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1973 R75/5 Rebuild Project Journal

Brook, before you send your frame off carefully inspect the passenger peg/muffler mounts. The "U" that the battery vent tube passes through creates an excellent stress riser; the worst case scenario is that a crack develops (where I've drawn a red line) ... check top and bottom. The right side on my '73 /5 was cracked, the left was not. I've purchased two frames in the past for projects; both had cracked brackets; one on both sides, one on one side only.
 

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kantuckid,

Thanks for looking and sharing about frame painting. What attracted me to powder coating is the ability to cover round tube completely and to have a hard finish. I've spray painted them and never seem to get the uniformity I'm after ( read that, missed areas).

I'm very interested in your comment about 3M fineline striping. Can you provide a link to that product? I'm going to paint the bike myself (as I did on my R75/6 "S" replica project) and this time, I want to do painted pin stripes.

I hope some of my pictures help you on your project.

Best.
Brook.
You might take a look at a current thread on ADV under airheads that has a guy redoing the same bike. I commented on stripes & he tells his plan for same-I gave him a link too. Take a look at KBS website and their finishes. I've seen some paint brush frame jobs that were astounding using the Blacktop Chassis paint. It is tough stuff.
 
I've seen some paint brush frame jobs that were astounding using the Blacktop Chassis paint. It is tough stuff.

That reminds me, Interlux and Pettit make epoxy and urethane "topside" paints for marine application that give excellent brush finishes. For flat surfaces the process is call "roll and tip"; roll on the paint and follow up with a fine bristle brush to knock off the "tips" of the roller marks; generally a specific reducer is called for that slows the set time and allows the paint to flow out. On compound surfaces (like a frame tube) a brush alone does well.
 
Thanks for that tip! I'm going to check my frame closely based on the metal fatigue crack issue. I've been on other stuff so the frame is still in my barn.
On the KBS Blacktop paint: I was getting ready to paint my 1971 Honda project frame & when I opened the can it had hard sediment in the bottom that wouldn't incorporate into the mix. As the qt cost near $50, I called the tech line( nice guy too! offered to mail it but I was going that way to the AP store where I got it) & learned it was part of a bad batch/lot so just used black base coat on that bike but my new can of KBS still goes on the R75.
While painting is up for discussion in this thread I have a fender painting question: I have my fenders & tank sanded & ready for the epoxy primer I'm using & it's tough stuff. I really don't see a lot of appearance reason to paint the inside of the fenders as they obviously don't show much. The thing is, the holes were fatigue cracked a little bit and a couple holes needed redone as they were enlarged. That repair was made using epoxy & came out fine, probably stronger at the holes than originally as I reinforced each hole.
I was thinking that the epoxy primer would strengthen the fenders composite material just a bit but there was no paint there from the factory, so maybe being anal? How often are they painted inside?
 
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How often are they painted inside?

Depends on how cold it gets in your neck of the woods this tima year .. .. ..
09.gif


I'm a slug, I've painted my /5 four times since 1974, and I don't think I've ever painted the underside of the fenders. If it was intended to be a garage queen I might, but it's a road bike.

I had some stress cracking going on around the mounting holes as well. I chose to laminate a piece of 1.5oz. fiberglass cloth (using epoxy) onto the entire underside of both fenders, with a few extra pieces at the mounting holes, and turn signal housing boss. I didn't paint it then either.....
 
no paint "inside" is my real lean and this bike is being built to become a replacement for my oilhead and the trip bike. As for "how cold in my area" , I have maples tapped & the sap has run a little but not a good run yet, when it runs it's riding weather too!
 
Brook, before you send your frame off carefully inspect the passenger peg/muffler mounts. The "U" that the battery vent tube passes through creates an excellent stress riser; the worst case scenario is that a crack develops (where I've drawn a red line) ... check top and bottom. The right side on my '73 /5 was cracked, the left was not. I've purchased two frames in the past for projects; both had cracked brackets; one on both sides, one on one side only.

Lew,

Oh, that's a great suggestion. I added that to end of that section and included these photos.

8499688548_fcef231373.jpg


8499688582_7db693a7f5.jpg
 
1973 BMW R75/5: Progress Report

At this stage in the project, the bike is apart. Last week, I took the frame, sub-frame, center stand, battery box halves, headlight ears, license plate bracket and the handlebar controls to Brad at BFN Industries, a local company near me in Arvada, CO.

8508130179_b16762c1c7.jpg

Parts for Powder Coating

8509237974_b82ae77d4f.jpg

Zip Ties Marking Threaded Holes

You can see more on my progress including the work plan at my web site, 1973 BMW R75/5: Progress Report
 
1973 R75/5 Parts Back From Powder Coating

My parts are back from powder coating by Brad at BFN Industries. I wrote a check for $190 and change. I think this was a good price.

I posted a number of pictures here, 1973 BMW R75/5: Powder Coating Done in my latest blog post.

Also, I'm posting all the pictures I take here on Flickr --> 1973 BMW R75/5 Rebuild

Here are some from the blog.

<a title=".Faring braket rust by ScooterScum_52, on Flickr" href="http://www.flickr.com/photos/brook-reams/8316720804/"><img alt="Faring bracket rust" src="http://farm9.staticflickr.com/8351/8316720804_3682eb0c9c.jpg" width="375" height="500" /></a>
Frame Corrosion

<a title="Paint and rust by ScooterScum_52, on Flickr" href="http://www.flickr.com/photos/brook-reams/8315665727/"><img alt="Paint and rust" src="http://farm9.staticflickr.com/8361/8315665727_e7653f090a.jpg" width="375" height="500" /></a>
Frame Corrosion

<a title="Battery Box Rust by ScooterScum_52, on Flickr" href="http://www.flickr.com/photos/brook-reams/8391352546/"><img alt="Battery Box Rust" src="http://farm9.staticflickr.com/8184/8391352546_6dd35b2fc6.jpg" width="500" height="375" /></a>
Battery Box Corrosion

<a title="Left Control Disassembled by ScooterScum_52, on Flickr" href="http://www.flickr.com/photos/brook-reams/8391354446/"><img alt="Left Control Disassembled" src="http://farm9.staticflickr.com/8503/8391354446_2e3db06e30.jpg" width="500" height="375" /></a>
Left Handlebar Perch

<a title="Powder Coat Presents by ScooterScum_52, on Flickr" href="http://www.flickr.com/photos/brook-reams/8534919197/"><img alt="Powder Coat Presents" src="http://farm9.staticflickr.com/8513/8534919197_fa1c18dc39.jpg" width="500" height="375" /></a>
Presents from the Powder Coater

<a title="Powder Coat - Controls by ScooterScum_52, on Flickr" href="http://www.flickr.com/photos/brook-reams/8536026386/"><img alt="Powder Coat - Controls" src="http://farm9.staticflickr.com/8096/8536026386_f210531fbe.jpg" width="500" height="375" /></a>
Handlebar Control Perches

<a title="Powder Coat - Frame, Sub-frame by ScooterScum_52, on Flickr" href="http://www.flickr.com/photos/brook-reams/8536026266/"><img alt="Powder Coat - Frame, Sub-frame" src="http://farm9.staticflickr.com/8227/8536026266_a97fd56698.jpg" width="500" height="375" /></a>
Frame and Sub-frame
 
1973 R75/5 Clutch Throw-out Rod Wear

Here's a link to picture of the throw out rod. I've not seen a new one, so I don't know if the ends look OK or show abnormal wear.
What's the opinion of the knowledgeable?


<a href="http://www.flickr.com/photos/brook-reams/8451536483/" title="Clutch throw-out rod by ScooterScum_52, on Flickr"><img src="http://farm9.staticflickr.com/8248/8451536483_e5a7341cfe.jpg" width="500" height="375" alt="Clutch throw-out rod"></a>

<a href="http://www.flickr.com/photos/brook-reams/8452627120/" title=".Clutch throw-our rod by ScooterScum_52, on Flickr"><img src="http://farm9.staticflickr.com/8375/8452627120_7d87885847.jpg" width="500" height="375" alt=".Clutch throw-our rod"></a>
 
I'd say you did good price wise on the powder coating. I got the "family" discount last fall and paid $150 just for frame and subframe. I'm guessing I'd have been over $200 for what you did
 
Pushrod

Brook -

I'd say the pushrod tip looks fine. The aft end, though seems unusual with the wear right next to the step. Not sure why it would do that. If that allowed any sideways movement of the race and/or bearings, it might be worth a replacement.
 
8391354446_2e3db06e30.jpg


Hey Brook. I see lots of parts but I don't see control perch wedges; referred to in an old thread on this site as the Triangular Thingy Doofer (TTD).

They get lost early on in the life of most old airheads. Sometimes the perch will grip the handlebars sufficiently not to rotate without them, but sometimes not.
If you look "inside" the perch you will see a "V" shaped groove molded into the perch at the split line; the wedge slips into this "V" when it is placed on the handlebar. It's a tight fit.
When I had my perches powder coated the over-spray filled in the grooves just enough that I could not get the wedges back in; I removed the paint to get back down to bare metal.

The wedge is item #13 on the drawing. P/N: 32 72 2 072 223 - they are listed on many BMW sites as NA (not available), but they are... Hucky has them. They do come dearly.

B0000666.png


The "divot" on the backside allows the pinch-bolt to pass over the wedge.
The "internal" side is serrated longitudinally (you can see it in the bottom pic) to better grip the handlebar tube.

perch5.JPG


TTD.jpg
 
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I agree with eagle eye Lew. If you don't have the triangles, get them and put them in. Otherwise, the clamps won't be tight enough, the controls will move, you will find yourself "snugging" them up, and then they will strip.

One other thing, I'm pretty sure your levers have a nylon bushing where the pivot pin goes through. You can replace the bushings for a dollar or so to tighten up the levers.

Barron
 
I agree with eagle eye Lew. If you don't have the triangles, get them and put them in. Otherwise, the clamps won't be tight enough, the controls will move, you will find yourself "snugging" them up, and then they will strip.

One other thing, I'm pretty sure your levers have a nylon bushing where the pivot pin goes through. You can replace the bushings for a dollar or so to tighten up the levers.

Barron

Lew and Barron,

Indeed, I hadn't removed the "perch" wedge from the control barrels when I took that picture. But, they are safely squirreled away in the zip-lock bag for each control. Thanks for calling out how critical they are.

Thanks for the tip about the nylon bushing. I'll look into that.

Best.
Brook.
 
Brook -

I'd say the pushrod tip looks fine. The aft end, though seems unusual with the wear right next to the step. Not sure why it would do that. If that allowed any sideways movement of the race and/or bearings, it might be worth a replacement.

Hi Kurt,

I'll look at the aft end more closely. Perhaps a new throw-out rod makes sense. Checking Hucky's site:
23 21 1 230 106 clutch thrust rod / 5 4 speed $ 22.40

This isn't priced like Germanic Unobtanium :)

Thanks

Best
Brook
 
1973 R75/5 Powder Coating Update

I posted an update about cleaning up any over spray of powder coating. Permatex Gasket Remover works very well.
http://brook.reams.me/2013/03/07/1973-bmw-r755-powder-coating-done/

<a href="http://www.flickr.com/photos/brook-reams/8554200695/" title="Permatex Gasket Remover by ScooterScum_52, on Flickr"><img src="http://farm9.staticflickr.com/8112/8554200695_08d37866a9.jpg" width="500" height="375" alt="Permatex Gasket Remover"></a>
Permatex Gasket Remover

<a href="http://www.flickr.com/photos/brook-reams/8554200687/" title="Put Permatex on Threads of Swing Arm Pivot by ScooterScum_52, on Flickr"><img src="http://farm9.staticflickr.com/8101/8554200687_7c81e854ed.jpg" width="500" height="375" alt="Put Permatex on Threads of Swing Arm Pivot"></a>
Put Some on the Bolt to Soften Any in the Threads
 
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