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Re: New front discs at 34,000 miles? (55,000 km in new money)

Posted: Wed Dec 02, 2020 2:05 am
by littlescrote
Nibbo wrote:
Mon Nov 30, 2020 3:33 am
New calipers for mine, NOT under warranty.
Outrageous isn't it? You shouldn't need new calipers after that distance should you?

Re: New front discs at 34,000 miles? (55,000 km in new money)

Posted: Thu Dec 03, 2020 5:54 am
by Nibbo
Well I thought I was hard done by...
A work colleague who bought his PHEV after a quick go in mine has just been told his need new pads, disks and calipers ALL ROUND!!! :o :evil:
His is a 2014 with £45k miles.

Re: New front discs at 34,000 miles? (55,000 km in new money)

Posted: Fri Dec 04, 2020 4:30 am
by ThudnBlundr
Am I missing something? I've never replaced callipers on any car in normal service, even my '72 MG which I've owned since '85. In fact the only car I've owned that has had them replaced is the PHEV, and that was under warranty because of a design fault.

Re: New front discs at 34,000 miles? (55,000 km in new money)

Posted: Fri Dec 04, 2020 5:57 pm
by jaapv
I doubt whether your MG weighs 1900 kg... ;) Never had to replace the callipers on my '63 TR4, which I own since 1993, either.

Re: New front discs at 34,000 miles? (55,000 km in new money)

Posted: Sat Dec 05, 2020 2:18 am
by ThudnBlundr
But what wears out on a calliper? Why would it ever need replacing?

Re: New front discs at 34,000 miles? (55,000 km in new money)

Posted: Sat Dec 05, 2020 5:07 am
by oscarmax
It is mainly the piston seals, the piston can corrode especial if the piston boots deteriorate and allow in moister and debris, in the worst case scenario damage to the calliper body .

Re: New front discs at 34,000 miles? (55,000 km in new money)

Posted: Sat Dec 05, 2020 7:13 pm
by jaapv
The problem is that ABS systems must use Glycol-based brake fluid which can easily absorb moisture and thus cause corrosion. TheDOT5 Silicon-based fluids are better in that respect. However, they cannot be interchanged.

Re: New front discs at 34,000 miles? (55,000 km in new money)

Posted: Mon Dec 07, 2020 4:23 am
by littlescrote
The PHEV caliper issues are generally neither of those 2.

For the fronts it is a bit piston corrosion, but also sliding pin corrosion. Both of these issues are nothing to do with fluid used etc, but are all about them not getting exercised much. The way that we tend to try and drive these things for best range means that we use regen braking and easing off the gas pedal rather than hard stops on the brake pedal which move the pistons significantly and frequently.

For the rears, it's a bit of the same of the fronts, but with the additional problem of the parking brake mechanism corroding as it doesn't always get used enough due to lack of piston movement and owners just putting it in P (or just switching off without applying the parking brake which defaults to P and locks the transmission negating the perceived need for the parking brake).

Both of these issues can be avoided by better quality materials, but as the calipers are platform shared with French cars, that doesn't happen due to cost constraints on the suppliers. So, as owners we have to take care of them ourselves by protection/lubrication (regular cleaning and servicing) and regular exercising of the calipers through hard braking.

Basically, they don't make 'em like they used to!

Re: New front discs at 34,000 miles? (55,000 km in new money)

Posted: Wed Dec 09, 2020 9:18 pm
by BCbackroader
My dealer here in Canada services the slider pins as part of every routine 8,000 km service. I now have 131,000 km on my '18, and the brake pads are not yet worn enough to replace.

Re: New front discs at 34,000 miles? (55,000 km in new money)

Posted: Thu Dec 10, 2020 3:32 am
by Nibbo
BCbackroader wrote:
Wed Dec 09, 2020 9:18 pm
My dealer here in Canada services the slider pins as part of every routine 8,000 km service. I now have 131,000 km on my '18, and the brake pads are not yet worn enough to replace.
Your mileage / wear ratio is what I would expect driving it the way I do with very little actual braking.
Perhaps MMC are aware of the issue but let it go on as a money spinner for the dealer network :o :twisted: