[ThomasR]

I also went with reman'd semi-loaded calipers front and rear. I ordered factory pads to go with this. While the Akebono's are great on my wife's E90 they are horrible on the X3. I want that touchy stock BMW brake feel again (well touchy stock except for stock F25 brakes).

[hardparker]

Originally Posted by ThomasR

I also went with reman'd semi-loaded calipers front and rear. I ordered factory pads to go with this. While the Akebono's are great on my wife's E90 they are horrible on the X3. I want that touchy stock BMW brake feel again (well touchy stock except for stock F25 brakes).

Cool. Let us know how you like the X5 50i / 550i rear setup once you've got it installed. I love mine with EBC YellowStuff pads. I suspect you'll appreciate the upgrade, too.

[ThomasR]

I just got all of the parts in. Good grief the rotors are HUGE! The rear Brembo rotors are a thing of beauty...polished aluminum hats. The Brembos front and rear also came with the set screw which was not listed in the description. I know the stock X3 rotors use the same set screws but it was a nice surprise they included them.

[hardparker]

I just posted up some info about the rear upgrade.

https://x3.xbimmers.com/forums/showthread.php?t=1706110

and posted up an eBay auction for them as well.

https://www.ebay.com/itm/254550397143

PM me if you want both front and rear sets and I'll give you a discount.

[doodlebro]

I'm getting occasional shaking with this setup that I haven't been able to pinpoint. It seems to happen most heavily from 60-80mph and above 120mph, but I know it's not warped rotors because A) I'm not driving THAT hard and B) it seems dependent on speed and foot pressure more than something that sticks around.

It's like I'm finding a resonance in the brakes/suspension at medium foot pressure. Emergency braking/heavy pressure always gets past the shaking once the caliper clamps fully, and super light pressure doesn't cause shaking either. I can feel shaking as the calipers compress from light to heavy pressure, but not at those extremes. Any ideas @hardparker or other installers? My mechanic has taken a few good looks and doesn't see anything immediately obvious.

[hardparker]

That would be the first report I've heard of such a thing. I've had zero issues over the course of 18 months and about 22,000 miles, with a tire change in there somewhere.

I'd start by getting all of your tires rebalanced. When I've seen issues similar to what you're describing in the distant past, that was the cure.

What components are you using for your setup for wheels, tires, suspension and brakes?

Originally Posted by doodlebro

I'm getting occasional shaking with this setup that I haven't been able to pinpoint. It seems to happen most heavily from 60-80mph and above 120mph, but I know it's not warped rotors because A) I'm not driving THAT hard and B) it seems dependent on speed and foot pressure more than something that sticks around.

It's like I'm finding a resonance in the brakes/suspension at medium foot pressure. Emergency braking/heavy pressure always gets past the shaking once the caliper clamps fully, and super light pressure doesn't cause shaking either. I can feel shaking as the calipers compress from light to heavy pressure, but not at those extremes. Any ideas @hardparker or other installers? My mechanic has taken a few good looks and doesn't see anything immediately obvious.

[doodlebro]

Originally Posted by hardparker

That would be the first report I've heard of such a thing. I've had zero issues over the course of 18 months and about 22,000 miles, with a tire change in there somewhere.

I'd start by getting all of your tires rebalanced. When I've seen issues similar to what you're describing in the distant past, that was the cure.

What components are you using for your setup for wheels, tires, suspension and brakes?

Thanks for the tip, if I can't find another reason this is happening I'll have my shop rebalance wheels/tires. I must be finding some resonance with the way they are currently set up.

I'm on OE suspension, OE rear brakes, these 50i fronts with stock 50i pads (semi-metallic Textar). I did add a strut tower bar on the front from ultra-racing, but I don't think that would cause this. And the tires are Pilot Sport A/S 3+ on OE 19" wheels. Later this year I plan to do KW V2's which might also help.

Outside of the shaking at those precise speeds, the brakes feel great though. Feels like my face is coming off when I really step on them.

[bimmer ///man]

It sounds like a sticking brake piston. Had the same symptoms on my M3. Front right piston was sticking which caused pulsing under light braking but heavy braking it would get past.

[hardparker]

Originally Posted by bimmer ///man

It sounds like a sticking brake piston. Had the same symptoms on my M3. Front right piston was sticking which caused pulsing under light braking but heavy braking it would get past.

Possible, but unlikely in this case. The calipers are like new, freshly rebuilt and tested.

Doodlebro, keep an eye on it and let us know what you find after you the the tires balanced.

[doodlebro]

Originally Posted by bimmer ///man

It sounds like a sticking brake piston. Had the same symptoms on my M3. Front right piston was sticking which caused pulsing under light braking but heavy braking it would get past.

Did you notice it at all speeds? I really only notice it above 120mph or between 80-60. Otherwise light pressure feels like it should.

[agent_orange]

I carried out the X5 50i front conversion last Easter thanks to the bolt and spacer kit from hardparker.
Not sure if it was the Carbotech 1521 pads I went with or the strong rear brake bias that these cars seem to have under light-moderate braking, but it only made a modest improvement in braking performance from seriously bad stock to almost acceptable.

Edit to clarify, from experience since gained: The impression of the stock brakes being rubbish was entirely down to the cheap local-brand low-dust pads that were already fitted when I bought the car.
100% stock brakes with stock pads aren't thaaat bad performance wise for normal street driving.
The Carbotech 1521, while great for having virtually zero dust and actually zero rotor wear, have nowhere near the coefficient or initial bite of the stock BMW GG-rated pads or other ECE R90 rated aftermarket pads.
If I had gone straight from stock brakes with low-dust pads to big brakes front and rear with pads that actually have decent coefficient like stock BMW or EBC Redstuff or Yellowstuff, it would have been a massive upgrade in braking power/reduction in pedal effort. /edit

So then in November I carried out a rear upgrade using the F10/11/12 calipers but with F01 370x24mm rotors instead of the easier 345x24mm rotors.
It required caliper adapter brackets which I made myself.
This finally made a significant improvement to the braking.

Would it be appropriate to post pictures of that in this thread or should I start a new one?

[hardparker]

Let's see those rear adapters.

[ThomasR]

Originally Posted by agent_orange

I carried out the X5 50i front conversion last Easter thanks to the bolt and spacer kit from hardparker.
Not sure if it was the Carbotech 1521 pads I went with or the strong rear brake bias that these cars seem to have under light-moderate braking, but it only made a modest improvement in braking performance from seriously bad stock to almost acceptable.

So then in November I carried out a rear upgrade using the F10/11/12 calipers but with F01 370x24mm rotors instead of the easier 345x24mm rotors.
It required caliper adapter brackets which I made myself.
This finally made a significant improvement to the braking.

Would it be appropriate to post pictures of that in this thread or should I start a new one?

Modest?!? Great, I'm about to do my conversion this weekend (front and rear). You just killed my excitement and motivation.

[hardparker]

Originally Posted by ThomasR

Modest?!? Great, I'm about to do my conversion this weekend (front and rear). You just killed my excitement and motivation.

I don't think you'll be disappointed. Especially doing the fronts and rears at the same time. The only unknown factor are the OEM pads, but hopefully they'll work well.

[agent_orange]

The adapters look like aluminium but don't worry, they are galvanised steel.
The F10/11/12 calipers for 24mm thick rotors have an offset from centre on their mounting holes, unlike the stock F25 calipers.
This actually reduces the offset/clocking from the brackets so in total the calipers end up probably only 15mm (~0.6") lower than stock, and the stock brake hose isn't stretched or kinked.

I used Meyle rotors as that was all I could get in my country for a reasonable price.
Pads are Porterfield R4-S as they were less than half the price of Carbotech 1521 and meant to be comparable.
They seem to work well but are very dusty. Have to wash the rear wheels after only 100km (~60 miles) of town driving while the fronts are fine for many times that!

Sorry ThomasR, I didn't mean to kill your excitement.
If you are doing both front and rear it will definitely make a significant improvement as hardparker has said.

[hardparker]

Nice work, agent_orange! Those are the rear rotors I'd wanted to use originally, but the 345 mm setup was far simpler. When I'd asked Tronik about the 370 mm rear setup, he said, "Impossible!" Which I scoffed at. Glad to see that it can be done.

Do you think you could have move the caliper location up, rather than down, to avoid stress on the brake line? I know my ECS rear lines are like a centimeter or more shorter and at full droop they're getting close to being badly stressed.

[agent_orange]

Thanks.
Yeah I also asked Tronik as some of his rear adapters looked like they may have worked for this conversion, and he told me the same thing: 370mm is impossible, must use 396mm and M5 calipers.

I tried mocking it up in every which way, and you can't go 'up' because the knuckle/bearing carrier casting gets in the way of the caliper bolt heads and even the bracket itself. You can see this in the photos.
Down has clearance for both bolts and the bracket.
I'm still using the stock brake lines and yes there is a little bit of tension on them at full droop, but not enough to kink or damage them I'm pretty sure.

The other thing that I would add for anyone doing this or the 345mm rear conversion, is that eBay is a minefield for the wrong calipers.
Searching by say 'F10 550i' or even the correct BMW part numbers brings up plenty of listing from auto dismantlers selling the 330x20mm spec calipers which don't work.
The way to tell in photos is that the incorrect 20mm calipers have two raised ribs that run across the outside, while the rarer 24mm ones don't.
In better/less dirty photos you can see the 44/24 numbers too.
I've even seen some F01 calipers with no electric park brake motor listed as compatible with F10 550i.
Buyer beware.

[hardparker]

Originally Posted by agent_orange

I tried mocking it up in every which way, and you can't go 'up' because the knuckle/bearing carrier casting gets in the way of the caliper bolt heads and even the bracket itself. You can see this in the photos.

Yeah, I thought as much but wanted to confirm.

Regarding calipers, good tips. Make sure you know what you're getting. Also, I got one remanufactured caliper that was junk, so even that's no guarantee. It had had the piston parking brake shaft that protrudes out the back hammered on so badly that it was deformed and the parking brake wouldn't go on.

[ThomasR]

Hardparker are you torquing these new bolts to the factory 75Nm? Also factory bolts are supposed to be angle torqued after to 45 degrees then 10 degrees. I figure these don't need to be?

[hardparker]

Originally Posted by ThomasR

Hardparker are you torquing these new bolts to the factory 75Nm? Also factory bolts are supposed to be angle torqued after to 45 degrees then 10 degrees. I figure these don't need to be?

The factory 75 Nm (55 ft. lb) and angle torque is adequate if you like. I've been using 65 ft. lb. (88 Nm) because the bolts are slightly longer and will take a little more stretch. Plus, it's easier and more straight forward than the angle torque procedure. In the end, either is fine.

The NordLock washers make it impossible for the fastener to loosen as long there's reasonable stretch and torque on the bolt. If you ever loosen them, be prepared to hear the nasty "pinging" sound that the washers make as the ramps release. It's kind of scary and sounds like something broke, but it's normal. The NordLocks work by requiring slightly more torque than they were tightened to initially to loosen them, due to the ramp design.

The bolts are reusable as long as you don't exceed ~100 Nm (~74 ft. lb.) when releasing them, which you shouldn't if you tighten using either method above. If you do loosen and tighten them, it's advised to lube in between the washer halves. I always use anti-seize compound there and on the bolt threads and shoulders where they face the brake mounting tabs, too. Just to make it corrosion resistant and easier to loosen next time.

Good luck with your install!

[ThomasR]

I got the rear done. There's a good bit of trimming needed for the dust shield. One tip I can offer is to loosely bolt the new caliper bracket up against it and use a white paint pen to trace a cut outline against the bracket on to the shield. I use a variety of Wiss tin snips (left, right, straight) to cut and then followed it up with a dremel to smooth and deburr the edge. One thing I was surprised to find (only after trying to use a extendable reaching magnet to pickup the scraps under the X3, LOL) that the shield is NOT steel but aluminum.

Hardparker those bolts come ever so close to almost hitting the inside rotor! Like 2-3mm close! This is close to the inside 'drum' which I assume the 550i uses for it's parking 'shoe' brakes.

[hardparker]

Originally Posted by ThomasR

I got the rear done. There's a good bit of trimming needed for the dust shield. One tip I can offer is to loosely bolt the new caliper bracket up against it and use a white paint pen to trace a cut outline against the bracket on to the shield. I use a variety of Wiss tin snips (left, right, straight) to cut and then followed it up with a dremel to smooth and deburr the edge. One thing I was surprised to find (only after trying to use a extendable reaching magnet to pickup the scraps under the X3, LOL) that the shield is NOT steel but aluminum.

Hardparker those bolts come ever so close to almost hitting the inside rotor! Like 2-3mm close! This is close to the inside 'drum' which I assume the 550i uses for it's parking 'shoe' brakes.

Good tip regarding trimming the shield and I'm surprised to hear it's aluminum. I figured it was steel.

Yeah, the bolts are super close, but it all clears, thankfully.

Did you do the rears first, or have you already done the fronts?