Hey that last thread was getting a little long so I started this. I unpacked what's left of the conversion kit. And I found the pins. What's weird is one is under 2.25" long (the one in the booster) and the another one is almost 3.75". The booster instructions talk about mounting the whole thing and then based on pushing in the brake while viewing the fluid to find out if the pin is long enough or whether it needs to be replaced or adjusted by pulling the master cylinder off and pushing it in or out. Hell it just slides in by hand, any pulling out of the pin will be changed as soon as you put a load against it. Seems alot of tearing back apart. I think the supplied 2.25" one should work. Here's the pics.

 

I'm no expert on this but I think what you have shown is a shallow piston master cylinder. Mine has a bore that the booster pushrod goes into. This bore is about 1 inch deep and the booster pushrod projects from the mounting surface (of the booster) about 1 inch.

You should be able to easily pull the pushrod (that pushes on the cylinder piston) out of the booster. It should look like a large nail, about 6 1/8 inches long. Like I said, I am really only familiar with early C3's and I think the master changed in later years. I know people have run into this shallow master problem with Hyroboost conversions. Maybe someone will jump in here.

 

This is one a 68 vert, I think that since the bore is shallow once you push on the rod on the other side the 2.25 should be enough to open both ports. I'm guesing here but since the booster is from another company they probably provide both pins to fit any GM application. When I unpacked it the 2.25" was mounted inside. If your bore is deep and mine is definetly shallow I should safetly assume the 2.25" rod is the one I need. By the way BB thanks for all your help.

David

 

BB, I got the firewall drilled, hole elongated, glassed in the upper hole, pulled the vacuum tank (it was in the way) painted it and reinstalled everything. It was actually a simple process. Problem is

1. The pedal once connected to the clevis is 1/2 way to the floor. There is no adjustment for this, I called the company. Unless there is a long clevis out there I can buy the only choice I have is to take the clevis out and take it to the Machinery repairman on my ship and have them make a extension out of stock aluminum to extend the clevis to it's normal pedal height. The brake switch on the 68 is the C2 variety. It connects to the outside of the pedal assembly and with the pedal down so low it does not work. I'm going to try to get a piece of stock T504, have it milled with female threads to connect to the booster's threads with a 2" shoulder the male threads to connect to the clevis.

2. The Speed Demon carb has it's fuel bowls so low you cannot clear the vacuum tee on intake. Any more carb spacers will result in the 2.5" air cleaner not clearing the hood. I have no choice but to connect the booster's vacuum line to the vacuum port on the rear of the carb which shares vacuum to the headlight/ wiper door system. Which should work since it's a closed system.

One step forward three steps back. Today I bench bleed the MC, and whole system then take the clevis back off and take it to work to make the extension piece.

David

 

David,

Does your clevis look like this? It should be about 5 3/4 inch from the booster mounting face to the clevis hole center:



I just verified this. My car is apart but I do have the pedal assy installed. If I measure from the firewall to the hole in the brake pedal arm it is about 6 inches. I wonder if the short and long pins you have shown in the pictures have something to do with your pedal height? Seems like you could get a 3/8 coupling nut and a 3/8 stud to extend the rod.

 

The clevis is only 2 1/4" long. I'm trying to find a nut long enough to weld to the clevis.

 

Something just doesn't seem right. The underdash end of your booster looks just like mine and I can see the clevis in your picture and it looks just like mine (and is also about 2 1/4 inches long). When I put my booster in, the clevis hole lines right up with the lower hole in the brake pedal arm.

With the booster out of the car; if you push on your clevis, does the pushrod that goes to the master start moving with it? It should be a solid stack, no freeplay.

 

Yes there is instantaneous movement of the pin when I push on the shaft or clevis. I decided to do this, weld on a 3/8 nut with a thick washer, which makes up the 1/2" difference



The booster installed.

 

Looks like you solved the problem. Now you get to bleed your brakes!

 

Bleed/ installed the master cylinder last night after watching the Chargers hand over their Superbowl chances to the Pats. Just need to install the welded clevis then shim, 3/8", the brake switch to clear the clevis and bleed the four calipers and I'm back on the road.

 

Glad all that worked out for ya Dave! It'll be good to see ya driving that car again. How much longer ya gonna be here in town?

 

Looks like you are ready to go. I was pulling for SD and you are right, they gave the game away. The SD guy that intercepted (then fumbled) the ball on 4th down should be removed from the NFL. I don't know why DB are always going for an interception rather than taking possesion on downs. I guess they want to pad their stats.

Sorry, way off topic but a pet peeve of mine.

 

Well got everything put back together. Clevis lined right up and spent 2 days shimming the brake switch so it clerared the clevis pin just to find out after all that the brake switch burnt out (probably from being on for 2 plus weeks) I'm deploying in 7 days so it will have to wait but all I have left is bleed the brakes and replace the switch and I'm back on the road.

 

The reason you had problems with the position of your pedal based on the new setup...is pretty easy in theory but hard to fix. I'm guessing your car used to be a manual brake car? The hole in the brake pedal where the clevis clips is in a different position on the pedal, giving you more power via a fulcrum effect.

The power brake setup has a different length rod, changing the dynamics. You can do what you did, or remove the pedal and drill a hole int eh same position that would be found on a power pedal.

 

Your right. The setup shown above worked and it ligned up just perfect.

 

The brake switch on a 68 is a difficult item to find. Hope you don't need a new one. I converted mine to a 69-up but the pedal assy was removed so it was easier.

Speaking of that. You did put the clevis in the lower hole on the barake pedal arm, right? If you want to convert your switch, let me know'

 

Did the old manual brake cars have two holes? One for manual and one for power?

 

Has 2 holes. The power hole, lower one lines up with the bottom. Believe all cars have 2 holes right?

 

Yes, the brake pedal is the same 68-up. The top hole is used for clevis attachment on manual brake cars and bottom for power brake cars.

 

How is this done?