Littlebeefy Posted March 30, 2022 Author Share Posted March 30, 2022 I was an automotive machinist for 30 years. Back in the 90's I discovered that the Dayton calipers used on the later 80's F250 and F350 would expand a measured .060 in. Causing a mushy pedal feel at times. Usually on the diesels with a vacuum pump that delivered a full 25 in. of vacuum giving the booster more power. We would sell the customer a 1 1/4 Dia. master cylinder from the Super Duty reducing the maximum pressure output. This solves nothing, but gives the customer a better pedal feel. The original Dayton calipers used in the 70`s did not do this they were much heavier built! I also resealed a lot of the Bendix hydroboost units, even the ones from GM diesel cars. They are good units and pretty trouble free. Resurrecting this thread. I had to pull the chunk on my 9 inch so I already have the drums off and could swap out wheel cylinders pretty easily. Should I put in the f350 wheel cylinders? Is my Wilwood 1.125 bore sufficient for the upgrade? Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 31, 2022 Share Posted March 31, 2022 Resurrecting this thread. I had to pull the chunk on my 9 inch so I already have the drums off and could swap out wheel cylinders pretty easily. Should I put in the f350 wheel cylinders? Is my Wilwood 1.125 bore sufficient for the upgrade? Chad - First, thanks again for the Bronco bucket seats. Just got home late last night and will be reporting on them soon. And, btw, I had a sticker for the forum laid out in the truck for you but forgot to give it to you. Will mail it to you soon. Second, brake mod issues are complicated, which is surely why you've not gotten a response. But let me try to find the spec's involved and let's see if we can find an answer. The standard brake wheel cylinder for your Bronco was 1" in diameter, and an '84 and later F350 SRW would have a 1" wheel cylinder. However, the MPC seems to say that they are different part numbers, although I can't really confirm that as I can't find the number for the Bronco, but the F350 is E2TZ 2261-B and E2TZ 2262-B. So, I'd go back with the appropriate cylinder for the Bronco. Link to comment Share on other sites More sharing options...
Littlebeefy Posted March 31, 2022 Author Share Posted March 31, 2022 Chad - First, thanks again for the Bronco bucket seats. Just got home late last night and will be reporting on them soon. And, btw, I had a sticker for the forum laid out in the truck for you but forgot to give it to you. Will mail it to you soon. Second, brake mod issues are complicated, which is surely why you've not gotten a response. But let me try to find the spec's involved and let's see if we can find an answer. The standard brake wheel cylinder for your Bronco was 1" in diameter, and an '84 and later F350 SRW would have a 1" wheel cylinder. However, the MPC seems to say that they are different part numbers, although I can't really confirm that as I can't find the number for the Bronco, but the F350 is E2TZ 2261-B and E2TZ 2262-B. So, I'd go back with the appropriate cylinder for the Bronco. Gary - you are welcome. I'm glad they found a home where they will get another life. Use them in good health. As for the brakes, I did some research Rock Auto style. OEM 84 Bronco MC bore: 1" Wheel Cylinder bore: .93" OEM 84 F350 (diesel, non-dually) MC bore: 1.125" Wheel Cylinder bore: 1" Napkin style calculations on W = F x d would indicate that I am still maintaining relative force between MC and slave. Plus, if I am using a Wilwood 1.125 bore, I would think I'm close to stock F350 on the MC (admittedly no idea on stroke). Anyone see any flaws in my numbers or logic here? Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 31, 2022 Share Posted March 31, 2022 Gary - you are welcome. I'm glad they found a home where they will get another life. Use them in good health. As for the brakes, I did some research Rock Auto style. OEM 84 Bronco MC bore: 1" Wheel Cylinder bore: .93" OEM 84 F350 (diesel, non-dually) MC bore: 1.125" Wheel Cylinder bore: 1" Napkin style calculations on W = F x d would indicate that I am still maintaining relative force between MC and slave. Plus, if I am using a Wilwood 1.125 bore, I would think I'm close to stock F350 on the MC (admittedly no idea on stroke). Anyone see any flaws in my numbers or logic here? Chad - I agree with your calc's, but I'm not sure you have the right data. In fact, I'm not sure what the right data is! In the screen grab below, which is from a portion of the MPC that is on our page at Documentation/Driveline/Brakes and is for your Bronco, I've highlighted things that confuse me. But first, a word about nomenclature. When the MPC says "80/" it means from 1980 through the end of the coverage of the catalog, which was 1989. But "84" means for that single year. In the listing at the top for Cylinder Repair Kit it seems to say that a 15/16" wheel cylinder was used from 1980 through 1989, but in 1984 only there were 1" wheel cylinders used on vehicles built prior to 10/83. In the listing for the Piston it seems to say that there was a 15/16" piston used from 1980 through 1989, and a 1" piston used from 1984 through 1989. In the listing for the Shoe & Lining kit it seems to say the 15/16" piston was used for 1980 through 83, and a 1" piston was used for 1984 & 85, but there is no mention of 1986 and later. So, were I you, I'd measure my wheel cylinders. But my guess is that the 15/16" piston was used from 1980 - 10/83 and the 1" piston used from that point on. Also, did you use the hydroboost brake pedal in your conversion? It has a different "throw" than the stock pedal. Link to comment Share on other sites More sharing options...
Littlebeefy Posted March 31, 2022 Author Share Posted March 31, 2022 Chad - I agree with your calc's, but I'm not sure you have the right data. In fact, I'm not sure what the right data is! In the screen grab below, which is from a portion of the MPC that is on our page at Documentation/Driveline/Brakes and is for your Bronco, I've highlighted things that confuse me. But first, a word about nomenclature. When the MPC says "80/" it means from 1980 through the end of the coverage of the catalog, which was 1989. But "84" means for that single year. In the listing at the top for Cylinder Repair Kit it seems to say that a 15/16" wheel cylinder was used from 1980 through 1989, but in 1984 only there were 1" wheel cylinders used on vehicles built prior to 10/83. In the listing for the Piston it seems to say that there was a 15/16" piston used from 1980 through 1989, and a 1" piston used from 1984 through 1989. In the listing for the Shoe & Lining kit it seems to say the 15/16" piston was used for 1980 through 83, and a 1" piston was used for 1984 & 85, but there is no mention of 1986 and later. So, were I you, I'd measure my wheel cylinders. But my guess is that the 15/16" piston was used from 1980 - 10/83 and the 1" piston used from that point on. Also, did you use the hydroboost brake pedal in your conversion? It has a different "throw" than the stock pedal. In my case I am certain of what wheel cylinder is in there because I put them in myself last year. They are definitely the .93" bore. I may have originally had a 1" in there, but I definitely don't now. But seeing as a 1" bore wheel cylinder was in there at some point with only a 1" bore MC (according to the MPC), I don't think I have any concern about popping in 1" slaves Luckily because of your forum I knew how important that brake pedal was and I did get it. Quick lesson to all: I went to the yard to pull the hydroboost and other parts from a single F450. I was about to leave with all of the parts, but I went ahead and measured the rod distance just to double-check. Lo and behold, someone had already swapped the pedal assembly out with a vacuum style and I was about to leave with the wrong one! The moral of the story is, always double-check your measurements and part numbers because parts trucks don't come straight from the factory. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 31, 2022 Share Posted March 31, 2022 In my case I am certain of what wheel cylinder is in there because I put them in myself last year. They are definitely the .93" bore. I may have originally had a 1" in there, but I definitely don't now. But seeing as a 1" bore wheel cylinder was in there at some point with only a 1" bore MC (according to the MPC), I don't think I have any concern about popping in 1" slaves Luckily because of your forum I knew how important that brake pedal was and I did get it. Quick lesson to all: I went to the yard to pull the hydroboost and other parts from a single F450. I was about to leave with all of the parts, but I went ahead and measured the rod distance just to double-check. Lo and behold, someone had already swapped the pedal assembly out with a vacuum style and I was about to leave with the wrong one! The moral of the story is, always double-check your measurements and part numbers because parts trucks don't come straight from the factory. Yep, I think you’ll be fine then with the 1” slaves. And glad you got the right pedal. I suspect that it makes a huge difference in the “feel” of the brakes. Link to comment Share on other sites More sharing options...
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