other Reviving the tii after five years hibernation.

[JohnH]

I recon if you squint a bit and glance quickly, you'd swear they were yellow passivated zinc. Just kidding!

['76mintgrün'02]

A funny thing has been happening with my electrolysis set up.  I've used copper wire to hang the pieces and the copper is also dissolved into the solution.  I find that after several batches have been de-rusted, the amperage starts to drop.  If I reverse the leads, the amperage is pegged on high again and it fizzes like crazy and the dissolved metals can be pulled out of the solution.  I went into some of the details on this thread

 

http://www.bmw2002faq.com/topic/164133-exhaust-manifold-rust-pitting/

 

The weird thing is that the pieces I have put in to clean, are now coming out with a light copper plating.  I do not understand it, because it is the cathode which is being plated.

 

I will be mixing up a fresh solution and using steel wire from now on.

 

Copper plated calipers would be fine by me, (though I didn't intend to make a copper colored cast iron pan).

 

 

Gold calipers look nice.

Edited May 6, 2015 by '76Mintgrun'02

[JohnH]

Spooky things happen with electricity. I find that if I use copper wires to hang the anodes that the artifact gets coated in a black deposit. I guess thats some form of copper. You really have to scrub to get it off. I often give my anodes a brush over to remove rusty crap that has accumulated. The amperage then increases again. I have heard but never tried it, that stainless steel works well and everything stays sparkly clean. 

 

I love this process. Its so restful and hassle free. Heres an E28 rear subframe getting the treatment using four lengths of rebar;

 

 

 

I just wish I had a taller dustbin!

 

Right, back to these brakes. They are all painted up, the other hardware been refurbed;

 

 

Just a vanity shot really, to show the bits and bobs, and some of the tools and materials and products used. Clingfilm is great stuff, for wrapping your brushes in between coats. The piece of Western Red Cedar shingle (top left) is the essential stirrer. Shingles are good, well the WRC variety are and the other kind, not so much.

 

I've just got to clean up the bores and remove any extraneous paint and reassembly will be good to go, but first I have got to exercise my democratic right and go and vote. I fear the results of this General Election are not going to be good. The lights may be going out soon. Electrolysis may be a thing of the past.

 

 

 

 

[JohnH]

Okay, the lights are back on and we've just celebrated VE day, when the lights came back on though out Europe seventy years ago. Lest we forget.

 

Right, brake caliper reassembly. Its useful to clean out an threaded areas, so its worth aquiring M10x1.0 and M7x1.0 taps and dies to clean things up;

 

 

you will also note that I have cleaned out the bores with Metal Prep and some Scotch bright. It does a good job. You need to make sure that the groove for the seal is nice and clean so a scraper made from #8 fencing wire comes in handy for getting around those corners and into nooks and crannies you cant see;

 

 

Just file to the shape you want.

 

Next up grease the top of bore and seal groove. We dont want any more rust here. I use Miller Red Rubber Grease. Castrol make something similar, and I know others do as well. You often read to use brake fluid. I disagree, it just makes a mess and promotes rusting at the top of the bore. Dont do it, use the appropriate grease; 

 

 

An old tooth brush is very useful. Insert the seals and give them a wipe over, then fit the dust seal to the piston;

 

 

Then brush on some grease onto the lower part of the piston and just onto the end;

 

 

You dont want too much. Now sit the piston into the bore and jiggle it about to get it sitting level;

 

 

then gently with both thumbs press the piston into the bore. Dont force it, just ease it in. It doesn't take much effort. You might have to wiggle it a bit.

 

 

Press it all the way home and set the dust seal into its groove. Its useful to not get this all greasy as it will keep slipping off! 

 

 

Fit the wire clip;

 

 

And you're done. The ones that came with the kit are not round wire ones, rather they are flat bands and are a bit reticent to stay put, but a bit of action with a small screwdriver and they seem to be okay. 

 

Final assembly to come. Stay tuned!

 

 

[peterschop]

Great write up, I will have this in mind on my next caliper rebuild.

[JohnH]

Thats kind of you Peter, thanks for the compliment.

 

Okay, joining the caliper halves together and refitting to the car

 

Take the smaller, outer half of the caliper and hold it in your vice;

 

 

Note the poly jaw protectors. These are a great vice accessory  and will save your delicate components and newly painted stuff.

 

Now take your dinky square sided o-rings and sit them into the reliefs surrounding the fluid channels. Make sure that these reliefs are nice and clean. And then place one of your clamping bolts up through the lower caliper, lift the other half over the bolt, gently lower it down onto the o-ring, then screw on a nut, finger tight so the caliper halves are free to move.

 

 

repeat for the other three bolts. The halves have a degree of movement. Dont allow them to pull the o-rings out of kilter. Now, following the sequence in the picture below tighten up the nuts;

 

 

Hold the bolt head with your Ribes R6 bit socket and using a ratchet and 14mm socket tighten the nut, wrist tight, then using your torque wrench do the first stage tightening, and then finish the job with the final stage tightening. Remember you're tuning the nut, not the bolt.

 

What tightening torque to use? There seems to be conflicting information out there.

 

BMW originally quoted a final stage figure of 42 - 5 Nm (30 - 3.6 ft.lb) and then revised that to 55 - 10 Mn (40 - 7.2 ft.lb);

 

 

(source - 

 

Kamax, a bolt manufacturer used by BMW, give a range for an ISO class 8.8 bolt between 28 and 54 Nm  (20.65 to 38.82 ft.lb) depending upon the coefficient of friction; 

 

 

 

(source -  http://www.kamax.com/en/ - google  www.kamax.com/fileadmin/user.../pdf/Bolt_and_Screw_Compendium.p... )

•  
•  

 

PMB Performance, a company who rebuild brake calipers, quote a final figure of 39Nm (29ftlb)

 

 

(source - http://www.pmbperformance.com/brakehowto.html )

 

Coefficients of Friction fro RoyMech;

 

 

(source - http://www.roymech.co.uk/Useful_Tables/Tribology/co_of_frict.htm )

 

I went with PMB as my head was hurting.

 

Heres the final results on the bench;

 

 

dig those funk bleed screw covers. I'm not to sure myself!

 

On the car;

 

 

 

Thats the end of the Goldfest (thank the Lord).

 

When I originally started fiddling with these brakes, I realised that there was a rats nest of pipe work and servos hidden in the engine bay, so I assembled a diagram to help me see what was what;

 

 

Its for a RHD car, so may not be completely relevant to all the LHD guys. I liked the look of it. Its nice and colourful.

 

After bleeding and a quick road test (on a private test track of course!), all seems to be well. I'm booked in for another stab at the dreaded MOT test on tuesday. We will see what they dig up.

 

Meanwhile I've found that the cold start injector isnt injecting, so I will take a look at that next. In the meantime I'm running a K&N cone filter so its easy enough to slip that off, open the throttle and give it a squirt of cold to liquid. With foot to the floor, it starts on the first tun of the key and runs at a fast idle. 

[JohnH]

Good news, she passed her MOT. Heres the proof;

 

 

No advisories!!! We are almost good to go. Just one last hurdle, Historic Vehicle Tax. Here in the UK vehicles over forty years of age can avoid road tax, but only if you apply. 

 

I'm pleased to report the brakes are excellent. The best they have ever been and apart from no ABS, are as good or better than my other more modern vehicles. Changing the brake fluid and carefully bleeding have paid dividends, though as others have said, getting the rear brakes adjusted correctly is the key to success. As I brake now, the pedal is nice and firm, the harder I press, the faster it stops, and this happens until I lock the front brakes.

 

It maybe, that the tires are a bit old. They are at least ten years old, but are still soft and flexible, with no signs of cracking. They are Yokohama S306 175/70R13 on KN Minator MN1355 5.5j-13 ( http://home.btconnect.com/knwheelsltd/products.html ) and it seems a shame to ditch them.  

 

 

 

The drivers seat has seen better days,

 

 

The foam in the squab had turned to dust and every time I got in or out it puffed up everywhere. I couldn't have this for my faithful MOT tester so I decided to refit the original rippencord seat but after retrieving it from storage, discovered that a mouse had set up home there and chewed a hole in it. Very irritating!

 

As chance would have it, I had some E28 manual comfort seats knocking about so I took a close look at them;

 

 

E28 on the left and E10 on the right. With all the mounting hardware removed, the bases are almost identical. The E28s are 1/4" wider. All the rail bolt holes are spaced the same.

 

 

By elongating the mounting holes in the E10 rails so you can squeeze them together, they fit okay;

 

 

Colour mismatch and a bit tatty, but not to bad. I find them a bit low at the back of the squab and need to come up about an inch to be perfect. One other problem, is that the inner backrest "hinge" mechanism cover sticks out a bit and interferes with the seat belt tunnel stalk. Not badly but enough to be annoying. Removing the cover may fix the problem. It'll do for now.  

 

Next up I'll be sorting out the electrical side of the cold start. More to follow.