AUDI’s UFO Brake System

I never had heard of this.  

https://www.fcpeuro.com/blog/reinventing-the-rotor-audis-ufo-brake-solution

I saw one at the JY a few years ago, first time I'd heard of it. It's a good concept, not sure about the execution.

Execution's about as good as it could be.

"Hey how do we get as big brakes as possible for our 4000lb turbocharged tank?  Difficulty: we have to fit it under 15" alloy wheels."

"Why not put the caliper inside the rotor so we can make the rotor as large as possible?"

AngryCorvair (Forum Supporter) said:

I saw one at the JY a few years ago, first time I'd heard of it. It's a good concept, not sure about the execution.

I've never owned one, but they were pretty universally hated by Audi owners of the time.  They were expensive, heavy, prone to warping, and didn't cool as well as normal rotors.  Dissatisfaction with UFO brakes launched "BIRA" (which stood for "brake improvement research association" or something like that) -- an early "open source" project for making brackets to swap Porsche brake components onto the UrS4s and other Audis with them.

(Edit:  But yeah, it turned out that people would much rather pay for bigger wheels and have brakes that didn't suck)

In reply to codrus (Forum Supporter) :

I thought the "fix" was just using strut housings from a non UFO Type 44.  I forget if people used 5000 or V8 strut housings.

I think it was V8 housings, at least that's my hazy memory from what I read in German classic car mags. Of course, those are found at every corner, too.

And I guess pretty much every Audi dealer's parts person also hadn't heard of these.

BTDT, bought a 200 TQ for the wife and it had UFOs.  They were a blast to replace the rotors, access to them was not good.  I still have a UFO rotor, great garage conversation piece.  Fun trivia about the car, sold it to Brian Scotto, of hoonigan fame.  He used the motor in his 90 coupe project.  About as close to famous as I got!

Audi actually swapped these out for traditional rotors and G60 calipers of the owner asked. They're unicorns now because of the level.of dissatisfaction 

BoxheadTim said:

I think it was V8 housings, at least that's my hazy memory from what I read in German classic car mags. Of course, those are found at every corner, too.

And I guess pretty much every Audi dealer's parts person also hadn't heard of these.

I've seen them in the catalog, but never had a car in the shop or a client request for them in my 20+ years on the Audi parts counter. 

I was active in Audis back when they were a thing. The message boards were filled with discussions about those awful things.

It's a fascinating the amount of effort they went to, just to not upsize the wheels.

iansane said:

It's a fascinating the amount of effort they went to, just to not upsize the wheels.

Would it have been that simple?  Late 80s, early 90s the tire size for pretty much everything non-performance spec, in this weight class was 15", right?

Changing tire size introduces all sorts of variables with ride quality, and still may not have done what the engineers wanted for braking.

Typical German. Instead of just using a proven system like inboard brakes, they try to reinvent the wheel and come up with a design that not only doesn't work but is universally hated by owners and technicians everywhere. 

Mr_Asa said:

iansane said:

It's a fascinating the amount of effort they went to, just to not upsize the wheels.

Would it have been that simple?  Late 80s, early 90s the tire size for pretty much everything non-performance spec, in this weight class was 15", right?

Changing tire size introduces all sorts of variables with ride quality, and still may not have done what the engineers wanted for braking.

Either create an entirely new brake caliper design or bump the wheel size up to a more expensive tire size? I guess I'm just used to bigger wheels from a modern era but it seems like a no brainer. (hindsight is 20/20?)

In reply to Toyman! :

I don't know that inboard brakes would have worked with the longitudinally mounted quattro system. Also I wonder about the leverage forces on a cv joint under hard braking while in a turn? Maybe it would have been fine.

In reply to iansane :

Design constraints are a bitch and a half.

I was thinking about it, this probably cane damned close to maximizing the space inside a 15" wheel.  An equivalent normal disc and rotor may not have fit inside a 16" wheel.

iansane said:

Mr_Asa said:

iansane said:

It's a fascinating the amount of effort they went to, just to not upsize the wheels.

Would it have been that simple?  Late 80s, early 90s the tire size for pretty much everything non-performance spec, in this weight class was 15", right?

Changing tire size introduces all sorts of variables with ride quality, and still may not have done what the engineers wanted for braking.

Either create an entirely new brake caliper design or bump the wheel size up to a more expensive tire size? I guess I'm just used to bigger wheels from a modern era but it seems like a no brainer. (hindsight is 20/20?)

 

In reply to Toyman! :

I don't know that inboard brakes would have worked with the longitudinally mounted quattro system. Also I wonder about the leverage forces on a cv joint under hard braking while in a turn? Maybe it would have been fine.

It was the late 80s.  16" wheels and tires were expensive and 17" were for exotics.

I at least give props to Audi for trying something new. Rolls Royce was so concerned about ruining the ride quality by stepping up from 14 inch wheels with an 80 series tire that they put two calipers per rotor

Which just meant that the brakes got really, really hot. 

iansane said:

I don't know that inboard brakes would have worked with the longitudinally mounted quattro system. Also I wonder about the leverage forces on a cv joint under hard braking while in a turn? Maybe it would have been fine.

And it's not like inboard brakes are particularly fun to service either.