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What is the brass distribution block from? Being a 65 didn't it originally have a master cylinder with only one reservoir? My 66 goat originally had a single reservoir master cylinder and I installed a distribution block from a 72 chevelle with power disc brakes so as to install a dual reservoir master cylinder. My set up is 98-02 fbody disc brakes front and back with a CPP master cylinder with built in proportioning valve. I know for a fact the distribution block for a chevelle is different for a car with power disc brakes and a drum brake car.
It's not a stock part. It's manufactured by The Right Stuff Detailing (at least their logo is stamped into the side of it). It came with the disc brake conversion kit.
Dave,
On my setup upfront, I used large bore GM Metric calipers from AFCO. In the rear, I used the standard bore GM metrics. I think the cadillac calipers are a derivative (but with parking brake). I would double check. And I have the same size rotors front and rear.
You want more stopping power upfront as even if your vehicle has 50/50 weight distribution, when you brake, weight transfers forward. Forgive me if you know all of this.
So....
If you look at the calipers, the larger the piston size (area) the more force they apply to the pads for a given level of system pressure. So normally, the piston area fronts divided by piston area rears is somewhere on the order of 70/30, in most vehicles.
In my case, the ratio is a bit lower than 70/30, but I use an adjustable proportioning valve like you pointed out to reduce rear braking pressure so the rears don't lock up first. If the fronts lock first, then the vehicle is less likely to spin in an emergency braking situation.
I hope that makes sense.
Doug
Doug,
Yes that makes sense. What concerns me though, is that the rear Cadillac calipers I have are from an Eldorado. I purchased a replacement caliper for a Seville (before I was informed I had an older Eldorado-based kit). The Seville caliper accepted the same brake pads, and looked the same, however when I tried to put the slide pins in, they allllllllmost lined up, but were off by like 2mm. It made it so that it was impossible to get the pin into the outward side of the caliper.
This means that there are at least two different size GM calipers that look pretty much identical from the outside. The piston of the Seville caliper was larger though...is this what you mean by larger and smaller GM metric calipers? If I find a front caliper with the same size piston as the current calipers I have on the rear of the car now...the slide pins should line up?
I would LOVE to get rid of these stupid Cadillac calipers. They are nothing but headaches. Plus the Camaro ones (if they fit) are like $25!
Talked to the people at The Right Stuff Detailing. They told me that I can swap out the troublesome Cadillac rear calipers for 1979 G-Body front calipers. They were $30 shipped each. Bought a set today Amazon Prime. ANNNNND the Hawk brake pads I just bought for the Cadillac calipers will fit the G-Body calipers too!
It's a real pain to have to keep throwing parts at this car, but surely I need to be able to stop. These Cadillac calipers have been such a huge headache and I will be thrilled to see them go. How much do you wanna bet as soon as I put on the new calipers it stops like a Porsche?
Talked to the people at The Right Stuff Detailing. They told me that I can swap out the troublesome Cadillac rear calipers for 1979 G-Body front calipers. They were $30 shipped each. Bought a set today Amazon Prime. ANNNNND the Hawk brake pads I just bought for the Cadillac calipers will fit the G-Body calipers too!
It's a real pain to have to keep throwing parts at this car, but surely I need to be able to stop. These Cadillac calipers have been such a huge headache and I will be thrilled to see them go. How much do you wanna bet as soon as I put on the new calipers it stops like a Porsche?
Dave,
My first car was a 65 Impala and I have been following your build with great interest! It looks awesome and I for one am eagerly awaiting the final outcome!
Randy
Dave,
My first car was a 65 Impala and I have been following your build with great interest! It looks awesome and I for one am eagerly awaiting the final outcome!
Randy
haha thanks Randy me too....but it'll be quite a while before the car is ever complete though. It may never happen, for all I know.
It has taken longer than I thought, but I got the brakes "done". I bought brand new calipers for the rears to replace the STUPID Cadillac nonsense. I wish I could say they bolted right up, but it took like 8 hours to swap them. The brackets needed to be trimmed in a few spots to allow for a slightly different shape than the originals. The pins still fit perfectly fine, but some of the bracket was in the way and had to be trimmed off.
Then I ordered that Wilwood proportioning valve I posted earlier. That install was not exactly straightforward either. Needed adapters and some tricky work with brakes lines to get it all working.
Took the car out today, and the brakes were terrible. Almost broke a window in the house throwing a wrench.
Then I noticed there was a leak at a rear caliper at the flex hose. I also noticed that the flex line was touching the axle housing, and it wouldn't be long before a hole was worn into it. The calipers would only allow me to have the hoses pointed in one direction, so I got a Dremel out and filed some of the caliper away so I could point the flex lines wherever I wanted. I tightened the lines up and leak was gone. Bled the whole car again.
When I drove it the next time, the brakes were much better. I couldn't really test locking up at high speed, as I was only in my neighborhood and there's kids and dogs and whatnot. Brakes still seem just a little soft, but if I push really hard, it will tighten up quite a bit. Like I said, I couldn't lock them up still, but the car will definitely respond now.
Wondering if I should upgrade to a larger booster, or just drive it like this a while until I can afford to do a hyrdoboost conversion. Thoughts?
I haven't seen this mentioned, unless I missed it, but have you replaced all the rubber lines in the brake system? Especially the hose running to the rear axle, it can develop an internal leak that will shut off flow under pressure, causing a soft pedal and no rear braking power, just a thought.....
Hey Dave,
I had some of the same experience in terms of not being able to lock up. When I got the short throw, firm pedal I wanted, my small diameter (and single diaphragm) booster wouldn't aid me enough to be able to lock up without really smashing the pedal with high level of force. And there was no way my wife would be able to do that.
That's when I decided to go hydroboost.
Now the pedal feel is great and the level of boost it provides WAY more than my old vacuum booster. And I can lock up the brakes at any speed. I have the adjustable proportioning valve set so the rears won't lock up (that would possibly induce a spin)
Glad to hear of your progress .... sometimes you have to fight for it. Yes, I fought a bit with trimming the brackets for those metric calipers too. They don't seem real consistent in size from vendor to vendor.
The ultimate setup for you might just be a Hydroboost and a 1 1/4" master cylinder (I know you are at 1 1/8", now). That's where I settled after some calculating, but also trial and error.
BTW - I assembled my own hydroboost setup.
It was about $150 for a new ACDelco unit on Amazon. $200 for the custom hoses, but think you could use OEM hoses, since the relationship between your power steering pump and the firewall is similar to many OEM vehicles. (In my truck, the master cylinder is below the driver's seat on the frame).
It also cost me some fabrication time to get it all connected. Still, I'm certain a bolt-on adapter exists for your application.
I haven't seen this mentioned, unless I missed it, but have you replaced all the rubber lines in the brake system? Especially the hose running to the rear axle, it can develop an internal leak that will shut off flow under pressure, causing a soft pedal and no rear braking power, just a thought.....
That line is new with the kit, and all the flex lines at the wheels are new as well. I have never clamped any of the 5 lines either.
Originally Posted by DW SD
Hey Dave,
I had some of the same experience in terms of not being able to lock up. When I got the short throw, firm pedal I wanted, my small diameter (and single diaphragm) booster wouldn't aid me enough to be able to lock up without really smashing the pedal with high level of force. And there was no way my wife would be able to do that.
That's when I decided to go hydroboost.
Now the pedal feel is great and the level of boost it provides WAY more than my old vacuum booster. And I can lock up the brakes at any speed. I have the adjustable proportioning valve set so the rears won't lock up (that would possibly induce a spin)
Glad to hear of your progress .... sometimes you have to fight for it. Yes, I fought a bit with trimming the brackets for those metric calipers too. They don't seem real consistent in size from vendor to vendor.
The ultimate setup for you might just be a Hydroboost and a 1 1/4" master cylinder (I know you are at 1 1/8", now). That's where I settled after some calculating, but also trial and error.
BTW - I assembled my own hydroboost setup.
It was about $150 for a new ACDelco unit on Amazon. $200 for the custom hoses, but think you could use OEM hoses, since the relationship between your power steering pump and the firewall is similar to many OEM vehicles. (In my truck, the master cylinder is below the driver's seat on the frame).
It also cost me some fabrication time to get it all connected. Still, I'm certain a bolt-on adapter exists for your application.
Doug
I saw the Amazon unit everyone was buying...I think it's $132 now. If the whole price was in the $200 range, I would probably just do it and be done with this mess, but I am afraid of the cost creeping up up up as I get all the fittings and lines and stuff. The complete kits are like $500+, and I can't afford anything close to that right now.
I think I might try an 11" booster first. I can get one of those for $98 and free shipping from Jegs. I'll drive it around this fall and a little in the winter. If the brakes are vastly improved, I'll stick with the booster. If I still can't stop well, then I will gather parts over the winter and have a new hydroboost setup installed before the snows melt.
Thinking back on it, I remember the people at Right Stuff asking me if I wanted the 9" or 11" booster. I went with the 9" to save money (dummy). If this car really does require a bigger booster to get the job done, you'd think they would have just TOLD me that and not offered the weaker booster at all.
sounds like relying on the folks at the Right Stuff to give any good guidance would be a mistake.
I don't like the idea of throwing money at an interim solution, but an 11" diaphgram will provide about 1.5 times more force on the master cylinder pushrod:
11 x 11 = 121
9 x 9 = 81
121 / 81 ~ 1.5
I don't know an analogous ratio for a hydroboost unit.
sounds like relying on the folks at the Right Stuff to give any good guidance would be a mistake.
I don't like the idea of throwing money at an interim solution, but an 11" diaphgram will provide about 1.5 times more force on the master cylinder pushrod:
11 x 11 = 121
9 x 9 = 81
121 / 81 ~ 1.5
I don't know an analogous ratio for a hydroboost unit.
Doug
1.5x the power sounds like it would give me a pretty reasonable pedal feel. At low speed it feels like any normal car, but at like 30 mph I have to try kinda hard. If I could get that extra 50%, I think I would be happy.
Let us know if you can lock up at higher speed once you can make it to a safe testing spot. Also, give some feedback on how much pedal travel you use to lock up.
I hate to keep guessing with your setup. Still, it seems we are going the right direction!
Is there a 12" booster unit you can locate for similar cost? Might be worth poking around.
Let us know if you can lock up at higher speed once you can make it to a safe testing spot. Also, give some feedback on how much pedal travel you use to lock up.
I hate to keep guessing with your setup. Still, it seems we are going the right direction!
Is there a 12" booster unit you can locate for similar cost? Might be worth poking around.
Doug
I'll be sure to keep you posted with my boring brake problems haha.
Did not even know they made a 12". I'll have to look around for that. Also I should probably take some measurements in the car before I go any further
After several weeks of gathering parts and doing research, I have FIXED the brake issues completely. You guys who have suggested to do the hydroboost swap are my heroes! This thing stops on a dime and gives back 9 cents change!
I need to do some longer test drives to confirm everything is functioning properly. I also would like to pull the MC off the hydroboost unit and do the clay test on the rod to ensure it's not like 2mm too long and causing brake drag. It could totally be my imagination but I thought I felt it dragging ever so slightly.
The pedal is a little slow to return to the up position, but from what I have read, this is typical of a newly installed system (or one that has sat for a few months) In my short drive, it did appear to get better.
I was able to put the complete system together for a little over $100. I got a used '95 Astro hydroboost unit for $55 (shipped) on Ebay. (Local yards had a few Astros but they were all robbed of their HB units). With some clever routing, I was able to use stock lines instead of spending $200+ on custom ones. Since I have the '98 Jeep grand Cherokee steering gear, the ports are metric so the threads were the same as the Astro's. I could only use the steering gear supply line from the Astro. The other line (from pump to HB unit) was from a 2002 Silverado HD. I also had to buy 8 feet of 3/8" transmission hose for the return lines, and a brass T fitting that was a few bucks.
Had to raise the HB unit up higher than the power booster was in order to line up with the upper hole in the brake pedal and not the lower. There were already 2 studs in that exact position, so I bolted it to them. The studs are a little short though, so I plan to knock them out and replace with bolts. Had to drill one hole in firewall, and one hole in the plate the HB unit is on. This is because on my particular car, one of the studs on the HB plate was going to end up in a place where I could not get a nut on it. You probably will not run into the same issue.
I have listed the parts and part numbers below, but be aware that if you have not upgraded your steering gear to a newer (metric) gear, then these lines will not work for you.
-- Hydroboost unit from '95 Astro ($55, used, ebay)
-- Pressure line from pump to HB unit - EDELMANN 92084 ($14.64, Rock Auto)
-- Pressure line from HB unit to steering gear - EDELMANN 80056 ($14.56, Rock Auto)
-- 8' 3/8" transmission cooler line for return lines ($28, parts store)
-- 3/8" brass T fitting ($3, Amazon)
Pardon the messy, dirty engine bay and the rusty master cylinder. I plan to get it all pretty again, I swear.
Last edited by superdave84; 09-15-2015 at 04:54 PM.
08-19-2015, 10:19 PM
