BMW 57/25 Front Brake Calipers. Slider Lubricant required?
Discussion
Title say it all. Having recently given the front Brake Calipers a severe cleaning and lots of TLC on my Rover 620ti which improved the braking on that car, thought I'd do the same to my MG ZT which has numerous BMW parts including the front Brake Calipers. Partially dismantling those 57/25 BMW Calipers for cleaning, revealed the twin sliders of these single pot calipers are housed in rubber or something rubber like, and no trace of old lubricant. Lubricant helps the sliders ... slide .. and also protects the slider metal from corrosion. However, I suspect the BMW slider design runs without lubricant in their rubber housings. Even so, I'm tempted to apply a smear of say LM Grease if only to protect the metal sliders from corrosion.
Before doing so, can anyone confirm these sliders are designed to run without lubricant or not. In the latter case, which slider lubricant would be recommended.
Both cars are well over ten years old and both have passed their MoTs without any Brake issues. That does not mean the brakes are working at maximum efficiency as is clearly demonstrated by benefits of the TLC which included changing the Brake Fluid for fresh on my sixteen year old Rover 620ti.
Before doing so, can anyone confirm these sliders are designed to run without lubricant or not. In the latter case, which slider lubricant would be recommended.
Both cars are well over ten years old and both have passed their MoTs without any Brake issues. That does not mean the brakes are working at maximum efficiency as is clearly demonstrated by benefits of the TLC which included changing the Brake Fluid for fresh on my sixteen year old Rover 620ti.
When I did some reading about this recently the concensus was either leave them dry, or use a silicon based grease, but don't use a mineral oil based grease like Castrol LM or copper slip as it will cause the rubber bungs to swell up and make the brakes bind.
When I got a new (well, refurbed) caliper it came with a little vial of silicon based grease.
When I got a new (well, refurbed) caliper it came with a little vial of silicon based grease.
I have since searched some BMW enthusiasts sites. Opinions are divided but, a print copy of the BMW Workshop manual ( a post on one of the USA BMW sites ) states quite clearly that lubricant should not be used on these sliders.
My slider pins were remarkably totally free of any signs of corrosion and little dirt present either. Both the rubber housings the slider pins slide into were cleaned and the carriers slid back smoothly when I reassembled the Calipers without any lubricant. Required quite a bit of effort though.
The end of each of the four pins have a hex ( six flats ) location for an Allen Key. These are accessible by prising off the plastic end caps of the rubber slider housings. Apparently these can be undone and removed via those access caps and the caliper then is free to be removed. I only briefly read that part of the workshop manual copy in that USA post.
Considering those sliders will move very fractionally over the next few years of use, that they have survived remarkably well for thirteen years now, I think I'll leave the sliders and their rubber housings dry, but very clean.
My slider pins were remarkably totally free of any signs of corrosion and little dirt present either. Both the rubber housings the slider pins slide into were cleaned and the carriers slid back smoothly when I reassembled the Calipers without any lubricant. Required quite a bit of effort though.
The end of each of the four pins have a hex ( six flats ) location for an Allen Key. These are accessible by prising off the plastic end caps of the rubber slider housings. Apparently these can be undone and removed via those access caps and the caliper then is free to be removed. I only briefly read that part of the workshop manual copy in that USA post.
Considering those sliders will move very fractionally over the next few years of use, that they have survived remarkably well for thirteen years now, I think I'll leave the sliders and their rubber housings dry, but very clean.
e39darren said:
I've always used a bit of copper slip and never had any problems in nearly 20 years of doing my own and family and friends brakes
I've got to say I've done this too (unless the parts for the job included the slider grease), never caused me any issues either. Probably another one of these things that were common place before the internet was popular though!Gassing Station | General Gassing | Top of Page | What's New | My Stuff