'S'-type wrote: ↑Wed Nov 18, 2020 9:15 pm
....... I was of the understanding that it wasn't worth mucking around with old calipers especially if there was any kind of corrosion in the bores. Heard bad things about splitting them too......
I used to fret quite a bit about the bores, but if you think about it they are pretty tolerant of bore corrosion. I think the primary functional surface is the piston and the seal in the bore.
EDIT I would think that they are very intolerant of any corrosion around the seal area of the bore however! That situation could be very dangerous.
Maybe this is all a waste of time since I didn't realize new ones were so inexpensive. Think I will be buying new ones!...
Last edited by Gary Schulz on Thu Nov 19, 2020 12:30 pm, edited 2 times in total.
I've rebuilt many brake callipers and it is a very straight forward job, for the best results they do need to be shot blast first and then if very corroded do immerse them for 24 hours in a soloution such as Eastwoods rust dissolver to eke out of those areas that the blast media might not reach. I'm presently setting up a plating system to do this myself since I had a poor experience via my local plating shop...
There is a company in the west country called big red and they supply the new rubber seal kits.
There are a couple of things that (as far as I am concerned) make a calliper not worth refurbing. The first is the bleed nipple, if this area shows any sign of wear, damage or fatigue at all, bin it, it's not worth worrying about. In the dark & distant past I repaired many callipers by fitting an insert that could fix this, but with new callipers cheap as chips, why bother.
The second is corrosion, if the are around the dust seal or main seal shows any serious corrosion, chuck it.
If you want to keep as much of your car as original as possible, I can understand why someone would want to refurbish callipers, however when you can buy new ones for around £50 I haven't bothered for years. Lst pair I did were 997 Cooper ones.
Personally, I would NEVER plate any of the machined surfaces on a brake calliper. These were left unplated / never plated for a reason. Refurbishing stuff is all well & good but making stuff shiny over keeping it safe or as the manufacturer intended seems crazy to me!
Just digging around the garage yesterday I found I still have a nos caliper in it's grease proof paper and was surprised to see it was not plated but just satin black.
I don't have any NOS, but all the ones I have refurbished seem to have been finished with some sort of dark gray or "blackish" finish as well.
I just thought mine were too old and nasty and all the plating was gone! You are right, coating with some high temp paint is far more practical and if original makes it all the better.
Gray wrote: ↑Mon Nov 23, 2020 4:19 pm
Just digging around the garage yesterday I found I still have a nos caliper in it's grease proof paper and was surprised to see it was not plated but just satin black.
I don't recall them being 'in the day' having a plated finish, but just black. All the same, I feel if restoring, plating them is an ideal finish for longevity, they can then be painted over to look the part.
Gray wrote: ↑Mon Nov 23, 2020 4:19 pm
Just digging around the garage yesterday I found I still have a nos caliper in it's grease proof paper and was surprised to see it was not plated but just satin black.
I don't recall them being 'in the day' having a plated finish, but just black. All the same, I feel if restoring, plating them is an ideal finish for longevity, they can then be painted over to look the part.
The only parts that need to avoid corrosion are internal. There is plenty of material on the outside to corrode before it is a functional issue. Once you have blasted off the last fifty years of corrosion I bet you would be hard pressed to tell the difference with new. Plate if you want but it achieves not much accept a nice feeling you have done your best.
From a professional Mini Restoration specialists view, someone who actually does this every day and gets paid for it, when we recondition genuine callipers, I strip them bare, blast them with glass bead or have them Hydroblasted. Then send them off to be Zinc/chromate plated. I have done hundreds of callipers this way, with zero issues.
"Yellow Zinc Plating refers to the color of the chromate that is applied after zinc has been deposited on to the surface of the part. Yellow chromate prevents the zinc from corroding and increases the overall protection of the finish. This finish provides a rainbow or iridescent appearance with dominant yellow tones"
You do not have the required permissions to view the files attached to this post.
Just thought I would mention that the calipers can crack at the thinnest point in the bores due to the corroded pistons expanding so if you have seized pistons get the magnifying glass out before going any further.
For those that are quite rusty and you'd like to see if they can be salvaged, I've been using a product called 'Metal Rescue' the past year or so. It doesn't seem to harm most metals, so even if you have a combination of materials, there's no issue with it, in fact I started using when I have a piston that wouldn't budge for rust, I tried all the usual stuff and Metal Rescue was the only thing that worked. I also find it doesn't go off or loose it's zing like so many other things I've tried, it would be ideal for cleaning up Calipers, just clean them as best you can, including inside, then leave them soak a few hours.
Andrew, you mentioned having your Calipers Nickle Plated before Zinc. I can well see that working but sadly for me, there's no local firms who do Nickle. Copper Plating for a Base for Zinc would also work.
So, the callipers are back from a decent plater and ready to reassemble with new pistons and seal kits. Will also be using new bolts with I will Loctite in.
What does one use for seal lubricant to use when reassembling ? Brake fluid , red brake grease or something else ?
I wouldn't ever use brake fluid to lubricate anything Andy. It's hydroscopic - and so-said, can sop-up or absorb up 1/3 its own weight of water. BAD news if the part is not going to be used quickly. Lube the seals, the pistons and inside the bores in rubber grease/red grease according to an old Lockheed letter I had as a student note regarding keeping rebuilt brake parts on the shelf or in storage. That way the seals and pistons will be ready to go once you fill the system with your choice of brake fluid. In my case, it's NON hydroscipic silicon fluid . Why does it keep spell checking hydroscopic????
Apart from Peter's excellent advice, I just hate the feel of that stuff on my hands. Yes, I should wear gloves, but having worked on so many things without them for so long, I've tried and not succeeded. Too old school.
The very last thing I do on restoration/rebuilds, is the brake hydraulics, and, as Peter says, never ever assemble them with brake fluid, they will start to rust very soon.......
I use only proper brake assembly grease, many different brands and types, I get mine from a local brake rebuilders, and, completely coat any areas that will be exposed internally before being properly filled and bled, which, is the very very last thing I do......
I know a guy that had 5 or six restorations going on, and, once he got the rolling shells done and painted, spent a good deal of time doing all the brakes on all of them (wanted to get the job done and out of the way), used regular dot 3 brake fluid, as assembly lube....Needles to say, when he finally got some of them finished 2-3 years later, the brake systems were useless, needing complete replacement again.....I did try to warn him, but, we all know how that goes.....
Thanks guys, I was planning to use red rubber grease but made the mistake of watching a few You Tube videos on the topic and they used brake fluid !! I wasn’t keen on the idea so thought I’d run it past the forum
Andrew1967 wrote: ↑Mon Mar 22, 2021 7:39 am
Thanks guys, I was planning to use red rubber grease but made the mistake of watching a few You Tube videos on the topic and they used brake fluid !! I wasn’t keen on the idea so thought I’d run it past the forum
Shows again that whatever information you source from YouTube and similar media needs thorough fact checking. So much half-truths and misinformation out there..
I second the use of special brake assembly grease - I use ATE brake assembly paste
In all fairness, Brake Fluid is what's recommended by BMC / Leyland and many of the component manufacturers, one just needs to be aware of it's short comings.
Likewise, rubber grease can dry out, which is usually less of an issue but has in extreme situations led to tearing of the rubbers, but usually, when that happens, the seals just stick.
