Is it the end?

[s2driveruk]

As some of you know, i am in the middle of refurbing my S2…its been a slow burn but recently been making progress. Today however, we dropped the exhaust and after removing the heat shield, things looked pretty crusty. However, that was nothing compared to the drivers side rear subframe mount.

i need to make a decision about whether this can be sensibly repaired or not. I know i cannot do it myself and i am worried what else now lives under the underseal elsewhere. There is more across the rear valance, looks like the factory underseal process is really crap at the rear with barely any behind the subframe towards the bumper.

Thoughts? Given how thick the metal is for the subframe mounts, i am amazed at the deterioration and all behind the underseal.

[mdz]

Any decent welder could fix that, simple part that can be hand-made from fresh metal. It would be shame to scrap an S2 because of that.

[K Simmonds]

As above any bodywork welder worth his salt would have that sorted out properly in less than a day, we've got to remember these cars are now around 30 years old and as good as Audi were at preventing it effectually it'll rust will always find somewhere to take hold.

That said I've never seen one with such bad corrosion in that location, though it is perfectly repairable, to be fair to Audi compared to other cars from this era the rust protection is very good. What condition is the the rear subframe itself in? As these are notorious for rotting.

[s2driveruk]

Dont get me wrong, it is 30yrs old this Sept so it had done remarkably well in reality. However i was amazed at how bad this was when we discovered it…especially for such a structural and load bearing part.

the subframe should be ok, was refurbed with a blast, epoxy primer and paint. Had a bit of patch welding near the rear, centre diff bracket years back but generally, at first glance, looks ok.

my issue is how much more there may be that i havent found yet. Am also presuming that would need to be fabricated and welded in the garage as it has no engine, front suspension, steering and gearbox is almost ready to be removed too. I presume only other way is to build a dolly and roll it out for transport.

[K Simmonds]

I'm also pretty amazed by how badly that's corroded given how thick the metal is there... As for how much more there is the only way to find out is to start peeling off the underseal and having a look, hopefully it's just surface rust that can be dealt with fairly easily.

Not being able to drive the car to a garage does indeed complicate matters somewhat as ideally you want the car on ramp to be able to get at that, I'd also probably want to drop the rear subframe completely to be able to get at it properly or at least loosen all the bolts and let it hang out of the way. However there are some very enterprising folk out there who offer mobile repair services so perhaps you could get someone to come to you to tackle it?

[s2driveruk]

Yep, lots to ponder on at the moment. Just looking at scissor lifts.

[steve briance]

You need to stary by getting the subframe off and away and get an angle grinder with twist knot wire wheel on it. That will remove the underseal pretty well and keep going until you get to good metal which has its e-coat primer on it.

Do it for each of the 4 mounts as if one has gone that badly, the others may be close behind.

The problem with those mount points is that there is a drain hole in the bottom which blocks up and they no longer drain...

Mine had a LOT of dried mud in the there which i scraped out best possiblr then washed out and once satisfied dry - flooded it with cavity wax. The mounts are not sealed from elements so need a drain point.

Clean back all 4 points to good metal and then worry about it, you never know - it might be just that one thats bad. Any mobile welder will thank you for prepping the area and that in turn will save money.

Just a thought on wel repairs though - a jig would need to be made up to make sure the 'new' threaded hole is in the right place in relation to the other holes. A welder should consider that but, if you make that yourself, you know it will be considered. Sheet of 6mm ply will do it.

[B5NUT]

As above that's a somewhat simple fix for a professional welder. Far as the jig goes I think that will be a must. You could even make it out of 3 sections of steel box section (B&Q sell it) and steel plate in the middle to bolt the three sections together if you don't have a access to a welder. It would allow them to use the jig during the welding work.

[K Simmonds]

Making a simple jig is an excellent idea, good thinking chaps.

As Steve says you want to get the subframe off and attack the mounts and surrounding areas with a knot wheel, hopefully it's just that one but as he says they do act as traps for dirt and moisture so there could be more corrosion lurking.

[bluequattro]

I've done b2 front mounts when a nut cage broke inside.
The metal is pretty thick, so to get to that point on an s2 I'd be checking everywhere else before spending money on that part of the car
Finding a good rear end chassis pressing from another car would be an option as long as it is removed and fitted correctly.
When I did the b2 I put the subframe back on to get it all square before starting (I've ali subframe bushes so didn't have to worry about melting bushes)
One mount has a captive nut so you can adjust the other three floating ones-I assume it is the same on the rear and the s2
I good welder/fabricator would knock that up pretty quickly
Then get plenty of protection in it after its done-I did consider going in from the top to do this

[Ian Simmonds]

It’s fascinating the difference between cars of a similar era, our Avant is in for a full suspension/running gear refurbishment. Basically everything below the shock towers. The subframes are off and the body to subframe area is fine.



(basic photo of as is today).

Is that just corrosion damage over decades or has it been previously repaired due to subframe ‘whack’ because it looks pretty gnarly? Also, has it run stiffer suspension for years because that transfers extra lateral load into the body?

[newsh]

That’s nasty David! If you need a shell I know a bloke who’s got one, you’ve got my number.

[Tractor Dave]

The consul brackets were available at Audi Tradition but now I can only find the front ones. They are just weld on and maybe ring your local Audi dealer to see if there are any rear ones left in the UK?
part numbers on 7zap.
https://audi.7zap.com/en/rdw/audi+co.../803-803040/#6

[s2driveruk]

Thanks Dave, thats super helpful. I never even knew they existed as a part number! Will give audi a call in the morning

[Tractor Dave]

No worries. If you can't find new, they are common to the avant as well as long as it's a Quattro (according to AT).