View Full Version : B5/B6 Suspension Mashup + StopTech Brakes... A Documentary...

11-23-2018, 10:10 PM
Documenting the work on my B5 Avant.

I've done quite a bit of research in recent months on front B6 suspension and B5 suspension. I feel like there's a lot of misinformation out there.
I'm not building a race car here, I have a very late 2001 B5 2.8 Avant with 250k miles on it and a rust hole the size of a baseball in the floor. Why waste my time on it? My first car was a 98' 2.8 sedan and a loved it. I spent a long time looking for a facelift avant with a manual transmission in any color except silver. My only intent is to keep this car going as a great, reliable daily driver. With that being said, I'm all for upgrades. First and foremost I have no issues with the 2.8, it's far more reliable than the 2.7t and the 1.8t ([:D] I might get flamed for that [:D]). If I ever swap the engine I'll likely attempt a 3.0, or maybe even a 4.2, it would only be to get something with less miles under the hood. As far as the transmission goes, I would like to lower the RPM's on the highway, maybe a diesel transmission or 6 speed, 0A3/01E in the future. Brakes need an upgrade. Had I not owned a B6 S4 maybe I wouldn't say that, but I LOVED the brakes in my S4.

SO I picked up a set of B6 S4 front brakes from a local dismantler. (Guy near Austin, TX has a front yard full of torn up Porsches and Audis).
B6 S4 brakes are VERY heavy.

The weight of these suckers sent me to the junkyard in search of B6 aluminum uprights. It didn't take me long to spot a B6 with BRIGHT RED calipers hanging off of the uprights. Not only that but a set of H&R coilovers. I won't tell you how little I paid...
The calipers were StopTech ST40's from a 355mm big brake kit (83.112.4700). Unfortunately, the rotors/hats were nowhere to be found and it doesn't make sense for me to spend the $300 EACH to pick up new hats PLUS the rotors on top of that. I originally intended to sell the calipers, then I weighed my options [:D].
8lbs, less than half the weight of the S4 calipers.

The stoptech kit sits at 355mm, B6 S4 brake rotors are 345mm, some C6 A6's came with a 347mm rotor. Since I had an upright and a 345mm rotor I decided to mock it up and sure enough, the caliper lines up perfectly with the OEM rotor offset. So I'm thinking with the 347mm rotors, these calipers are sturdy enough that I can shave 5mm off and still be comfortable mounting them. That would put me 3mm off of the intended fit, as well as the rotor being 2mm thinner. What do you think?
Notice how far the rotor sits from the center.

B5 = 21.6lbs. I added an extra control arm and subtracted the difference.

B6 = 16.4lbs... Just over 5lbs of unsprung weight savings. Hardly significant, but it's something.

Moving on to the coilovers I read a lot of information that lead me to believe (that despite the B6's strut mounts being located top of the strut bracket vs underneath) they were a direct swap, other than the lower control arm (straight) having a thinner bushing on the B6. So I snagged up a couple B6 control arms and got to work today. I pulled the uprights and go to work mounting the coilovers, and quickly found out this does not work! The B6 strut bracket mounts horizontally to the body, while the B6 bracket has a bit of an angle. It will line up if the bolts go in at a 45 degree angle to the body of the car, and you'd be stupid to roll like that.

B5 Strut Bracket (TOP) vs B6 Strut Bracket (BOTTOM)

I'm going to attempt to swap the coilovers onto the B5 strut bracket tomorrow and see how it goes. I'll have to pull some new brackets off of a donor Passat I have sitting around as mine self destructed upon removal, pics coming soon.

11-23-2018, 10:15 PM
I did a B6 front end swap too.

I used B5 coilovers, but Iíve heard B6 fronts will work FWIW

I pressed a B5 bushing into a B6 lower straight control arm.

B6 uppers, completely interchangeable

B5 S4 wheel speed sensors

B7 RS4 braided brake lines

Edit: forgot to add, I used a B6 sway bar and endlinks too

11-23-2018, 10:34 PM
Good info on the speed sensors, I hadn't even thought of that. I pulled the B6 ones and I was going to try and swap the connectors, but that's much less messy.

If I'm able to make these StopTechs work I'm thinking the braided line used in the Porsche BBK should work for me. It's just a M10 banjo fitting.

11-23-2018, 10:37 PM
The B6 wheel speed sensors bolt in, and I donít think the B5 ones do, plus different connectors. The B5 S4 one bolts in and has the right connector. Only thing I had to do was use a washer to space out the sensor so it didnít interfere with the axle.

The RS4 lines are the same but I think theyíre a little longer. I did the 993 calipers so itís just what I was told to use and it works.

11-23-2018, 10:42 PM
The RS4 lines are the same but I think theyíre a little longer. I did the 993 calipers so itís just what I was told to use and it works.

Ah I see what you mean now. I never would have guessed RS4 parts to be the cheaper alternative, but there it is. Thanks for the info!

11-24-2018, 08:49 PM
Did some more work today, got one side finished. Currently I have the S4 mockup brakes installed. I actually didn't realize the B5 brakes wouldn't mount up to the B6 upright.

I was hoping to use a 16" set of snow tires to get through this winter. Obviously these won't fit over S4 brakes. So I was comparing some part numbers and it turns out the caliper itself is the same between the B6 and the B5 A4. I just need B6 carriers. Another trip to the junkyard will suffice.

As a side note it looks like B5 share the same carrier as the C5. So if you went the route of C5 uprights, B5 brakes would bolt on.

Out with the old. I still owe this thread the exact weight difference between the aluminum and the iron.

Swapping the strut brackets from the B6 coils. Big C-Clamp for leverage.

Success! B6 struts definitely fit.


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11-25-2018, 05:40 PM
Passenger side was a disaster.

Axle bolt was completely frozen and even started to wallow out. Luckily I had a spare axle for an automatic laying around and was able to swap the outer CV. As I was trying to smack it off I ended up popping out the inner and had to pull the whole axle.

Lower control arm nut was messed up and wouldn't keep a socket/wrench on it.

Tie rod pinch bolt completely stuck. Once I got the upright out I managed to get it to move a couple millimeters. I chopped the head off with some bolt cutters and sent it out backward. What a mess.

Not so productive. Spent a lot of time stuck. I did finally get it all put together. Next step is to put load on the wheel and tighten it all up.

11-25-2018, 05:51 PM
Also, if you ever find yourself pulling the lower rear (curved) control arm. PUT THE DAMN BOLT IN THE OTHER WAY, save the next guy a headache.

12-12-2018, 06:58 AM
The suspension is all back in action. Took me 5 tries to set the height of the coilovers, everytime I lowered the car the fenders sat on the tires. No good. I finally gave in and raised them all the way, which of course granted me monster truck status. Oh well, I'm done busting my knuckles up for now. Coilovers are a PITA incase you didn't know, I sure didn't.

I had a slight side to side play in the passenger side which almost had me pull the inner tie rods. I went through all the work of preserving the boot and carefully trying to knock the ear clamp off. I finally got the clamp and the boot off in one piece and then noticed I never tightened down the lock nut on the outer tie rod. Which allowed for a bit of thread play I suppose.

I picked up some B6 carriers so I could mount the B5 calipers to the spindles.

12-12-2018, 07:19 AM
Also, if you ever find yourself pulling the lower rear (curved) control arm. PUT THE DAMN BOLT IN THE OTHER WAY, save the next guy a headache.

This is something I tell anyone when they ask for advice on control arm swaps.

12-19-2018, 10:11 PM
I finally edited in the weights of the uprights and I removed my engine work documentation as I'm running into some issues that required me to start a help thread. I may leave this thread here, if anyone has any use for the information. Questions are welcome.