135i Calipers Fitted to Z4M

[Meds]

Nice one! Keep us posted with how the install goes,!

Hmmm... I've hit a snag...
The disc will not fit between pad gap. Bugger.
It fits between the caliper opening, but the pads (with pistons pushed far back as possible) close the opening by another 2mm or so.
The disc will not go..
My only way around this is to grind the pads down? (the pads are nearly new)

 

[Ed Doe]

Nice one! Keep us posted with how the install goes,!

Hmmm... I've hit a snag...
The disc will not fit between pad gap. Bugger.
It fits between the caliper opening, but the pads (with pistons pushed far back as possible) close the opening by another 2mm or so.
The disc will not go..
My only way around this is to grind the pads down? (the pads are nearly new)

Are you sure? I fitted new pads and had no issues with this?

You might find that as you push the top pistons down, the bottom two 'creep' back open?

If you open the pistons up as much as possible can you hold the pads apart with your fingers and wiggle the calipers onto the disc?

 

[Meds]

I've tried a few things to get the pads far enough apart..
With no luck.
Had the pads out and pushed all the pistons back in turn. The callipers are not attached to the brake lines yet, so not under any pressure.
I'm going to get the pads out and clean them down as they're still caked in black dust from my previous install. Then I can try again, with a cleaner set up.

 

[Meds]

OK.. if I really push, the caliper with pads go over the disc.. but with zero wriggle room.
It's like I need .5mm shaving off the pads.!
I've done this in the garage, off the car, I'm sure of I proceed with the actual install, they'll be rubbing away until the pads wear down.
How very odd.. and a real downer.
These brakes will be the end of me, I'm sure..

 

[Ed Doe]

OK.. if I really push, the caliper with pads go over the disc.. but with zero wriggle room.
It's like I need .5mm shaving off the pads.!
I've done this in the garage, off the car, I'm sure of I proceed with the actual install, they'll be rubbing away until the pads wear down.
How very odd.. and a real downer.
These brakes will be the end of me, I'm sure..

Does the disc rotate with the pads in?

Imo as long as the wheels are able to rotate relatively freely, chuck the pads on, chuck it all together and go for a drive. See how warm it all is after a short drive... Then go for a longer one and so on.

Id be prepared to bet the pistons will resettle after a bit of use and you'll have no drag.

 

[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-ds2500-brake-pads-front-ap-6-pot-caliper-frp3076h-fer3076h.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? :lol:

 

[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...?!

 

[Meds]

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

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.