dual bowl master cylinder, 7/8 or 1" bore and whats the diff (besides 1/8")?

[steveh326]

ok ok, sorry for the flurry of questions from me last week or 2, but working on cleaning up the firewall area, going to pull the m/c off so I can clean up behind that area, and got to thinking would be good time to upgrade to dual bowl.  manual front disk/rear drum for now, MAY convert to rear disks at some point in the future.

The stock replacement dual bowl m/c's don't specify what their bore is.  Wilwood comes in 7/8 or 1".  SSBC m/c comes in 1".

my assumption is that the 7/8 vs 1" will affect pedal feel.  at least that was my experience changing to different size m/c on a motorcycle I had (I changed from twin calipers up front to single caliper, and had to change m/c from 11/16 to 9/16 to get the proper lever feel back)

What I don't know is which would be better for my application of manual front disks+rear drums, or if it makes that much difference in my case...

[Horseplay]

We all end up with this same question it seems. Don't bother calling Wilwood for advice as they will not steer you one way or another. I ended up going with a 1" bore. Smaller bore will give you a little less pedal effort necessary but maybe a bit more travel. The slightly larger bore will need a bigger leg but less travel. Also, since I have some big multi-piston calipers up front they will require more fluid volume than a smaller diameter caliper piston to function so I wanted more bore for that reason as well.

Bottom line seems to be that either will work it's just a matter of personal preference as to pedal feel/travel.

[steveh326]

thanks Terry, thats kinda what I was thinking and you confirmed it.  I'll have new SSBC multi piston calipers to install up front and stock drums in the back, at some point I would like to upgrade the rear to disks also, I think 1" is the way to go for me.

thanks for the info.

[silverblueBP]

FWIW, I have a dual MC, 1" bore with discs up front and drums out back. Works fine without too much effort or pedal travel.

[AzPete]

I thought you just exploded the engine to stop.....

[silverblueBP]

I thought you just exploded the engine to stop.....

Nope, it's never exploded. It just kinda spits a part out here & there, causing just enough damage to warrant getting off the track and driving it into the trailer. It has NEVER (knock on my head) been winched or pushed INTO the trailer.

so






    

[steveh326]

FWIW, I have a dual MC, 1" bore with discs up front and drums out back. Works fine without too much effort or pedal travel.

thanks Mark.  brakes were so bad on the old gal before I pulled her off the road several years ago that the new setup is bound to stop way better than before.  hell, just having brakes on each corner that WORK will be an improvement !  I was young and stupid back then, now I'm old and stupid but now quite as much...

[steveh326]

Thanks for all the input, really appreciate it.  I have a follow-on question...

I hate all the mess of hard lines up at the master cylinder.  I am aiming for clean, sanitary engine bay.  Why could I not use flexible braided stainless lines from the m/c down to a distribution block (and prop valve if necessary) that's hidden from view down along the frame rail?  I've got braided stainless for the flexible lines at the caliper ends, why not something similar on the m/c side ?  I can't be the 1st person to wonder about this...

[apollard]

You're not I'm sure. But, flex hoses all have some give. The more you add in, the less firm the pedal will feel as the hoses expand. I would work on another way to clean them up.

[Horseplay]

You're not I'm sure. But, flex hoses all have some give. The more you add in, the less firm the pedal will feel as the hoses expand. I would work on another way to clean them up.

Yep. You need to use hard lines wherever possible for the reason given. Those fancy little curls up by the MC are also important. They permit the necessary movement that occurs between the MC connections and the body hard line mounting points. Yes, the apron and the firewall do not move in unison and over time you will crack lines without those curls.

[Opentracker]

My thinkin' is that you don't want any flex lines except where needed. I run both hard lines from the MC straight down ( or back to the firewall ) and to a T for the front,  then down the firewall and back for the rear, neat and clean. The prop. valve can be anywhere. You just have to set it. We do like to play with 'em while we're driving on the track so I put it by the seat in the track cars.

On most cars, I like to put a line-lock in the front brake system to be able to do a full-on burnout when needed. That comes just after the T. My favorite place for the switch is the cig. lighter. I pull the guts and put in a push switch so all you have to do is push on the lighter.

[steveh326]

thanks for the input...   I was just wondering what if/why not...   based on my motorcycle analogy I used in another post, my 800lb harley uses braided stainless brake lines for both front and rear.  Lines are approximately 40" long, with no ill effects, but again, I guess you can't compare an 800lb motorcycle to a car weighing a couple thousand pounds.

John - awsome idea on tying a line loc into the cig lighter... I might have to steal that at some point in the future !

[AzPete]

Squeeze your front brake lever hard and watch for line flex/movement. My Wings that had the same lines always had a bit of flex but the bike itself never needed so much application that it was an issue.

Leg pressure vs hand squeezed application also makes a difference.

[steveh326]

Squeeze your front brake lever hard and watch for line flex/movement. My Wings that had the same lines always had a bit of flex but the bike itself never needed so much application that it was an issue.

Leg pressure vs hand squeezed application also makes a difference.

ya Pete I agree.  I'll have to focus my efforts on other ways to clean up the engine bay.  I figured there was a good reason I had never seen it done before.  NOT STOPPING is a pretty good reason... lol.

[RyanG85]

You could always use hard lines and still run the dist block or prop valve to another location. Braided or hard line, youre still going to have a couple of lines in the engine bay.