Project Lazarus

[S2central.net]

Took about 2.5 hrs with a fresh head and no distractions to drill out that pesky subframe bolt today.

Started with a 3.5mm bit, then to 4.5mm. Stepped up to 6 and tried too hard - broke that bit - back to 5.5 then 6.5, 7.5 and finally 8.5mm which is as big as you dare with an M10 bolt.

Poked and based out the remaining bits of thread and chased it through with an M10x1.5 tap.

It's damn awkward to do on axle stands but those cobalt drill bits are awesome - eye protection is an absolute essential as huge chunks of swarf are produced.

Some pics for posterity. Only other note is that a used a cone shaped grinding stone on a dremel to find and mark the centre of the damaged bolt. I wavered on and off centre due to awkward working position below the car.

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[S2central.net]

All that done - I was a bit surprised not to find M12 subframe bolts on mine.

Due also to lots of rusty dust coming out of some of the other subframe mounts I am going to open them up from above in order to treat any hidden rust and upgrade to M12 captive nuts / plates at the same time.

[S2central.net]

I am also weighing up whether to go for a certain pair of tubular subframes which cost a packet but will save many hours of cleaning, prep, welding and painting to refurb my OE items to track-day worthy fashion. Gonna have to think hard about !

[Audi imsa racing]

I am also weighing up whether to go for a certain pair of tubular subframes which cost a packet but will save many hours of cleaning, prep, welding and painting to refurb my OE items to track-day worthy fashion. Gonna have to think hard about !

Maybe we could talk to a certain member and purhaps organize a group buy for the tubular subframe?

[Greg_S]

Nice work Paul, those types of jobs are never much fun. Well done getting the old bolt out

[newsh]

As above, well done

[S2central.net]

So I starting taking the rear diff apart - 20plus yrs of rust and grime on the difflock bracket.

Very hard to see in the photos but there is a little c-shaped clip that connects the vacuum actuator to the link rod into the diff. With the clip removed, you can press out the pin with help of some vice grips and a little socket.

PlusGas helped free the 3 x 8mm bolts holding the actuator onto the bracket.

Then I decided it was time to try some electrolysis on that gnarly looking bracket.

http://www.youtube.com/watch?v=ndfZEID6goU

[Bowie69]

Oh you will like electrolysis....

[S2central.net]

Forgot to say - actually cracked the plastic actuator housing while removing one of the 3 bolts - should have let it soak longer.

I was able to fix it easy though with some 2-part epoxy glue. It now passes the ill tasting suck test.

I had to extend the threads in the housing with an M5 tap so that a longer bolt will work.

I may never refit these parts of course as I don't expect to need a lockable rear diff where I am going - so the restoration efforts may benefit someone else.

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I also cleaned up the end of the actuator rod and primed it for a lick of POR15.

The YouTube link explains the electrolysis and mixture etc but I will be improving my setup on this with a circuit that I can control current etc

Really needs a container with anode material surrounding the cathode part - so some searching for suitable plastic mesh so I can set larger parts into without creating a short circuit.

[Error404]

I tried electrolysis, but submersion in water / molasses mix is actually much easier and more effective, if you have time to wait

[S2central.net]

I will maybe try that method another day - its even less technical than the electrolysis method - zero electric cost and some weird science involved !

[S2central.net]

So after my initial dabbling with electrolysis - I decided to make up a decent tank where I could surround things with a decent surface area of anode material. Hopefully the pics are self sufficient. I made an insulated spacer tray at the bottom from an offcut of garden trellis and plastic conduit.

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[S2central.net]

Next for the treatment was these two minging rear top mounts - never been off the car since 1993.

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[S2central.net]

Into the tank and charger on. Bubbles started almost immediately - it's much faster than the test tank with a single anode plate.

By utter fluke - the tank lid even sits on nicely with plenty of room for the fumes to vent. This stops me from watching the wonderful patterns of chemistry.

At this point the missus wants to know why my garage looks like a scene from breaking bad, but I will take that as a compliment.

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[S2central.net]

After about 4hrs loads of rust already gone.

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