E21 front brake upgrades

[niske]

Somebody has some experience with remanufactured Volvo calipers from Cardone, Centric, Beck Arnley, Raybestos, that can be found on eBay?

[Odin]

Im in doing the Volvo 4 pots from EvilBay at the moment. Looks to be good quality, and I havent had any isues other then the known sloting etc we already know needs doing. The caliper came in a box branded Bosch, but the casting on the caliper says ate. Dosent realy matter to me, both Bosch and ate are good known brands.

[Jeroen]

Fully agree. Already fitted now?

[Wilmo]

During the trip in the Eifel of last week I mentioned the brake upgrade to some people and at least one (me) is interested. I would like to look at it as a good, nice and scaleable solution and I generally don't like sitting on knowledge so I share drawings without any problems.

The problem is of course that we drive our cars to fast and that the solution is to drive slower, but I'm not an engineer to solve things that way. I have a stock setup with solid discs and Ferodo 2500 pads. The amount of thermal mass in our discs is relative small, cooling things down can help of course by using the vanes of the 323i. But I feel fading at about the same moment as the stock 323i that I was tailing. Thegs (with his red 323i) mentioned that he feels fading at about the same moment that Jeroen (with his Wilwood Powerlite and stock discs setup) feels.

So to have more thermal mass and to be able to use modern disc technology my suggestion is to move to two piece rotors. In that way everybody can choose their own rotors, slotted, drilled, 279mm or 356mm or whatever. The only thing is that hearts are needed. No big invention, Massive and IE et al sell these kits. But I am not willing to pay that much money.

The Wilwood calipers are dimensioned in such way that a bracket to fit the caliper is easy to parameterize. I think I can set up a group buy to make these brackets but if someone in the future wants to make it themselves, just take the fitted rotor diameter, calculate a dimension and send the drawing to a machine shop.

To select things this info is needed: Rotor diameter, rotor width, radial or normal mount, number of pistons and piston area and pad area. This forum has some experience with the Powerlite caliper (120-8729). These can take maximum 279 (11") discs, 21.8mm width (0,86"), radial mount, 4 pistons width 19.35cm2 (3in2) and pad area is 11,6cm2 (1.8in2).

Powerlite:


For simplicity reasons I like the 'normal' way of mounting a caliper, I would like not to be limited by the diameter and I'll accept the 20.6-21.8mm (0.81-0.86") width, however wider is absolutely an option of course.
These are the options: https://wilwood.com/Calipers/CaliperLis ... tarea=3.00

For some reason I like this one, the Forged Narrow Dynalite:

When a bracket is needed, strength will be an issue and this thing is designed with a large mounting height, which makes the bracket less complicated. It is available for 20.6 (0,81"), 25.4 (1") and 31.7mm (1.25") wide discs. Pad area is 19.35cm2 (3in2). Max disc diameter is 323mm (12.72").


So, from the caliper no real limitations. Let's move to the rotors, here it is different and it will help us/me out of our dreams. For 20.6mm (0.81") wide rotors there are some options:
https://wilwood.com/Rotors/RotorList1?a ... l=&appCat=

Diameters are 273 (10.75) and 279mm (11").

For 25.4mm (1") wide rotors there is one option:
https://wilwood.com/Rotors/RotorList1?a ... l=&appCat=

Where the diameter explodes in our face with 327mm (12.88").

For 31.7mm (1.25") there is more choice:
https://wilwood.com/Rotors/RotorList1?a ... l=&appCat=

It is one or another. The bolt pattern of the 0.81 and 1.25 is different and of course the height of the heart. I don't know. If one invests, one wants to do it good. The price of 31.7mm stuff is not more or less than for 20.8mm stuff. I don't know about clearances, but I would like to go for 31.7mm wide rotors, if it fits. 298mm (11.75") diameter is not too crazy and I guestimate that it fits 15". The inside of the disc is fixed, the wider it becomes, the closer it comes to the rim. So it would be nice to have a small survey how much space there is between the inside of the rim and the outside of the disc, most of us are on 15" Alpina and I am at 15" BBS Mahle.

Next thing... The hearts. Most often they are made of aluminium. The rotor is cast iron and screws and bolts are often ferritic as well. The latest months I have become aware of galvanic corrosion. The calipers' aluminium is painted or anodized so it is isolated. Hearts could be protected as well, but it does not seem to be sustainable to me, the smallest scratch could be catastrophic (the smaller the contact area, the quicker the corrosion). The hearts can be isolated as well by other means (plastic washers and so) but I don't know. Maybe I see bears on the road where there are no bears, but I would make the hearts out of steel. I mocked up something on my work pc and with 279mm rotors I ended up with the same weight as for stock 255mm 323i discs.


Please: shoot, discuss and improve my writeup.

[Duracel79]

You may want to look at my setup, 296mm x 22mm (E39) discs with the wilwood superlite caliper. fits inside MSW & Mahle 15" wheels. Will not fit inside MIM 15".

The powerlite is only really n upgrade in terms of weight (unsprung mass), in fact the pad is smaller than the stock E21. I preferred a set of aluminium alfa twin pots over the powerlites I tried afterwards.

But the superlites a a big step in pad size and bite.

[Wilmo]

Ow wauw, what a difference!



Do you have the 20.6 or the 27.9 version? The bracket looks really sleek.



Later I read that, of course, the braking force increases with the diameter, so less heat is generated anyways for the same braking effort. You don't want the disc to cool like a maniac either, so maybe it works out with the 20.8mm width setup. What do you think? Do you use them on the track with one of your S54 beasts? Do you get these discs to cook?

And actually, this totally fits to a modular system. The end user can choose self what caliper to buy, the same bracket can be used!

[Wilmo]

I was really fed up with it. Got offer after offer of 500-1000 euros for two of those damn hearts. I went instead with the suggestion of Duracel79, with the E39 528i discs (34111163013). E34 is slightly larger in diameter but as well a bit heavier. These are 7.4kg (!) compared to 5.1kg for the E21 ventilated discs. The originally intended rotors, Wilwood Ultralite 32, are 3.7kg each.




The 5x120 bolt pattern will be closed with inserts and J-B Weld, as well as the centring diameter. I will turn an insert for that as well and turn the complete thing to 63H7mm. The new pattern will then be drilled, the J-B Weld seems to be so strong that it can take the forces. And when installed... No forces are exerted on the epoxy. I do not want to braze the holes because of the high temperature involved.


When my new company is up and running and the machine works and the materials are proven, I will 'print' the hearts as I want them for a price I decide myself.

[Wilmo]

So, time for a complete write-up.

I have driven some some thousands of kilometers with the new front brakes and I am very content with them, let's put that up first. As I wrote previously, the hearts are still to come, but it works already pretty well with the E39 brakes. Thing that I learned is that it is tight. So tight that I would not recommend the E34 brakes, though they are just 6mm larger in diameter. I needed to replace the balancing weights in the wheel. That tight. Somewhere in the future I will test the Alpina wheels as well, but with my 15" BBS Mahle it works out.

First the balance:


I bought the callipers and Ultralight discs at DansHouseOfSpeed through eBay, so I needed to pay the Dutch import costs. Proportioning valve I bought in the Netherlands at Hendriks Motorsports and is mostly a must have for all E21's that are driven a bit more vividly since you gain 15-20% more braking power at the rear, regardless whether you have discs or drums. The brake hoses I have ordered custom made at Remkaflex.

I started this all because I did not believe that the Volvo 4-pot option was anything of an upgrade and the other described option of the Wilwood Powerlite Radial Mount actually offers a smaller pad area compared to stock E21. I did not want to pay the amount of money asked by the different shops and hoped to save some money. Did I? Yeah, but in hours researching and actually still having the heavy E39 discs... I don't know. I actually forgot it all already since it brakes wonderfully.

Some more numbers:
BMW E21 stock: 32.8cm2 pad area / 3.8kg calliper weight / 255mm max disc D
Wilwood Powerlite: 32.25cm2 pad area / 1.27kg calliper weight / 279mm max disc D
Forged Narrow Dynalite: 41cm2 pad area / 1.86kg calliper weight / 323mm max disc D

Discs:
34111163128 E21 solid: 255mm D / 4.9kg
34111163125 E21 vented: 255mm / 5.1kg
34111163013 E39 vented: 296mm / 7.4kg
160-0471 Wilwood Ultralite 32 vane rotor: 298mm / 3.7kg


So I went from (4.9+3.8 ) 8.7kg to (7.4 + 1.86) 9.3kg per side. Plus bracket. Imagine that the hearts can be 1kg each, combined with the Ultralights, I could save some kg's of unsprung weight.

I chose the Forged Narrow Dynalite since I wanted a tangential mount since the brackets for these are far less complex, just 2D. I chose 296mm since I wanted the maximum diameter disc.

Shopping list:
Wilwood Forged Narrow Dynalite 120-11575
Wilwood Forged Superlite Internal 120-11128
Wilwood Proportioning valve 260-12627
BMW E39 528i Ventilated 34111163013
Ferodo DS2500 FRP504H or FRP502H and redrill the holes like I did to match the aluminium tube


Brackets:

Thickness is 6.5mm.

Brake hoses are really nice ones. This is the drawing I send:


This is what I received:


Note that the Wilwoods will be delivered with some Imperial thread while BMW used M10 fine thread.

From the calipers I removed the plastic tube and replaced it with an aluminium tube. The weird bolt is replaced with M6x120:


The two mounting holes in the calliper for the bolts I drilled to 12.5 to clear an M12.


The discs come with 14.5mm holes, there I tapped M16 and fitted M16 bolts, which I glued in place with JB-Weld. Later I cut them and ground it all flat again.


And redrilled a 4x100 hole pattern:


I completely removed the dust shield:


And fitted nicely:



And some animation:





So... Where I got my pads fading with ease with the solid E21 discs at about the same points where the heavier 323i's get problems as well, I have not felt anything with this combination. At one point I have braked like a complete mental, really like I never have done. From 160km/h to standstill and over and over again. Yes, they get hot, yes there is smoke, but there is no pad fading. I feel absolute confident in entering the Alps with these. On top of that, a lot more feeling to the pedal. Where I was used to blocking brakes at high speeds, I can really control the amount of breaking and kind of feel where the tipping point is. The only downside is, which I mentioned earlier as well, is that when everything is cold, the Ferodo's don't really perform. At braking from for instance 140 back to 80, nothing happens really until there is temperature at 120 and then it starts.

When you don't think that the Dynalite is enough, you can go with the Superlite Internal as well. Outside radius of these is the same, as well as the mounting points, so you can use the same brackets. They weigh 2.4kg and have a pad area of 52.9cm2.

Good luck!

[Jeroen]

Very detailed write up JW, thanks, and good to read how well all the hard work worked out! One day I should do this upgrade as well. I have enough stopping power to my opinion with the Wilwood calipers but the stock discs are too small to absorp the excess heat generated by some spirited driving in the mountains.

[uwbuurman]

Yeah, nice work and good write-up!

[Wilmo]

Very detailed write up JW, thanks, and good to read how well all the hard work worked out! One day I should do this upgrade as well. I have enough stopping power to my opinion with the Wilwood calipers but the stock discs are too small to absorp the excess heat generated by some spirited driving in the mountains.

Let's pick a Saturday for a small test drive

Maybe there is a disc to be found of 279mm with 4x100 and a 63mm hole. In that case you can keep the Powerlites and increase brake force because of the larger moment.

[Jeroen]

Let's pick a Saturday for a small test drive

Maybe there is a disc to be found of 279mm with 4x100 and a 63mm hole. In that case you can keep the Powerlites and increase brake force because of the larger moment.

that would definitely be an option to me, and I can imagine that others who also did the Wilwood upgrade might be interested as well

[Wilmo]

I suggest the Jeep Cherokee discs: