135i Calipers Fitted to Z4M

[Meds]

Does the disc rotate with the pads in?

Hard to tell as this is all a dry fit, off the car.
I had to rubber mallet them on. Both sides. Seriously tight.

The pistons are fully depressed and sitting flush with the seals, no doubt.
The pads are as far back as possible. The callipers are not connected to the brake line so nothing is pressurised.

The calliper needs to be forced onto the disc, and then forced off again. It's too tight.
Both sides share the same symptom.

After some research, there are a few different pad widths available. Ranging from 16mm to 17mm.
My Brembo pads, part number: P 06 041 are 17mm.

I know someone with a bench sander and I'll head over there to shave a trifle off the pads for an experiment.

Either way, thinner pads will solve my issue and something to note for others doing this uprade.

[Ed Doe]

Really strange - I fitted these to mine with new discs and had no issues (you can see from the specs they were 17mm pad depth too) - that's a real puzzler!

https://www.burtonpower.com/ferodo-ds25 ... 3076h.html

[Meds]

maybe, just maybe the replacement pistons and seals sit further out in the calliper body than the OEM pistons and seals?
And this was not noticeable when using the thinner discs I was using before, 26mm from memory.
And that's what's causing my lack of room for the 28mm CSL disc. ?

[Ed Doe]

maybe, just maybe the replacement pistons and seals sit further out in the calliper body than the OEM pistons and seals?
And this was not noticeable when using the thinner discs I was using before, 26mm from memory.
And that's what's causing my lack of room for the 28mm CSL disc. ?

Yeah that could be it, I forgot to ask (I've not read back over the thread in a while!) if you'd had them refurbed and if the seals were definitely seated right...!

I think all things being equal, a tickle of the pads with a sander sounds like the best solution, if you can't drive the car with the pads as is...

[Meds]

maybe, just maybe the replacement pistons and seals sit further out in the calliper body than the OEM pistons and seals?
And this was not noticeable when using the thinner discs I was using before, 26mm from memory.
And that's what's causing my lack of room for the 28mm CSL disc. ?

Yeah that could be it, I forgot to ask (I've not read back over the thread in a while!) if you'd had them refurbed and if the seals were definitely seated right...!

I think all things being equal, a tickle of the pads with a sander sounds like the best solution, if you can't drive the car with the pads as is...

Here they are, but with the calipers not budging, they're stuck on and the only way to remove them is either a tap from a rubber mallet or man-handle them, rolling around the floor like a Jiujitsu fighter .

Over the next few days, I'll hopefuly get the pads sanded a touch, then go from there.

[Meds]

The plot thickens..
It's not the pistons that are preventing the pad moving outwards enough. It's the groove in the caliper where the pads slide, there's a small shoulder that prevents the pads moving any further outwards.
My pads are firmly against this shoulder.

Pads are 17mm and disc is 28mm.

My only option is thinner pads.

[Ed Doe]

Can you grind/fettle the pad backing plate to clear the groove in the caliper?

Looking at that photo it also looks like the screws are pushing into the pad backing plate too - can you wind them out a bit?

[Meds]

Can you grind/fettle the pad backing plate to clear the groove in the caliper?

Looking at that photo it also looks like the screws are pushing into the pad backing plate too - can you wind them out a bit?

I'm not sure I can, that shoulder looks to serve a purpose and if the pads are allowed to move inside it, it may case rattle/squeek ?
It looks like my pistons are exactly inline with this shoulder, too. So even if I did that, it wouldnt give me any more room.

Yes, the photo does show the pin threads protuding into the pads, but they're not. loadsa room behind them. I think the photo perspective is kidding us.

[Ed Doe]

Stupid question, but you definitely have the pads the fitted the right way up?

[Ed Doe]

Dunno if any of these pics help, it's all the pics I could find of my old setup (after I took them off prior to selling the car). I'm not quite sure if mine had the same ledge as yours or not...?!

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IMG_20181118_144630.jpg (144.01 KiB) Viewed 272 times

IMG_20181118_144624.jpg (179.61 KiB) Viewed 272 times

IMG_20181118_144603.jpg (134.33 KiB) Viewed 272 times

[Meds]

Stupid question, but you definitely have the pads the fitted the right way up?

Yes, all present and correct.

[maupineda]

I had a similar issue where it was a tight fit, it was not that bad to the point it would not rotate, I assembled and drove it slowly for 20-30 miles, and all bedded in correctly. I am sure the next pad change it won’t be an issue as the disc wears off a bit, or as you have mentioned, file the pads down 0.5 - 1mm and all will be good.

[Meds]

I had a similar issue where it was a tight fit, it was not that bad to the point it would not rotate, I assembled and drove it slowly for 20-30 miles, and all bedded in correctly. I am sure the next pad change it won’t be an issue as the disc wears off a bit, or as you have mentioned, file the pads down 0.5 - 1mm and all will be good.

Interesting to read that yours were also tight. Thanks for sharing.
We all know this conversion is a tight squeeze but maybe there's some manufacturing differences among the 135i calipers or pistons that result in some being tighter than others.

They'll rotate once on the car, but I can imagine it'll take a good heave on the wheel rather than it spinning free. It's very tight.
I have everything ready to sand the pads down, just a trifle, .5mm will be fine.
Belt sander and verniers at the ready. But it's flipping cold today (I want to do outside), and I'm rammed with work, so maybe a weekend task.

[B21]

I've come to this late..I use the same calipers on my 35is..are you using some custom pads?

[Meds]

I've come to this late..I use the same calipers on my 35is..are you using some custom pads?

No, OEM pads here.
Brembo in my case. 17mm thick.