painted Grimeca hubs

N

nimrodneil

New member
Location
Portsmouth
out of interest what are peoples views on painted or not painting the hubs and brake plates etc. I have seen painted in various colours, just the hub painted, polished and unpolished, blasted and polished rim around the brake plate.
 
If you are going to paint Aluminum, It has to be spotless clean using acetone 1st, buff with say 400 or 600 grit water sand paper. Use a base coat such as 3M Zinc Chromate Epoxy under coat primer. Wet Sand again. You may need 2 or 3 coats of that Epoxy Primer. After that you can finish her with whatever top coats you want.

I recommend the same steps for your frame. I suggest using a Hi-Gloss Black Auto ENAMEL (NOT Lacquer or Acrylic) that is impervious to Gas, Brake Fluid and Paint Thinners. This finish is better then having the frame Electrostatic Painted (There's another name for it but it escapes my mind right now) because if you do damage the finish it's easy to repair.

Electrostatic Paint Method is very hard and tends to chip and about impossible to repair.
 
Last edited:
Yes polished Aluminum with Wax - But if you want to save the skin on your fingers - There is an alternative.

Hell! You can apply 3M Epoxy Green Zinc Cromate Under Coat with a paint brush. I'm not talking about the pissy 3M Zinc Chromate Epoxy Primer but the Under Coat. The Pissy 3M Primer may work for the time being but not like the Under Coat product which will last forever.

3M Green Epoxy Zinc Chromate Under Coat is rather expensive ;o(

3M does make a Red Ferris Epoxy Under Coat for a little less but it's NOT as good.

I've shot Emiron over 3M products - Not healthy considering they are full of ISO-Cyanide.

But the end result is indestructible over any surface.

I've shot Imron on 3M Epoxy Base Coats through the years - I'm 73 and don't have cancer. I do not know if and individual or what permits you need to purchase and use these products today. I primarily used a 3/4 Devilbiss paint gun at approx 45/60 psi with a charcoal face mask.

One thing I can say is that the old ISO Cyinade Paints where 10 x's stronger then the new Water Based paints they use today.
 
Last edited:
I just bead blasted then vapour honed my rear Grimeca hub and sprocket carrier, I think they look beautiful, I may polish but think they look good in raw alloy, much too pretty to hide under paint.
 
In my experience, painting causes problems with heavy use (e.g. stone chips) at some point.

if you sandblast the cast parts with a medium that is not too aggressive (e.g. broken Wallnut shells) and spray something with petroleum once a year, you will get a nice look.

the kerosene evaporates quickly and leaves a protective layer on which dirt does not stick.

Works even fine at your motor.

Thomas aus LAU
 
Thomas aus LAU said:
water + sand/glas pearls + 100 psi air presure. It's well explained here: vapour honing

Thomas aus LAU
Click to expand...
Exactly, but a little further info:
Bead blasting uses larger glass beads which get broken and jagged so they actually remove material so is a good process for removing deep staining, major corrosion and thick paint, typically higher air pressure so very abrasive.
Vapor hone uses microscopic (almost like flour) glass beads in a water slurry so they just roll over the surface and clean off small amounts of surface discoloration, corrosion or paint, not nearly as aggressive as bead blasting, usually lower air pressure (I'm using 65psi on Laverda alloy parts) and lots of water leaving a very smooth finish like a dull polish. Anything steel needs immediate protection from rust, alloy looks great left as it comes out and rinsed.
 
arancia said:
Exactly, but a little further info:
Bead blasting uses larger glass beads which get broken and jagged so they actually remove material so is a good process for removing deep staining, major corrosion and thick paint, typically higher air pressure so very abrasive.
Vapor hone uses microscopic (almost like flour) glass beads in a water slurry so they just roll over the surface and clean off small amounts of surface discoloration, corrosion or paint, not nearly as aggressive as bead blasting, usually lower air pressure (I'm using 65psi on Laverda alloy parts) and lots of water leaving a very smooth finish like a dull polish. Anything steel needs immediate protection from rust, alloy looks great left as it comes out and rinsed.
Click to expand...
Vapour blasting.... got it. The ‘honing’ bit threw me.
 
arancia said:
Exactly, but a little further info:
Bead blasting uses larger glass beads which get broken and jagged so they actually remove material so is a good process for removing deep staining, major corrosion and thick paint, typically higher air pressure so very abrasive.
Vapor hone uses microscopic (almost like flour) glass beads in a water slurry so they just roll over the surface and clean off small amounts of surface discoloration, corrosion or paint, not nearly as aggressive as bead blasting, usually lower air pressure (I'm using 65psi on Laverda alloy parts) and lots of water leaving a very smooth finish like a dull polish. Anything steel needs immediate protection from rust, alloy looks great left as it comes out and rinsed.
Click to expand...
I describe the differences between Bead and vapour blasting as - Bead blasting leaves the pores of the aluminium open which means it will stain again easily. Vapour blasting seems to leave a closed pore surface which is more resistant to staining or corrosion.
In my experience, if you're going to paint an alloy surface, I'd bead blast to get a good key for the paint. Etch prime before paint of course.
 
And then there's soda blasting ... personally I like the dull finish but I can see the advantages fo the 'closed' effect, as Laverda cast alloy absorbs filth with ease. Cases look great until you actually ride the bike through a winter! I just live with it.
 
Thanks for all the above input, I have had them vapour and bead? blasted and will get the outside rim polished pics will follow. BUT the front hub needs a new bearing on the speedo drive side and we are struggling to remove it. does the speedo drive ring need to be removed? if so how does the ring come off. if I heat it the alloy will heat quicker than the ring. I wouldn't have thought it would need that process but worried about forcing the bearing out, any suggestions please Thanks in advance
 
If the hub warms up, the bearing will come out of the seat more easily.

If it is a small Grimeca hub from the 68/69 Laverdas you should check, that there are no cracks outside of the brake ring / reinforcement struts in the drum. This is a weak point with these brakes and it can lead to the hub collapsing.

That was the case with my Eagle and Brettoni confirmed that to me.

Thomas aus LAU
 
Thomas aus LAU said:
If the hub warms up, the bearing will come out of the seat more easily.

If it is a small Grimeca hub from the 68/69 Laverdas you should check, that there are no cracks outside of the brake ring / reinforcement struts in the drum. This is a weak point with these brakes and it can lead to the hub collapsing.

That was the case with my Eagle and Brettoni confirmed that to me.

Thomas aus LAU
Click to expand...
I remember a post many years back from Jean-Louis Olive concerning that problem and it was due to there being two differing types of Grimeca, they don't mix and lead to the hub collapsing if mixed.

Paul
 
In my case it is definitly a construction problem. The material is too thin and the rips are to small and they are ending without a round corner. That has to break.
Brettoni told me that wight and brake forces where too high for the early Grimecas.

That might be the reason why Laverda developed an own brake.

Thomas aus LAU
 
to get the bearing out weld in a six inch piece of 16mm threaded rod, and then use a large tube, washer and nut, to pull it out, don't change one side and not the other, the bearings are cheaper than chips. with one bearing out you can bash away at the centre of the old one, which you are scrapping, don't do that when you fit the new ones, only press/or knock on the outer rim., sometimes an old fashioned expanding metal bolt such as Rawlbolt, will do the job, tightened into the bearing, and then drifted out from the other side
CLEM
 
You must log in or register to reply here.
Back
Top