Manual brakes brake pad selection

[87geeinn]

Modified the pushrod so that it's longer/adjustable. I would have liked to have gone with a a fine thread count in either standard or metric but I'm limited in my options here in Hawaii. Ended up having to pull the pedal and bracket out again because I couldn't slip the ring on the pivot pin due to it being be too long AND the pedal bracket was in the way. Ground the pivot pin down to be slightly shorter and removed a little bit of material from the bracket.

Not much of a difference from the 7/8" bore MC but it is a slight bit stiffer due to the 1/16" larger bore. Also of note,...due to the flange design of this MC, it will leave a small gap at the firewall adapter IF you have trimmed it wider already. Not really an issue IMO.

In any event, just showing yet another option that is doable for those interested.

 

[87geeinn]

Was reminded to update this thread about the Hawk 5.0 pads. Only downside is the Hawk pads do take a little heat to get working good. Until you make 4-5 decent stops, braking power feels significantly reduced. However, once they are brought up to temp, it's almost difficult to tell they are manual. Quite a significant change from cold to hot.

I still have the Wilwood pads that came with the calipers (stamped EBB...whatever that means?) and may try them some rainy day or when the Hawk pads wear down enough. According to Wilwood, these have a "peak friction rating" of .46 which would place them in the GG rating as far as DOT is concerned...if"peak friction rating" is the same thing as the friction coefficient. Either way, I am going to assume their rating is assuming the pads are fully up to temperature.

 

[RmvBfrFlght]

The Wilwood BP10 pad compound is an FF rating. The peak friction rating (Mu) isn't hit until a little over 700* F. It is a decent performance street pad. From the link scroll down a little for a graph of the friction versus temperature curve.

Interesting about the Hawks pads. And being where you are they don't start out all that cold. In cold weather, say 30's to low 40's the Stoptech pads do get a little better as they get some heat in them.

RemoveBeforeFlight

 

[Kellysgn]

In my opinion for the money spent, if using the stock brake system, going with a stock rebuilt caliper for a daily driver is the best bet for manual brakes. The 2.75" big bore Wilwoods I have are a very nice caliper, but it not worth the extra expense because I had to up size my master with it and I still have a 10.5" rotor with the same size brake pad. In hind sight, I would have kept the stock, NON low drag calipers (or bought rebuilt ones), a 7/8" or 21mm STRAIT bore master cylinder (if using rear drums), kept the stock size (0.75" for a daily driver) rear wheel cylinders, and went with an organic, semi metallic front pad and rear shoes. I still would still use flexible, stainless, steel brake lines instead of the rubber lines.

Usually the rebuilt caliper part numbers are the same from 1978 - 2004, so any year should be fine. The 1998 - 2004 S10s have 2.5"piston caliper versus earlier 2.38" piston calipers, but the part numbers are usually the same for earlier years. For the area that the piston contacts the pad, the size doesn't make a huge difference and you probably will not tell the difference between the 2.38" and 2.5".

For a daily driver/occasional drag car, I would not change much. If you can lock up your front tires, you have sufficient brakes. If you are trying to save as much weight as possible there are other options than stock brake systems. If you are road racing, there are other options other than the stock brake system.

Hey Guys , you seem to be knowlegeable on brakes , could I ask , our stock calipers are they 2.50" ? I ve seen the larger calipers 2.75" ? they are around 100 bucks , would that 2.75 caliper equal "more front brake " stopping power ? thank you

 

[malibudave1978]

Hey Guys , you seem to be knowlegeable on brakes , could I ask , our stock calipers are they 2.50" ? I ve seen the larger calipers 2.75" ? they are around 100 bucks , would that 2.75 caliper equal "more front brake " stopping power ? thank you

IF you could run a 7/8" bore master cylinder with the larger 2.75" brake caliper, it would equal "more front brake" stopping power, but a 7/8" bore master cylinder cannot supply the volume of fluid that the larger 2.75" brake caliper needs. I have tested it and, sorry to say, it does not work. You will need to increase the bore of the master cylinder to supply more fluid volume to fill the larger 2.75" brake caliper. Increasing the bore of the master cylinder reduces the fluid pressure which reduces braking performance even when switching to the larger 2.75" brake caliper.

Lets compare two brake calipers. A stock, single piston, "metric" Buick Grand National caliper and 2002 LS1 Camaro caliper.
1987 Buick Grand National caliper has a 2.5" single piston. The piston area is 4.91 square inches.
2002 Camaro caliper has 1.77" dual pistons. For two 1.77" pistons, the piston area is 4.92 square inches.

Both the above pistons deliver the same clamping force regardless of number of pistons. I am not saying that the Buick Grand National caliper is better or even equal to the Camaro caliper. I am saying that the clamping forces are the same.

From my experience, there is a sweet spot for manual brakes.

1. 7/8" bore master cylinder is the optimal bore if using a production type master cylinder for manual brakes.
2. Around 5.0 square inches of caliper piston area is optimal for manual brakes regardless of number of pistons.
3. 6 to 1 pedal ratio for manual brakes is optimal for manual brakes. Usually a 6 to 1 pedal ratio gives around a 1.0" piston travel in the master cylinder.

All bolt in dual piston calipers for the Buick Grand National have less piston area and therefore less clamping force.
All late model Corvette brake calipers (that I know about) have less piston area and therefore less clamping force.

What more can you do to optimize your stock brakes in a g-body when converting to manual brakes?

• 7/8" bore master cylinder
• 2.5" single piston stock caliper
• 6 to 1 pedal ratio
• 100% Organic brake pads in the front and 100% organic shoes in the rear. 100% organics have better friction properties when cold.
• Braided stainless steel flexible brake lines front and rear. Old rubber lines will wear out and balloon, reducing brake performance.

 

[Kellysgn]

IF you could run a 7/8" bore master cylinder with the larger 2.75" brake caliper, it would equal "more front brake" stopping power, but a 7/8" bore master cylinder cannot supply the volume of fluid that the larger 2.75" brake caliper needs. I have tested it and, sorry to say, it does not work. You will need to increase the bore of the master cylinder to supply more fluid volume to fill the larger 2.75" brake caliper. Increasing the bore of the master cylinder reduces the fluid pressure which reduces braking performance even when switching to the larger 2.75" brake caliper.

Lets compare two brake calipers. A stock, single piston, "metric" Buick Grand National caliper and 2002 LS1 Camaro caliper.
1987 Buick Grand National caliper has a 2.5" single piston. The piston area is 4.91 square inches.
2002 Camaro caliper has 1.77" dual pistons. For two 1.77" pistons, the piston area is 4.92 square inches.

Both the above pistons deliver the same clamping force regardless of number of pistons. I am not saying that the Buick Grand National caliper is better or even equal to the Camaro caliper. I am saying that the clamping forces are the same.

From my experience, there is a sweet spot for manual brakes.

1. 7/8" bore master cylinder is the optimal bore if using a production type master cylinder for manual brakes.
2. Around 5.0 square inches of caliper piston area is optimal for manual brakes regardless of number of pistons.
3. 6 to 1 pedal ratio for manual brakes is optimal for manual brakes. Usually a 6 to 1 pedal ratio gives around a 1.0" piston travel in the master cylinder.

All bolt in dual piston calipers for the Buick Grand National have less piston area and therefore less clamping force.
All late model Corvette brake calipers (that I know about) have less piston area and therefore less clamping force.

What more can you do to optimize your stock brakes in a g-body when converting to manual brakes?

• 7/8" bore master cylinder
• 2.5" single piston stock caliper
• 6 to 1 pedal ratio
• 100% Organic brake pads in the front and 100% organic shoes in the rear. 100% organics have better friction properties when cold.
• Braided stainless steel flexible brake lines front and rear. Old rubber lines will wear out and balloon, reducing brake performance.

Hi Dave , thank you for sharing , very hehelpful , I have to diguest some of it yet , now I bores of master cylinder , I don t have the plastic stock one I have hydroboost
Master Cylinder cardone 10-1984 trying to find exact specs . I am doing the S10 wheel cylinder experiment , to try to hold more boost , some guys have lock up issues , others have no problem and love em , so thats why I was inquiring , if I have a little loc up , would more front brake help correct , thank you for your time

 

[Kellysgn]

Hi Dave , thank you for sharing , very hehelpful , I have to diguest some of it yet , now I bores of master cylinder , I don t have the plastic stock one I have hydroboost
Master Cylinder cardone 10-1984 trying to find exact specs . I am doing the S10 wheel cylinder experiment , to try to hold more boost , some guys have lock up issues , others have no problem and love em , so thats why I was inquiring , if I have a little loc up , would more front brake help correct , thank you for your time

just found bore size 1.062 " on my master cylinder thanks again

 

[No disintegrations]

IF you could run a 7/8" bore master cylinder with the larger 2.75" brake caliper, it would equal "more front brake" stopping power, but a 7/8" bore master cylinder cannot supply the volume of fluid that the larger 2.75" brake caliper needs. I have tested it and, sorry to say, it does not work. You will need to increase the bore of the master cylinder to supply more fluid volume to fill the larger 2.75" brake caliper. Increasing the bore of the master cylinder reduces the fluid pressure which reduces braking performance even when switching to the larger 2.75" brake caliper.

Lets compare two brake calipers. A stock, single piston, "metric" Buick Grand National caliper and 2002 LS1 Camaro caliper.
1987 Buick Grand National caliper has a 2.5" single piston. The piston area is 4.91 square inches.
2002 Camaro caliper has 1.77" dual pistons. For two 1.77" pistons, the piston area is 4.92 square inches.

Both the above pistons deliver the same clamping force regardless of number of pistons. I am not saying that the Buick Grand National caliper is better or even equal to the Camaro caliper. I am saying that the clamping forces are the same.

From my experience, there is a sweet spot for manual brakes.

1. 7/8" bore master cylinder is the optimal bore if using a production type master cylinder for manual brakes.
2. Around 5.0 square inches of caliper piston area is optimal for manual brakes regardless of number of pistons.
3. 6 to 1 pedal ratio for manual brakes is optimal for manual brakes. Usually a 6 to 1 pedal ratio gives around a 1.0" piston travel in the master cylinder.

All bolt in dual piston calipers for the Buick Grand National have less piston area and therefore less clamping force.
All late model Corvette brake calipers (that I know about) have less piston area and therefore less clamping force.

What more can you do to optimize your stock brakes in a g-body when converting to manual brakes?

• 7/8" bore master cylinder
• 2.5" single piston stock caliper
• 6 to 1 pedal ratio
• 100% Organic brake pads in the front and 100% organic shoes in the rear. 100% organics have better friction properties when cold.
• Braided stainless steel flexible brake lines front and rear. Old rubber lines will wear out and balloon, reducing brake performance.

Capliper clamp load can be the same but a larger diameter rotor would make a ton of difference. The outer edge of swept area will do the majority of the work.

 

[malibudave1978]

Capliper clamp load can be the same but a larger diameter rotor would make a ton of difference. The outer edge of swept area will do the majority of the work.

Correct.

 

[Kellysgn]

Capliper clamp load can be the same but a larger diameter rotor would make a ton of difference. The outer edge of swept area will do the majority of the work.

thank you the wildwood 2.75 " is the way I ll go , thats for sharing knowledge

 

[Kellysgn]

Correct.

thank you

 

[malibudave]

Capliper clamp load can be the same but a larger diameter rotor would make a ton of difference. The outer edge of swept area will do the majority of the work.

Are you talking about a larger diameter piston or a large diameter brake rotor? If you are talking brake rotor, then correct. If you are talking caliper piston diameter, then incorrect.

thank you the wildwood 2.75 " is the way I ll go , thats for sharing knowledge

I have tried a 2.75" piston Wilwood caliper and a 7/8" bore master cylinder. The 7/8" bore master cylinder will not have the volume of fluid needed to fill the 2.75".
I have tried a 2.75" piston Wilwood caliper and a 24mm bore master cylinder. This works, but clamping force will be lower than a 2.5" piston caliper and a 7/8" bore master cylinder combination.

If you are keeping your stock brake setup, save your money and keep the stock size 2.5" NON low drag calipers and use a 7/8" bore master cylinder if you are going manual brakes. Put that money into stainless steel braided flexible brake lines front and rear and 100% organic pads

What more can you do to optimize your stock brakes in a g-body when converting to manual brakes?

• 7/8" bore master cylinder
• 2.5" single piston stock caliper
• 6 to 1 pedal ratio
• 100% Organic brake pads in the front and 100% organic shoes in the rear. 100% organics have better friction properties when cold.
• Braided stainless steel flexible brake lines front and rear. Old rubber lines will wear out and balloon, reducing brake performance.

 

[No disintegrations]

Are you talking about a larger diameter piston or a large diameter brake rotor? If you are talking brake rotor, then correct. If you are talking caliper piston diameter, then incorrect.
Brake rotor. Larger rotor has more leverage to work against the tire. Simple way but not cheap to make stronger brakes.


I have tried a 2.75" piston Wilwood caliper and a 7/8" bore master cylinder. The 7/8" bore master cylinder will not have the volume of fluid needed to fill the 2.75".
I have tried a 2.75" piston Wilwood caliper and a 24mm bore master cylinder. This works, but clamping force will be lower than a 2.5" piston caliper and a 7/8" bore master cylinder combination.

If you are keeping your stock brake setup, save your money and keep the stock size 2.5" NON low drag calipers and use a 7/8" bore master cylinder if you are going manual brakes. Put that money into stainless steel braided flexible brake lines front and rear and 100% organic pads

What more can you do to optimize your stock brakes in a g-body when converting to manual brakes?

• 7/8" bore master cylinder
• 2.5" single piston stock caliper
• 6 to 1 pedal ratio
• 100% Organic brake pads in the front and 100% organic shoes in the rear. 100% organics have better friction properties when cold.
• Braided stainless steel flexible brake lines front and rear. Old rubber lines will wear out and balloon, reducing brake performance.

Brake rotor. Larger rotor has more leverage to work against the tire. Simple way but not cheap to make stronger brakes.

 

[Kellysgn]

Brake rotor. Larger rotor has more leverage to work against the tire. Simple way but not cheap to make stronger brakes.

Hey Dave , I was thinking the 2.75 " caliper / piston because I have hydroboost and MC bore is 1.068"

 

[NY Twin Turbo]

thank you the wildwood 2.75 " is the way I ll go , thats for sharing knowledge

What 2.75 Wilwood caliper? On their website, I only see only 2.5. Part #140-12097. I don't see any 2.75 in a stock style replacement.

 

[Kellysgn]

What 2.75 Wilwood caliper? On their website, I only see only 2.5. Part #140-12097. I don't see any 2.75 in a stock style replacement.

this wilwood , the one in the center of the page http://www.wilwood.com/Search/PartNoSearch.aspx?q=gm metric caliper

 

[NY Twin Turbo]

this wilwood , the one in the center of the page http://www.wilwood.com/Search/PartNoSearch.aspx?q=gm metric caliper

Oh, I see. Sorry. Sometimes my eyes skip over the uglier parts even though they sometimes work better.

 

[Kellysgn]

Oh, I see. Sorry. Sometimes my eyes skip over the uglier parts even though they sometimes work better.

yeah , are you familar with these ? and hydtoboost ?

 

[NY Twin Turbo]

yeah , are you familar with these ? and hydtoboost ?

Nope. Just bought the 2.5 piston type. The last couple of days I've been asking for a whole bunch of brake info in 2 other forum threads. The 2.75 was never mentioned. Too late for me anyway. Today I might begin the work. Seems like it's going to be a nice day for mid-winter in NY.

 

[Kellysgn]

Nope. Just bought the 2.5 piston type. The last couple of days I've been asking for a whole bunch of brake info in 2 other forum threads. The 2.75 was never mentioned. Too late for me anyway. Today I might begin the work. Seems like it's going to be a nice day for mid-winter in NY.

what 2.5 did you buy