flexing master cylinder..

[icetech]

soo... sitting at work thinking about things and i have a problem that has been bothering me since i put things together.. hitting the brakes on my car the MC moves up and down at least 1/4" not like loosely but still moves without really standing on the brakes.. so.. i thought maybe this is normal but last year i was at DVW's sons house and had him stand on his brakes in his '62 and it didn't budge at all..I have the same setup as him pretty much.. The later aluminum/plastic MC with the drdiff alum 4bolt>2bolt adapter.. but the flexing happened with a cast iron old style MC also.

I am mainly curious if there is a bracket under the dash or something that could be missing to cause this? I have the big heavy plate between the MC/firewall.. i had stripped this all down to metal before paint and it had zero rust/rot anywhere near this area.

Yesterday i had a neighbor help me bleed brakes and i watched the MC/firewall and saw the firewall flexing in this area (older pic with older MC...) the yellow is where it was flexing..

Not sure if i'm missing some braces inside or something.. the car was bone stock when i got it and i didn't take the pedal box out or anything..

 

[khryslerkid]

Hard to tell in your pic what your plate looks like. Here's the one on my '62. I never had anyone apply the brake while I watched for movement.

 

[icetech]

Hard to tell in your pic what your plate looks like. Here's the one on my '62. I never had anyone apply the brake while I watched for movement.
View attachment 1847352

yeah that's the plate on mine.. i'm gonna get some better pics and underdash ones when i get home. Just sitting here obsessing at work

 

[RemCharger]

Give the bolts another retorque?

 

[icetech]

Give the bolts another retorque?

going to do that also.. i'm getting ready to start driving it so now it's down to triple checking everything and making sure i don't miss something....

 

[Bird 426]

It's gonna be hard for us to diagnose this this, my opinion. Yes, there is pedal bracing under the dash for the pedals and the steering column is also tied into it. You are going to have to see why and where it is flexing. This is not normal, none of my cars do it. Also, I do not like the 2 bolt to 4 bolt adapters. One of my Darts has it, but the first sign of trouble and it's going away.

 

[icetech]

It's gonna be hard for us to diagnose this this, my opinion. Yes, there is pedal bracing under the dash for the pedals and the steering column is also tied into it. You are going to have to see why and where it is flexing. This is not normal, none of my cars do it. Also, I do not like the 2 bolt to 4 bolt adapters. One of my Darts has it, but the first sign of trouble and it's going away.

Yeah, i had someone else tell me it's normal so i wanted to make sure before i ignore it and crack the firewall eventually. I would question the adapter also except i first noticed the issue with a 4 bolt iron MC installed. i'm gonna get pics and look a little deeper tonight. Just figured it might be a common thing as i tend to overthink/overworry bout things.

 

[khryslerkid]

soo... sitting at work thinking about things and i have a problem that has been bothering me since i put things together.. hitting the brakes on my car the MC moves up and down at least 1/4" not like loosely but still moves without really standing on the brakes.. so.. i thought maybe this is normal but last year i was at DVW's sons house and had him stand on his brakes in his '62 and it didn't budge at all..I have the same setup as him pretty much.. The later aluminum/plastic MC with the drdiff alum 4bolt>2bolt adapter.. but the flexing happened with a cast iron old style MC also.

I am mainly curious if there is a bracket under the dash or something that could be missing to cause this? I have the big heavy plate between the MC/firewall.. i had stripped this all down to metal before paint and it had zero rust/rot anywhere near this area.

Yesterday i had a neighbor help me bleed brakes and i watched the MC/firewall and saw the firewall flexing in this area (older pic with older MC...) the yellow is where it was flexing..

Not sure if i'm missing some braces inside or something.. the car was bone stock when i got it and i didn't take the pedal box out or anything..

View attachment 1847336

So you went and got my curiosity up

I'm pressing pretty hard!

 

[icetech]

So you went and got my curiosity up

I'm pressing pretty hard!

Jesus.. ok yours move sideways..... and a lot.... see that terrifies me but at least i know i'm not the only one i'm gonna make a vid tonight.. with normal/semi-hard pressure it's not bad but that looked like you were almost 2 footing it

 

[RemCharger]

There's going to be some flex . Its a bunch of sheet metal after all

 

[BeepBeepRR]

So you went and got my curiosity up

I'm pressing pretty hard!

Watch the bottom right post.. Its moving in the bracket. Id tighten that thing from under the dash would be bottom left. Hell re tighten them all.

 

[icetech]

There's going to be some flex . Its a bunch of sheet metal after all

i get that.. i just wanted to make sure rather than be sorry later.. the other 62 i saw, that thing didn't budge at all which is why i was like WTF....

I hate getting old... **** like brakes when i was 25.. didn't care much, i would have just bout opened the door and flintstoned to a stop.. now i stress about every nut and bolt..

 

[icetech]

BTW.. thanks KK for doing that

 

[icetech]

Watch the bottom right post.. Its moving in the bracket. Id tighten that thing from under the dash would be bottom left. Hell re tighten them all.

Just looked again, it almost looks like his nut isn't even tight on the bottom right, that thing is really moving

 

[BeepBeepRR]

Just looked again, it almost looks like his nut isn't even tight on the bottom right, that thing is really moving

At about the 3rd brake pump you can see a slight gap open up around the post. I guess its not tight and needs to be reseated in the knurling.

 

[icetech]

At about the 3rd brake pump you can see a slight gap open up around the post. I guess its not tight and needs to be reseated in the knurling.

yeah, you can see his firewall flex below it which is exactly what mine does, so i feel better but i'm going to double check everything tonight anyway. a few minor things to do before driving still... setting spare parts and tools in the trunk and all that.

A guy offered to buy the car yesterday but.. i don't think i could get near what i have into it, plus i would like to drive it a bit Random guy pulls up.. said he runs the ramchargers historical site and saw me working on it (i live on a main road) and wanted to check it out.

 

[khryslerkid]

Just looked again, it almost looks like his nut isn't even tight on the bottom right, that thing is really moving

At about the 3rd brake pump you can see a slight gap open up around the post. I guess its not tight and needs to be reseated in the knurling.

It's tight. Stop looking at my nuts!

 

[RemCharger]

It's tight.

If you say so!

 

[BeepBeepRR]

It's tight. Stop looking at my nuts!

Nooo I like pointing out loose nuts.

 

[khryslerkid]

It's common for some flex. Like already stated it's only sheet metal with no bracing for the exception of the plate. IIRC they used a different plate for the power booster. I don't remember the difference at the moment.

That's the Brakes!