Let me get your opinion on my brakes. Last time before I went to the track, I had rewired the car,installed a manual steering box and took the booster off the brakes. I just took the booster off,trimmed the pushrod(its adjustable)and bolted the M/C to the firewall on two of the studs. It stops fine and the pedal feels better now,since I never made any vacuum after the first solid cam. The car has factory discs on the front and drums in the rear,but I have the shoes adjusted in so they dont grab much if at all. Thsi is my only problem with the setup:the push rod pocket in the M/C is so shallow that I am having problems keeping the pushrod in there. I tried putting very slight preload into it but its not enough,and if I put more preload into it,the brakes are going to drag. I guess my question is what M/C should I use in this situation? Thanks...Fish
I think Oldsmobile used a manual disc brake master cylinder on their W30 cars. It could have been the W31's too o No: You could also use an aftermarket master cyl. set up for disc/drum. I know a lot of the chassis folks, like Morrison, Alston, etc... used to and maybe still do use an alum. M/C that was originally intended for a Mopar application. There were several bore diameters available (1 1/16", 1 1/8", etc...). Since I wanted power brakes I used an alum. M/C from an 82 LeSabre and a booster from a similar year Chevy Cavilier (small diameter). The M/C has a stepped bore and piston arrangement and was orig. setup for disc/drum. Since I have discs front and rear I just removed the internal valve going to the rear drums, made up a pushrod between the M/C and booster, an adj. pushrod between pedal and booster and used an adj. proportioning valve (Kelsey Hayes) to bias the brakes front to rear. I couldn't be happier with the results.
Her's another way. S-10 master, it's aluminum. Bolt pattern is the same but you will have to open the hole up a little, "cylinder bore larger". make a bracket shaped like a top hat with a hole in the center for the pushrod to go through so the pushrod can't fall out. The S-10 master plumbs in reverse, the front is the rear vice-versa. No proportion valve needed. If you do want one I have a brand new Wilwood. My 68 is like this and works perfect.
Good thoughts; I am watching this with interest because I am in a similar situation. My vacuum is a bit "spotty", that is, some times it's there and some times it's not. I tried running the booster off the engine vacuum pump (for crankcase evac) but it didn't really perform as well as I thought it would. I would like to go to a manual system, change the pedal ratio but keep the current foundation brakes (at the wheels; ie, not go to a lightweight aftermarket system). That would hopefully give me a more consistent apply and I wouldn't mind picking up the extra space in the engine compartment. I even went so far as to find the original engineering release charts for my car, and for a late 80's Chevy Pickup truck, but I haven't done anything with them yet. Jeff - do you have a part number or "broadcast code" (ie, a small sticker that says "MF", or "KD") for the S10 master cylinder you are talking about? K
Fish - a) Did you change the pedal ratio? b) Can you explain in more detail how you attached the master to the firewall? Were there four studs for attaching the booster and you used two of them? c) As far as the push rod falling out - YOU DO NOT WANT THIS TO HAPPEN! (But you knew that...). Maybe you could drill the pilot hole in the end a slight bit deeper, or try the "hat section" retainer that Jeff mentions. Thanks, K
Someone else mentioned it, did you move the rod to the other hole on the pedal? I did the same thing om my '65 before I went wtih the wilwood. I ran a power brake master (with no booster) from a '68 pont. with front power discs, and drum rear, had to make a new rod, moved the rod to the other pedal hole, and gave it alittle pre load, worked great. Like mentioned, a '70 442 w30 had non power front discs and drum rear, but the lighter master cylinder options mentioned would probably be your best bet for racing. Good luck Fish. Gary G.
Like the others said there is a power brake hole and a manual brake hole in the pedal. Top hole Manual, lower power.
yep,moved the pushrod to the manual hole the m/c slid right over 2 of the studs the booster used,i ran down 2 nuts and i was done and jeff that looks like the fix..where do i get one? thanks for the help Gary,Keith,Jeff WE1 ...Fish
That picture is from appliedracing.com site. It's for a Wilwood "Mopar" master. It's very simple to make. Do you have a welder or access to one? It would be easiest to weld this to your pedal ass. after install. Because the studs on the stock pedal ass. are welded in. That is where it needs to mount.
Here's a thread with some of this discussion: http://v8buick.com/showthread.php?t=104438 There was another thread earlier this summer full of parts numbers from NAPA, etc... too. I can't find it right now though.
It sounds like you trimmed the pushrod to much. The pedal all the way pulled back, the push rod should just move a little ,if not just a tad pre load.The last thing you want is the push rod to fall out. Why would you back the drums off so they dont drag,which they shouldnt anyway,when your stock disc brakes drag the whole way. Try master power brakes for recomendations.
Fish, If you need the correct legnth bolt I can make you one from a grade 8 bolt. If you want it send me your address.
Dont worry bout it Jeff...I'm going to find a M/C with a deeper pushrod pocket and go from there...I still like that bracket you showed us...Fish
On factory manual brake cars there is a completly different pushrod that bolts to the master some how, and goes in the top hole on the pedal. I can't remember how exactly, but I have 2 of them. I could post a picture when I get home later tonight if you are interested. Its bassically what the picture shows but would already be the right length. I could sell one of them. I have plans for some racecar in the future and would like to keep one.
Same problem different solution I converted both my 78 Malibu and 84 Regal race cars over to manual brakes and had the same problem with the brake pedal rod wanting to fall out. I bolted the master cylinders in then used a piece of coat hanger wrapped around the bolts with a slight dip in the middle and secured the coat hanger "support" with two more washers and nuts. This way the rod just lays on the coat hanger "support" and can't fall down. I must admit though that I like the bracket that 10 sec 455 suggested if you can find one. My Malibu has been raced this way for 10 years and the Regal for 6 years with no problems. Hope this helps :Smarty:
Similar question for you: do you know the part number or two letter broadcast code of the master cylinder you used? Thanks -
