Galvanising front and rear subframes
 

My recently purchased 2.8QS needs a complete front & back control arm and shock absorber set and seeing as both subframes are quite rusty on this almost 20 year old car I was also thinking of getting them sand blasted and galvanised.

Have any of you done this?

I don't want do do powder coating as its not as permanent and protective as galvanising.

Any opinions?

Interesting idea. The only challenge I see with it is that the bushes are pretty much unobtanium now, and you'd need those out to hot dip it otherwise they would just burn up. IIRC I bought the last full set of S8 bushes with the last subframe I stripped, but the 2.8 bushes may still be around somewhere. If you can find them and are willing to spend the cash then go for it.

Generally I just blast and re-paint with something like Rust-oleum combicolor when the bushes are intact. I agree powder coat is definitely not tough enough for a job like this - it tends to flake off the sharp edges and welds quite easily.

I looked into galvanising when I had my subframes replaced a while ago but decided to go with a coating of POR-15 instead.

I really like the idea of galvanising the subframes. I managed to get hold of a pair of very good condition front and rear subframes last year. Both have very little corrosion and are ideal for galvanising.

I managed to get hold of a full set of bushes actually quite easily. The fronts (8 of them) from Audi main dealer and the rears (4 needed but 2 different part numbers) from ECS Tuning in the US. Except to pay good money for them though. I think mine were around £700 for them all.

Removing the old bushes is also a challenge. Especially the front ones as they cannot simply be pushed through. I managed to get hold of the genuine Audi tools for removing the bushes but I still had to do some improvising.

When I get done with my rear suspension refurb in the spring I'll start to look at getting the frames galvanised or some other suitable coating. I want something that involves "dipping" as the frames are hollow and painting the inside would be difficult.

You bought the last set then +++ I know when I asked recently there were three left. Fat lot of use that is!

According to my info the pn for the bush is 4D0399415K and its shared between phaeton and found lots of them on ebay?

My plan was to buy the 2 subframes from forum sponsors then get them galvanised and then give it to my mechanic, this would avoid the car being in bits for probably weeks.

These are the 2 subframes I bought as spares. As you can see they are in pretty good condition already. I was in no rush so I held out until I found some that came from a dry climate.

I can't remember where the front one came from but it was somewhere in Europe. The rear came from southern Italy, a nice dry climate.

All the UK ones I looked at seemed pretty rough.

Wow thats a good tip, to buy some from a warm country. Those look like they were taken off a 3 year old car or less!

Tread carefully with hot dip galvo, it's hot, really hot and can cause deformation. I'm fairly familiar with the sub frames can from memory they have holes everywhere and that's good as it'll explode if there are any pockets. Also anywhere that is a tight fit before will be tighter after dipping, it's quite a thick coating.
Lastly choose your galveniser wisely, some are rough even for ships, Crediton are OK depending on when they last changed it out as they are a bit agricultural toward the end it can be lumpy and thick.
We would send stuff to Liverpool from Devon

Thats the A8 V8 bush. The S8 version is L and I think that's used on various Bentleys too. The A8 V6 bush is F - not sure what else that might be found on, maybe the V6 Phaeton?

The subframe will probably need dipping in something to strip it in the first place to get all the paint off the inside too. Sandblasting won't work for that, and I suspect molten zinc may not respond well to paint. I'm not sure what sort of hellacious paint stripper you'd need to get the factory coating off because its amazingly tough. Except where its rusty :rolleyes: