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Chat Area => General Car Chat => Topic started by: Doctor Gollum on 12 February 2026, 14:33:43

Title: A simple disc and pad change...
Post by: Doctor Gollum on 12 February 2026, 14:33:43
...yeah right >:(

You know you're in trouble when you have to cut the pad retaining pins off because they're too bent to push through.

Pad warning light has been on a while. Got the pads and new discs because, well, you know...

Turns out the warning was on because a seized piston was making the opposite ones work harder.

Needs a new caliper and my thought process is to fit a pair.
Title: Re: A simple disc and pad change...
Post by: Andy B on 12 February 2026, 16:52:03
I'd to go & buy a 7mm allen key and then later buy an 11mm allen key when I did brakes on the R Class. I went to various motor factors for them ... not a chance. Had to order off the interweb  ???
Title: Re: A simple disc and pad change...
Post by: Andy B on 12 February 2026, 17:00:59
.....
Needs a new caliper and my thought process is to fit a pair.

When my daughter's Yaris was suffering from a sticker caliper (only happened after new pads) I looked into a new pattern caliper. They weren't expensive but my thoughts were it'd be better to spend money & time fitting a new piston & seals to an OE caliper rather than using an unknown quality pattern replacement. In the end it was only about £20 for the parts to refurb the original caliper.
Title: Re: A simple disc and pad change...
Post by: Doctor Gollum on 12 February 2026, 17:42:42
To be fair to MB, considering they're 4pot Brembos jobbies, they're £360 plus VAT...

If I had known beforehand, I might have looked into the S65 set up, but I already have the discs and pads for mine ;D

Local factors can't get them and all the pattern ones on line look to be for the V6 cars which have smaller discs.

If they can be refurbished then happy days, but it's a wait for the calipers or the rebuild kit and if the bores are done then I won't be any better off. Notwithstanding that I would rather not leave the brake system open for that long.
Title: Re: A simple disc and pad change...
Post by: Andy B on 15 February 2026, 10:51:09
.... and if the bores are done then I won't be any better off. Notwithstanding that I would rather not leave the brake system open for that long.

The bore of a caliper is irrelevant  .... the seal stays static in the bore while the piston slides through it ie the  complete opposite of engines pistons
Title: Re: A simple disc and pad change...
Post by: Field Marshal Dr. Opti on 15 February 2026, 11:16:08
I'd to go & buy a 7mm allen key and then later buy an 11mm allen key when I did brakes on the R Class. I went to various motor factors for them ... not a chance. Had to order off the interweb  ???

I have an old coffee tin with probably more than 100 allen keys in it. Yet to come across a size I don't have.....so far. >:D
Title: Re: A simple disc and pad change...
Post by: Doctor Gollum on 15 February 2026, 14:18:17
.... and if the bores are done then I won't be any better off. Notwithstanding that I would rather not leave the brake system open for that long.

The bore of a caliper is irrelevant  .... the seal stays static in the bore while the piston slides through it ie the  complete opposite of engines pistons
Will find out when it gets stripped down. ;)
Title: Re: A simple disc and pad change...
Post by: Andy B on 15 February 2026, 20:51:58
I'd to go & buy a 7mm allen key and then later buy an 11mm allen key when I did brakes on the R Class. I went to various motor factors for them ... not a chance. Had to order off the interweb  ???

I have an old coffee tin with probably more than 100 allen keys in it. Yet to come across a size I don't have.....so far. >:D

I've hundreds of them  .... tiny 1.5mm up to 19mm & probably bigger. But as above, no 7mm or 11mm (did actaully have a 7 but it wouldn't fit in)
Title: Re: A simple disc and pad change...
Post by: Kevin Wood on 15 February 2026, 20:58:28
I've hundreds of them  .... tiny 1.5mm up to 19mm & probably bigger. But as above, no 7mm or 11mm (did actaully have a 7 but it wouldn't fit in)

Same when I got the XE. One end needs a 7mm long hex key and I think that's an 11mm at the other end. Probably the same manufacturer of calipers. Fancy picking the two sizes that nobody will have in their toolbox. >:(
Title: Re: A simple disc and pad change...
Post by: Andy B on 15 February 2026, 21:32:56
I've hundreds of them  .... tiny 1.5mm up to 19mm & probably bigger. But as above, no 7mm or 11mm (did actaully have a 7 but it wouldn't fit in)

Same when I got the XE. One end needs a 7mm long hex key and I think that's an 11mm at the other end. Probably the same manufacturer of calipers. Fancy picking the two sizes that nobody will have in their toolbox. >:(

Indeed ... fancy that ... obviously an oversight!  ::) ::) ;D ;D
Title: Re: A simple disc and pad change...
Post by: YZ250 on 15 February 2026, 22:39:56
I'd to go & buy a 7mm allen key and then later buy an 11mm allen key when I did brakes on the R Class. I went to various motor factors for them ... not a chance. Had to order off the interweb  ???

I had to go out and buy a couple of sets of triple square sockets (XZN) when I bought the BMW’s and the Audi’s. I daresay you’ll come across them somewhere on Mercedes as well, as the Germans like fitting them on high torque applications, although strangely they’ve used them to hold the undertray in place on the Audi’s.  :-\
Title: Re: A simple disc and pad change...
Post by: Doctor Gollum on 16 February 2026, 00:08:18
Not seen one on a Mercedes yet, but VAG use them for everything and tighten them to 40,000 Nom before building the rest of the car around it...

Case in point... Replacing vented rear discs on pretty much every Golf based horror is almost impossible without wondering if you really need to remove the subframe >:(

To Andy's earlier point, the pistons are aluminium and pistons appear to be coated with something. The offending one is corroded enough to be in grippable... The surface is chamfered powder.
Title: Re: A simple disc and pad change...
Post by: TheBoy on 16 February 2026, 08:18:13
I'd to go & buy a 7mm allen key and then later buy an 11mm allen key when I did brakes on the R Class. I went to various motor factors for them ... not a chance. Had to order off the interweb  ???

I have an old coffee tin with probably more than 100 allen keys in it. Yet to come across a size I don't have.....so far. >:D
They are Teves/ATE callipers that us "less than common" allen keys.

Fords from the 80s and 90s often used Teves with the 7mm allen bolt, but with discs and callipers getting larger, 11mm ones are becoming more common.

Most allen key sets or socket sets with allen bits do not include these sizes, hence many peiople get caught out when starting the job....
Title: Re: A simple disc and pad change...
Post by: TheBoy on 16 February 2026, 08:22:49
I've hundreds of them  .... tiny 1.5mm up to 19mm & probably bigger. But as above, no 7mm or 11mm (did actaully have a 7 but it wouldn't fit in)

Same when I got the XE. One end needs a 7mm long hex key and I think that's an 11mm at the other end. Probably the same manufacturer of calipers. Fancy picking the two sizes that nobody will have in their toolbox. >:(
Yup, XE uses Teves/ATE brakes, and are 7mm at rear and 11mm at front.  Worth ensuring you have both, and I'm staggered you haven't had to change the pads at the front yet :o

Additionally, when you do, the wear sensors are stupid money from JLR - something like £25 a pop last time I bothered checking.  If you're not in a hurry, they are around £2 each from Ching Chong land, which makes it almost worthwhile replacing them rather than pissing around trying to short them.
Title: Re: A simple disc and pad change...
Post by: Andy B on 16 February 2026, 08:31:03
......

To Andy's earlier point, the pistons are aluminium and  .....

I believe that some MB calipers even have some kind of plastic piston  ???
Title: Re: A simple disc and pad change...
Post by: Doctor Gollum on 16 February 2026, 12:08:53
......

To Andy's earlier point, the pistons are aluminium and  .....

I believe that some MB calipers even have some kind of plastic piston  ???
I have heard that rumour in relation to them... Possibly lacquer or something but the piston is definitely aluminium from the corrosion on it.

Someone on MBWorld is constantly slagging MB off about inferior parts and crappy electrical components... Doesn't stop him driving a 17 year old S Class though ;D Plastic pistons were another of his observations. :-X
Title: Re: A simple disc and pad change...
Post by: YZ250 on 16 February 2026, 13:09:19
………
Doesn't stop him driving a 17 year old S Class though ……

There’s a 1998 (W140 as opposed to W220 I believe) Mercedes Benz S500 around our way. I don’t know the guy but he doesn’t hang about in it, which is brave considering the mpg.  ;D  He drives like he’s racing someone and he’s clearly local judging by the lines he took on the B4011 when I tagged along behind him.  ;D  I was impressed.  :y
Title: Re: A simple disc and pad change...
Post by: Doctor Gollum on 16 February 2026, 14:25:23
………
Doesn't stop him driving a 17 year old S Class though ……

There’s a 1998 (W140 as opposed to W220 I believe) Mercedes Benz S500 around our way. I don’t know the guy but he doesn’t hang about in it, which is brave considering the mpg.  ;D  He drives like he’s racing someone and he’s clearly local judging by the lines he took on the B4011 when I tagged along behind him.  ;D  I was impressed.  :y
They're pretty agile considering the sheer bulk 8)

Nowadays we take multilink suspension for.granted, but when the W140 came out it was a big deal...
Title: Re: A simple disc and pad change...
Post by: Field Marshal Dr. Opti on 16 February 2026, 14:28:17
………
Doesn't stop him driving a 17 year old S Class though ……

There’s a 1998 (W140 as opposed to W220 I believe) Mercedes Benz S500 around our way. I don’t know the guy but he doesn’t hang about in it, which is brave considering the mpg.  ;D  He drives like he’s racing someone and he’s clearly local judging by the lines he took on the B4011 when I tagged along behind him.  ;D  I was impressed.  :y
They're pretty agile considering the sheer bulk 8)

Nowadays we take multilink suspension for.granted, but when the W140 came out it was a big deal...

My 2006 CLS 500 was decently quick considering it's cooking 5 litre V8 only churned out 306BHP.
Title: Re: A simple disc and pad change...
Post by: Kevin Wood on 16 February 2026, 15:32:22
I've hundreds of them  .... tiny 1.5mm up to 19mm & probably bigger. But as above, no 7mm or 11mm (did actaully have a 7 but it wouldn't fit in)

Same when I got the XE. One end needs a 7mm long hex key and I think that's an 11mm at the other end. Probably the same manufacturer of calipers. Fancy picking the two sizes that nobody will have in their toolbox. >:(
Yup, XE uses Teves/ATE brakes, and are 7mm at rear and 11mm at front.  Worth ensuring you have both, and I'm staggered you haven't had to change the pads at the front yet :o

Additionally, when you do, the wear sensors are stupid money from JLR - something like £25 a pop last time I bothered checking.  If you're not in a hurry, they are around £2 each from Ching Chong land, which makes it almost worthwhile replacing them rather than pissing around trying to short them.

Oh, I have changed them several times and consigned the wear sensors to the bin.