Aug 21, 2023. Brake Booster/Master Cylinder Bracket Update - Well bought a piece of 6-in HSS to begin fabbing the bracket for the booster and master cylinder that came with my front disc brake replacement kit. The big error in my plan was that I didn't measure how tall the frame member was. It turns out the the inside dimension of the frame behind the transmission crossmember is less than the outside dimensions of a 6x6x3/8 piece of HSS. However, a couple more measurements showed that from the underside of the top horizontal section to the outside of the bottom horizontal section is only 1/16 of an inch more then the outside of the HSS to the inside across from it. So no problem. I figure. I'll just cut out a slot from the HSS so that the bottom of the HSS will will slide to the outside of the frame on the bottom and 1/16th of an inch shouldn't be an issue to snug up with a couple of bolts.
So I pick a top side and cut wedges out on both sides bordering what I picked as the top. I bought a 6" length of the HSS and marked out 5 in long wedges that were three quarter inches at the widest. The actual cut ended up being four and a half inches long. Mostly a struggle with the thickness of the HSS. I then put it on my anvil and hammered down the top piece so it's angled as intended. This is intended to be the side the booster bolts to.
Then I mark up where I need to cut the slot out so bottom of the HSS can slide below the frame. As I make the first cut and get to the end and finally cut through the last bit, the internal stress of bending the top piece down cause the HSS to spring out of shape. Well [censored].
I still wanted to see how it would fit up so I made the second cut and clamped it to the frame. Got it all clamped up and actually it's not bad when I stood back to think about it. The angle I created by cutting out the wedges was darn near perfect to get the rod almost straight to the brake pedal. I can set the height so that the booster is only a half inch above the level of the frame.
One issue is that I only got four and a half inches out of my 5-in wedge. That's causing the booster to sit away from the angle bit I created. But I can cut the total length down to fix that. I'm going to take the bracket to my body guy tomorrow to weld up where I cut the wedges. He should be able to pull most of the dimensions back where they should be.
The sprung dimension I'm going to struggle with the most is the bottom piece that's going to be below the frame. But I'm pretty confident I can pull it into where it needs to be.
I thought long and hard about how a 5x5 piece of HSS would work, but I think the angle I created with the 6-in makes the arm line up almost perfect with the brake pedal. I think creating the same angle with a 5X5 would create interference problems with the arm and the transmission cross member. And if I didn't create the angle, I'm pretty sure the arm would have to angle to get to the brake pedal. The current setup I created today is pretty close to straight on.
Description of the pictures are as follows. Picture 1 is the mock up of the bracket with the booster clamped on. Picture 2 shows how high booster is above frame height. The wood is about 3/8 of an inch thick. In pictures three and four, I've done my best to place a stick from about the center of the booster to the lowest point of the brake pedal connection trying to see what the clearance is from the transmission cross number. Not sure it's clear in the pictures but there's plenty. Pictures five six and seven show the original HSS across dimension and a couple of the biggest sprung dimensions. Picture 8 shows how far below the frame the HSS comes after it sprung when it was supposed to be 1/16th of an inch.
Looking forward to getting the welding done and see how the shape turns out.
