944 rear arch under battery repair

[Wh1t3Kn1ght]

Hi Folks,

Happy new year! I hope everyone is well, fingers crossed for a better 2021.

I'm beginning to get cracking on some jobs around the 944 and one of them that is on my list is some corrosion in the rear underneath the battery tray.



The outside of the arch has been patched already inside the wheel well so I'm hoping it is only surface rust on the inside...

Now my question is maybe I can tackle part of this job myself?

I think I would need to carefully remove the battery tray to begin with by cutting it out so that I can gain access to the corrosion.

Then treating the corrosion with a mixture of abrasives to remove the loose rust and then chemical rust treatment (Bilt Hamber Deox Gel) and then re-painting with a layer of zinc oxide primer.

Finally getting someone to weld the battery tray back into place.

Has anyone repaired this area on their 944 and how did you go about it?

Alternative is just to find a reputable bodyshop and get them to do it for me....

My main concern is I don't want to damage the paint finish on the outside as that was only completed recently.

Thank you for taking the time to read my post

[Waylander]

I would give it a coat of Hydrate 80, before your primer, and the battery tray not removable other than cutting it out is a real pain in the ass

[Wh1t3Kn1ght]

I would give it a coat of Hydrate 80, before your primer, and the battery tray not removable other than cutting it out is a real pain in the ass

Yes I was looking at the Hydrate 80, I have all the others just not that one

I may be able to squeeze a wire brush under the battery tray perhaps to remove the loose rust and then clean it up.

I sprayed it all with Dynax S50 earlier last year to give it some kind of treatment, will have to degrease and clean it off first before attacking the rust with the wire brush....

[kongsodoken]

I made the battery tray bolt in so it’s easy access to treat in the future

[Wh1t3Kn1ght]

I made the battery tray bolt in so it’s easy access to treat in the future

Awesome idea - do you have any pictures?

[Waylander]

Knowing Ken, there is bound to be a picture

[Wh1t3Kn1ght]

Well I went out at lunch time now it is a bit warmer (0.6C instead of -4.0C)

Think it is about 4C in the garage... (another project to get it insulated and perhaps a radiator added).

So I took out the battery and examined the battery tray, it looks like one end is held on with several spot welds (these could be drilled out), the other end has a tack weld, one edge isn't attached and the other edge slots into the chassis rail with a tack weld to hold it on.



I wonder if Ken replaced the spot welds with bolts and nuts?

Pretty confident I can cut the tack welds, drill out the spot welds and hopefully remove the battery tray in one piece so that it can be re-attached after I treat the rust.

Had a good tap around with a socket extension and it seems solid so hopefully it is just surface rust that needs mechnical removal with wire brush and then some chemical treatment before painting.

[kongsodoken]

I don’t have my photobucket account anymore so can not get the photo
I made 2 brackets that were welded in place one each end
Then made a new tray that slotted into these brackets

Simon has one he may have a photo

[Wh1t3Kn1ght]

I don’t have my photobucket account anymore so can not get the photo
I made 2 brackets that were welded in place one each end
Then made a new tray that slotted into these brackets

Simon has one he may have a photo

Hey guys - whilst I was waiting for the Deox-Gel to do its thing on the rear jacking points I took another look at the battery tray area.

Finally managed to remove the battery tray which was hard work trying to cut off all the welds, four along the one side, three at one and and two at the other! It didn't want to come out

The corrosion underneath looks like I just caught it in time, there is a top layer of scale which I started chipping away at, will need to completely chip that off and then wire brush the whole area. Will then soak it in Deox-Gel like I am doing with the jacking points.



Looks like someone (Porsche?) went a bit overboard with the thick sealant, you can see one massive piece at the top of the photo, there was another below it which I managed to chisel away.

[Wh1t3Kn1ght]

Had another chance to have a go at the area under the battery tray!

So luckily it wasn't as bad as it look, the flakes came off and looks like there is an old but quite good repair underneath with clear signs of previous welding.

Whoever repaired it didn't drill the drain hole in the repair section they welded in (circled), the same thing happened when I had the opposite side repaired before the respray, so today I drilled out the drain holes and ordered some more of the VW rubber drain grommets. Because this hadn't been drilled out I think it contributed to the accelerated corrosion in this area as any condensation or moisture that got into the rear arch well would have had no where to go without the drain.

After an hour or so with various wire brush attachments and the black and decker power file I managed to get rid of the battery tray welds and most of the loose rust, almost ready for a treatment of Deox-Gel.

Unfortunately in my haste to remove the battery tray I inadvertantly damaged the skin of the rear arch and made a small hole the metal looks sound so I'm hoping that whoever I get to weld the battery tray back in can patch the hole for me...

[IanK]

Luckily, my Cab has a large drain hole in that area - I dont need to worry about it holding water

And it appears a previous owner has repaired it with filler rather than use a material that could go rusty.

[Wh1t3Kn1ght]

Luckily, my Cab has a large drain hole in that area - I dont need to worry about it holding water

And it appears a previous owner has repaired it with filler rather than use a material that could go rusty.

Ouch - you might want to take the left lower diffuser off to see the condition of the arch behind it.

[IanK]

I did briefly think about that a few weeks back but couldnt quite see where the fixings were - any tips?

Basically, I doused it in Kurust and decided to wait till it gets a bit warmer.

[Wh1t3Kn1ght]

I did briefly think about that a few weeks back but couldnt quite see where the fixings were - any tips?

Basically, I doused it in Kurust and decided to wait till it gets a bit warmer.

Yes there are two bolts on the outside above the exhaust tail pipe and two nuts on the inside of the wing just above the battery tray. Takes 5 minutes to remove it, make sure you are holding on to it or supporting it but it shouldn't come loose as the two threads that go into the wing should hold it on even when the nuts are undone.