Master cylinder packing piece

[GregW]

I am trying to finish up my brake system today but that pesky black hole that hides in my garage has sucked up the packing pieces that go between the master cylinders and the firewall. I can figure everything out except how thick the pieces are. If I remember correctly, they are made from aluminum. Anyone know?

Thanks much,
Greg

 

[Lin]

Greg,
Here is a photo of the two pieces.
Each is .055" thick and they are aluminum.

Lin Rose
1960 BT7 in restoration
1959 Bugeye

 

[vette]

I'm just curious, why are these packing pieces needed. I had just one, and when I rebuilt my master cylinders I forgot which one had it. Right now I don't know which one I put it behind. Are they needed?

 

[JamesWilson]

They're used on the Brake M/C.

They move it out from the firewall to help position the brake pedal an appropriate distance from the floor. Or so I've been told....

But I'm gullible.... /ubbthreads/images/graemlins/confused.gif

 

[GregW]

Hi Lin,
Thanks for the measurement and photo. I did eventually find the pieces. The CO had stupidly installed them under the distributor retaining bracket. I’ll admit, it fits nicely there. I made 2 sets for both masters and they’re in the car.

Like you Vette, I recall only having one pair. I looked in the Moss catalog, for the brake MC, the part is a “packing piece”. For the clutch MC, the same part number is called a “shim”. Hopefully you didn’t put the shim where the packing piece is supposed to go or vice versa. /ubbthreads/images/graemlins/wink.gif

Got the front SS braided lines installed also. All that’s left for the hydraulics is attaching the pedals, adding fluid and bleeding (crosses fingers).

 

[Keoke]

BUT!!,the other set is not of the same shape Greg. But has same part NO.---Keoke-- /ubbthreads/images/graemlins/laugh.gif

 

[Keoke]

HI Vette, I think you can liken those shims/packing pieces to crisps being thrown out the car window to keep elephants off the freeways.---Keoke-- /ubbthreads/images/graemlins/laugh.gif

 

[Cutlass]

A shim of .055" doesn't seem like enough to make a spacing difference. Could they be sacrificial material to keep galvanic corrosion from eating into the cast aluminum master cylinders?

 

[GregW]

Hi Cutlass,
When I found my shim (or was it the packing piece?) it measured .067” thick. It was a little mashed so I figured standard .063” would work. Seems to be a different shim from Lin’s. If they are to adjust pedal height, that would explain the difference in thickness. If you take the pedal ratio into account (say 5:1), that .055” makes more than a quarter inch change in height at the foot pad. Looks like I should check the height of all the pedals before I proceed with adding the brake fluid. /ubbthreads/images/graemlins/crazyeyes.gif

 

[Keoke]

Hi Cutlas, No I do not think so, since the shim/packing pieces were added just like any other shim on an "AR" basis to accomplish what ever they were suppose to accomlish.Reportedly to Balance pedal height---Keoke

 

[vette]

Both ideas are plausable, but also wouldn't the shim/packing piece limit the travel of the pistons depth into the bore. A well bled brake system won't need much stroke, but too much stroke on the clutch master might blow out the slave. Where's Jerry Coker or one of those guys when you need them?

 

[anthony7777]

"crisps to be thrown out the window to keep elephants off the highway"as editor reid might say ''sir you trully are a poet" my dear friend keoke,please next time you go out for dinner dont order the mushrooms!check your e mail for a preview of the next fabulous a7777 giveaway,i think youll like it since you own a rather nice bn-type,ill pay the postage this time. /ubbthreads/images/graemlins/yesnod.gif

 

[Jerry]

While we are on this subject, my clutch is engaging closer to the bottom of the pedel these days. Is that adjustable with the shim pieces?

Jerry

 

[Keoke]

HI Jerry, No there must be some wear or air in the system someplace.---Keoke

 

[anthony7777]

ok here she goes,having rebuilt both brk.mst cyl.and slv.cyl,it accured to me that if they realy wanted to totaly lock up the hydrolics in the lines and in that type cylinder they might have used a set up more like that of an engine piston ring to totally seal the pressure,nowing that a liquid [depending on its composition for all intents and purposes]can not be compressed,they use a rubber seal that would have a good amount of 'bleed back' fluid running back past it to discourage exploding lines and brake cyls. dispite the total arm=levered movement of travel,i dont think that a .063 shim would have that much of a drastic effect,im gunna call whats his name,bernulli?bannuli,how can i get his phone number if i cant spell his name? the primary shafts are limited to travel consistant with thier lenght and that of the case,were can they go?no place youd get 'bleed back into the resivour due to the flexability of the 'rubber seal'.imho.oh boy my ears ara a ringin,i can hear KEOKE now!!!!!!!.and oh yes volume is inversely proportionate to pressure,thats probably all i remember from hydrolics 101. /ubbthreads/images/graemlins/yesnod.gif

 

[Keoke]

/ubbthreads/images/graemlins/shocked.gif Every body else but CHU got adjustable push rods on both of their cylinders and don't need no shims/packing pieces at all!.Of couse you don't get up to this level until you have had: Post Grad; 205---Keoke- /ubbthreads/images/graemlins/cool.gif
Well Anthony! for once we agree,you forgot everything else but the last line.---- /ubbthreads/images/graemlins/grin.gif

 

[anthony7777]

keoke,from anthony7777,yo man,you talkin to me?,i dont need no stinkin adjustable pushrods!i put dah wood blocks on the pedals!kus my legs to short!!!!!!!!!! /ubbthreads/images/graemlins/cryin.gifu bedda watch it man,im gunna meat ya some day,im gunna make a point of it,you shouldnt make fun of me kus i got my 'edookaton'from the back of a matchbook kuvah,and i wuz borned in brooklyn.-did ya get my e mail? on giveaway?,check my pre posts here.laddah /ubbthreads/images/graemlins/devilgrin.gif p.s dont eat any more mushrooms!!!!"elephants off highway"pahleeese! /ubbthreads/images/graemlins/crazyeyes.gif

 

[Keoke]

No Anthony, I have not seen the E-mail yet---Keoke /ubbthreads/images/graemlins/nonod.gif I did find the post with the attachment I did not understand where to look at first.---Keoke /ubbthreads/images/graemlins/grin.gif

 

[anthony7777]

keoke,couldnt get e mail through,check ya 'private messages'

 

[Keoke]

Did You get an off list E-mail from me???