Manual brake second Gens
 

OK guys with manual brakes-if you really stand on them to get max pressure does the dash/steering wheel move?

Don't know about the "Dash/Steering Wheel Move" deal but I do know that when I was a SCCA "Scrutineer" (Tech Inspector), I burst a few brake lines that were not up to the "Gorilla Stomp" technique commonly called a PANIC Stop.

Tom Vaught

Go to one of youre other birds pump the vac out of the booster then stand on. My guess is they all will move but if manual brakes were offered on 2gen maybee there is extra bracing available. Or put them handle bars on and brace back to the firewall. Rod

I had this car for a short time and end up parting it out. Column did move a little during heavy bracking. I dont have a lot of pics but I don't see any extra bracing. Strange car with a/c, power steering and manual brakes.

Since you are using more force(foot not just toes like a booster) with manual I assume the whole thing will flex some . The pedal bracket attaches about where the coulmn does.

you converting over to manual?
if so what parts have you used for the swap?
i was going to do that
right now i just put in a smaller booster, makes like around the engine/headers so much easier
just hope it works as good as it looks

Don I moved the pushrod up to the hole where the brake light tab bolts on-takes a 7/16" bolt. Got a MP Brake rod and clevis. To center the rod I actually had to cut off half the clevis and space it over about 1/4", a 3/8 Heim end could work for spacing as the female end is the same threads as the pushrods but the hole in them is only 3/8 and the pedal has a 7/16.

Got a bad "new" Vette 1" MC so put on a Strange Mopar style 1 1/8 MC I had. Wilwood Dynalite 1.75 4 piston/10.75" rotor kit on front. Swapped GM metric 2.5" piston calipers in for the rear TA ratchet caliper and TA rear rotors about 11 1/8" and yes no E brake.

Since it has been years since I've had a manual brake car I don't remember what is normal.

As stated,the steering wheel may move ever-so-slightly,but the dash does'nt move around all that much.

The dash itself is'nt really tied directly into the brake pedal bracket or the steering column mounts.

There is a "drop" bracket that comes down from the upper part of the firewall that the steering column and brake pedal bracket both tie into,that drop bracket from above kinda "triangulates" those two assemblies.

That deal kinda isolates the dash to some degree.

The way the brake pedal bracket is designed,also kinda isolates it from the rest of everything else,but not 100%.

If you look at how it all is designed from the factory,you can see that they did a pretty good job of trying to direct all the forces where they should be going,now that's not to say it's absolutely 100% rigid,but it's pretty dang good.

I got some pics of all the under-dash stuff if it'll help ya'll visualize all this.

My '72 bird is a lot like the one SergeF posted pics of.

Mine is factory manual disc brakes A/C & P/S.

FWIW

Bret P.

Bret unfortunately doing all this MC swaping and rod adjusting I've had a good bird's eye view of all the. I HATE being under dashs and the big side supports of the Recaros and the door opening in my garage make it fun.

I think the dash moves as the column moves. Now it (column) isn't moving alot but it does shift down maybe 1/2-1".

So Bret how much effort to stomp it to the floor-full range of travel? How much to stop driving?

I think the factory manual discs used a 1" , I think the large rear calipers may need more volume there are some 1 1/16 MC that may still give me volume and less effort.

Guys I'm to understand that there are two positions on the brake peddle axis point and the master and actual brake lines themselves all play into the braking ability...

I was looking at possibly converting my 73TA Pro-touring car to manual brakes and had some discussions with the guys over at Wilwood about this very subject... A real good place to also get info would be a dirt track forum as these guys are brilliant with manipulating the braking systems... Hope that may help...

Hi Skip,

I know on my car (now crashed car) I got a lot of firewall flex when you are hard on the brake pedal (even just in the garage) and its power brakes. I thought about making a removalable brace that came off the booster to somewhere near the fender (or a gbrace).

I think its normal, not ideal but normal.

didn't some of the older second gens F bodies come with manual brakes that could just swap those parts over with?
i do remember driving i think it was a 70-72 BB camaro we had in the shop
i remember needing to apply force for the brakes to work, and that was just a 30mph drive to test the car

but then again, a nice set of gears of in the rear would certainly assist with that
i should any day now have my junk running and see if this motor makes enough vacuum for the brakes
i'll post some details of it soon

Johnny -hard on the brakes? I thought you were supposed to be smoother:) That's my road race style -go in too hot and oh crap hard on the brakes!

Hopefully when actually using the brakes I won't be that hard on the pedal. If so might have to try some other MC sizes.

sorry if this detracts Skip but do you notice its more difficult to push the pedal down with the 1 1/8 master as opposed to the 1" master?

Like I said,my '72 bird came that way from the factory,so yes there are cars out there like that. ;)

The firewall flexs noticably enough yes indeed,but on my car the steering column/wheel only moves a little bit,and my dash does'nt really move much,if at all.

Maybe ya'll are really stomping on the pedal or something?

I dont know why some guys seem to be having so much trouble with the 1" MC's lately,my car has the OE master still,so it should be a 1" MC,and the pedal effort was'nt bad @ all back when it was still running/driving,and it's not real spongy either,it's pretty firm and that's with the ??? old brakes/hydraulics all around.

:noidea:

Bret P.

If you really have to push/slam the brakes to get them to work, I'd say the pedal ratio is wrong.

Disc brakes are harder to apply or keep applied than drums.
Yours being different combinations could require a re-think.

My dragster when first put together wouldn't stop the wheel when jacked up in the air.
(with out cramming/stomping on them)

I made the brake pedal longer and it made a world of difference.
(it wasn't that much longer either, 1/4" maybe)

Do you have a residual valve in it also?

Skip...my car also came with manual disk/drum, pwr steering and a/c. Drove it quite a bit before converting to pwr brakes. The master cyl would move a little when pressing the brakes hard. NEver noticed anything in the car moving. I have heard of firewalls getting stressed and weak from this movement and needing reinforcement at some point. Some go as far as cracking around master cyl area.

I'm thinking there's something wrong. The 1-1/8" cylinder gives about 22% more pressure for the same force applied, compared to the 1" cylinder.

I'm thinking your pedal ratio must be wrong. Is the pedal real hard right at the top? If the ratio is right then you should get some range where you can apply light pressure. My '81 GMC pickup had manual discs and tookl some extra effort, but not too much. My 115 pound wife never complained about it.

I just realized what you have in the way of calipers. With that much piston area, the pedal should move an appreciable amount to move the pistons. Discs take more effort than drum and the effort for four wheel discs is pretty hefty.

I wonder about a bigger master cylinder?

Sorry,but that's 100% dead wrong (backwards @ the minimum).

The 1" bore MC gives more pressure all else being equal than the 1 1/8" bore MC would give.

The 1 1/8" bore will move slightly more volume than the 1" master will though.

That's basic hydraulic theory 101,go ahead and look up Pascals law.

http://www.mpbrakes.com/technical-su...-cylinders.cfm

http://www.stoptech.com/tech_info/Th...%20Systems.pdf

http://www.stoptech.com/tech_info/wp...lections.shtml

http://www.wilwood.com/TechTip/TechFaqs.aspx#MC

FWIW

Bret P.