Frozen rear caliper slider pin

Casey · Postby **Casey** » Thu Dec 20, 2007 6:45 am

I was trying to change my rear brake pads last night, wound the piston back with an allen key, removed the bottom slider pin with a 10mm spanner and then tried to flip the piston part of the caliper up. Uh oh

- it was stuck fast.

Used the handle of a rubber mallet and was eventually able to work this part of the caliper loose enough to swing it up and out of the way. The problem is that I cannot move this part of the caliper sideways as the top (fixed) slider pin seems to have an absolute death grip on it. It will swing in the vertical plane and I can get a side-to-side wobble on it but it will not slide off (to allow me grease the pin) or slide closer to the mounting bracket to allow new pads to be fitted. In desperation I emptied a can of WD40 under the dust boot, wacked it with the above mallet as hard as my mechanical sympathy would allow, and will give it another bash tonight.

Anyone been here before and how did you separate the two? Or am I up for a new caliper?

Juffa · Postby **Juffa** » Thu Dec 20, 2007 8:18 am

Happened to me on my '90 Mariner Blue.

The fixed pin is actually threaded and screws into the caliper bracket. While it is still seized inside the caliper body it is now rotating at the threaded end. Great you think, I will just rotate/screw it off. No such luck, you will find you can't rotate it through a full 360 degrees.

I took the whole thing off the car and used the BFH to no avail. I ended up getting a 2nd hand (but good) unit from a wrecker, cost me about $165.

I did some reading on the big forum when it happened to me and believe that you can buy a replacement 'fixed' slider pin. In theory this means if you damage the slider pin when trying to free it, you can get the pin on its own. Maybe check with your dealer to see if the part is available?

Good luck.
J

mazlot · Postby **mazlot** » Thu Dec 20, 2007 8:27 am

Troy,

All as Juffa said, but before using the BFH, I dosed mine with copious amounts of DWF/CRC, and it eventually freed itself with some encouragement.

Use a quality heat resistant grease when you refit

Jeff

Casey · Postby **Casey** » Thu Dec 20, 2007 9:53 am

Thanks guys. I will try again after the WD40 has had a chance to penetrate a bit.

I pulled the dust boot away and noticed that the slider pin has two longitudinal grooves (less then 0.5mm square) machined into it approx 180 degrees apart. Are these simply a lubrication galley or are they some form of sinister keyway locking the assembly in place unless correctly aligned?

mazlot · Postby **mazlot** » Thu Dec 20, 2007 10:01 am

I reckon lubrication, I don't recall anything inside the caliper, because it will rotate on the pin.

Garry · Postby **Garry** » Thu Dec 20, 2007 10:07 am

Lubrication

trader · Postby **trader** » Thu Dec 20, 2007 10:54 am

Casey, I have the same problem with my Eunos 500. I bought a second hand unit because the new ones were gold plated. This is the second time I've had this problem and although Mazda do not mention it in services I now lubricate every twelve months. I am currently soaking mine in 303 (supposed to be better than WD40). To do this I have drilled a hole in the end of the casting. I will make it big enough to put a rod down it so that I can hit the slider with a hammer. If it works I'll let you know. I then intend to tap in a grease nipple. At least I'll have a spare.

trader · Postby **trader** » Thu Dec 20, 2007 5:44 pm

Casey, your post got me moving. My caliper has been sitting in the vice for days with oil pentetrating the slider through the hole I drilled in the caliper. I was then able to use a cut down drill bit to hammer on the end of the slider. Took awhile but eventually it came apart - did the final bit by just hammering on the bracket while I held it in my other hand. The slide grooves were clogged up and main damage was on the bore of caliper. When I put it back together I will just bog the hole up after using silicone brake grease.

Casey · Postby **Casey** » Thu Dec 20, 2007 7:42 pm

Its no better tonight - still no budging.

Being an impatient bugger and with a number of jobs piling up around the house I'll just refit the worn pads and take it to the lads at Carco or to a brake specialist to sort out.

Casey · Postby **Casey** » Thu Jan 03, 2008 6:14 pm

Well - I finally got this fixed today (in case anyone else has the same problem).

ACT Brakes in Belconnen did a fabulous job and unfroze the caliper, replaced both sets of brake pads (genuine Mazda which I provided), greased the lot up and adjusted the handbrake. All for a total of $60 which I think is absolutely brilliant - considering I had already spent about three nights on it and got nowhere.

I also bought the right type of grease to stop this happening again - Sta Lube Brake Caliper Synthetic Grease. Made by CRC.