98 Volcano Black Avant V6-QS build thread; 2.7T swap, C6 RS6 brakes & more...

Farmer Broad

Farmer Broad

Ruining cars since 03.
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Hey everyone,

I hope not to bore you all too much but I wanted to start a quick build thread on my B5 Avant.

About 5months ago, after quite literally years of looking for a very particular spec of B5, a friend of mine called me and said he had the exact car that I wanted, a pre-facelift but 98MY, so has the flicky key, 30v engine and a few other changes over the earlier cars, 2.8 Quattro sport Avant with Terracotta heated leather, BOSE and most importantly finished in Volcano black... I genuinely could not believe that after all of this time my perfect car was just 15miles away! Needless to say I bought her and this is what I've been doing to her since...

As I'm sure you've guessed from the title the plan is to turn her in to a very fast weapon of a wagon while retaining the basic looks of a normal non S A4 Avant. The first thing I did was buy a donor car, a C5 A6 2.7T QS. That car has been stripped for the engine, 6speed manual gearbox and front hubs.

Up next I wanted to look in to braking options. I've always been a total brake whore so decided I wanted a multi-pot Brembo set-up up front and thought that there really wasn't a better option than keeping it OE and getting the absolutely stunning C6 RS6 set-up. After some searching on eBay I found what I wanted and snapped it up before the money was used on silly things, like food. Even though I'm seasoned with big brakes I really was blown away buy the size of these things, 390mm front rotors with oversized 6-piston callipers... They're seriously beautiful but, annoyingly, also very heavy.

Chassis wise she is sat on 19" staggered RH wheels with 225/40 & 235/35 tyres. For the drop I'm using AP Racing coilovers but have only been able to fit the rears so far as I'm still in the process of changing the front hub assembly as the original B5 hubs use a smaller bolt pattern for the calliper carriers.

Unfortunately progress is pretty slow on my B5 at the moment as I'm also building my Smart Fortwo Cabrio but I'll throw some pictures to you so you can see where I'm at... if you're even interested!!

Cheers to all of you that have actually read my dribble, you're good sports... and can be my friends :)

I'll update as I go and hope to perhaps meet some of you when I finally get her on the road!



Her as bought





The C6 RS6 Brakes






The donor A6


How the rear currently sits


With my Smart car... the keen eyed may have spotted that I've had the Smart painted in Volcano Black to match my baby Avant



How she is today after my unsuccessful attempt at fitting the A6 hubs! B5 hubnuts are rather annoying.

 
Last edited:
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Welcome, Same colour as my car. :)

And where the original wheels you took off ??

Think youll need prop and diff to match the gearbox as im sure the A6 rear end is totally different to that of a B5 was the A6 2.7T a quattro ??

Looking forward to see the sleeper in finished form !!
 
I see the A6 rear subframe sat next to your car in your pics answer my own question lol
 
Cheers for the welcome and comments chaps!

You're right Bradderz regarding the diff and bits... I believe the prop may be a tad longer on the A6 but I'm planning on buying all new and uprated shafts as I'm looking to extract good power from the 2.7 lump... I could bang on forever about the details so I've deliberately left lots of info out as I don't want people to age while reading my posts haha.

That rear subframe is actually from my BMW E38... unfortunately had a bad blowout and lost control of her, wiping out a good portion of my village at the same time so I had to break her... it was a shame but allows me to focus more on my B5!

 
Sorry, forgot to say the C5 is a Quattro, yes. The original wheels are in a stack at the moment, I really like them but I don't have any use for them anymore so I'll probs sell them soon!
 
Yeah i think your maybe the second volcano black A4 ive seen on here.

Not too serious needs some TLC and a good strip down and rebuild to a 2.0 with a BT setup.
 
The rear diff ratio is different on the 6 speed box, so you'll need a matching B5 S4 rear diff and a B5 S4 propshaft. Worth checking the gearbox code before you buy anything to ensure the A6 box is the same as the S4 one.

Dont bother messing with the shafts, the standard S4 parts are fine to over 600hp, and even once beyond there only the rears tend to break if your being stupid with launches and suchlike. "upgrading" them is just ******* money away.

I love that brown leather! It would look much better with black interior plastics and carpet though.
 
audi upgrades
Ha ha cheers for all of the replies, it's refreshing to find a forum full of nice, happy people!!

Aragorn,

Thank you for the info, I'm having to look at all of the part numbers on the A6 very carefully as she was originally an auto that was converted to manual... hence I'm not sure if they changed the rear diff as I would presume the auto & manuals would differ in ratios? The plan was, as you've said, to buy the S4 bits if things do not match up. The other issue that I have is that the A4 is a drive by cable throttle body and the A6 is drive by wire. I'd much rather keep her with a cable throttle but we shall see what I end up doing! That's also good news on the capabilities of the OE drivetrain, I'm just one of those tossers that tends to go OTT on the "build strength" as I'm pretty harsh on my cars! I also agree about using more black in the interior, the dash and door tops are all dark brown too so it's a little over-powering but I can't bring myself to change any of it as I just love her so!

JBH

Ha ha cheers for the comments, pretty sure my love for the brakes is unhealthy... The background car you say? Well, I actually rent the units on the farm out to my friends and this is one of the many projects that we have here. She is a 1974 BMW E3 3.0S, currently being built with air-ride, 18" BBS splits, Weber DCOE carbs and soon to be matte black. Seriously, seriously cool car. I've been tempted to buy her off of my friend many times as the S is a very rare example but, as an example, just the front panel where the grill goes has cost over £1k to buy so she would cripple me financhially rather quickly! Maybe I'll get a good deal when she is complete and he is poor? Who knows haha!

Cheers again all
 
The A6 diff housing is different to the A4 one, the A4 has a torque tube on the front of the housing and i'm not sure the torque tube will fit onto the C5 diff. You will need the B5 diff and prop. If you give me the code of the gearbox, i can tell you what ratio rear diff you need.

From memory, S4 DSY box has a 4.11:1 final drive, the 2.8Q uses 3.89:1

All S4 engines are DBW, so your stuck with that. PFL S4's have a cable throttle pedal, with a small sensor thing attached to it with a short cable, getting one of those saves changing the pedal box, but unfortunately you need to remove the pedal box to fit the sensor. And at that point, your probably just as well to fit the whole DBW pedal box.
 
What size are those rims and pad?
 
Hi Chap,

They're 19" RH Toplines in 8.5" & 9.5" widths respectively. Personally I would have prefered 18" wheels on the B5 but because of the brakes I didn't have a choice. Sorry, what do you mean by pad?
 
Right, no major progress I'm afarid but I have fitted the C5 front arms and hubs to the B5 and I've started to strip the C5 down. The engine and box are out and ready for more tinkering!

I started to fit the C6 brakes but all is not well! A friend of mine fitted the same set-up to his Mk2 Seat Leon and only needed a small spacer between the hub and disk to space it correctly... unfortunately for my B5 it looks far more involved! Due to this I am going to have to send the entire hub, disk, caliper and carrier to a company so they can make custom spacers and possibly bolts so the fitment is perfect!

Anyway this first picture is really for Aragorn as I'm hoping you can tell me which differential I'll need to use with this gearbox!


The second is... well, stupid :eek:
 
Hold the horses on going mental with the uprights and machining. VAG stuff mostly bolts together, and if it doesnt theres often a simple solution.

Certain R/S6 models used a wheel hub with a 6mm spacer sort of "built in" which pushes the disk out by that same 6mm. If you try to fit the disks to a car without the spaced hubs then the disks can collide with the upright and the caliper wont line up. If thats whats wrong, you should simply need to fit the hub flange with the spacer to your car, and it'll all slot together. If you like i can get you the part number!
 
Cheers as always for the info... in honesty I am, as you have said, used to VAG stuff just bolting on with little effort so I was genuinely suprised that the brakes are putting up this much of a fight!! Very much worth it though as when I mocked them up the other day they looked fapping gorgeous... it's just a shame that I have to run 19" wheels to clear them as they're just a tad big for the shape of the B5 in my opinion, but hey, that's the price of having an addiction to stupidly pointless and oversized brakes haha!

If it's ok with you Aragorn I may mock up the brakes today and take a few pics as it all looks way out! The caliper appears to sit too far in towards the hub and the disc rubs on the hub assembly where the lower arms attach... I'd be very interested in that part number though so I can see what it is... just don't want to be too much of a pain in the **** to you!!
 
The hub i mention is part number 4D0407613E. It was used on the C5 RS6 as well as the C5 models with a V8 engine (they all had widebody). Its also used as standard on the cooking spec C6 A6 models (the larger S6 etc use bigger wheel bearings) This will push the disk out about 6mm and should hopefully get it away from catching on the upright/arms etc.

Not sure why your caliper isnt aligning, some photos of that area would be useful? But if you can get the disk on, it might just be a case of making up a spacer to sit between the upright lugs and the caliper carrier to push it out.
 
Well, I actually cannot believe it has been nearly a year since I posted on here!!

Due to other commitments and projects I hadn't even looked at my B5 until a week ago when I decided to pull her out of the barn and give her a wash. It still amazes me just how much I adore my near 20year-old weapon and how every time I sit in her she just feels special, different and right. Not one of my other cars, past or present, make me feel the way I do for my B5. Still, I'm sure on this forum I'm not the only person to feel that they are in some-way a very special car that belie their humble value.

Anyway, sentiment over... it was at this point, I suddently realised that I needed to get this project moving again. Unfortunately money is very tight at the moment due to my biggest project being the building of a container/eco home to live in; and no matter how much love I have for my B5 a house and my relationship have to come first!

The good news is that a friend of mine who predominantly builds looms and does custom mapping/electronical stuff that I don't understand has agreed to pop over so we can finally strip the C5 A6 donor car of its wiring to start looking in to building a loom that will let me keep the original pre-facelift dials and also get the Bi-turbo lump running, not that it is installed yet, plus what-ever other electronical issues that we may encounter to enable the 2.7T conversion.

This next bit is mostly aimed towards Aragorn... I decided yesterday to strip the A6 of its rear subframe and diff as we were both a little unsure if the A6 diff would work with the A4 considering it uses a torque tube and the A6 does not. I must say that so far it looks as though it would fit and that the torque tube would bolt on to it but I want to humbly ask for your help regarding the part numbers. From my research I'm fairly certain that the differential on the A6 is the original one that came with the auto transmission (the A6 I bought had been converted to a 6speed manual from an Auto) but would you be kind enough to confirm that it is not the correct diff for my gearbox (gearbox part number shown in pic a few posts up) The differential is: 01R525053E with PR-A27 also stamped on the casing. Thanks in advance as you've already been a star with your previous posts.

If you've read all of this you're a trooper and I hope everyone on the forum is doing well!
Martyn.
 
On the loom, you shouldnt need anything particularly fancy, after all, 98 S4's existed. Best case you get a '98 S4 wiring harness and it plugs right in.

Worst case you need to swap some plugs in the Plenum box.

I put a 1.8T into a '98 S4 and had to swap the plugs as my loom was from a passat. I chose to fit the S4 plugs to the 1.8T harness as i had them both out the car.

I think that as you've suggested the actual diff housing is the same, and you should be able to simply swap the B5 torque tube onto it.

You need to get the gearbox code and the diff code. Both are 3 letter codes like "DSY" or "DAJ". Get me those and i'll check properly for you.
 
Ah, right... That explains why I wasn't getting far with that part code! The three letter diff code is EUU. I'll look closely over the gearbox tomorrow to see what it is. Thanks as always for your help Aragorn.
 
Righto, it has taken longer than I'd hoped to get the info I needed off of the gearbox but the following appear to be the codes I have.

Gearbox: EDU
Differential: EUU

Annoyingly I did find a website a few days ago that had all the information I needed but now I can't seem to find it :-/ Teaches me for not adding it to my favourites I guess! I'll keep searching but if anyone can put me out of my misery and tell me if these are compatiable or not I'd seriously appreciate it.

Thanks!
 
Sorry for the terrible quality pictures (taken with the iPad) but I thought I'd give a quick up-date, seeing as the weather is bad and not much is happening on the farm!

I'm now basically ready to do the engine swap, technically a dry run as the enigine is still in stock tune, so once it has been fitted and I have it running I'll be able to start looking in to larger turbos, intercoolers, pipework and so on... I'm also thinking about using the heads from my 2.8 block, but that is another post for another day, and I guess depends on just how much I can afford to spend and how far I want to go with the build. Anyway I won't go any further in to that as many people will say it is pointless and I haven't looked in to it enough to justify doing it yet!

I have had a real spurt of enthusiasm recently for my cars and decided I'd make some changes to the ride height on the B5 (It has gone higher, not lower btw!) and I finally decided to buy the wheels that I actually want to run on her... Pics below, feel free to tell me if you like or hate them!! They're not on the car yet as I cannot afford the tyres that I want them shod in... but I may give in and buy some cheap tyres to fit them as I'm not sure how long I can last just looking at them in the barn, I mean, I've waited a year and a half to buy them as it is.

I haven't bothered looking into the ride height or stance of the front as until the 2.7 lump is dropped in and the new uprights, hubs & brakes are fitted I don't see the point. The rear however is very nearly where I want it to be... it doesn't really show in the pictures but I love the fitment and it looks hard... real hard.







The new (to me) wheels.

Mercedes concave CLS AMG 19"ers in 8.5" & 9.5" widths, I've always wanted these on my B5 but let me know what you all think! I cannot wait to see what the C6 390mm brakes look like behind them though, personally.





 
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Hey everyone,

Thought I'd just post a few quick pictures... I decided to fit the new rear wheels the other day and am pleased to say they look exactly how I had expected/hoped! I know wheels and looks are subjective but to me they totally transform the look of the car and I think they are just perfection!

Further to that I decided to do a quick test fit of the rear brake discs (no caliper yet but that's another story/mission that I'll come to another day!) I know they are completely excessive and kind-of pointless but, in my opinion, they just look so lovely! For reference they are 356x28mm in size and sat behind a 19x9.5" wheel.

I'll also state that I've had the brakes for around a year so they're looking a little rusty but they will soon come back to life, so disregard the condition of them, and the fact that the car is filthy and the fact that the ride-height is all over the place at the moment...

Oh, lastly, I am picking up the front wheels from the tyre shop late Monday so hope to get them fitted this week. I'll also be popping to my local garage to get new bearings pressed in and to have the RS6 hubs fitted so I can finally get the front brakes on.

Here are the pics:








 
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Thanks for the comment. The rears are ET36. They are basically flush with the arches, so I opted for a 235/35 tyre that gives a minimal amount of stretch over the 9.5" rim for assured arch clearance. The suspension can fully compress without the wheels or tyres touching/rubbing the arch or any suspension component & I probably should state that I am not, and do not intend, to use spacers.

Cheers again!
 
To be quite honest I have been looking at lots of tyre sizes but for some reason a 255/30 hasn't crossed my mind... I think I may crunch some numbers on a tyre size calculator to see if it's possible. The only issue I seem to have (which every B5 must have) is that the top upright is just mm's away from the tyre so any increase in diameter will result in it touching. I do like the sound of 255 rubber on the back though! To Google I go!
 
-11mm in diameter over a 235/35.... Why the hell didn't I think of that size before?!! Looks like I'm going to be spending a few more hours pondering sizes again as I really want to go a little wider on the front too. (currently 225/35 on 8.5" rim)
 
Its exactly the same rolling radius as the 225/35r19, which in turn is the same radius as all the standard B5 tyre sizes like 225/45r17 and 225/40r18.

Used on many BMW's with staggered fitment wheels :)

BMW would use 225/35 on the front the 255/30 on the rear.

On the B5 there tends to be a bit less room up front anyway, so those sizes could work quite well?
 
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Well, that sounds perfect then! I did want a little more width up-front but, in truth, I guess matching the rolling radius' is more important on the Quattro than an extra 10-20mm of front tread!
 
Interesting thread. Fast forward a few months after all the mechanical work is done, are you fitting one piece headlights, and what about gun-metal grey roof rails to match the alloys? Too much bling? Understated rear roof spoiler on the cards too?
 
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