Topic: Any good tricks for restoring the front brake disk on a CB750?

[Bankerdanny]

I don't think you can go wrong with either service. Like Sean I try to throw business to members when possible, but in terms of quality of work I wouldn't hesitate to use either one.

[sixthwisconsin]

Both services look great and I would have no problems using either.

I have Godffrey roters on two of my bikes with twin disc set up and I like them very much. I was just curious as to opinions on thinning the 7mm Honda rotors to 4mm. Personally, I don't have an issue with it as others have stated. Both of my bikes are on Godffrey's gallery for the product and I do believe they are Blanchard ground but I can't confirm that. I don't have a lot of mileage on either of them after conversion but I have no reason to think there will be a problem.

I really was just trying to spur on conversation about thinning vs not thinning.

Here are my Godffrey disks:

[Can550]

I simply got mine vapor blasted. Initially wanted it to be blasted to paint, now considering to leave it as it is




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[seanbarney41]

I think what mister calj meant is it will corrode, although it may be years before you ever see it, as it is aluminum.
  The actual rotor is made from a stainless alloy that will not rust in our short lifetimes.

[Can550]

It will promptly rust. Paint it or powder coat the center.

Will powder coat !


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[Can550]

Clear powder coating is good idea but think will go with black keeping its stock looks


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[SohcCBs]

Go with dual disks:

http://www.salocal.com/sohc/tech/dual_disks/dual_disks.htm

[754]

The carrier is forged aluminum, not a major corrosion issue where you like..
If not stock, gold paint makes them look exoticer.....
 New word for the Dickshunary..

[markb]

I’ve been experimenting with different methods to duplicate the original appearance of the brake disks and haven’t been real happy with the results. The sanding method worked OK if you just want freshen up the appearance which is plenty good for most users. But to be considered restored it’s understandably not there. The Blanchard ground finish looks great but not original so I decided to try to get them done on a surface grinder. I found a shop that said they would try it but quoted me $200 each for six of them, which I think actually wouldn’t be a bad price for one but to do just one would be more. Here is one of my disks that had 1/8” turned off the mounting surface on the back (I think for a dual disk setup) so I’m probably not going to use it for anything and figured it would OK to experiment with.


I decided to make a motorized turntable that I could put on a surface grinder. Fortunately I have access to one at my company’s shop. I scrounged the materials and a few of the parts around the shop and bought the rest and have been working on it on and off the last couple of weeks. At this point I have less than $200 into it if you don’t count the labor. The hardest part was getting the turntable indicated in so it was flat and parallel. I think it turned out pretty good. I even planned ahead and have a dresser mounted (idea from member kmb69, thanks Keith) so I don’t have to remove the tool to redress the wheel.


Here it is on the grinder.


Here is a before pic…


…and after. I ended up grinding about 0.005” off. Still a few grooves and pits in the surface but pretty pleased with the results. I have a NOS K1 disk and the finish on it is rougher than my test piece. I am going to try a courser wheel to see how that looks. It should grind faster and not load up the wheel as much too. I’ll try that on the other side and report back with my results.

[MauiK3]

Mark
Great tool making! Looks like a really good finish. Also looks like a business opportunity, as if you need one with all your other things going.
Is the stone full width? Hard to tell from the photo.
Sure would be fun to see a photo of how they did it back in the day at the factories.

[kmb69]

Mark,
That's awesome! Anxious to see the other side.
Keith

[markb]

Mark
Great tool making! Looks like a really good finish. Also looks like a business opportunity, as if you need one with all your other things going.
Is the stone full width? Hard to tell from the photo.
Sure would be fun to see a photo of how they did it back in the day at the factories.

Thanks. I thought about that but so far this first one took a while and I'm only half done.  Maybe the pace will pick up once I get it down.
The wheel is 3/4" wide. They would have to been done similar to this to get the look they had.

Mark,
That's awesome! Anxious to see the other side.
Keith

Thanks. You were my inspiration. 

[markb]

I’ve finally finished restoring one brake rotor. I think it turned out pretty good. I got three of six ground. I masked and painted one for now. The masking was a challenge because of the spokes and the rivets on the inside.

I tried different tapes and trimming with an exacto knife but couldn’t get decent results. I finally made a tool that has a hole the same size as the diameter of the rivet with a flat land around it.

Then I drilled the same size hole on the other end and machined an angle to make it sharp.


After trying masking tape, vinyl tape and some others I found that the tape that worked the best was duct tape. The flat end of the tool formed the tape around the rivet head.


Then the sharp end trimmed the tape perfectly.


Here’s a pic of the finished product on the outside…


…and the inside.


The only thing I don’t like is that the area that is turned where the rivets are on the outside was originally blueish in color, presumably from getting hot during machining. All of my disks had enough corrosion that had to be removed so there was no saving the blue. I thought maybe using some gun bluing might work but no luck with that so I left it alone.

[MauiK3]

Wow, way cool
Are you grinding dry?
With stainless being so "sticky" I can imagine your concern with loading up the wheel and keeping the thickness uniform, quite a task.
Great job.
Oh, one point of order
Silver cloth tape used to be called duct tape but it no longer is as code duct tape is now a metal tape with a sticky surface. Silver cloth tape is called "duck tape" or just cloth tape by some companies wanting to avoid code complaints.
:-))
All the best and I hope the wonderful #97 is alive and well. I've read that thread several times. Real inspiration.

[markb]

Are you grinding dry?

No, I am using coolant.

You're correct, it is a cloth tape.

[disco]

Both services look great and I would have no problems using either.

I have Godffrey roters on two of my bikes with twin disc set up and I like them very much. I was just curious as to opinions on thinning the 7mm Honda rotors to 4mm. Personally, I don't have an issue with it as others have stated. Both of my bikes are on Godffrey's gallery for the product and I do believe they are Blanchard ground but I can't confirm that. I don't have a lot of mileage on either of them after conversion but I have no reason to think there will be a problem.

I really was just trying to spur on conversation about thinning vs not thinning.

Here are my Godffrey disks:

Those discs look awesome imho. Love the dual disc setup!

[RustyF]

+1 on truedisk -  did a great job on my rotor too!