down to the metal? Many times when you wait too long to replace the brake pads the pistons will get jammed and it takes a lot of force to break them loose.

If the parking brake mechanism is not 100% functional, the caliper is a total because no parts are available to repair it, and the only choice is to replace the caliper.

Caliper repair kits are actually only caliper seal kits, because the only parts included are the dust boot and the piston seal.

The TRW (OEM) caliper seal kit (available from autohausaz.com $6.55 and europartsdirect.com $9.50) includes detailed instructions.

Since you will be replacing the dust boot anyway, it's okay to peel it away, to gain access to the crude and wash it away. You can wipe most of it away with a clean dry cloth and soak the rest with PB Blaster. Caution, it' important to remove the PB Blaster and any cleaning ageant you use completely, or they will contaminate the brake fluid and attack the new rubber parts.

To remove the piston, you need a tool to turn the piston counter-clockwise. DO NOT GRAB THE PISTON WITH PLIERS, YOU WILL RUIN IT. If you are using the Harbor Freight Rear Brake Tool Kit, the tool is too thich to allow you to wind the piston all the way out. Close to the end, you will need a thinner tool to turn the piston the rest of the way. I use a bicycle bottom bracket tool.

While the piston is out, DO NOT ACTIVATE THE PARKING BRAKE LEVER, YOU WILL DAMAGE THE PARKING BRAKE MECHANISM (NO REPLACEMENT PARTS) SO BE CAREFUL.

You will need to coat and lubricate the inside of the caliper, the piston, the new dust boot, and piston seal before reassembling. I use silicone brake assembly grease, you can also use brake fluid, but it's messy and corrosive.


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## hootyburra (Feb 19, 2007)

germancarnut51 said:


> Which tool did you use to try to retract the pistons?
> 
> Were the brake pads worn down to the metal? Many times when you wait too long to replace the brake pads the pistons will get jammed and it takes a lot of force to break them loose.
> 
> ...


Thanks for all the info. 
It was a tool with the notch that turns while pushing. The pads were not completely worn down but definitely got my moneys worth


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## hootyburra (Feb 19, 2007)

I am going to do some work to the car and decided to rebuild all the calipers while it is down. 

Anyone have recommendations for buying the parts?


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## bomberbob (Sep 19, 2004)

I am getting ready to do both fronts and rears on my MK II. I rebuilt the calipers and replaced the rotors years ago, its time to do it again. I buy my parts from german auto parts, previous post provides other sources of parts. You have the process of removing the pistons right?


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## hootyburra (Feb 19, 2007)

from what I have read you just use an air compressor to get them out?


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## germancarnut51 (Mar 23, 2008)

hootyburra said:


> from what I have read you just use an air compressor to get them out?


It doesn't take much air pressure to make the front caliper pistons come flying out. I use a bicycle hand pump with the hose held by hand against the hole where the brake hose is normally attached. Before trying to extract the pistons place one used brake pad back in the caliper with a rag to cushion the piston.

The rear pistons must be removed using the rear caliper service tool set to unscrew them out. DO NOT USE AIR PRESSURE TO BLOW THE PISTONS OUT. You will damage the parking brake/self-adjusting mechanism, and be forced to buy replacement calipers.


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## hootyburra (Feb 19, 2007)

Thank you for the info. 

I have the tool for the rears.

I am a little worried because the boot was pretty bad on the rear passenger side and screwing it back in was miserable. 


I am having trouble finding what rebuild kits I need. 

I have found the 337/20th/GLI brakes are the same as the TT 225 but not painted.


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## hootyburra (Feb 19, 2007)

updated first post


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## germancarnut51 (Mar 23, 2008)

hootyburra said:


> Thank you for the info.
> 
> I have the tool for the rears.
> 
> ...




The links you posted all lead to Dorman Brand Parts, and Raybestos buys lots of parts from Dorman. Dorman parts are all pretty much Chinese made junk. Not worth the price, or time you will waste installing.


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## hootyburra (Feb 19, 2007)

germancarnut51 said:


> The links you posted all lead to Dorman Brand Parts, and Raybestos buys lots of parts from Dorman. Dorman parts are all pretty much Chinese made junk. Not worth the price, or time you will waste installing.


Thanks for saving me the time on that. 

So I have found the calipers are the same as the 1.8t/vr6 it is the carrier and rotor that is bigger. 
Is it correct that I can just get a rebuild kit for a gti and use that?


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## hootyburra (Feb 19, 2007)

Found some kits on GAP. 

I just want to be sure I am ordering the right kit so when i pull them apart I am not screwed. 

Someone has had to have done this to MKIV brakes before?


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## hootyburra (Feb 19, 2007)

I have everything but the pins and parts associated with them


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## hootyburra (Feb 19, 2007)

I am having trouble getting the dust boot to seat into the caliper. 
The piston went in easy and sealed around the piston no problem? 

Any suggestions or tricks? 

I tried using a punch to push it in and couldn't get anywhere


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## IJM (Jul 30, 2001)

Yes, the rebuild kits for the front should be the same for the GTI, 20th/337, and TT, as they all use the same caliper. Getting the dust boot seated is a bit of a PITA, but I've managed to do it successfully. 

IIRC, here's how I did it:
Insert the new piston seal (square cross-section O ring) into the bore and lubricate it with fresh brake fluid. Then take the piston, lubricate it with brake fluid, and slide the dust boot over it such that the boot is all the way at the far end of the piston away from the groove it normally sits in when the piston is fully installed. 

Here comes the tricky part. You need to extend the boot away from the end of the piston so that you can get the outer edge of the boot to sit in the groove in the caliper while the other end of the boot is still over the piston, which means you need to support the piston so that it's aligned with the caliper bore but not actually pushed in at all. If successful, the boot will be around the smooth (non-groved) end of the piston and also hooked under the lip/groove on the caliper. Be careful you don't pull it out, as the only thing holding it on there is the little groove on the inside of the caliper bore. 

Now you have to push the piston into the bore without it binding up. I recommend using the brake caliper tool here, as it seems be the best for keeping the piston aligned properly. Mine is from Harbor Freight. As you push the piston into the bore of the caliper, the boot should slide up the piston until it pops into the groove at the other end when the piston it almost all the way in. If the piston gets hung up when it first starts going in, take a large screwdriver and place it inside the open part of the piston to pry it loose and straighten it out. Do not force it in by cranking the crap out of the piston tool, as this can scratch the bore and mess up your caliper. Having everything lubricated by brake fluid helps. Once you do it the first time, it's really easy to do it again. Good luck.

EDIT: From what I can tell, there's no way to get the boot seated in the groove inside the caliper bore once the piston has been inserted, as you seem to have found out yourself. That's why you need to do it like I explained above. Some online DIY instructions for generic caliper rebuilds showed the guy just slipping on the dust boot after putting the piston back in, but the VW calipers won't allow you to do this, which makes it a little more difficult.


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## germancarnut51 (Mar 23, 2008)

The method that I use for installing the boot on the piston and onto the caliper is the one that I read on the instruction sheet that came with the OE TRW caliper seal kits that I use.

Using the right brake seal lubricant is important. You can't use WD40 or dishsoap, or just any slippery liquid you come across (like bearing grease). Using the wrong chemical lubricant can contaminate the brake system or can attack the rubber seals in the brake system. It has to be a lubricant specially designed for brake systems. I've read that Permatex makes a product. I use something named "Sil-Glyde" from a company by the name of "AGS" that I bought from "Automotion" about 20 years ago. I came in a big tube. Last year I did some research, and the company is still in business, and still makes the product, but I didn't look for a current retail source.

First lubricate the piston, the boot (inside and out), caliper/piston seal, and the caliper bore. Install the piston seal on the lower groove of the caliper bore, making sure that the seal is not twisted in the groove when it's installed. Next, slide the boot onto the piston (do not set the piston end of the boot into the groove), and all the way to the bottom of the piston. Now, place the caliper end of the boot into the upper groove on the caliper bore. Next, push the piston down into the caliper bore, sliding the boot higher on the piston as the piston is pressed into the caliper bore. At some point, the piston end of the boot will drop into the groove on the piston.

This procedure working is based on clean, smooth, and properly lubricated (with the correct lubricant) parts. If your parts are dirty, rusty, or have crud build up, you need to clean or replace them.


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## hootyburra (Feb 19, 2007)

I have the fronts done. Ripped a few boots but in the end I won. 
I used the method described above. I was actually going to post how I did it for future reference but your directions are great. 


Now the rear calipers are really being a pita. 


I can not get the piston to turn out unless I use a breaker bar on the tool. 

The dust boot was ripped when I changed the pads a few months ago and I think the caliper may be done. :facepalm:


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## JJ2K1 (Apr 10, 2003)

germancarnut51 said:


> The method that I use for installing the boot on the piston and onto the caliper is the one that I read on the instruction sheet that came with the OE TRW caliper seal kits that I use.
> 
> Using the right brake seal lubricant is important. You can't use WD40 or dishsoap, or just any slippery liquid you come across (like bearing grease). Using the wrong chemical lubricant can contaminate the brake system or can attack the rubber seals in the brake system. It has to be a lubricant specially designed for brake systems. I've read that Permatex makes a product. I use something named "Sil-Glyde" from a company by the name of "AGS" that I bought from "Automotion" about 20 years ago. I came in a big tube. Last year I did some research, and the company is still in business, and still makes the product, but I didn't look for a current retail source.
> 
> ...


I used your method here and it came out impressively easier than I thought the job was going to be. I used the Sil-Glyde like you mentioned, happened to have came with the TyrolSport brass caliper bushing set I just purchased. Once you seat the boot into the groove of the piston housing on the caliper, you can then begin to push the piston in gently by hand until it is seated all the way to the bottom.


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