Brakes: 60 Champ brake conversion issue

[Kdancy]

A couple of years ago I installed a Turner front disc brake kit with dual MC in a 60 Champ PU. Since then brakes have never been good, really kind of scary and I am trying to find out why.
Maybe some one here that has done the same conversion has some insight? (I've e-mailed and left Jim phone message - haven't heard back from him)

We have and are still having a soft pedal over all and the fluid seems to be bleeding back into the MC as we have to double pump on the first braking action when going down the road. We do seem to have good brakes but soft pedal and double pump. I have ordered new in line residual valves and will install them but right now we have taken the original ones made by wilwood out of the system to see if we could tell any difference but have noticed none. We have bled the system after each change was made and then some more. No air coming out, just fluid. Using Dot 4 brake fluid.
We put new shoes, brake pads, flex lines and replaced the original MC in the kit with a new one,Raybestos MC36237-74 (One application that this mc fits -AMC Ambassador power front disc/rear drum) and took out the valves, checked the residual in line valves-10lb rear and 2lb front. I pulled the cab brace off by drilling the spot welds on the cab portion out so we could better judge the action of the pedal and rod assembly into the MC. I wound up building a different connection pin out from the pedal assembly to give the "into" mc rod a much better angle to go into the MC. All that checks out now. I checked the rod distance into the mc piston and that seems ok - makes contact with the piston inside dished area. There seems to be a very small distance for adjusting, a smidge too much and the front disc's lock up, a smidge the other way and very little pedal- to the floor.
At this point I am wondering if the dual chamber mc in the kit is properly sized for the PU brake system and if that is the root of the problem?
??

[StudeRich]

'60 Truck Disc Brake Conversion

This is pretty confusing. You say you replaced the M/C in Jim's Kit with a "New" one? In that case I don't think he could help you. Was something wrong with it?

Then you say: "fits -AMC Ambassador power front disc/rear drum) and took out the valves, checked the residual in line valves-10lb rear and 2lb front." How could you check them if you REMOVED them?

It seems to me since that M/C was for a front Disc. Rear Drum, it should have been fine as is.

However, with the '60 Truck Type non-self energizing Rear Brakes like Avanti I don't think I would use a Proportioning Valve, did he recommend or include one?

Are you using a Hydrovac or other Brake Booster? I see you do have a "Power" Brake Master.

[Warren Webb]

Is your Champ a 1/2 ton or 3/4 ton? That makes a difference in the bore of the master cylinder. Do you have it plumbed correctly? The port nearest the mounting bracket (which normally would be against the firewall/cowl)should go to the front brakes. If not then the front brakes are getting less pressure than expected & the rear brakes, more. Did you replace the 3 brake flex lines? If not, I would strongly suggest you do. If they are the originals then they have well outlived their expected service & could be a cause of loss of braking action.


I did the change on my 3/4 ton Champ that took a 1&1/8" bore master cylinder. All questions I had Jim kindly answered when I called. I also put on his brake lines & opted for the stainless steel braided lines. I always called around 7 pm or so, his time zone.

[Kdancy]

This is pretty confusing. You say you replaced the M/C in Jim's Kit with a "New" one? In that case I don't think he could help you. Was something wrong with it?

Then you say: "fits -AMC Ambassador power front disc/rear drum) and took out the valves, checked the residual in line valves-10lb rear and 2lb front." How could you check them if you REMOVED them?

It seems to me since that M/C was for a front Disc. Rear Drum, it should have been fine as is.

However, with the '60 Truck Type non-self energizing Rear Brakes like Avanti I don't think I would use a Proportioning Valve, did he recommend or include one?

Are you using a Hydrovac or other Brake Booster? I see you do have a "Power" Brake Master.

Well, lets see if I can clear up the confusion-
After spending days trying to get the original parts that came in the kit to work (calipers, mc bracket and mc, flex hoses and 10lb residual valve and 2lb residual valve and a manually adjusted rear brake valve that you plumb in-lin) and continuing to not see one single improvement,
I focused on the MC. I used the number off the one in the kit that I had installed on the PU and crossed it with the Raybestos MC36237-74, then purchased a new one. When you put that part number in an MC search, it is listed as fitting a number of vehicles with the AMC Ambassador being just one. The new MC looks and fits exactly like the one I took off. Jims instructions are to remove the valves in the MC and use the external 10lb to rear and 2 lb to front disc in line residual valves. This I did.
A Proportioning vavle is not used.
No pb booster is used.
Is the water even muddier now?

[Kdancy]

Is your Champ a 1/2 ton or 3/4 ton? That makes a difference in the bore of the master cylinder. Do you have it plumbed correctly? The port nearest the mounting bracket (which normally would be against the firewall/cowl)should go to the front brakes. If not then the front brakes are getting less pressure than expected & the rear brakes, more. Did you replace the 3 brake flex lines? If not, I would strongly suggest you do. If they are the originals then they have well outlived their expected service & could be a cause of loss of braking action.


I did the change on my 3/4 ton Champ that took a 1&1/8" bore master cylinder. All questions I had Jim kindly answered when I called. I also put on his brake lines & opted for the stainless steel braided lines. I always called around 7 pm or so, his time zone.

Warren-
This is a 60 Champ 5E7 1/2 ton.
Yes, the port nearest the mounting bracket or front one is plumped to the front brakes. The MC bore is 1". The one I used to replace the first one is exactly like the first one as far as I can tell.
Yes, all three flex hoses have been changed. The front ones were changed again this week.

[StudeRich]

Thanks that is a lot clearer now, maybe that will lead to someone coming up with a brainstorm idea!
I am all out of ideas, sorry.

I would rather not say what I really think about under the floor Dual Master Cylinders.
Maybe; "if it's not broke don't fix it" will have to suffice.

[Studebakercenteroforegon]

Thanks that is a lot clearer now, maybe that will lead to someone coming up with a brainstorm idea!
I am all out of ideas, sorry.

I would rather not say what I really think about under the floor Dual Master Cylinders.
Maybe; "if it's not broke don't fix it" will have to suffice.

I think what you really wanted to say was "If it's not broke, fix it until it is."

[RadioRoy]

I think what you really wanted to say was "If it's not broke, fix it until it is."

I think a lot of folks do it this way.

A friend of mine used to say "we'll either fix it, or fix it so that no one else can fix it."

[Ron Dame]

I had a similar problem on my 8E, though it is a suspended pedal. I started with a 1" MC that I had on the truck ( Drum/drum Nova) which Jim thought would be fine, but I had a soft, way to low pedal despite pedal-bleeding, vacuum bleeding, and gravity bleeding. I could not find a pressure bleeder except for modern MCs with the plastic reservoirs and screw on cap. Jim offered many suggestions, but nothing worked. BTW I was using DOT4, but if you are using DOT 5, I understand it can get air bubbles that are a bear to ever clear.

Seeing how Turner has mid 70's big GM brakes, I found a Cadillac 1 1/8" cylinder, figuring the extra fluid moved by the larger piston was needed for the big bores in the calipers. It still was no good, despite multiple bench bleeds and bleeds of the system.

I contacted a hot rod brake manufacturer, and they insisted that I needed a proportioning valve, though many Turner installations have done well without one. I thought WTH, got it, installed it, and I had usable brakes. Firm pedal, still a bit low despite adjusting the push rod and rear brakes, but still plenty usable. Did the proportioning valve fix it, or did I finally get a problematic air bubble out of the system? I don't know.

OTOH, on Saturday, I really got to see how good the brakes are: I was on my way to Spencer to play with the trains (shameless plug, www.fireup611.org), and just outside of Statesville I saw a big buck cross the road about 1/4 mile ahead. I kept my eye on the big guy, and sure enough, he hit a fence on the other side, panicked, and shot back into the lane just about where I was! Sure, the original 8E drums could have stopped me, but discs are so much easier to modulate so I could avoid a full lock-up. Everyone, including the truck and buck were fine, though my shorts were a bit worse for the wear.

Good luck on getting this sorted, maybe bleed and bleed and bleed, or find a pressure bleeder that you can fit. worse case, try a proportioning valve.

[Kdancy]

I had a similar problem on my 8E, though it is a suspended pedal. I started with a 1" MC that I had on the truck ( Drum/drum Nova) which Jim thought would be fine, but I had a soft, way to low pedal despite pedal-bleeding, vacuum bleeding, and gravity bleeding. I could not find a pressure bleeder except for modern MCs with the plastic reservoirs and screw on cap. Jim offered many suggestions, but nothing worked. BTW I was using DOT4, but if you are using DOT 5, I understand it can get air bubbles that are a bear to ever clear.

Seeing how Turner has mid 70's big GM brakes, I found a Cadillac 1 1/8" cylinder, figuring the extra fluid moved by the larger piston was needed for the big bores in the calipers. It still was no good, despite multiple bench bleeds and bleeds of the system.

I contacted a hot rod brake manufacturer, and they insisted that I needed a proportioning valve, though many Turner installations have done well without one. I thought WTH, got it, installed it, and I had usable brakes. Firm pedal, still a bit low despite adjusting the push rod and rear brakes, but still plenty usable. Did the proportioning valve fix it, or did I finally get a problematic air bubble out of the system? I don't know.

OTOH, on Saturday, I really got to see how good the brakes are: I was on my way to Spencer to play with the trains (shameless plug, www.fireup611.org), and just outside of Statesville I saw a big buck cross the road about 1/4 mile ahead. I kept my eye on the big guy, and sure enough, he hit a fence on the other side, panicked, and shot back into the lane just about where I was! Sure, the original 8E drums could have stopped me, but discs are so much easier to modulate so I could avoid a full lock-up. Everyone, including the truck and buck were fine, though my shorts were a bit worse for the wear.

Good luck on getting this sorted, maybe bleed and bleed and bleed, or find a pressure bleeder that you can fit. worse case, try a proportioning valve.

I have both soft pedal and after it sets -no pedal until I pump it then it brings the pedal up and I have good brakes, still don't like pedal feel. No air in system. Ive double checked to make sure the cap is vented.
Well, I'm at wits end and was just about to get a 1 1/16" bore disc/drum manual brake mc to replace the 1" bore one that is on there now.
I'll pick up a proportioning valve and install it first.

[Kdancy]

A couple of years ago I installed a Turner front disc brake kit with dual MC in a 60 Champ PU. Since then brakes have never been good, really kind of scary and I am trying to find out why.
Maybe some one here that has done the same conversion has some insight? (I've e-mailed and left Jim phone message - haven't heard back from him)

We have and are still having a soft pedal over all and the fluid seems to be bleeding back into the MC as we have to double pump on the first braking action when going down the road. We do seem to have good brakes but soft pedal and double pump. I have ordered new in line residual valves and will install them but right now we have taken the original ones made by wilwood out of the system to see if we could tell any difference but have noticed none. We have bled the system after each change was made and then some more. No air coming out, just fluid. Using Dot 4 brake fluid.
We put new shoes, brake pads, flex lines and replaced the original MC in the kit with a new one,Raybestos MC36237-74 (One application that this mc fits -AMC Ambassador power front disc/rear drum) and took out the valves, checked the residual in line valves-10lb rear and 2lb front. I pulled the cab brace off by drilling the spot welds on the cab portion out so we could better judge the action of the pedal and rod assembly into the MC. I wound up building a different connection pin out from the pedal assembly to give the "into" mc rod a much better angle to go into the MC. All that checks out now. I checked the rod distance into the mc piston and that seems ok - makes contact with the piston inside dished area. There seems to be a very small distance for adjusting, a smidge too much and the front disc's lock up, a smidge the other way and very little pedal- to the floor.
At this point I am wondering if the dual chamber mc in the kit is properly sized for the PU brake system and if that is the root of the problem?
??

Looks like I finally got the brakes taken care of. Decent pedal and good stopping power.
After all of the above, I changed out the residual valves, no difference. Talked to George Klutkowski in Tallahassee Fl and he suggested I put a 1/4 spacer in the deep MC piston. I made one up and that did bring the peddle
up off the floor. I'm still not thrilled with the pedal but it is serviceable and safe.
If I had to do another one, besides re-engineering the linkage geometry, I think I would change out the MC to a Raybestos 36456, this has a 1 1/16 bore and is a dedicated front disc manual brake application.
Thanks to all!!

[Mike Van Veghten]

One question -
Where did you mount the residual valves ? They should be as close to the master cylinder ports as possible.

Bore sizes do NOT have to do with car/truck weight or size. Master cylinder bore decision has to do with the wheel cylinder bore, square inches...all four added together.

Small master cylinder bore equals less volume and higher system pressure.
Large master cylinder bore equals more volume and less system pressure.

With the proper lever arm (pedal length vs. M.C. pivot length), and master cylinder bore diameter, you don't need a power booster and should have a very positive brake pedal feel.

Mike

[Kdancy]

One question -
Where did you mount the residual valves ? They should be as close to the master cylinder ports as possible.

Bore sizes do NOT have to do with car/truck weight or size. Master cylinder bore decision has to do with the wheel cylinder bore, square inches...all four added together.

Small master cylinder bore equals less volume and higher system pressure.
Large master cylinder bore equals more volume and less system pressure.

With the proper lever arm (pedal length vs. M.C. pivot length), and master cylinder bore diameter, you don't need a power booster and should have a very positive brake pedal feel.

Mike

Mike, both valves are within 6" of the MC.
You don't have as much to play with for arm length on the early champ PU without major modding. Stude used the same arm for both power and non-power brakes, unlike the Hawks where two different
arms were used. The turner kit is supposed to be a turn key kit.
I understand how the bore sizes work as I did a lot of reading on that during this exercise. The GM calpers have large single piston bores and the champ rear brake cylinders are 7/8" bores.
I am close at this point and feel a 1 1/16 mc bore would give me the best feel. If I build another, I'll go that route.

[JoeHall]

If your 60 Champ has an under floor MC, then I have the same setup as yours, on two different Hawks. Have also successfully installed the same setup on two other Hawks. They have late 1970s FoMoCo, 12" rotors and the huge, early GM calipers, with the 1", under floor MC, converted to the AMC type, dual reservoir, 1".

They are a bear to get right, but once done, are superior to anything else I have experienced. The pedal is a little soft, exactly the same as a Volvo 124 with PB, I had not long ago. The do not need pumping however, and will lock the wheels up easily and predictably when needed.

Replacing the rubber front brake lines with stainless helps to raise and firm-up the pedal substantially. Probably could do the same with Jim's latest, super high pressure rated lines, custom made to order.

Also, not sure the pads you are using, but I run pads by a company named "Hawk", in their SRC ("street & race compound") series if memory serves. Those pads are popular with the Corvette guys, and if you ever try a set you'll see why; great initial grab, and no fade.

[Kdancy]

If your 60 Champ has an under floor MC, then I have the same setup as yours, on two different Hawks. Have also successfully installed the same setup on two other Hawks. They have late 1970s FoMoCo, 12" rotors and the huge, early GM calipers, with the 1", under floor MC, converted to the AMC type, dual reservoir, 1".

They are a bear to get right, but once done, are superior to anything else I have experienced. The pedal is a little soft, exactly the same as a Volvo 124 with PB, I had not long ago. The do not need pumping however, and will lock the wheels up easily and predictably when needed.

Replacing the rubber front brake lines with stainless helps to raise and firm-up the pedal substantially. Probably could do the same with Jim's latest, super high pressure rated lines, custom made to order.

Also, not sure the pads you are using, but I run pads by a company named "Hawk", in their SRC ("street & race compound") series if memory serves. Those pads are popular with the Corvette guys, and if you ever try a set you'll see why; great initial grab, and no fade.

Joe,
The Hawk pads are the ones I just put on.
I'll keep the rest of the info in mind!
Thanks