1979 GS 750 café "Stella Green"

[gmoore]

OK, so I'm getting closer to having a finished tail plug. Once I get the mold made I need to make the parts.

Here's my question: Do I need or would it make my finished part a better product if I use Gel Coat for the first layer as opposed to regular fiberglass resin?

I'd rather not spend the $30 on the gel but if it mean a truly superior finished product I will.

Thanks guys!

 

[gmoore]

Drilled rotor #1. Should I chamfer this a bit? Or just de-glaze.

My pattern

Drilling

Drilled

 

[3DogNate]

OK, so I'm getting closer to having a finished tail plug. Once I get the mold made I need to make the parts.

Here's my question: Do I need or would it make my finished part a better product if I use Gel Coat for the first layer as opposed to regular fiberglass resin?

I'd rather not spend the $30 on the gel but if it mean a truly superior finished product I will.

Thanks guys!

If your plug and mold are not immaculate and you are shooting for a "ready to use" out of the mold... forget gel coat... you are going to need some priming, filler, sanding... sealing anyway.

 

[gmoore]

If your plug and mold are not immaculate and you are shooting for a "ready to use" out of the mold... forget gel coat... you are going to need some priming, filler, sanding... sealing anyway.

Definitely! I have been filler priming, sanding, filling, spraypainting repeat for quite some time now. The plug is almost in its finished state. i.e. smooth as a baby's ass & ready to make a mold. I just want to make sure I've got the process down-packed so I don't waste 40+ hours of work! I think I've got it though, It's going to be a 2 part mold & I have a couple really good release agents.

I'm hoping the actual parts will only require minimal fixing up here & there.

 

[gmoore]

This is my order of operations:

1) finish plug to a glossy finish
2) apply release agents liberally & evenly
3) Apply a layer of Gel Coat
4) Let dry for 4-10 hours
5) Apply fiberglass resin & first layer of fiber & let dry for a bit
7) Apply second & possibly 3rd layer for added rigidity
8 ) Cut mold in half directly up the center
9) Use cardboard to make a "frame" for the mold so it hold it's shape
10) Let dry & pull plug from mold

After that I should be able to pull a couple parts out of my mold... hopefully.

 

[50gary]

Do not chamfer the cross drilled holes. De-burr only.
Cheers, 50gary

 

[gmoore]

Do not chamfer the cross drilled holes. De-burr only.
Cheers, 50gary

OK, that's kinda what I thought but I've seen some guys chamfer them. What is the disadvantage to chamfering a drilled rotor?

 

[gmoore]

Pattern for the rear. Less holes. It seems that typically there's less holes drilled in the rear rotor. Is the only reason for this because there is a smaller contact surface?

 

[gmoore]

Do not chamfer the cross drilled holes. De-burr only.
Cheers, 50gary

How would you suggest de-burring a rotor? It seems most people use a countersink bit ever so slightly but I don't want the chamfer. Any Ideas?

 

[gmoore]

Or there's this. I don't think it covers the surface of the rotor as evenly though. Looks a little more spread out though... which I like.

 

[3DogNate]

Pattern for the rear. Less holes. It seems that typically there's less holes drilled in the rear rotor. Is the only reason for this because there is a smaller contact surface?

I like this one.

 

[50gary]

Chamfering rotor holes reduces the amount of "bite" on initial application. That's all I would do, simply remove the burr, it won't take much at all. I didn't notice, did you also cross drill the rear? As I recall all three rotors are the same. Of course the obligatory stainless steel lines. I use Galfer.
Cheers, 50gary

 

[50gary]

Yes, holes should overlap.
Cheers, 50gary

 

[gmoore]

Chamfering rotor holes reduces the amount of "bite" on initial application. That's all I would do, simply remove the burr, it won't take much at all. I didn't notice, did you also cross drill the rear? As I recall all three rotors are the same. Of course the obligatory stainless steel lines. I use Galfer.
Cheers, 50gary

I am going to do the rear. The rear rotor is different. The outer radius is larger but the inner radius is smaller creating less braking surface.

 

[Hoosier Daddy]

Yes, holes should overlap.
Cheers, 50gary

Exactly, the purpose of cross drilling isn't just cosmetic, it's to relieve the trapped gasses when hard braking, you want the hole spacing to overlap and eventually open all of the contact area to venting.

I am going to do the rear. The rear rotor is different. The outer radius is larger but the inner radius is smaller creating less braking surface.

You might want to recheck this, I think you meant even though the outer radius is larger than the front rotors, the inner radius is larger yet, giving you less surface area... right?

 

[gmoore]

Exactly, the purpose of cross drilling isn't just cosmetic, it's to relieve the trapped gasses when hard braking, you want the hole spacing to overlap and eventually open all of the contact area to venting.

You might want to recheck this, I think you meant even though the outer radius is larger than the front rotors, the inner radius is larger yet, giving you less surface area... right?

Exactly! Less surface area.

Doing the last one today. Then off to finish the tail plug, mold & pull the parts... Well, as soon as the gelcoat arrives anyway.

 

[Hoosier Daddy]

Please post details with lots of pics!

 

[gmoore]

Here's a couple pics of the finished plug. Going make the mold sometime this week.

- what the underside looks like. The tail light fits right up in there.

 

[Hoosier Daddy]

Nice stuff so far