I was finally forced into a clutch change recently because as the clutch slip was so bad I could have been riding a moped insofar as acceleration was concerned. Stripping the backend of the bike to drop the gearbox off revealed the usual peeling paint but also something far worse; a shedload of rust under the paint. Additionally, the brackets that hold the Z-frames and mudguard were so badly spalled with rust that they weren't going to survive cleaning up. The two small additional brackets that go on top of them just fell apart. I really didn't like the look of the rust and just briefly I considered replacing the rear frame loop with a new one, but then decided I could probably cut the old brackets off with a bit of care. Assuming, that is, the main frame wasn't quite as bad as it looked.

Things got left that way for a few weeks as

a. The temperature took a nosedive and dumped a load of white stuff.
b. Just as that cleared up, I shot off to Florida for ten days to join the snowbirds but..... the temperature wasn't much higher than here for the first four days i.e. yes, it did drop to zero Celsius. Good old Frosty Florida. Bollocks.

Yesterday I realised I couldn't really put this off much longer as I wanted LFB back in use. The sun was shining and it was warmer than Florida, so what more could I want? How about getting lucky?

It turned out that the rust wasn't quite as bad as it first appeared. In this pic, on the left the paint has been dragged off with a rotary wire brush in a drill and the first pass to remove the rust has been done. The frame loop has just had the paint removed and shows the extent of the rust. On the right of the pic, the frame hasn't yet been touched. On full size you can just make out the spalling on the brackets.



Before I cut the brackets off, I needed to know where to weld the new ones on. Just about this point I did start wondering about BMW's frame jigs, because after I'd set up a datum point in the middle of the frame loop (i.e. a black line from a marker pen!), I found that the leading edge of one bracket was 64mm forward of the datum point, but the other was 70mm forward of the datum point. Also, the rear of the loop is not square to the frame tubes.



To get the brackets off, I cut through three of the four welds with a 1.0mm cutting disc. There wasn't enough room to get the cutting disc in to slice the fourth weld without hitting the frame loop, so I hit the bracket with a BFH and cold chisel to open up the gap and then cut the fourth weld with a hacksaw.



This amused me - it's under the paint of the front mudguard mount and isn't normally visible. I think there's a '/11' next to the '03' on the right, denoting November '03 and corresponding with the build date of the frame number.



Stage four - paint off and the rust sanded back to bare metal as best I could. The irony of having to wash the bike again to remove the rust dust didn't escape me and of course, within a few minutes that nice clean steel had assumed a slightly yellow hue.



New brackets made from 3mm steel.



-and that's how you clamp them up for gluing to the frame! That mudguard clamp is not going back on. It's being replaced by one made from stainless steel.



After the application of the first lot of glue. The weld isn't as bad as the photograph makes it out to be - I haven't cleaned it up at this point beyond chipping the slag off. The tack for that weld took immediately; however, the one nearest the camera was a bit of a bitch. There was obviously more rust in this area because on first application of the welding rod to tack the bracket, I promptly blew a hole in the rear loop. I hate chasing holes.

I really hate chasing holes.

This one hit stronger metal pretty quickly and, to my relief, didn't take long to close up. The weld is an ugly mess though. Once it had all cooled down I went for a try-fit of the mudguard and seat; perfect. The offset from the datum point is 65mm!

End of play for this week. I need to make up a jig to align the lower brackets and clamp them to the frame, but for that, a trip to a hardware store is called for.

Nice work Dai. 

That rear loop area is obviously a real rust magnet - I have just been cleaning up mine on the project bike and had to resort to a smooth file to get rid of the worst of the lumpy imperfections that the wire brush was only tickling. 

I guess the Germans didn't expect the bikes to be lasting 30 years and skimped on their paint application.  Elsewhere, the frame only suffers light corrosion, probably as a result of nicks and knocks when doing maintenance. But the rear loop - out of sight, out of mind and protected by the rear mudguard and the tail cowl (not), it seems to be a perfect rust factory. At least my brackets were reasonably sound.

That same job awaits me on the double.! Out of sight from above but unprotected from below I think.

Mine too, just done the ABS carrier frame, back end will be done later in the year.

Main seal 1 

Rusty  frame 0 

Bob

bit late to add advice in removing rust Dai

but keep in mind I see a lot of places around the shock mount and seat lock area , besides the loop itself on lfb that still need attention before being painted over

try one of these  mesh type paint strippers on a wheel , they cut back really well , wire brush will smooth out and disguise the rust under by burnishing

note   they cut quite severely  

heres what I have found to be doing a good job  , Chinese versions abound and quite cheep



good luck with the further repairs , doing a good job

Look into a system called Paint Over Rust(POR).  I learned about it from some acquaintances who restore antique cars.  They have a complete system from cleaning to rust neutralizing to an incredibly hard paint.  The only weak point that I have found is their topcoat.  It just isn't very hard.  I use Duplicolor Satin Black engine enamel.

https://www.por15.com/

Good idea Charlie - two ordered, one for the angle grinder and one for the drill. Most of the final layer of crud was ripped off with a sanding disc in the angle grinder; the marks are clearly visible where I've hit good paint. I'm aiming on using brush enamel (same as I did on Brick2's frame). The undercoat is an etch-enamel that is capable of being applied over existing clean painted surfaces and 'light rust'; the intention is to clean up the frame and paint as far forward as the main tubes under the tank. I don't have the time to strip the whole bike down this time.

Anyone know how to get the lifting handle out? It's got me beat so far.

.75: I have ten litres of brake cleaner which is by far the best degreaser I've ever come across. It's also extremely unfriendly and has to be treated with serious care.

the lift handle is a tricky little sucker

but basically 2 pieces of metal bridges the top and bottom of the pivot assembly holding the handle in place  with a spring connection between  the 2 pieces of metal retainers ,   you just lift the top side retainer against the spring force and pull slightly , the spring will put the other end of the retainer back down the recess releasing the whole lot ....careful bits may fly,  so be prepared

Dai wrote: I hate chasing holes.

I really hate chasing holes.

You are not alone! Neat little replacement brackets tho' 

Thanks Will!!

88 wrote:

Dai wrote: I hate chasing holes.

I really hate chasing holes.

You are not alone! Neat little replacement brackets tho' 

I have a big bag full of them if you want them, found them in the corner under the bench some of them were full of those springs and bits from the switch blocks.
8 bucks a dozen

Reminds me of a funny incident with a local man who woke the whole house coming in late and a bit the worse for wear. 

He was making a racket trying to stab the key into the front door and hitting the glass several times. His wife (known to all as the Dragon) stuck his head out the window and shouted "What's going on?" The slurred reply came back: "Throw me out a bag of keyholes there, like a good woman!" 

lol 

Stick a few hairs around the keyhole and he would find it no problem.

Point-Seven-five wrote:Look into a system called Paint Over Rust(POR).  I learned about it from some acquaintances who restore antique cars.  They have a complete system from cleaning to rust neutralizing to an incredibly hard paint.  The only weak point that I have found is their topcoat.  It just isn't very hard.  I use Duplicolor Satin Black engine enamel.

https://www.por15.com/

I am a fan of the rust inhibitor and use it for the last 30 years.
The best product that I ever used is Neutrarust 661 The only problem, it's not available in North America anymore but good for you, it is in the UK.
The way to apply it that works all the time is by sanding the part to the bear metal and leave it outside to the elements for a couple of days. When the metal is coated again with a very light dust of rust, apply the Neutrarust and 24 hours later you can paint it. I also use a High temperature satin black paint which is the closest to the original frame color. If Neutrarust is properly applied, it will never corrode again (unless you knick it)

My wife's car is an 18 YO Honda accord with the original paint and doesn't have a spot of rust (really rare in Canada). First, every year the car is spray with Rust Check
Every time I wash the car (Maybe once a year), if I find any stone chip, I treat it with Neutrarust and then touch it with a paint pen. The good thing about this process is that the rust inhibitor is basically filling the the stone chip hole and the repair is hardly visible.

Crazy Frog wrote:The best product that I ever used is Neutrarust 661

£20 a litre...! I've been 'off' rust inhibitors for years because I had so many problems with the phosphorus-based ones, mostly when trying to paint over them. This got my attention:

http://netpanel.netbydesign.net/user_files/total_bodyshop_item_attach2947.pdf

Wonder if they're trying to protect seabirds too? I'll give it a try.

Your link doesn't work Dai.
I know that it's expensive, but you are better to put a bit of money first and have the job done only once.
I had a liter of this stuff and it lasted me for over 20 years. The only problem is that the last time I wanted to use it, the original plastic container had cracked (because of age) and the product dried and turned into a big glob of rubbery stuff.
If you get some, put it right away in a sealed glass bottle.
This product was used by the Canadian navy to coat their torpedoes. They may be still using it, but I don't have access to it anymore.

Must be blocked from the Dominions . It's techinfo about Neutrarust. The cause of the poor joke about seabirds  is a misprint on the list of advantages which says 'Long tern protection'.

I VPN into a UK server and the document is now available.
That must be a big secret weapon that the UK doesn't want to share with Russia .

The first of Charlie's paint cutters arrived this morning. A litre of Neutrarust is on order. This leads to a minor change of plans - I'm now going to zap the spots'o'rust (TM) on the main frame tubes as well.

When I built my steel boat it needed to be sand blasted when it came to 1st coat of paint and the instructions were to wet blast (sand and water) then wait 12 to 24 hours to get a faint rust colour then phosphate it then paint with a 2 pack stuff.  The 1st coat stayed till painting time when colours were decided but a few times I needed to weld extra bits on and that 1st coat was almost impossible to shift even with a grinder.  When welding the fumes were very toxic and it was recommended to wear a respirator.
Don't know if it was as good as claimed as I sold the boat well before the next slipping was due.

Two pack = cyanide fumes. Most people don't realise that heating Hammershite also produces cyanide; or at least, it used to. The formula was changed a few years back and chances are that it doesn't any more.

I took a quick look at LFB this morning when rolling out the Blandit. There ain't any shiny bits on the rear frame loop, not no more. It's now a beautiful ferrous oxide in colour. Again.

Dai wrote:I took a quick look at LFB this morning when rolling out the Blandit. There ain't any shiny bits on the rear frame loop, not no more. It's now a beautiful ferrous oxide in colour. Again.

yep .. only the quick and the rusty ,, always best  to whack a protective coat of something on before letting the dust settle overnight , to keep it shiny

Dai in our specifications for structural steel the steel is shot blasted and must be coated with what is referred to as a blast primer within 20 minutes to prevent that happening. Atmospheric humidity does it, especially if the steel is cool when it will get a degree of surface condensation. Otherwise some of the high specification corrosion protection paints work well. I went at my RT back in 2013 to repair previous acid damage on the frame and I used one of these paints. You can buy small tins of it, one is Rustoleum which is heavily used in external steelwork and shipping and oil rig protection. The satin black is a perfect finish on the K frame and warmed to room temperature doesn't leave you with brush marks.

Dai wrote: There ain't any shiny bits on the rear frame loop, not no more. It's now a beautiful ferrous oxide in colour. Again.

According to how I understand Crazy Frog's post #15, that light oxidation is the condition that is wanted; after it occurs, the Neutrarust is applied over it.

Crazy Frog wrote:The way to apply it that works all the time is by sanding the part to the bear metal and leave it outside to the elements for a couple of days. When the metal is coated again with a very light dust of rust, apply the Neutrarust and 24 hours later you can paint it.

Laitch wrote:

Dai wrote: There ain't any shiny bits on the rear frame loop, not no more. It's now a beautiful ferrous oxide in colour. Again.

According to how I understand Crazy Frog's post #15, that light oxidation is the condition that is wanted; after it occurs, the Neutrarust is applied over it.

I was taking the p!ss out of all my hard work! The Neutrarust should be here tomorrow.

Dai wrote:
I was taking the p!ss out of all my hard work! The Neutrarust should be here tomorrow.

More coffee over here, please!

NeutraRust works by creating a chemical reaction with the rust (The reaction creates an epoxy type of coating).
If there is no rust, it will not work.
It doesn't take very long for a piece of metal to start corroding if you clean it with water and don't wipe it off.

Dai

This stuff is good for dealing with rust...



And this stuff is good for you while you are waiting

The following must be the relevant flow chart:

CF > Motorbikes > TT > Isle of Man > Manx > Manx Cat > Paddies.

I'm on the Teelings ATM.

https://teelingwhiskey.com/teeling-whiskeys/small-batch-whiskey/

I used to work for Esso in Bass Strait. They had a product called LPS 3 (US made) which forms a waxy coating and stops rust from taking hold.  Quite a few years ago I managed to buy a US gal of LPS 1 ( contact cleaner lube) and LPS 3 from a local flea market. Every couple of years I fill my centre stand with it let it sit for a while then drain. As an experiment I coated a piece of steel with it and left it outside. After 5 years still no sign of rusting, I have moved since so it could still be going.
Regards Martin.

One hi-tech welding jig constructed from a piece of 10mm threaded bar and two cableties:-



Job done. I suspect I'm now going to have to spend some time modifying the Givi rack mounts when it goes back on. I made the mounting arms to fit the original brackets and I don't for one moment think the new brackets are in precisely the same place as the old ones.



The Neutrarust arrived today but I'm inclined to let the frame rust for another week. Also, it's too bloody cold to spend too long outside - the temperature is back down to 2 degC again. Similarly, the etch-primer doesn't like that temperature either.

Ah - this looked as if it was rusty enough, so time to read the instructions on the bottle.



Got carried away a bit... if it showed a spot of rust and I could see it... not sure about the colour though!
 

Twenty-four hours later and some parts needed another coat. I was well impressed with the overall effects - the original black paint has faded so badly that it's difficult to see what is paint and what is Neutrarust. Hopefully sometime this week I'll be able to apply the etch-primer round the rear loop.

When the Neutrarust is dry (The one that I used turned black where it was rusty), you can lightly sand it before the put the primer.

There was one thing I didn't mention along the way when changing the clutch and it's hidden now, so no pictures. The anti-vibration mounts for the battery tray were corroded solidly in the top of the gearbox. The only way I could get them out was to cut the rubber off, punch a hole somewhere vaguely resembling the centre of the metal mushroom and put a 6mm drill very carefully through what I hoped was the corroded thread. That involved a serious juggling act with the gearbox and the pillar drill, but I don't think I qualify for Britain's Got talent just yet.

Plan A was to refinish with helicoils.
Plan B was to tap out to 8mm.

Plan A rode off into the sunset all on its lonesome because of course, one of the mushrooms wasn't quite centred under the pillar drill. In my defence, I really was holding it with my left hand with a spirit level on top to indicate somewhere nearly there. So, Plan B it was and a set of ebay's finest 20mmx20mm anti-vibration mounts arrived within a couple of days. But there's a catch. There's always a catch. Two catches.

The original 6mm AV mounts have male threads on both ends but an 8mm nut is just too tall and protrudes above the nut recess. A half-nut would fit but at this point you're relying on about three threads to hold everything down. Just - no. So the new AV mounts had a female thread on top to take an 8mmx8mm dome head Allen bolt which sits below the top of the nut recess.

The second problem is that the mounting point forward-right on the gearbox is a blind hole and it's only about 6mm deep. To open the hole out to 7mm for the tap I had to grind a 7mm drill so it looked more like a milling cutter than a drill bit i.e. I ground almost the entire point off but left a tiny area of cutting flutes on the sides, sufficient to open out the hole. There wasn't enough depth to get the 8mm thread going with a taper cut tap but the second cut tap bit just enough to start the thread; however, there was no way that the bottoming tap was going to cut the threads all the way down. Out with the grinding wheel again... my only spare (and brand new) 8mm bottoming tap had its lead threads ground off so the face was completely flat.

Some very careful cutting later (remember; no lead threads so the cutting surfaces clogged up dead fast) I had a blind 8mm x 6mm hole cut in the right-forward battery tray mounting point. All that was left was to put a 8mm drill through the battery tray holes. I was delighted to find that I only had to file one hole slightly offset to match up with the new mounts. You can just see the domeheads in the two pictures above.

And yes; I used half a ton of copperslip when I wound the new AV mounts in.

I put a coat of etch-primer on last weekend but forgot to take a picture The first thing I did this morning (even before I'd had a cup of tea!) was to top-coat with enamel because with any luck, it would dry overnight and I'd be able to start reassembly tomorrow. Considering that I was only really interested in getting a thick protective coat on the rear frame loop, this came out remarkably well. The gearbox triangulation tubes were coated too.



Surprisingly, the frame loop had hardened when I went back out three hours later.

Amongst other things chewed up and spat out by three years or so of winter salt were the threaded hex spacers used to mount the Givi rack. If you think you recognise size and shape you're probably right; the originals were liberated from a mounting kit for Krauser Mk2 panniers. These are their stainless-steel replacements.



I hit one nasty problem with these. The spacers are 40mm long, but the tap set would only do around 30mm before hitting the shoulder. Nothing for it but to introduce the first cut tap to the grinding wheel:



Yeuk. Once the first cut was the whole way through I was able to reverse the spacer and use the second cut to clean up the threads without getting mis-threaded (is that word? It is now!). I also made a pair of stainless mudguard brackets - the threaded parts are button-head allen screws.



Unfortunately I found out that 'paint hardened' does not mean 'paint dry'. One big, fat palmprint:



Damn...

Done. Almost. LFB is running again but the fast idle isn't fully returning and the radiator overflow pipe is leaking where it meets the header bottle. I suspect it's just a result of old age and hardened pipe; not that it's a problem as I bought a 30 metre reel of suitable pipe when building Brick 2. Someone was having a clearout and the 30m reel cost barely more than the three metres I needed to replace the main overflow pipe and the level indicator pipe.

The clutch now... that is just

In the U.S. one can buy a spray can of ACF-50 for inhibiting rust.  It has a good reputation.

ACF-50 is great for long-term storage (ask all the newly-chromed stuff I have in various bags) and it's also great for areas that don't attract dirt. Unfortunately it's a really good sh!t magnet when it's in the way of flying road dirt.

How did my rear frame score on the " Rustometer ".

Shocking, but not surprising unless it was ridden next to the coast all of its life.

Halfords best primer and glossy top coat, plus lacquer.

Only went as far as the tubes under the tank as the coating around the front of the bike was good.

Battery tray and grab handle done, just the centre stand to do .

Bob

LFB looked like that when I first got it. I slapped a hasty coat of Hammershite on it and then ignored it for the next few years  Recently it developed a couple of minor electrical problems, so given the current mileage (106,000-odd) and the fact that the wiring loom had done some 70,000+ miles since I made it, I decided to strip the bike down for a major check over, a change of clothes and a new wiring loom. The rear frame has grown an acne rash in the enamel over the last 13,000 miles but I think I'm going to ignore it for the next few years...