840i Brembo caliper test fitted

[Jake]

Not sure if everybody realizes this, but the E46 M3 disc is 2pc. Not in the same manor as the bolted together custom bell and disc assembly, but it works the same essentially; however it is not "floating". But then again a 2pc custom bell and disc assembly is not necessarily floating either; and in fact is normally "fixed" anyway. So unless you spec a genuine floating design, there are no advantages over the E46 M3 disc in this respect.

Colin, from '93 the E31 got Brembo's; prior to that they used fist type single piston calipers.

Dietrich, I talked to John a bit about floating discs, and the disadvantage with them was that you have to routinely disassemble and lube them; not very realistic for the road car. The advantage was that they contributed less to negative pedal feedback due to minor pad transfer and/or warpage.

HTH,
Jake Larsen

P.S. I'll try to get seme new pics tomorrow.

[SunnyM3]

Hey Jake,
Hope all is well.

I was just wondering.... Instead of using the spacer behind the rotor fot the e46 disk, Is there room behind the hub to push the calipers back using smaller, cheaper 14mm spacers to increase the offset of the caliper.

I wasn't sure if the it would interfere with the lower ball joint.

-Sunny

In
NJ

[Ian Godney]

Dietrich , Yes I should be able to make up some spacers , Have emailed Jake for some drawings when he gets them ,

Wookie1976 - you dont need to drill the holes out if you wanted to fit a specific discs , as long as I know what you want I can supply them to fit.

With regards to discs and bells , the main reason of having a discs and bell is to reduce the chances of the discs warping , when a disc warps its usually the centre of the discs goes out of shape , by having a disc and bell , the 2 can move slightly when they get hot , if you have them and use them hard , stop and have a listen to them cool down you can hear them making noises as they cool down and retract ,by them moving doesn't deform the bell shape so dont warp , the other good reason for having alloy bells is that they will dissapate heat quicker than a one piece iron disc , which reduces the amount of heat into the bearings , as well as being able to fit any disc to any car as they can be made to suit.

Sunny - you cannot run the E46 discs without spacers as the discs will hit the bottom ball joint

Cheers Ian

[Jake]

Originally posted by SunnyM3
Hey Jake,
Hope all is well.

I was just wondering.... Instead of using the spacer behind the rotor fot the e46 disk, Is there room behind the hub to push the calipers back using smaller, cheaper 14mm spacers to increase the offset of the caliper.

I wasn't sure if the it would interfere with the lower ball joint.

-Sunny

In
NJ

Hi Sunny. :D

Just to add to Ian's comments, the caliper bolts to the outboard side of the mounting ears on the strut. Placing a spacer here would actually move the caliper further out. Here is a pic for better visualization.





Dietrich,

I don’t have the spacer yet so I can’t get any fully built up pics but here are some that may help in the mean time.

The new caliper does not come with the “BMW” logo anymore as previously mentioned.



Here are a few attempts to depict the spacing from the hub mounting face to the outboard side of the caliper. I measured approximately 2.4”.





I can’t remember if this is what the call the BMW style 5 wheel, but here is a pic of E39 Sport wheels with the Brembo caliper, stock 280mm disc, and 36mm’s of spacer. The net result was approximately 0.225” of clearance between the back of the spokes and where I felt it came the closest to the caliper.



Now here are some pics showing the Euro E46 M3 disc in detail.





Here you can see the spokes which connect the aluminum bell to the disc.





Here are a few comparing it to the stock disc.







I hope this helps a bit. When the spacers arrive I’ll post up some pictures of the assembly built up as intended. It may be little over a week before I can because I leave for Denmark for a week this Saturday. I may not have the spacers before I leave but I’ll get right on it once I’m back.

Cheers,
Jake Larsen

P.S. Sorry Sleepyfox, I must have missed your post earlier. I measured the pistons for you and came up with approximately 1.432” for the lag piston and 1.586” for the lead.

[Eric]

I like how thick that E46 rotor is, I'm sure it can dissapate much more heat that the stock units.

on the post earlier you quoted a price in the 1200 ish range... that is about the same price as a brembo kit from brembo. other than the this is cool all BMW parts (except for the spacers) what is the advantage to using used 8 series calipers over the brembo setup?

while typing this I thought of some pro's and cons

pro's
BMW discs, easy availibility
wide variaty of pads
no spacers for caliper

con's
used calipers
spacer is behing the wheel instead of on the caliper

did I miss anything?

p.s. jake I shot you a P.M.

[Jake]

Hi Eric, I posted that a completely new assembly, new E31 calipers, E46 M3 discs, spacers, lines, pads, hardware would approach $1700. This is more than a comparable Brembo big brake kit. If you can source used calipers you could save a few $$ of course.

what is the advantage to using used 8 series calipers over the brembo setup?

Both are Brembo, the only difference between them is the E31 specific calipers bolt up without using an adapter bracket.

As far as con's, a used caliper is only a con if you use a.... used caliper. So you can't really count that against this assembly. Obviously you don't have to use a used one; I just picked up new ones from my dealer. More expensive, but then they're new.

The spacer behind the disc is not something I prefer, or really like at all to be honest. But I don't like the caliper adapter bracket needed on the typical Brembo BBK either. Which is the lesser evil? I'm hoping to find out. I will be comparing this E46 M3 disc set up with a proper 2pc custom bell and disc assembly in the future and I will post my opinion.

I do believe the best overall set up with regards to using Brembo calipers is with the E31 calipers and a custom bell and disc assembly. No spacers anywhere. I likey. For now, I'm curious how well this E46 M3 set up is going to be.

Now I really have to go or I'm going to be late for work :D

HTH,
Jake Larsen

[Dietrich]

Jake: thanks for the pics and explanation -- very helpful. And yes, those are "style 5" wheels. So you had to use 36mm of spacer to get clearance? That would mean you have neg 16mm of offset (assuming the wheels are +20mm ET)??? Ugh. Sounds like this is going to be a setup for high offset wheels (e.g. +40 ET).

Ian: Thanks for considering fab'g the spacers. Any *guesses* at price?

-Dietrich

[Ian Godney]

I can supply discs and bells that would fit perfectly with the 850 brembo 4 pot calipers for £395 a pair , they can be grooved , drilled or both , drilling is not recomended for track use as they will crack around the holes , spacers to fit behind the E46 discs will be about £150 a pair , will have to wait for Jake to email me the details on them to work out an exact price , it will depend on numbers.

I think it would be cheaper to fit the discs and bells , than fitting standard E46 discs and spacers , I would prefere not to use internal spacers on my own car.

Cheers Ian

[Jake]

Although it seems I'm pretty gung-ho about using these E46 M3 discs, I actually completely agree with Ian here. The proper way to bring this kit together is to use a custom bell and disc assembly. Why then am I even screwing with it? For fun really, and to offer this up as an option.

At the moment I could immediately test fit the E46 M3 disc. But I really need to sit down and research what disc I want to use before asking for custom bells. Just a matter of time, or lack there of really.

Anyway, I just wanted to point that out because I think it was beginning to seem like I was claiming the E46 M3 disc was the better solution. I think it will be a good factory solution, but not truly the better option all around.

Cheers,
Jake Larsen

[Dietrich]

Ian,

Thanks for the input. Just so I understand... In short, a spacer is needed to clear the much wider than stock E31 caliper. That's independent of which rotor is used. Why would you rather have the spacer outside of the rotor, than inside the rotor? What difference does it make? Seems like you might have a small advantage in having it inside the rotor b/c it keeps the rotor heat further away from the wheel bearings. ???

OTOH maybe it's that the clamping force is now farther removed from hub, where it has less strength. ???

Just curious.

-Dietrich

[sleepyfox]

OK, so what are we comparing? Are the E46 M3 discs of a comparable price to the AP lightwieght disks or is there a big price differential? Remember what I'm considering here is a kit that I can accept moderate to high one-off prices (calipers, bells etc.) provided that the running costs (disks and pads) are economical...

Fox
---

[Eric]

Originally posted by Dietrich
Jake: thanks for the pics and explanation -- very helpful. And yes, those are "style 5" wheels. So you had to use 36mm of spacer to get clearance? That would mean you have neg 16mm of offset (assuming the wheels are +20mm ET)??? Ugh. Sounds like this is going to be a setup for high offset wheels (e.g. +40 ET).

Ian: Thanks for considering fab'g the spacers. Any *guesses* at price?

-Dietrich

or get a set of wheels with a high spacing from the hub to the back of the wheel.

it just so happens that the BBS modular race wheels I have, have 37mm of clearence

[Jake]

Originally posted by Dietrich
Just so I understand... In short, a spacer is needed to clear the much wider than stock E31 caliper. That's independent of which rotor is used.

Correct.

Originally posted by Dietrich
Why would you rather have the spacer outside of the rotor, than inside the rotor? What difference does it make? Seems like you might have a small advantage in having it inside the rotor b/c it keeps the rotor heat further away from the wheel bearings. ???

Well, the rotor is still just as close, no matter which route you go. The rotor needs to be in the same position, centered in the caliper. But I can see how the bearing may be a bit more isolated.

Originally posted by Dietrich
OTOH maybe it's that the clamping force is now farther removed from hub, where it has less strength. ???

This really isn't a factor. The length of the fastener will be the same assuming the same wheel and width of the spacer/bell assembly.

Cheers,
Jake Larsen

[Dietrich]

"Well, the rotor is still just as close, no matter which route you go. The rotor needs to be in the same position, centered in the caliper. But I can see how the bearing may be a bit more isolated." -Jake

What I should have said, is that the E46 rotor's hat/bell (which will absorb and radiate *some* heat) will be further away from the wheel bearings thanks to the inside spacer. I can't imagine it will make any real difference in practice.

To me, if I'm going to use a spacer, I'd rather have the spacer inside the rotor. Maybe I'm crazy. Of course, having the spacer effectively built-in to the bell is nice too. Just one less part to mess with. Oh man I'm just talking in circles. I'll shut up now.

-Dietrich

[Jake]

Originally posted by sleepyfox
OK, so what are we comparing? Are the E46 M3 discs of a comparable price to the AP lightwieght disks or is there a big price differential?

Fox,

Here are some prices taken from this thread:

Originally posted by John
>As the AP discs are quite expensive I can also supply our
>own make of discs the same size.the retail price on
>AP discs are £197 each

yes they are expensive. the price you quote is for the
5000 series AP disc (about 287 euro retail).
It gets even more expensive with their better discs,
385-400 euro for each disc.

I hear coleman in USA makes discs for $100 each
in 330x28 mm size. I doubt its the same quality,
but at those prices you can afford to throw them
away...

that being said, I have already 180 nordschleife
laps on my AP 3047 series discs. 3744 track km
(2326 track miles). and they are still in good shape.
Not bad at all IMO. When looking at prices also
factor in how long the part lasts...

John

Originally posted by Dietrich
OK guys - I got a quote from my favorite discount dealer:

-E31 Brembo caliper: 34-11-1-161-177/178 - $378.89 ea
-E46 M3 MS rotor: 34-11-2-282-801/802 - $186.48 ea
-Cool Willy (TMS) pads: $189 Note: There are probably other pads available, but these are quality race pads that can (at least) be driven to the track.
Total thus far: $1,323

Originally posted by Jake
Quick update, I just got back from the dealer with the new E31 calipers (1 161 177/8) and E46 M3 discs in hand. Final costs for these were £220.60UKP each for the caliper and £122.99UKP for the discs. All that's left is the spacer.

I've been talking to Ian at great lengths and he's been extremely helpful. For those interested, he's offered to make a batch of bells and I assume spacers too if asked nicely. :D I think a minimum of 5 sets for either will be required to see a discount. At this point he's offered to provide a batch of custom bells to fit AP discs for £150UKP a pair. Pretty good deal actually.

So to sum up:
E46 M3 disc = £244 pair
AP 5000 series disc = £400 pair (bells not included)
AP (like John’s) = £520 pair (bells not included)
Ian’s bells (GB) = £150 pair
Ian’s bells and discs = £395 pair
E31 Brembo calipers = £440

I’ll get you what I paid for my pads, hardware, and brake lines when I get home.

HTH,
Jake Larsen