Caliper Dust Boot Problem W124 1995 E320
 

Vehicle Information & Background:

I'm currently going through the brake system on my car. I have changed the brake hoses; removed, disassembled, and cleaned the front & rear calipers; and now I am trying to reassemble the calipers. I'm having difficulty getting the dust seals installed over the ridge on the caliper.

US Version
1995 Mercedes E320 Wagon
VIN Post F323055
W124.092 Chassis
M104.992 Engine

Dust Boot & Caliper Type:

Centric 143.35015 Caliper Repair Kit Front
Centric 141.35081 Front Brake Caliper

This is a fixed caliper with a ridge surrounding the piston housing. The Centric 143.35015 dust seals (38mm & 42mm) wrap around this ridge. Often the dust boots have a circlip that is expanded, and then placed around the dust boot to hold it in place. My dust boot, however, has the circlip built into the seal. It is not the type with the "teeth"...to be honest I don't know what that is, but I've seen others mention a type like that...this is not that. It is simply a rubber seal with a flat wire (the single piece unbroken circlip) embedded in it.

My Problem:

When I try to fit the dust boot onto the caliper it seems as if it is too small to fit, and I did lubricate the seal, the caliper, the piston...everything...with brake fluid before attempting installation. It's not off by much...probably less than a millimeter, but regardless of what I try it doesn't seem to fit. It definitely won't go in with just my fingers. I tried using 2 pairs of needle nose pliers and my fingers. I tried using a board & other various items in conjunction with a C-Clamp, my hands, and a hammer. I haven't tried a bearing/race/seal press to be honest because I don't happen to have one, but it just doesn't seem like even that would make a difference. I noticed that the seals I've tried pressing in have split basically right up the middle. It seems like that's where the diameter of the ridge and the diameter of the seal match up. Enough for half of it to make it around the ridge, but not all the way. It feels like a seal press would just be pressing it in the same half-way spot. Am I wrong? Would it somehow push it outward more allowing it to slide over the edge? I ordered 2 sets in order to redo both front calipers, and they both seem to be the same size. I don't know if these seals are just garbage and don't fit right, or if I'm missing something.

Someone Please Help Me! My car is up on jack stands right now, and I really need it. It's going to be a while anyways having to order & wait for parts, so I really need a response soon. I've been working on this thing for a while now, and every time I think I have it finished something else pops up. I desperately need to get it back on the road quickly.

Answers I'm Not Looking For:

1. Buy a new or manufacturer rebuilt caliper instead. I don't trust rebuilt calipers, and as cheap as they are I can't afford 4 calipers right now. My caliper bodies, housings, and pistons are all in good condition. I just needed to exercise the pistons, clean them up, and replace the seals to bring them back to being good as new minus the pretty paint that will quickly not be so pretty.

2. Bring it to a mechanic. Again, I can't afford that right now unless I can find a mechanic who would be willing to just connect the boots to the caliper for me, and only charge me for the roughly 5-10 minutes maximum it should take to do all four.

Answers I am Looking For:

1. How to properly install these seals

2. What tools I could use to properly install these seals

3. What seals people have used on their W124's that might work better, or be installed more easily.

4. Verification that this seal/caliper combination is generally problematic, and that the issue is not with the install method.

5. Kits that would work for my car that use the non-integrated circlip that you can spread to fit the ridge on the caliper.

Are you talking about the small gaitor that fits the slider pins of the ones that go over the end of piston itself? If it is the large one for pistons ,take it out wash it with warm water .Then try again ,.Never had a problem ,maybe the wrong size seals .

Yeah, these are the dust boots for the actual pistons not the pins. Actually, my calipers are fixed calipers, so they don't have the floating pins. These boots aren't really expandable at all either. They aren't the kind that you slide into piston housing to keep them in place. Instead they slide over a ridge just above the level of the piston housing They have a solid metal wire built into them, and the boot can only expand as wide as the wire. It's not like the ones that come with the clip that is cut to allow it to be spread apart and adjusted to a different size depending on how much or little you bend the clip.

I'm beginning to really think that these boots just can't be fit to it. I basically made a home made version of a seal press, and it made no difference.

Had the same problem with Centric kits on my SL. The boots were gray silicone and very slippery making install difficult. In the end I reinstalled the old boots ( black rubber ) with new piston seals.

In order to install the silicone boots a tool would need to be made that holds the boot square during install.

I agree with 97 SL320. I had the same issue with installing the Centric boots (silver/silicone type) on my 400E upgraded calipers. I was worried that I would not be able to use the brakes without fluid running out. Went to my mechanic after destroying 2 sets of boots and asked him if there was a trick and he said use silicone to lube the rim and it has to be pressed on squarely either by hand (near impossible) or with a tool. The boot seemed rather thin and I didn't want to risk destroying a third set. He advised using OE boots or reusing what I had. I told him my concerns about fluid pouring out of the boot if it wasn't seated properly or had a small hole, which mine did. I said the boot did not prevent the fluid from escaping the caliper, the inner ring did. The boot was just there to keep dirt out. He said I could even find some rubber or silicone sleeve that fit over the piston and use that as long as it could withstand the heat of the brakes. I reused my other boots and have not had any issues with the calipers since. Hope this helps.

Thanks guys. I've come to agree that in this case the dust boots can go perform unnatural acts with a duck. I put them on as best I can, and if that's not good enough tough. It's easy as can be when you have the type with the clips, but I will never try to install this type ever again!

Not sure on your caliper. They do make some seal installation tools that may help. Also, does this video on a VW caliper offer any help: https://www.youtube.com/watch?v=wvOpg7hASLs