So I figured while I had my suspension out awaiting Irelands coilovers I should re-paint the drums.
Before
http://img.photobucket.com/albums/v709/vtbmw525/IMG_0690.jpg
After
http://img.photobucket.com/albums/v709/vtbmw525/IMG_0700.jpg
http://img.photobucket.com/albums/v709/vtbmw525/IMG_0701.jpg

The dual calipers are next.....
http://img.photobucket.com/albums/v709/vtbmw525/IMG_0685.jpg

What do you think??

Could you explain the pros/cons of dual calipers?

Could you explain the pros/cons of dual calipers?
Pros- stops quicker, looks different
Cons- costs more in pads, cant use ti strut housings (not really a con)

I painted my drums flat black so they'd not visually compete with the wheels.

Just a thought.

Got a "tad bit" of tire rub going on there.

Its looks good. Lets see pics with the wheels on.

So in a car thats not set up from the factory for dual calipers, is it more benificial having two smaller ones than one big one?

I've seen duals used a few times but nobody has actually told me why you'd do it :)

Pros- stops quicker, looks different
Cons- costs more in pads, cant use ti strut housings (not really a con)
Cons- lots of added unsprung weight

Got a "tad bit" of tire rub going on there.


The large rub mark you see is old and no longer rubs there. However on the very corner of that rub mark it catches a bit. I used a persueder aka hammer to push the corner back a bit wich helped somewhat.
Not much of the paint shows with the wheel on so it should be subtle. I'll snap a pic on Monday and post.

Cons- lots of added unsprung weight
Lots? I dont know about lots. The car has been lightened significantly. The speakers I removed from the car wieghed as much as a set of calipers.

Are you sure thats actually going to make you stop faster? You do have twice the contact patch, but you only have half the force being applied on each one.


(Friction coefficient)x(Applied Force)= Stopping Power

Are you sure thats actually going to make you stop faster? You do have twice the contact patch, but you only have half the force being applied on each one.


(Friction coefficient)x(Applied Force)= Stopping Power
Dont really know for sure. I didnt put them on there. I assume the builder of the car put them on for a reason. What you say makes sense and thats what I was thinking because to me the breaking power is not that great. Im not sure how good you can make the brakes in a '02. Im used to bigger rotors/calipers and not drums. My heavy e34 w/ stock calipers, pagid sport compound pads, and cross drilled rotors can out brake my '02. I guess Im a little biased since I have never driven a '02 with stock brakes. Im sure the set up on it now is superior to the stock. I still think it could be better. I want to upgrade the rear drums to rotors but if I did that I would not be able to run 13" rims. :dunno

Dont really know for sure. I didnt put them on there. I assume the builder of the car put them on for a reason. What you say makes sense and thats what I was thinking because to me the breaking power is not that great. Im not sure how good you can make the brakes in a '02. Im used to bigger rotors/calipers and not drums. My heavy e34 w/ stock calipers, pagid sport compound pads, and cross drilled rotors can out brake my '02. I guess Im a little biased since I have never driven a '02 with stock brakes. Im sure the set up on it now is superior to the stock. I still think it could be better. I want to upgrade the rear drums to rotors but if I did that I would not be able to run 13" rims. :dunno

There are options available that will allow yo to run rear disks and 13" wheels. I used euro 323 trailing arms and relocated the shock tabs and 13" wheels fit fine over them. I just fitted my e30 rear calipers to the trailing arms (not shown below) because the pad surface area is nearly twice that of the 323 pads and the rebuild kits are much easier to find!

http://img.photobucket.com/albums/v521/iflytii/02%20suspension/rearsusp2.jpg

http://img.photobucket.com/albums/v521/iflytii/02%20suspension/rearsusp3.jpg

As far as the dual calipers up front, I have seen that on older racers and I think it's pretty cool, just because it's different. :)

I don't know what kind of booster you have, but if you don't already have it, get the tii booster which is much larger. You'll see a big difference.

booster from a Tii is smaller in diameter but longer thent he standard booster. Both produce the same amount of force. Tii master cylinder is different then standard one and is very good when used with the vented rotor/volvo caliper, 320 drum conversion. The stoping power of standard 02 on stock brake parts is pretty good. It is much better with better pads/shoes. Installing larger/vented/disk brakes increases heat decipation of the braking system.

vtbimmer: unsprung weight includes all the parts in the suspension, brakes tires, wheels. Some are 100%, some are split between sprug and unsprung. Imagin your car body as baing stationary and all suspencion peices moving. All that you can see move is unsprung weight. Lowering that weight, significantly improved hangling characteristics of the car. The reason to install aluminum calipers, light wheel, tires, rotors, struts, springs is too reduce unsprung weight. wheels, tires, rotors are also for reduction of the rolling momentum. Removing a pound of unsprung weight from a corner is worth a lot more then removing 10 lb out of the car

steve k.

http://www.kgb-racing.com/images/ax/bmwccaJuly16-2005_06.jpg

Wow iflytii you have a nice setup. Where did you buy your coilovers?

Wow iflytii you have a nice setup. Where did you buy your coilovers?

Thanks! Those are IE coilovers. They are several years old now and I think Ireland has updated them quite a bit.

I will second what Steve said about the booster. I have both a regular and tii booster and I couldn't tell a bit of difference between the two. The MC capacity is really where you will see the difference if you have upgraded to larger calipers.

http://img.photobucket.com/albums/v521/iflytii/02%20suspension/rearsusp2.jpg

That is a NICE! setup.
What hubs/rotors are you using? What is the difference between the 2002's trailing arm and the 323's that allows it to work? Would backspace be a problem with this brake system? I plan on doing this swap so if you could give me as much info/parts list ect. as possible it would be greatly appreciated. :)
Do you have the rear subframe inserts from IE also. Thought I could see them in that picture.

booster from a Tii is smaller in diameter but longer thent he standard booster. Both produce the same amount of force. Tii master cylinder is different then standard one and is very good when used with the vented rotor/volvo caliper, 320 drum conversion. The stoping power of standard 02 on stock brake parts is pretty good. It is much better with better pads/shoes. Installing larger/vented/disk brakes increases heat decipation of the braking system.

vtbimmer: unsprung weight includes all the parts in the suspension, brakes tires, wheels. Some are 100%, some are split between sprug and unsprung. Imagin your car body as baing stationary and all suspencion peices moving. All that you can see move is unsprung weight. Lowering that weight, significantly improved hangling characteristics of the car. The reason to install aluminum calipers, light wheel, tires, rotors, struts, springs is too reduce unsprung weight. wheels, tires, rotors are also for reduction of the rolling momentum. Removing a pound of unsprung weight from a corner is worth a lot more then removing 10 lb out of the car

steve k.


Thanks for the info steve. I learn something new everyday. :D
PS: There is a Tii booster in my setup.

Do you need a brake controler when you do a rear disk swap?

That is a NICE! setup.
What hubs/rotors are you using? What is the difference between the 2002's trailing arm and the 323's that allows it to work? Would backspace be a problem with this brake system? I plan on doing this swap so if you could give me as much info/parts list ect. as possible it would be greatly appreciated. :)
Do you have the rear subframe inserts from IE also. Thought I could see them in that picture.

The main difference between the trailing arms is the spring perch location and type. Here is a pic of both trailing arms:
http://img.photobucket.com/albums/v521/iflytii/02%20suspension/trailing_arms_compare.jpg

Notice there are no provisions for springs at all since the e21 shocks are more of a coil over setup. I simply cut the shock perch off the 323 trailing arms and welded tabs for the shock to mount to.

http://img.photobucket.com/albums/v521/iflytii/02%20suspension/DSCN1558.jpg
http://img.photobucket.com/albums/v521/iflytii/02%20suspension/alltogether_sm.jpg

The rotors and calipers shown are 323 stock but the trailing arms are so similar to the e30 setup that with a little massaging the e30 rear calipers will fit. I don't have any pics yet but I'll snap some soon. There is a sizeable difference in pad area.

As far as track difference, I gained about 5-6mm in track towards the outside. Obviously a problem if your tight on clearance but with flares it hasn't been much of an issue.

Do you need a brake controler when you do a rear disk swap?

A bias valve would be a good idea. Wilwood makes one that is cheap, around $50.