Grommet for Through Pedal Box Hydraulic Lines

[mach'er]

I found this grommet (Danchuk 820, for a 55 Chevy), and ordered one to see if it would work.



Lo and behold, it is almost perfectly sized for the clutch cable hole in the firewall (which I'm not using, since I've gone to a hydraulic clutch):




All it needs is the holes drilled out a hair larger than as delivered.

Anyone have a smart and successful way of drilling/reaming out holes in rubber? I ruined the one I ordered, but it fits so good, I'm willing to try it again.

Or, does someone have a better method of creating a sealed pass through for three reservoir 1/2" hoses (two brake, one hydraulic clutch) and one brake line? I thought this could work great, but am willing to look at other ideas.

Thanks!
--Curt

[NAZ]

I've used a small sanding disc and small grinding stone on rubber and urethane products with good results. I've never had any luck using cutting tools like a drill or reamer but grinding or sanding works. As a machinist I used to precision grind urethane rolls for coating applications. It grinds easy but won't cut to save your life.

[michael everson]

try freezing it before drilling it
mike

[JoeAIII]

A punch, like used to cut holes in leather or fabric to install grommets may work as well. Similar to these https://www.amazon.com/SE-7909LP-9-P.../dp/B0002964CC
I have used them to cut holes in rubber sheets before.

[Thunderball]

What Mike said. Leave it in the freezer overnight, chuck it up in the vice, high speed low pressure on the drill. Should be a clean hole.

Chris.

[CDXXVII]

If that ends up not working out you could just use three separate grommets. Separate grommets made my install pretty simple and clean.

[mach'er]

Thanks for the responses. I'm going to give it another go, or two, using the suggestions here. If it doesn't work out, I'll go the separate grommet route.

I'll post a picture in my build thread of whatever I end up with.

CDXXVII: I see your lines from the reservoir to the master cylinders. Where'd you choose to route the pressure lines (including to the clutch slave cylinder)? I don't see them coming out in that picture - but it sure looks like a clean and well thought out layout. Also, I like your braided lines. Nice!

[jrcuz]

Here is my solution.
JR