LM Dual Master Cyl Conversion

Need to know how? Want to show how?
Post Reply
User avatar
Goop Of Oil
Posts: 148
Joined: Tue Mar 23, 2010 7:43 pm
Location: Westminster, MD

LM Dual Master Cyl Conversion

Unread post by Goop Of Oil » Thu Jan 04, 2018 12:42 am

I finally got up the nerve to drill a hole in my 1966 Bronze Corsa for the Dual Master.
I ordered All Stainless Steel Pre-bent lines from Clarks for a 67-69 Corvair. I made the Template for drilling from a Picture I took in 2015 of the cut-out 1968 Corvair trunk I had in the shed at that time. You can see Grass showing through the master cylinder and wire harness holes in the 2nd picture. :chevy:
Template Source.
Template Source.
The template below is a JPG file. Print it on 8 1/2" x 11" paper Full Size and be sure "Fit Picture to Frame" is checked. Cut along dotted lines to help it fit your trunk better. You can verify you got a good print out if the two holes measure 5/8th inch from the flat side to flat side. -Thickness of the 67-69 brass fitting. Cut out the 3 holes in the Template. I used Both Brass fittings for a 67-69 so I not only had to drill the 2nd hole, I had to Enlarge the existing hole. If you just want to use a 2nd 66 style brass fitting with plugs, just put the threaded part onto the template 2nd hole and trace around it and then cut it out with scissors or sharp knife. You should see a 1/16" black boarder around your 66 brass fitting on the template. The 66 style is 9/16" from flat to flat. I wanted to keep the flat sides to prevent the fittings from spinning when the line gets tightened.
Here is what I started with.
Old Single.
Pic above and below. Remove bolt and Use small screw driver through small hole in template to align brass fitting holes.
Hold paper template down and spray paint through template.
Picture below shows where I used the 1/2 inch die grinder bit. It made quick work of the center but I used the 1/4 inch drill bit and the file the most for close to the end of the black paint and Many test fits of the brass fitting. MANY. :my02:
Drilled 2 1/4" holes then joined them then switched to the 1/2" die grinder bit.
TOOLS- 1/4" drill bit, 1/2" die grinder bit, file, small screw driver, Calipers.
The tape was there to catch the steal filings as I was drilling.
I plan to remove everything so I can paint the trunk and that is why I did not tighten the fittings down. That still remains to be done. :eek:
-------- Mark Holmlund --------

User avatar
Corvair of the Year
Corvair of the Year
Posts: 1615
Joined: Fri Dec 11, 2009 1:27 pm
Location: Phoenix, AZ

Re: LM Dual Master Cyl Conversion

Unread post by azdave » Thu Jan 04, 2018 6:21 am

Thanks for the template and tips!
Dave W. located in Gilbert, AZ
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed
65 Corsa 140 4-speed
66 Corsa 455 Toro V8
65 Monza 455 Toro V8
65 Monza 4DR 140 PG w/factory A/C
65 Monza 4DR EJ20T w/5-speed

User avatar
Corvair of the Month
Corvair of the Month
Posts: 7610
Joined: Mon Aug 06, 2012 12:33 pm
Location: Lake Chatuge Hayesville, NC

Re: LM Dual Master Cyl Conversion

Unread post by bbodie52 » Thu Jan 04, 2018 8:02 am

:goodpost: :ty: :clap: :tu:

Thank you for carefully documenting and photographing your effort to upgrade your LM Corvair to a dual master cylinder. I am planning to take on the same effort on my 1966 Corsa (when the temperature rises to a reasonable level) and I greatly appreciate your guidance!
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

Posts: 1485
Joined: Tue Dec 21, 2010 3:44 pm

Re: LM Dual Master Cyl Conversion

Unread post by 66vairguy » Thu Jan 04, 2018 9:32 am

That looks like a good installation.

For years folks have been avoiding bending up the inside lines (especially that long one to the rear) by mounting two fittings in the bulkhead. This is the shortfall of the Clark's kit and the Corvair Underground kits - they require you to bend the inside rear line in tight quarters and if you kink the line your in trouble. They also look amateurish in my opinion.

Here's a link to the same process with some good alternatives. http://corvaircenter.com/phorum/read.php?1,15306

Post Reply

Return to “DIY - Explanations and Demonstrations”