Manual brakes brake pad selection

[RmvBfrFlght]

I'm not sure how a low-drag caliper can be rebuilt as a non-low-drag caliper. The seal groove in the caliper body is machined differently between the two. Maybe by using a seal that fills in the bevel cut? Either way, need to disassemble the caliper to see which is which.

As for quick-takeup M/C's, they have one really bad flaw: they don't work in panic stops. Hit the brake pedal hard and fast and they don't build line pressure, braking is poor. If at all possible avoid that type of M/C. GM stopped using them after about 10 years of use.

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[RmvBfrFlght]

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".

The low-drag metric calipers have a 2.5" piston diameter where it counts, in the bore. The piston is stepped down to 2.375" where it contacts the pad backing plate.

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[87geeinn]

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.

You were right on those adapter fittings being hard to find! I think Classic Performance is the vendor that produces those specific sizes.

Okay, so I've placed my order for the 1978 Chevy Monza MC and rebuilt calipers. Taking a look at the link, it looks like Bendix may now be reproducing these MCs with the more conventional design and plastic reservoir. A thorough search of the web shows stock images of both the "new" design and the old cast iron version. I guess I'm rolling the dice on this one with Amazon but I don't really care which one I end up with. I'm not concerned with weight savings and I'm under the hood enough that I check all my fluids at least weekly.

FWIW, the Wagner MC101259 MC has a nice, large, level reservoir if one were so inclined to frankenstein a MC by using that reservoir and swapping it onto the other g-body 7/8" MCs that have the angled reservoir. Seems a bit of a waste of money to buy two MCs and the reservoir connections may not work. Hard to say without having them side by side to compare. Just a thought...

I already have the Russell steel braided flexible lines which I installed a few months ago. Once I finally get this all together, I should have a nice setup:

7/8" straight bore MC (coming soon)
new rebuilt non-low drag calipers (coming soon)
correct ratio manual pedal (coming soon)
Hawk 5.0 (FF rated) pads up front
AC Delco (FF rated) shoes out back
7/8" bore (S-10 manual brakes) wheel cylinders
Russell stainless braided flexible lines
new rotors and drums

 

[malibudave1978]

I'm not sure how a low-drag caliper can be rebuilt as a non-low-drag caliper. The seal groove in the caliper body is machined differently between the two. Maybe by using a seal that fills in the bevel cut? Either way, need to disassemble the caliper to see which is which.

As for quick-takeup M/C's, they have one really bad flaw: they don't work in panic stops. Hit the brake pedal hard and fast and they don't build line pressure, braking is poor. If at all possible avoid that type of M/C. GM stopped using them after about 10 years of use.

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Sorry, I read the below link incorrect long ago and had it in my head it was just the seal. Thanks for correcting me. That being said, I would only trust brand new, metric, D154 brake calipers.

See link below describing a low drag caliper.

http://www.remaninc.com/pdfs/lowdragcalipers.pdf

I think a step bore master cylinder is fine if the 100 lb residual valve is functioning correctly and it bled correctly with no air bubbles, but the secondary, 24mm bore is still too large, for manual brakes, with the 2.5" diameter single piston calipers. You will not get the clamping force needed to stop the car effectively.

In my opinion, the near optimal manual brake combination, IF using stock gbody parts, for a daily driver / drag car is:
* 7/8" strait bore master cylinder.
* NON low drag, stock size calipers.
* Using the upper hole in a vacuum boosted brake pedal for better leverage.
* Using a "cold bite" brake pads and shoes (Organics usually have the best cold bite).
* Replacing the rubber brake lines with new or aftermarket stainless steel flexible ones.

 

[87geeinn]

Update: Pulled the stock Powermaster pedal assembly and swapped in the vacuum pedal after fabbing up a new pivot pin. What I ended up doing was purchasing a large 1/2" grade 8 bolt which had a shouldered section equivalent to the existing pivot pin. I drilled a hole in the same spot as the other pivot pin and then cut of the threaded portion. I used my bench vise and a socket to press it into place. I then used my bench grinder to remove enough material off the head of the bolt so that there was no interference with the bracket. I reused the same pushrod that I was already using from the earlier manual conversion since it had the proper 1/2" eyelet and was the proper length. I put the pushrod between two new washers and used a new cotter pin. I can now brake boost it to about 3psi before it starts to bust loose. Also, I may have mentioned before that I drilled and tapped a hole between the cruise control and brake switches in order to screw in a M8 x 1.25 bolt which acts as a positive stop instead of relying on the switches as the back stop for the pedal travel.

I received the Bendix 11737 MC and it arrived as the cast iron unit. I will be installing it tomorrow along with the new calipers to complete the installation. The MC came with the rubber cup doohicky to aid in pushrod retention and the dimple in the MC bore is recessed approximately 3/10" (7.62mm) which should provide good retention for the pushrod. FYI, I hit the MC with a few coats of paint before the pics were taken.

Bob: Not sure if I will need to pull the pedal assembly again and fab up a return spring for the pedal. However, I did buy an assortment of Help! brand springs if I need to do this. Do you have any pics to show how you achieved this? I fiddled around with it a little bit but couldn't come up with a good solution as to how to attach a return spring.

 

[malibudave1978]

Austin,

You shouldn't need the return springs. You will find the fluid pressure in the system will return the brake pedal back to its UNpressed location.

Good work on the fabrication of the pin for the pushrod.

Look forward to seeing the final installation.

 

[RmvBfrFlght]

I needed to install return spring(s) as the M/C springs aren't strong enough to push the pedal back up against the switches. Can't be driving around with the brake lights on and the TCC unlocked.

I thought I had a picture but don't. To attach the springs to the pedal looped them over the vacuum pivot pin. Used a washer and cotter to keep them from sliding off. For the other end I think I drilled a hole in the pedal bracket assembly. This is the piece that the pedal mounts to and gets bolted to the under dash & firewall.

About the rubber boot and pushrod retention, GM used a metal cup for this. I wouldn't trust the rubber to not let go down the road. That rod falls out...

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[RmvBfrFlght]

OK, took some pictures, adding the return springs was a little more involved then I first thought. The rear spring anchor is in an under dash brace. Drilled and tapped a hole (1/4-20 most likely), inserted bolt and jam nut on the top.

The pedal attachment is the vacuum pivot, but I made an extension for it so that the springs cleared the pedal bracket. Here are two pictures that show it.

The plastic sleeve around the inner most spring keeps the coils from hanging up.

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[87geeinn]

Update: MC bench bled and installed, remanufactured calipers installed, and brakes bled.

The issue I have now is pedal travel and I suspect the reman calipers I purchased are low drag type. I made damn sure I had all of the air out of the system but the pedal still travels half way to the floor before I get any pressure. No bueno. I gambled on these and lost. Only reason I didn't go aftermarket in the first place was they were cheap and Amazon doesn't carry the Afco or Speedway non-low drag calipers. That said, I bit the bullet and spent $111 ($32 of which is shipping here to Hawaii) and ordered the Afco stock sized units from Summit, here and here. From all my reading, these are definitely non-low drag calipers. Oh well, at least they are a breeze to swap out.

To add extra insurance in regards to pushrod retention, I used a steel freeze plug to which I drilled and Dremeled a hole in the center. Also drilled and tapped three holes along the perimeter and installed three allen head set screws secured with red loctite. Also used an o-ring which adds another 2-3mm of distance from the piston to freeze plug hole. This ended up giving me a good 14mm or so of retention "room" and there is no way the pushrod can come out. See below for a pic of the allen key bolt that I installed between the two switches that acts like a positive stop for the pedal.

Bob, thanks for the pics of the return spring(s) and I see what you mean about the pedal not returning properly. I may need to do the same thing because as it stands now, the pedal kinda comes to a rest with about 1/4" preload still on the piston and doesn't fully depress the brake switches. For now, I adjusted the brake switch forward to keep the lights from staying on but I might just pull the pedal again to rig up something. I like the sleeve idea; makes it to where you can kind of go around corners with a spring a prevent binding. FWIW, pulling the pedal assembly is not as bad as some people make it out to be. The trick is having the right combination of long extensions and a swivel socket.

 

[malibudave1978]

"Necessity is the mother of invention". Nice work on your system. Make sure your rear brake shoes are adjusted out against the drums, this will also cause low pedal along with the low drag calipers.

Did you bench bleed the master cylinder off the car? If not done, this may cause air to stay in the master cylinder causing low pedal.

 

[87geeinn]

Brake shoes are adjusted properly and yes, I thoroughly bench bled the MC off the car.

Will update once the Afco calipers are on. Almost went with the Wilwood 2.5" calipers but couldn't justify spending $360+ on those.

 

[malibudave1978]

Brake shoes are adjusted properly and yes, I thoroughly bench bled the MC off the car.

Will update once the Afco calipers are on. Almost went with the Wilwood 2.5" calipers but couldn't justify spending $360+ on those.

IMO, the Wilwood calipers cost justification is mostly for weight savings. I thought about buying them myself, but I think the best alternative for the stock front brake system is stock sized, new, cast iron calipers. I think the AFCO calipers, that you linked to above, are the only ones that are suitable for manual brakes and stock brake system.

 

[87geeinn]

Fabricated a return spring which works great: Drilled and tapped a M8 x 1.25 hole below the vacuum brake pivot pin and used a locking nut to secure a stud which I drilled a small hole to loop the spring end through. I put a very small amount of preload on the spring before I bent the long wire around the stud and clipped off the excess. It does not contact the pedal bracket throughout its travel and has just the right amount of tension. The spring comes from an assortment pack, Dorman Help! part #29016.

 

[87geeinn]

Cancelled my order for the Afco calipers. According to the description, those calipers come with low drag seals and are basically remanufactured calipers. Not sure what route to take now. Might have to pony up for the Wilwood units--which claim to have square cut seals--unless I can find an alternative. Gonna call them up Monday and verify before I purchase.

 

[87geeinn]

Dropped the coin on the Wilwood units. The whole kit w/pads was only $30 more versus just buying the calipers only. Reused the Hawk pads since they are already bedded with the rotors. Good pedal feel and stopping power; feels like power assist brakes. However, I can still push the pedal to the floor if I stand on it hard enough and still can't hold more that 1psi boost at the line. I double checked the drum brakes and adjusted the shoes out just a tad more to take up what slack I could. Also noticed the rear master cylinder line was leaking. For some reason I had to reeeeally crank down on the nut to get it to stop leaking. Maybe some crud managed to get in there between the inverted flare on the steel line and brass sealing surface in the MC? Gonna re-bleed the brakes tomorrow just to make extra sure all the air out of the system. My guess right now is that the tiny 7/8" Chevy Monza MC just simply doesn't have the total volume to really push these brakes effectively. I mean, that MC is tiny.

Some notes on the Wilwood calipers: The thing that took the most time on this installation was figuring out the correct position in which to mount the flexible brake line. The Wilwood inlet ports are located on the back side and dead center of the caliper,unlike the stockers, which are located at the bottom. Also, with the stockers, the line can really only be bolted in one position due to the cast iron bosses; the Wilwood units are designed to be universal and you can bolt the banjo fitting in any 360* position you desire. I really wished I had a helper during this process since I had to get up and down probably 20 times to turn the wheels from lock to lock to check fitment, readjust, and repeat. What I found works best for the Wilwood units is to have the brake line positioned perpendicular with the 45* angled banjo fitting pointing down toward the caliper body and exiting toward the front of the car (see pic). This required me to essentially "flip" the hose around and necessitated loosening the fitting at where it attached to the hard line at the frame in order to prevent the line from kinking. All other positions either rubbed the frame or bent the line at an angle to extreme to seem safe. A braided stainless line that had a straight banjo fitting without the 45* angle would be ideal. I'm sure there are some out there; haven't looked. Also make sure you have some 10mm copper crush washers handy! The Wilwood kit does not come with any and I almost forgot to order some. A pack of ten can be had with Earl's #177101ERL.

Here's my next experiment: A master cylinder from a 1982-1986 Jeep CJ5/CJ7 with manual brakes is a bolt-on 15/16" straight bore MC. There are manual brake Jeep MC's that have a 1" bore but those all have different part numbers for each manufacturer (i.e., Bendix, Cardone, Wagner, etc) and correspond to different trim levels. It has the correct front and rear line fittings and the firewall bolt spacing is the same. What's cool about this MC is that it comes with a correct 1/2" hole size pushrod that is retained behind the snap ring in the bore by use of a small disc. I checked one of these out at O'Reilly earlier tonight and did all the measurements to make sure it'd fit. It also has a much larger reservoir on the disc brake side of things. O'Reilly only had the remanufactured version and it looked shady as hell. It had this rust/dust residue all up on the reservoir cap gasket and there appeared to be some down in the reservoirs near the small holes leading to the bore chamber. Ummm, no thanks.

If I had to do this all over again, I would just stay with the 1980's S-10 master cylinder and vacuum brake pedal with correct manual pivot pin installed. It's rather firm but it provides the necessary volume to stop the car in a panic...provided the rest of your brake system is in tip-top shape (i.e., braided lines, quality pads, correctly adjusted drum brakes, non-leaking cylinders). Also, I could hold about 2-3psi boost at the line. All said and done, I think this 15/16" bore MC will be the ticket. I know 1/16" doesn't seem like much but I think it will be a perfect fit with my current setup. Might also buy another set of brake shoes and do the two long shoe trick as suggested earlier.

 

[87geeinn]

Have more pics but the website is still having issues. Will post the rest of them when possible.

 

[626gn]

I really wished I had a helper during this process since I had to get up and down probably 20 times to turn the wheels from lock to lock to check fitment, readjust, and repeat.

Alls you had to do was pickup the phone bruh . Very informative post, BTW.

 

[87geeinn]

Alls you had to do was pickup the phone bruh . Very informative post, BTW.

I may enlist your services when the new master cylinder comes in. I'm out of IPAs!

 

[626gn]

I may enlist your services when the new master cylinder comes in. I'm out of IPAs!

LOL. Yup, just let me know.

 

[87geeinn]

Here's the 15/16" MC with integral pushrod. Note how the rod is retained behind the snap ring by the attached disc and washer. Only problem now is that the pushrod is too short. Will be cutting the rod, threading both ends, and using a coupling nut to lengthen it and make it adjustable. Also note the depression in the piston is well over 1" which would help in retention if other pushrods were used.