Disc vs. Drums, again.

[68 Suburban]

Ok here we go again. Since are "resident" board expert decided to bring this up "again" on my "for sale" post. I guess I will start a post here where it is more appropriate to discuss.

First of all, I NEVER have said drums are better than disc! I have said that drums can be made safe and perform as well as factory disc brakes.

I feel the drum vs. disc guys are just like Conservative Republicans and Liberal Deomocrats getting together..lol

I guess it is easiest to get my point across is to post my response to a fellow board member that PMed me:


My point was not that drums are better than disc, my point was that drums can be made to be very safe and operate great. I would never talk anyone out of puting disc on the front of their truck. But, randy makes claims like drums are unsafe period! Plus my gripe is, he does it on a thread where he has no business doing it.

The main problems with drum on our vehicles is that the technology
is 30 years old since the manufactures switched to disc. In the big rigs they still do use drum brakes. Why? Because you have a much bigger contact area with shoes than you do with disc pads. Now if you can update your brakes with todays technology, which you can, you are in business with your drum brakes.

All I can say is, with a $200 investment I have upgraded my drum system to operate as well as a disc system. I tow up and down mountains with out brake fade. I have great stopping power and I can lock up my drum brakes any time I need to.

Go to the following link if you want to find out what you can do with your drum brakes. By the way, I just did a 20,000 mile inspection on all my shoes and there is NO visible wear. Let me know what stock pads or shoes would look like after 20,000 miles on one of our trucks?

http://www.praisedynobrake.com/

Also, you might find the second paragraph of this article interesting what they say about brake drums.

http://www.praisedynobrake.com/Imag...Tech_Brakes.jpg

Let me know if you have any questions,
Christopher

I guess the ultimate setup would be a disc brake vehicle with the kevlar disc pads!

Also, are truck page made this guys site
http://www.praisedynobrake.com/testi...imonies.htm#rd

[68 Suburban]

Ok here is a picture of the Kevlar shoes on the front of my burb at about 16,000 miles. It is not a very clear picture, but you can see how much meat of the pad still is there How many with standard shoes or pads can show this much meat after that many miles

[68 Suburban]

I found this interesting. it was posted by Ben who is one of the experts on the following brake page. Obviously there are pros and cons to drum brakes, but they can be made to be very safe.

http://forums.vmag.com/suvsuburban02...ages/1382.html

Posted by Ben on February 25, 01 at 11:10:41:

In Reply to: Why Disc are better than Drum, IMHO...long posted by Ben on February 25, 01 at 10:56:25:

All things eqaul (dia, friction material, sized for load/application/etc) drums will out brake discs till the drums heat up and expand to the point that the PSI on the shoe/drum surface is lessened.

"Swept" area of drums is much larger than disc and it's *ALL* out there at the max dia, while disc has it distributed from max dia down to a much smaller dia (say about 50% of max dia).

The PSI between disc and shoe is actually opposite from what most think. Sure the disc piston dia is much larger than a shoe piston dia, *BUT* there is another component adding PSI to shoe brake application to the drum. The shoes are "levered" into the drum surface and the frictional forces actually add additional PSI pressing the shoes into the drum surface. This is also one of the old "bad" things about drums (they locked almost instantly and wouldn't disconnect, so you just skidded along watching objects come up and get hit by your vehicle). The spring technology has come a long way and shoes do retract better, but still not as well as disc pads (there is *NO* wedging effect).

Plus drum's have more thermal interia than disc's so until the drums heat up, they actually have more potential braking forces than a disc, which will walk right out of the temp range (why vented discs are now standard on most front disc's). Down side for this on drums is rotating mass is huge, but these are trucks, so not a big deal.

The two other things in the equation are friction material and tires. Cheap/poor tires will skid sooner and ABS will kick in sooner. Braking will appear not to be good even if you have the best friction material out there (Praise Dyno stuff). Vica Versa for cheap/poor friction material, you can have the best tires out there and it won't stop any better than the weakest link of this food chain.

[Southpa]

I was told by a friend yesterday that there is no more core rebuilding for brake shoes. Used to be when you are changing shoes you get a re-man set and bring in your old worn out shoes for a rebuild. Now you buy brand new shoes and toss out the old ones. Any reason behind this? are re-mans causing problems?
Before I swapped to front discs I used to go thru a set of shoes every year.

[68 Suburban]

Probably the cost of handling the cores was more than just making new ones.

[crews]

Just a side note to your reference on big trucks and the fact that most of them use drum brakes....while for the most part that is true, there is an important point to make concerning discs....When you buy a truck that is dedicated to haul fuel or other explosive liquid, you are required to purchase disc brakes on all axles.

I worked at a Kenworth dealership in the mid 80's and did pre-delivery inspections on them so I know that is how they were equipped...
I inquired as to the reasoning for NOT putting disc's on all big trucks and was told that it was a simple matter of cost effectiveness.

I know brake technology has evolved alot, but I would never trade my discs for drums...If you like 'em and they work for you, then that should be enough said.....

[Suicide-D]

we still require a core at O'reilly's on shoes. I am currently messing around with the 68 and am seriously considering keeping the drums up front after seeing the tech articles on the Praise Dyno brakes... not like this truck is going to haul a$$ with that 305v6 under the hood. $185 is still cheaper than me changing it over to disc and I have all the stuff I would need already from my parts truck.

[68 Suburban]

Dirt Dobber, it won't seem that expensive when you see how long they last. When I take that in to consideration, they are cheap. If you do order them, try asking John for a 10% board discount...lol Maybe it will work

[racedvl]

Raybestos quit the shoe core deal. They are all new now.

[Suicide-D]

Is what we carry at O'reilly's. I have no pedal pressure right now... I have manual brakes and I know I'm not getting fluid to the back. I'm replacing the master cylinder if I can find one this weekend. The stupid catalog supposedly only lists power brakes on that truck.... which I find hard to beleive. But then again.... I wasn't looking it up at the time...I was on the phone... I beleive it when I look it up...

[Bobs68LWB]

Dirt Dobber,

Before you replace the master cylinder check the rubber line that goes to the rear axle. As the lines get older the rubber will colapse internally. I changed all the rubber lines on my 68 and my brakes are awesome.



I have no pedal pressure right now... I have manual brakes and I know I'm not getting fluid to the back. I'm replacing the master cylinder if I can find one this weekend. The stupid catalog supposedly only lists power brakes on that truck.... which I find hard to beleive. But then again.... I wasn't looking it up at the time...I was on the phone... I beleive it when I look it up...

[68SWB4x4]

drums rule!

[Denny]

What is involved on improving the drum brakes? I have drum brakes on my 69 and they have been a real pain in the you know what. I would love to improve on them. Can you post any details on your brake system. thanks.

[68SWB4x4]

he got all his parts from www.praisedynobrake.com

[68 Suburban]

Denny, the praise kit comes with all the shoes and a heavy duty spring kit. Another thing you might want to try is get all the 30 year old brake fluid outo f your system. Praise now offers new wheel cylinders that are suppose to apply a lot better than stock. It will make your manual brake truck feel more like power brakes.

[Suicide-D]

I was wondering if they did that... and it does look kinda shotty....i will investigate it further... i'm getting anxious...I want to drive this truck...I havent driven it yet...shoot the tranny may not even work for all I know

[crazy longhorn]

I already have discs up front......would it be worth upgrading the shoes on the rear brakes?

[68 Suburban]

You can get Kevlar disc for the front and the Kevlar shoes for the back. You really would have some stopping power!

[crazy longhorn]

Its about time to go through the brakes, ill check out the link. thanks..........Al

[68SWB4x4]

whats the best way to get all the old fluid out?

[Denny]

Thanks for the info on the Praise brake system. I went to their site and they sound great. I have power brakes but I drive mostly highway and Missouri loves to put stop lights on highways with 60 mile and hour speed limits and fast changing lights. I have had some pretty scary stops on these highways LOL

[68 Suburban]

whats the best way to get all the old fluid out?

I just did it last weekend. I got an old big jar and a rubber hose that would fit over the bleeder screw and let each brake cylinder gravity bleed for a while. After there was enough fluid in the jar, I would pump the brakes 10 times. go and make sure the fluid was filled in the master, and pump it ten more times, etc.... I made sure the hose was under the fluid in the jar so no air would get it. After the fluid would start coming out clear, I knew it was time to move to the next wheel cylinder.

[71402BB]

Kale the way dad and I got the old fluid out was by just bleeding the brakes. I would pump up the brakes and hold them while dad would open the bleeder screw and let the fluid out. We did this to every wheel cyl at least 5 times! that way worked for us and we didn't have to drain the system of all the fluid! just keep an eye on the level of the fliud and keep adding as needed!

[68SWB4x4]

the thought of nice new clear fluid like 68 burb is talking about sounds nice though! plus the fact someone tried to put ATF in my master cylinder once (pleasent suprise when i poped the master cylinder cover the first time.....)....... i got it out though,,,,,,, sure theres still SOME in there though

[68 Suburban]

It s easy to do and is worth it. Just think of all the moisture that has gotten in that brake fluid in 30+ years.