Cut the firewall for 2 bolt Master Cylinder!

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CudaChris67

CudaChris67

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Has anyone modified their firewall INSTEAD of using a 4 to 2 bolt plate to run a 2 bolt master cylinder? I'd love to see pics as I am in the middle of smoothing the firewall and it would be a good time to take care of this at the same time.

Plan is to cut/weld existing studs, drill new holes to wels the 2 new studs in, and make the thru hole smaller if needed.

thanks
-Chris

PS: converting from 4 wheel drum manual to 73 front disk manual
 
here ya go, I welded nuts on the brake support bracket and shaved off the 4 studs that way I can install some nice button head 3/8" bolt heads instead of seeing 2 studs with nuts sticking out.

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You can buy a adapter plate for about 30 or forty dollars and use the stock push rod from the original MC that's what I did ill post a pic in the morning in working now
 
76orangewagon said:
here ya go, I welded nuts on the brake support bracket and shaved off the 4 studs that way I can install some nice button head 3/8" bolt heads instead of seeing 2 studs with nuts sticking out.

Thank you- looks great, btw I read through your whole build (over the last 2 weeks) and I was inspired to shave my fire wall after seeing your work. thank you!

I am going to copy your method I love the idea of using captive/welded nuts instead!
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I just drilled two 1/4" holes in the middle of the 4 holes. Didn't weld, just bolts. The 4 studs are part of the brake pedal bracket and just pass thru the firewall. I didn't cut them off. I used a big washer to cover the opening. Using a new MC for a ~99 Breeze. I have read that MP MC's are just Dodge truck ones you can buy for $25. I knew you can buy the adapter plate for ~$45, but too much of that and my $1000 Dart soon costs >$10K.
 
CudaChris67 said:
76orangewagon said:
here ya go, I welded nuts on the brake support bracket and shaved off the 4 studs that way I can install some nice button head 3/8" bolt heads instead of seeing 2 studs with nuts sticking out.

Thank you- looks great, btw I read through your whole build (over the last 2 weeks) and I was inspired to shave my fire wall after seeing your work. thank you!

I am going to copy your method I love the idea of using captive/welded nuts instead!
Click to expand...

Since your shaving your Firewall, I think it just looks better and gives the image of being a thought out build instead of an after thought, if you were just converting to a 2 bolt with a stock firewall it's not important.....but your past that point.
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here's a good photo of one converted (although its on a Chevy) you get the idea, Now imagine a nice allen head button bolt showing instead of the nut.

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yea..either looks fine to me. if the nut bothers you, use a fancier ARP 12 point. dont sweat the petty things, pet the sweaty things!
 
Seems like a lotta work to save 40 bucks.
 
..not wanting to hi jack but why do some want to change to 2 bolt aluminum instead of the correct style master?
..what am i missing?
 
StrokerScamp said:
Seems like a lotta work to save 40 bucks.
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I agree. Would Han a lot more the $40 of my time into doing that.

Watch push rod length. The newer master cyl are drilled shallow compared to the old ones. The adapter plate takes up the difference so you can use your stock rod.

Also stay away from the fwd car master cyl. They may not operate the correct way.
 
ir3333 said:
..not wanting to hi jack but why do some want to change to 2 bolt aluminum instead of the correct style master?
..what am i missing?
Click to expand...


easier to get, cheaper and used with disc brake upgrades.better all the way around
 
StrokerScamp said:
Seems like a lotta work to save 40 bucks.
Click to expand...

Thank you everyone for the input- exactly why I love this forum, you don't just get pats on the back and silence, people speak their minds!

you are right, I am not really saving the $40, but instead of looking like an afterthought of an adapter is on my car, the upgraded part will look like part of the car. Makes it a little more subtle, and a little more streamline.

My is car is completely disassembled, so some of these mods are a little easier to do than say doing so on a daily driver.

Hours of FABO research yielded that in the event of using the adapter, a longer (adjustable mancini/MP) pushrod is needed ($75) in addition to the $40 adapter.

I'll pocket the 100 bucks and get some weld time in!
 
CudaChris67 said:
Hours of FABO research yielded that in the event of using the adapter, a longer (adjustable mancini/MP) pushrod is needed ($75) in addition to the $40 adapter.

I'll pocket the 100 bucks and get some weld time in!
Click to expand...

Not true.
Installed the alum m/c on my 65 and used the stock push rod.
Works fine.
 
Hours of FABO research yielded that in the event of using the adapter, a longer (adjustable mancini/MP) pushrod is needed ($75) in addition to the $40 adapter.

I'll pocket the 100 bucks and get some weld time in!
Click to expand...


thats wrong. if you do not use the adapter you need a shorter rod. the new style master cyl. is drilled shallower then the stock ones. the adapter is the same thickness as the difference between the depth of the two master cyl holes, so with the newer master cyl and the adapter you will use the stock push rod. newer master cyl and no adapter you need a shorter rod.
 
Buy the adjustable push rod and adjust it to the correct length. It's all in the detail's and what makes you happy...
 
I wasn't criticizing in the least. It's just that I would do it differently. The welding work will look very neat for sure.
 
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