Brake thoughts and questions

[clean8485]

I read alot of posts and threads here about people who want to change and/or upgrade the braking systems on their G bodies.
I'll start out by saying that I've owned a number of these cars over the past 25 years or so, and I understand what people are talking about when they say that the original braking system on these cars can be kind of marginal at times, especially if you need to stop in a hurry.
Where I start to get curious is when people want to change the entire braking system to 4 wheel discs, or larger disc brake systems. I understand that larger brakes are more effective, and that disc brakes resist fading due to heat better than drum brakes, and that those people who use their cars for events like autocrossing, need good brakes.
I've read alot of posts and threads though, where people describe problems that arise when they do brake upgrades. Things like, "my 15" stock rims don't clear the new brakes", or "I've had to relocate my lower rear shock mount to provide clearance for the rear disc brake calipers", or "I had to go with an adjustable proportioning valve to get the correct brake bias from front to rear with my new brake setup", or "I can't get my 4 wheel disc brake setup to bleed properly", or other similiar concerns.
Has anyone ever done any kind of comparison test to try to determine exactly what upgrades yield the best improvements in braking performance, in terms of dollars spent versus overall improvement in braking performance?
I know that the 2wd Blazer front brake upgrade is the hot ticket for alot of people right now, and it offers the option of going to the larger Corvette style brakes later on, if desired, but what about rear brake upgrades? Alot of people want to remove the stock drum type rear brakes, and upgrade to discs, but is it really worth it, or are some people just going for the wow factor of seeing rear disc brakes on their car?. I know that the stock rear drum brakes are prone to a number of problems (they're kind of small for the size of the car, the backing plates ave a tendency to rot out, and the wheel cylinders are just held in with a clip, so they can twist and fail, etc.). If the stock type rear drum brakes are in good condition, and properly maintained, they will work well on a car that is just street driven, and even these stock rear brakes can be upgraded a bit (S10 rear wheel cylinders with larger bore pistons, and installing 4 secondary brake shoes). Has anyone ever tried to upgrade the rear drum brakes to a larger drum size? I know that some of the earlier mid 1970s GM A body cars were equipped with 11" X 2" rear brakes, and some of the GM wagons had even larger brakes. Does anyone know of anyone who has done this type of upgrade, as opposed to converting to rear disc brakes?
Sorry for the long-winded post, but after reading many threads about brake upgrades, I'm curious about how effective these upgrades are, and whether or not it was money well spent, and if there are other alternatives, that might yield the same results, with less headaches. Thanks for looking. 😀

 

[pontiacgp]

Drum brakes get a bad rap but tractor trailers still use them. If you keep the brakes in proper condition then they work as they were designed to work. If you want an easy upgrade use a premium brake pad up front,I use EBC pads and they work great. I do have the f body spindles but they only give me 1/2" more rotor than the G body. For the rear upgrade to the S 10 non power brake cylinder and install the bracket to secure the cylinder

 

[dlo253]

In for this discussion. Been browsing all of the brake upgrade threads lately.. Trying to get an overall game plan for my car.

 

[Brother Al]

Swapping drums probably isn't possible without swapping the entire assembly from the backing plate out... at that point disc conversions seem more appealing.. to me anyway. The drum would be larger but the stock backing plate won't allow the pads to extend out far enough to contact the larger drum... you might be able to cut and reweld things but that's probably not the best plan unless you removed the backing plate... because you'd cook the axle bearings and wheel cyls trying to weld if its attached... then you are back into the same deal vs swapping to discs again.

IMHO J41 aluminum drums, S10 7/8" wheel cyls, & that bracket are the best rear drum brake option because its all pretty straight forward and the alum drums are very much less prone to brake fade because they shed heat far better than cast iron.

 

[clean8485]

Brother Al, just to clarify, I am curious to know if anyone has tried to swap a COMPLETE larger rear drum brake setup onto a stock '78-'88 A/G body rear axle, including the backing plates and hardware, or if there is any hardware that is available to perform this type of conversion. I wasn't trying to suggest that anyone try to use an 11" rear brake drum on a 9 1/2" backing plate, or try cutting and welding on the rear axle while the outer seals and bearings are in place. It seems to me that a conversion like this would provide improved braking performance, by virtue of the fact that the 11" drums would provide a larger swept area, at least on the rear of the car, and wouldn't cause any interferance issues with the lower rear shock mounts.
I believe that there are aftermarket parts available, that will allow the installation of rear disc brakes on these cars, but I'm wondering if there are any parts available to allow the installation of larger rear drum brakes.
I think it would be interesting to test the braking capabilities of a '78-'88 A/G body car with the stock braking system (in good condition of course), then perform some of the more popular upgrades, and test the results with a view to looking at the improvement to the braking performance of the car, versus the cost of the upgrade, and whether or not any other changes are required in order to perform the upgrade (larger wheels to clear the brakes, relocating other parts, larger capacity master cylinders, different proportioning valves, hydroboost braking assist, etc.).
For me, part of the reason for starting this thread is to generate some conversation on this subject, and to try to get people to share some of their thoughts and experiences on this subject.

 

[GuysMonteSS]

While I cant comment on swapping bigger drums onto a stock rear assembly,I can comment on having bigger than stock rear drums.
When I bought my Ford 9 inch many years ago now,it came with full size LTD rear brake drums.Its been a while,but I did measure the difference at the time,and,IIRC,they were 1 1/2 inch bigger in diameter and the shoes were 1 inch wider than stock.Just putting this rearend in made quite a noticeable difference in stopping power.
Then,a few years ago,I upgraded the front brakes with a set of USBrake oversize metric calipers,(20 % bigger piston),slotted & cross drilled stock size rotors,Hawk HPS brake pads and Russell braided SS brake hoses.This made another substantial difference in stopping power.
This year I have another brake upgrade on my "To Do List".I will be putting on an electric hydroboost from ABS Power Brakes.
I'm hoping to see a dramatic difference in stopping power with this as compared to the stock booster.
Guy

 

[pontiacgp]

I noticed a difference in the rear brakes when I put the 8.2 in which has the bolt in cylinders. The drum and shoes are the same size as the G body brakes but the bolt in cylinder was unable to move so I think that was the reason for the better braking. I never knew about that clip I suggested to secure the floating wheel cylinder in my GP

 

[jociha]

NPD [National parts Depot] sells a 9.5" to 11" rear drum conversion kit originally used on the 1965 Chevelle big block. They say it is bolt on and go except the drum fins may rub on some 14" wheels. It says you will see a shorter stopping distance, [sounds correct] but you do not need to change your master cylinder, [ok] and you do not need to change your proportioning valve. In 65 there was no proportioning valve but this kit is being sold as an upgrade to all 10 and 12 bolt rears so my guess is it is bolt on for G bodys but I do not understand how it can not require an adjustment of the proportioning valve.

 

[clean8485]

First off, thanks to everyone for your comments and information. These are the kinds of things that I am hoping to bring out in this thread. I'm curious to find out more on this subject, and I hope it will help out others as well.
I've been a licensed mechanic in Ontario for many years. I spent 16 years as a GM dealer technician, and I worked there during the time of the recall over the backing plate/rear wheel cylinder problems with the A/G bodies, and the S10/S15 trucks. The design of the rear braking system on these vehicles (IMHO) didn't seem to be as well thought out as it should have been, especially in this part of north America, where winter, salt and corrosion are facts of life. I saw and repaired many of these vehicles, and was always surprised at how badly the rear brakes would rot out, and the carnage that the rust would cause. The repairs would usually extend far beyond replacement of just the backing plates and wheel cylinders. In most cases, I'd have to replace some of the brake lines, rear brake cables, brake shoes, hardware, axle seals (the rear axle shafts would have to be removed to install the 1 piece GM backing plates),etc. The results were always a major improvement in both safety (obviously), and braking performance. Currently, I'm working as a mechanic doing transit bus repair, so PontiacGP, I fully understand what you're saying about drum brakes still being an effective type of braking system.
Years ago, when I first started hearing and reading about rear (and front) disc brake upgrades, I wondered why nobody seemed to offer a larger rear drum brake upgrade. I understand about getting larger rear drum brakes as part of a rear axle swap, but it seemed to me that some kind of hardware kit that would allow larger rear drum brakes to be fitted to a stock A/G body rear axle would be a fairly simple, low cost alternative for these cars, that would provide a noticeable improvement in braking, for a fairly low investment. Jociha, I have heard about the larger rear drum brake upgrade for the older A body cars, but I don't think it would work for the '78-'88 A/G body cars, because of the style of mounting flange for the backing plates on the A/G body cars. If memory serves, the earlier A body cars have a 4 bolt backing plate mounting flange, while the A/G body cars have a kind of weird flange with 2 bolt holes below the axle tube, a large hole foraccessing the back of the wheel cylinder above the tube, and a fairly large hole above that for the anchor stud on the backing plate. I would think that in order to mount a larger backing plate, you'd need either a special conversion style backing plate that would bolt directly to the A/G body mounting flange, or you'd need to modify the A/G body mounting flange to allow a stock type backing plate to be installed. Either way, to me, it doesn't seem a whole lot more labour intensive than converting to rear disc brakes, when you take into account maintaining some kind of parking brake mechanism on the rear, fabricating/installing rear brake lines, and possibly updating the proportioning valve to something that would be compatible with rear disc brakes.
Like I said earlier, I'm trying to get some thoughts and comments from other people, and see if anyone else has ever considered anything like this.

 

[Clone TIE Pilot]

As for the rear brake cylinders, GM offered bolt on clamps to reinforce the retainer clips. Raybestos stills sells the reinforcing brackets, http://www.amazon.com/dp/B000C71FZU/?tag=gbody-20

Another upgrade are the brake boosters. GM was weird with them, installing single diaphragm boosters in 180 HP MCSSs while installing dual diaphragm boosters in base 110 HP V6 Regals.