B4 80 FWD - Quattro Conversion?

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Wondering if anyone has ever explored this in detail. I had assumed that the floor pan of the FWD and Quattro were completely different, but while looking in the parts catalogue for various bits last night I noticed that the main floor panels (i.e. the main shape of the underneath of the car) including the side members at the rear, etc. are exactly the same part numbers.

The diagrams are drawn and oriented differently, which makes numerous parts look different, but 99% of the parts are identical, which surprised me. Note that the cars in question are a '92 80 2.8 V6 (AAH) FWD, and a '93 80 2.8 V6 (AAH) Quattro. I've included part numbers of the bits which differ, for anyone who's sufficiently interested...

The only differences I can see on the parts diagrams are a few extra parts on the Quattro:

- Two or three reinforcement panels around the transmission tunnel on the front floor panel:
a) one around transmission p/n 893804041
b) support plate for manual gearbox (I'm guessing this supports the longer torsen box on the Q). p/n 893804803
c) a couple of small looking reinforcement parts which don't have part numbers/descriptions listed.

- Two sets of inserts which must be welded into the side members at the rear:
a) where the trailing arm mount bolts on to the FWD (this is where the front mount for the rear subframe goes on the Quattro - there is an extra support part which presumably welds in (p/n 8A0803353B/8A0803353D). b) further up on the Quattro where the rear mount for the rear subframe bolts on (p/n 8A0803295/8A0803296).

- Cross members for the rear floor panel (I think this is to reinforce where the centre propshaft mount probably bolts on) p/n 8A0803533/8A0803534/8A0803535.

- Inserts in the rear floor where the fuel tank straps attach on the Quattro.

I can't get under the car really today because it's so wet to visually confirm any of this. It would really depend on how possible it is to access the parts where the inserts would have to be welded in, or whether they're inside the chassis which would neccessitate cutting out bits of panel to weld them in. I thought it interesting enough to post because the difference seems very small in overall terms.

Anyone ever looked in detail at trying it?

James Cool

Posted: Tue Sep 09, 2008 4:53 pm

Me and Mark (Rotoryboy) as it spookily happens Shocked

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Jase, I might have known Laughing

. Are you thinking of doing 'sooty' then? I'll give you a buzz and we'll put our heads together, so to speak!

Posted: Tue Sep 09, 2008 5:39 pm

Was quite suprised when I got Titan to find a pukka transmission tunnel on a FWD car Confused

Don't think it would be worth fitting quattro to a 1.6, TDI yes as has better torque.

Posted: Tue Sep 09, 2008 11:03 pm

my coupe also has a tunnel, the exhaust runs through it

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Yep, all the major features are already there, there are only a few reinforcement panels (quite small) and potentially a couple of threaded bushes to add. It's all quite exciting, but will have to wait until the cars are up on a lift to have a really good idea of how difficult/possible this will be...

Just spoke to Jase, and very spooky that he and I have been having similar ideas and conversations quite separately over the last few days!

Does anyone have any idea of the position regarding the registration document (would you have to have an engineers report, could you re-register as a Quattro), MOT and insurance? Perhaps someone could comment who's done extensive modifications before and had to deal with this type of thing?

James Cool

Posted: Tue Sep 09, 2008 11:24 pm

Good to talk James Wink

Others may laugh, but the FWD and quattro have a LOT more in common than you'd think.
Certainly NO chopping out of rear floor pans Wink

Jase..

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Yep, the floor pans are here to stay! Wink

Posted: Tue Sep 09, 2008 11:36 pm

makes sense for them to come out of the factory the same, why spend all the time and money re-tooling if you don't have to? Just shove the chassis out the same, make alterations later to suit Wink

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Yeah, exactly. We're hoping they put in the rear subframe rear mounts but just didn't list them on the FWD parts because they would never be needed as a spare on that model as they'd be unused, for example.

James

Posted: Tue Sep 09, 2008 11:46 pm

Hopefully one of us will get a look at that this week. Fingers crossed when that bung is removed, there's a thread lurking up there Very Happy

Posted: Wed Sep 10, 2008 7:15 am

This is all very very exciting, i was also quite suprised to find a tunnle down the center of the car a few years ago when i had my saloon, never thought any more of it as didnt have the means to look into it further.

Wonder if it would be possible to make my 2ltr 16v coupe a quattro Razz

ha ha ha

Jim

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

I don't know about the coupe, only cross referenced the parts on a B4 saloon. It's possible though!

Cool

Posted: Wed Sep 10, 2008 12:48 pm

James, you seen all the silver B4 panels on ebay?

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Nope, where? PM me a link if you get a chance, please?

Ta,
James

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Oh, think I found them, and another estate breaking so emailed them. Cheers for the heads up! Cool

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Anyway, back to the thread. I had a quick (and I mean quick; I was late for work) crawl under the rear of the cars today. Sure enough, where the rear subframe rear mount bolts in on the Quattro, the FWD has the hole in the side member already there (of course, it's the same side member), covered by a rubber grommet. Couldn't get it out to see if the thread is present on FWDs and just redundant, or if Audi indeed welded the thread part in on the Q.

Also, the rear wheel arch shroud is covered in plastic next to where the mount is, so I couldn't see whether the U beam of the side member at that point is accessible to weld in the mount thread if it's not there, or whether the side member is welded into wheel arch. Will have to take wheel off and remove plastic shroud.

Spoke with VOSA and they said they likely wouldn't even bother to request a single vehicle engineer's report (I forget what they actually call it) since the chassis is not going to really be substantially altered, etc. Will check insurance situation too. Is there anyone who's insured a heavily modded car that has experience of this?

Cheers,
James Cool

Posted: Thu Sep 11, 2008 8:02 am

Presumably for insurance, you just insure it as an 80 quattro. After all, it isn't like you have susbstantially altered the chassis - just bolted a few things on Very Happy

Posted: Thu Sep 11, 2008 8:08 am

Once it has gone through an MOT, that would surely be classed as 'checked by an engineer' or engineers report Wink

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Yep, although insurance companies can be notoriously fussy about what you bolt on. They want to know about different alloys/wheel spacers, etc. and those are literally bolted on Laughing

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Yeah, just to clarify, the woman at VOSA thought it was very unlikely it would need an engineers report. In her opinion as long as it passed its MOT no one would have a problem with it. Cool

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Well, I can hardly believe it! Jase and I were talking the other night and wondering whether Audi might have been very kind and put the rear subframe rear mounts in the rear side member already.

The theory was that since it's the same side member, and floor pan, it may have been un-economical to make two versions; the redundant mounting points on each car would be present, but just covered with rubber grommets, etc.

We thought the reason they might not be present on the parts diagrams was that it would be unneccessary to replace the redundant parts as spares (you'd never need to replace the rear subframe rear thread on a non-quattro as it's not used, so Audi might not have bothered to put it on the parts diagram for the FWD).

Well, I hardly dared hope, but I've just taken a deep breath, and pushed a screwdriver through the appropriate little rubber grommet on the FWD. I can't see clearly unfortunately, but it feels very much like there is a thread there, and the metal is shiny and the right colour too. Take a look at these pics:

Don't ask me why in five consecutive re-frames, the digital camera won't focus on centre frame on the FWD and give us a nice view of what's hopefully a threaded mount, whereas on the Quattro from the same angle it will. But I think you'll agree the colour under the rubber grommet is encouraging as is the fact I can clearly feel what appears to be thread.

I'll confirm on the lift at the workshop asap, but I'm 90% sure it's there and if that is, it's encouraging for the rest of the bits too...

Well, just updating you all.

James Cool

Posted: Sat Sep 13, 2008 7:10 pm

Looking promising then Very Happy

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Yup!

Will try my best to get both cars out to workshop and up on a lift as soon as poss to check the other bits, but this was the main one I was concerned about as you wouldn't have really wanted to cut into the chassis to add this mounting point in, as the chassis around it has to be as strong as possible - not a good place to cut and weld. I think the other parts are just strengthening panels that weld on over the existing ones, but it's possible they are also already there. I'll have a check.

James Cool

Posted: Sat Sep 13, 2008 7:23 pm

Knew it'd be up there Very Happy

That means so far, you could actually take a quattro rear subframe and physically bolt it up. The mounting studs in the wheel arch for the shock/spring leg are the same between them too.
Looking very good chaps Smile

Good job James thumbright

Posted: Sat Sep 13, 2008 9:02 pm

Sounds very promising, look forward to hearing more about this.

Bandwidth Buster Joined: Dec 30, 2006 Posts: 631

Other good thing is that all those juicy parts like spoilers and hubs I've been tracking down and buying, will fit on whichever car ends up being the Quattro Twisted Evil

Audi Nut Joined: Dec 02, 2005 Posts: 70

I havent seen one made myself,but back in Greece many conversions were made from FWD to QUATTRO, and it was thought that only late 1994 and 1995 avants were able to get all the parts without cutting and welding back anything.I know for a fact of a FWD avant that is now a nice RS2 as well.
However i always thought that the sedans and avants shared the same shell,so if it was possible in avants,it should be possible in sedans as well.

Im going to keep track of this thread,as if this comes to be true,i might think in the future of getting a sedan(which are rebundand in greece) 1.6liter and turn it into a proper RS2 sedan!! yeah!

It looks as if this is something possible!

Posted: Sat Sep 13, 2008 9:56 pm

Vasilis, it was you that sparked this idea in my head back when I was helping you with the footwell lights. It's a great coincidence that James has quite by chance, thought of this at the same time, along with Mark.
Three heads are better than one.

I remember you telling me of the conversions in Greece of FWD to quattro.
The rear side member we have been talking about in this thread is shared between the FWD 80 saloon, the FWD 80 avant, the 80 quattro saloon and the 80 quattro Avant (including the RS2).
It all hung on whether the rear mounting had been welded in the side member the same as it is on the quattro. As thought, it's in there but just capped off with a rubber plug.
With it being there, along with the front mounting captive nuts, that means you could now actually bolt up the whole rear subframe from a quattro onto a FWD rear end. Once the subframe is up there, the diff will mount up and the rear wishbones will mount up.
As said, the studs in the rear wheel arches that the shock/spring leg bolt onto, are the same, so that's the rear suspension in.
The saloon would need a fuel tank from a quattro, either a B4 80 saloon quattro or quattro Avant. There is a strengthener on the quattro where the centre propshaft bearing bolts too, we'll need to see if this is already on the FWD, if not it wouldn't be hard to sort out.
Looking at the front, a quattro gearbox is longer, I'm not sure if some suitable mounts would be needed to be made up?

The beauty of James's situation, is that he has both a B4 80 quattro and a B4 80 saloon. He is in the best position to compare both side by side.

I am seriously thinking of doing this to the soot monster. I'll be slower at it though, as I'm going to need somewhere to do it, a donor car or someone like Sal who can supply me with the parts I need and the time to do it.

Talk about pushing the boundaries eh? Very Happy

Jase..

Posted: Sat Sep 13, 2008 10:08 pm

I thought that the boots where different i.e the boot in a quattro version was a bit smaller due to the fact they had to fit a diff to the rear?