Kelsey Hayes Brake Bias Adjuster
#1
Drifting
Thread Starter
Kelsey Hayes Brake Bias Adjuster
From my 69 race car we just removed this Kelsey Hayes brake bias adjuster from the rear line just out of the master cylinder. I believe this was listed in the Chevy racing parts catalog in the day but neither me nor my mechanic can figure why it was ever needed on a Corvette with the rear calipers already downsized? I am assuming this was installed in the 70's on the car?
I am not getting enough rear brake now so if taking this out creates a problem I will put a more modern one in.
This is the forum to learn more on this item so inquiring minds want to know.
Thanks
Steve
I am not getting enough rear brake now so if taking this out creates a problem I will put a more modern one in.
This is the forum to learn more on this item so inquiring minds want to know.
Thanks
Steve
#2
Melting Slicks
I believe that is a Proportioning Valve for an early J-56 brake system that came out on the C-2 corvette. My 66 has that option. Not sure if 1965 had it but I believe that they changed to a different system in 1967 so it is only made for 1 or 2 model years.
I think some other manufacturers used it also but I don't remember which ones they were.
I think some other manufacturers used it also but I don't remember which ones they were.
Last edited by 66BlkBB; 09-17-2016 at 05:50 PM.
#3
Team Owner
I have a number of those!
One of the old Chevrolet Power Books, maybe a couple of them have a graph and chart for adjustment! I can go dig those up! Everyone's car weights can be different, also for weight shift on your chosen setup based on many factors like fuel level, ride height etc. True you can race the car all day without one, but things like this just help to dial it in for when you want your car at its best!
I think White Post was last supporting rebuilds, but not sure now!
A modern one just has a nice **** style for adjustability, so you aren't getting out the tools! That would be best put inside the cockpit! I have two of those out in the garage as maybe future replacements!
Your car handles very nice! I didn't watch it to see what if any ills you have, but you mention above not enough rear? If you aren't sure as to where you are, it could be lessening the pressure to the rear too much! The unit is technically not designed to give more pressure, but less from 100% is the most basic explanation!
Have you scaled the four corners of your car? How are you sprung? Soft or heavy and also front to back?
One of the old Chevrolet Power Books, maybe a couple of them have a graph and chart for adjustment! I can go dig those up! Everyone's car weights can be different, also for weight shift on your chosen setup based on many factors like fuel level, ride height etc. True you can race the car all day without one, but things like this just help to dial it in for when you want your car at its best!
I think White Post was last supporting rebuilds, but not sure now!
A modern one just has a nice **** style for adjustability, so you aren't getting out the tools! That would be best put inside the cockpit! I have two of those out in the garage as maybe future replacements!
Your car handles very nice! I didn't watch it to see what if any ills you have, but you mention above not enough rear? If you aren't sure as to where you are, it could be lessening the pressure to the rear too much! The unit is technically not designed to give more pressure, but less from 100% is the most basic explanation!
Have you scaled the four corners of your car? How are you sprung? Soft or heavy and also front to back?
Last edited by TCracingCA; 09-19-2016 at 12:43 AM.
#4
Safety Car
Having a front brake bias is the safe way. The last thing you want is to have the rears lock up before the fronts.
That means you need to be very careful as you add rear brake to your car. You might want to begin using different pads on the front and rear. Talk to your brake pad company about this.
Richard Newton
Tech Ideas and Thoughts
That means you need to be very careful as you add rear brake to your car. You might want to begin using different pads on the front and rear. Talk to your brake pad company about this.
Richard Newton
Tech Ideas and Thoughts
#5
Drifting
Thread Starter
Thanks guys. Yes the 69 handles very well but the brake set up when I got the car was evil! Had a power booster which I took out after the first test session and braided stainless rubber lines from the master cylinder to hard line T up front and this thing toward the back. So it all had to go. Don't know how to race a car with power brakes
Steve
Steve
#6
Race Director
Hi Steve, that appears to be a Corvette J-56 proportioning valve, though early Mustangs used the same, or a very similar valve. 66-67 Corvettes with J-56, came with that valve, and maybe 68's, but 69 J-56 cars did not use it.
I'd guess it was added by a previous racer who wanted more adjustability to the braking system. We ran adjustable proportioning valves in both the BP Solo Corvette and GT-1 Corvette, we raced in the late 70's and early 80's. It allowed us to dial in more or less rear brakes, depending on the track. Both of those cars used the stock Corvette calipers.
As far as how it works or what to do with it, you should call Ken at Lonestar Caliper, there in Texas. Ken rebuilds them, and if you don't want it or need it, he'll buy it, as he's always looking for Corvette brake and steering cores, including the J-56 proportioning valves.
Below is a picture of the installation of a J-56 proportioning valve in a 67 Corvette.
I'd guess it was added by a previous racer who wanted more adjustability to the braking system. We ran adjustable proportioning valves in both the BP Solo Corvette and GT-1 Corvette, we raced in the late 70's and early 80's. It allowed us to dial in more or less rear brakes, depending on the track. Both of those cars used the stock Corvette calipers.
As far as how it works or what to do with it, you should call Ken at Lonestar Caliper, there in Texas. Ken rebuilds them, and if you don't want it or need it, he'll buy it, as he's always looking for Corvette brake and steering cores, including the J-56 proportioning valves.
Below is a picture of the installation of a J-56 proportioning valve in a 67 Corvette.
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C2Racer (09-19-2016)
#7
Burning Brakes
I have a number of those!
One of the old Chevrolet Power Books, maybe a couple of them have a graph and chart for adjustment! I can go dig those up! Everyone's car weights can be different, also for weight shift on your chosen setup based on many factors like fuel level, ride height etc. True you can race the car all day without one, but things like this just help to dial it in for when you want your car at its best!
I think White Post was last supporting rebuilds, but not sure now!
A modern one just has a nice **** style for adjustability, so you aren't getting out the tools! That would be best put inside the cockpit! I have two of those out in the garage as maybe future replacements!
Your car handles very nice! I didn't watch it to see what if any ills you have, but you mention above not enough rear? If you aren't sure as to where you are, it could be lessening the pressure to the rear too much! The unit is technically not designed to give more pressure, but less from 100% is the most basic explanation!
Have you scaled the four corners of your car? How are you sprung? Soft or heavy and also front to back?
One of the old Chevrolet Power Books, maybe a couple of them have a graph and chart for adjustment! I can go dig those up! Everyone's car weights can be different, also for weight shift on your chosen setup based on many factors like fuel level, ride height etc. True you can race the car all day without one, but things like this just help to dial it in for when you want your car at its best!
I think White Post was last supporting rebuilds, but not sure now!
A modern one just has a nice **** style for adjustability, so you aren't getting out the tools! That would be best put inside the cockpit! I have two of those out in the garage as maybe future replacements!
Your car handles very nice! I didn't watch it to see what if any ills you have, but you mention above not enough rear? If you aren't sure as to where you are, it could be lessening the pressure to the rear too much! The unit is technically not designed to give more pressure, but less from 100% is the most basic explanation!
Have you scaled the four corners of your car? How are you sprung? Soft or heavy and also front to back?
#8
Drifting
The rear calipers are sized for highway tires. With a sticky racing tire, you will get more weight transfer from rear to front and the rears will tend to lock. Fix: reduce pressure to rear calipers
#9
Team Owner
Especially at speeds of over 150 mph!
Last edited by TCracingCA; 09-19-2016 at 07:15 PM.
#10
Drifting
Thread Starter
#11
Team Owner
how much dive on the front with that big block? How much front spring do you have? If you dialed all of the pressure reduction out or removed that valve are you feeling a lighter rear end under heavy brake or your not feeling adequate stopping from the back!
I at one time had rubber lines and I think they were getting older, because when I put on the rear stainless steel braided ones, seemed to correct a problem that I wasn't realizing! The rubber I think was expanding and not holding shape! The reaction in correlation just seemed to feel so much better after I changed those! When I say not realizing, I just kept thinking air in the system was a possible problem and I needed to do something better to bleed them!
Last edited by TCracingCA; 09-20-2016 at 07:51 AM.
#13
Team Owner
i need everything I have for my cars! Nothing for sale! These are always available on EBay in various conditions and prices!
I have one car that was bought new with the set-up (our Dana Chevrolet car), and my good race car had a setup on it! Then I have just enough stuff to equip one more car and have some spares!
I I was going to pull the chart for these this weekend! Had to clear memory in my camera!
I have one car that was bought new with the set-up (our Dana Chevrolet car), and my good race car had a setup on it! Then I have just enough stuff to equip one more car and have some spares!
I I was going to pull the chart for these this weekend! Had to clear memory in my camera!
#14
Race Director
I believe the Ford/Mustang valves accepted 3/16 brake lines and the Corvette took a larger 1/4 brake line, they are asking a lot of money for them on Ebay but I wonder how many actually sell, I have the lever type on my racer (below) probably from Wilwood, one click to the rear and I have never adjusted it again.
#15
Le Mans Master
i need everything I have for my cars! Nothing for sale! These are always available on EBay in various conditions and prices!
I have one car that was bought new with the set-up (our Dana Chevrolet car), and my good race car had a setup on it! Then I have just enough stuff to equip one more car and have some spares!
I I was going to pull the chart for these this weekend! Had to clear memory in my camera!
I have one car that was bought new with the set-up (our Dana Chevrolet car), and my good race car had a setup on it! Then I have just enough stuff to equip one more car and have some spares!
I I was going to pull the chart for these this weekend! Had to clear memory in my camera!
I just wanted to ask some questions, but no need now.
#16
Le Mans Master
From my 69 race car we just removed this Kelsey Hayes brake bias adjuster from the rear line just out of the master cylinder. I believe this was listed in the Chevy racing parts catalog in the day but neither me nor my mechanic can figure why it was ever needed on a Corvette with the rear calipers already downsized? I am assuming this was installed in the 70's on the car?
I am not getting enough rear brake now so if taking this out creates a problem I will put a more modern one in.
This is the forum to learn more on this item so inquiring minds want to know.
Thanks
Steve
I am not getting enough rear brake now so if taking this out creates a problem I will put a more modern one in.
This is the forum to learn more on this item so inquiring minds want to know.
Thanks
Steve
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C2Racer (09-27-2016)
#17
Team Owner
9 of 10 PMs or emails I was getting were wanting to buy my stuff or wanting me to drop everything I am doing to research stuff for people! So just thought I would shut that down just in case!
On other possible topics related to these valves! I tried to load that adjustment chart up thru tiny pics but had loading difficulties and made three attempts and stopped trying!but will get it up one of these days!
The posts above covers most everything there is to know about these!
I have 3 or 4 of these valves, maybe a fifth, would have to go to the Garage and count! One of mine is a Shelby unit! It came on my 1964 Race car, and I assume someone when they put J-56 discs on the car front and rear twin pin that due to the smaller 3/16 line to the back on the early previous drum brake csrs, they put the Shelby unit in! I thought the thing wasn't doing much for me, so when I replaced lines with stainless, I changed the front to rear to the larger diameter and put an adapter in from 3/16 to 1/4! The adjustment still didn't get me much, so I pulled the unit out and took it apart to find it badly pitted and leaking internally! I didn't have another one back then in the 80s so I stuck it back in adjusted to max wide open and it was just there mounted and connected in for show! Then I eventually found a replacement and put it in, but just left it set to max mostly after some raceway testing and adjustment! My car was pretty balanced and heavy sprung! Weight transfer was nominal and I usually ran at 1/2 tank of gas and I wasn't old and getting fat back then to throw off the corner balances!
My Fathers new 1st Owner 1968 (Riverside Gold) Dealer Painted and tricked out car) had j-56 on it new from Dana Chevrolet (not an L88 car)! The pictures of it selling on Ebay calling it an L88 are not our doing! Some Russian website was the first to photograph his car and listed it as an L88!! The car does have quite a number of Mysteries! It has a strange GM cam that has specs from both the 30/30 and the 140! Heck maybe it is J-56 car #81!!!!! the valve has been off of the car for years because of an in cockpit **** unit from Guldstrand was installed (plumbed in)!
then i I was going to put the system on either our third (1963 C2) or our fourth car (another 68 C3)!
Then over 30 plus years, I have bought spares when I come across them! Especially the pads!
I will try this week to put that chart up, on my good work computer!
Last edited by TCracingCA; 09-26-2016 at 02:30 PM.
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63Corvette (09-26-2016)
#18
Le Mans Master
I think the real need for it was in a more or less stock configuration like the '60s Production rules were. These cars came with same size tires front and rear where most race cars used a much larger rear slick that gripped as much as the smaller fronts did even under heavy braking. I was running on the front 23.5 X 10.5 - 16 and 25.0 X 13.0 - 16 with 27 X 14 - 16 on rear. Taller and wider made it harder for the rears to lock compared to the front, even with weight transfer under braking. Plus tire technology from 1965 compared to even 1975 was a huge leap.
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C2Racer (09-27-2016)
#19
Team Owner
Never have I had so much trouble loading a picture!
But I would bet people first are adjusting these things in the wrong direction (counter clockwise decrease and clockwise more rear braking!
The internal piston (sprung plunger) is very similar to some shock absorber valving with the holed disc fixed basically, moved by the adjustment!
Another factor is that people might or might not be running the Heavy Duty Master Cylinder!
i was running pretty square on 10 inch tires all the way around! My springs heavy, etc. So my car brakes pretty good with the inherent difference of larger pistons vice smaller in the back! I could modulate the pedal pretty good! My Father's car, on the autocross tracks we weren't wanting the extra large rears biting as quickly, so we biased heavier or standard pressure in the front!
i find the opposite of you guys saying larger tires weren't as prone to lock up or grab! We are small blocks, so I wonder if the big blocks are causing the rears to get unweighted on dive, or weight shift?
But I would bet people first are adjusting these things in the wrong direction (counter clockwise decrease and clockwise more rear braking!
The internal piston (sprung plunger) is very similar to some shock absorber valving with the holed disc fixed basically, moved by the adjustment!
Another factor is that people might or might not be running the Heavy Duty Master Cylinder!
i was running pretty square on 10 inch tires all the way around! My springs heavy, etc. So my car brakes pretty good with the inherent difference of larger pistons vice smaller in the back! I could modulate the pedal pretty good! My Father's car, on the autocross tracks we weren't wanting the extra large rears biting as quickly, so we biased heavier or standard pressure in the front!
i find the opposite of you guys saying larger tires weren't as prone to lock up or grab! We are small blocks, so I wonder if the big blocks are causing the rears to get unweighted on dive, or weight shift?
Last edited by TCracingCA; 09-27-2016 at 12:23 PM.
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C2Racer (09-27-2016),
jerry gollnick (09-27-2016)
#20
Drifting
Thread Starter
Thanks everyone! Garrett, it may be a good thing you're not racing at COTA as that will be the first time out with the new set up
Steve
Steve