14 bolt disc brakes

tbshakie · 06-26-2015, 08:59 PM

I know going from drum to discs on a trail truck is easy on a 14 bolt, but that's not my question:

I bought a 1999 K2500 Suburban to haul the family and toys around, super nice shape. Brake pedal was kind of mushy, so I figured the rear drums may not be adjusted correctly. I put new caliper and pads on the front because the insides were wearing a lot faster than the others on 1 side (caliper wouldn't go all the way out 4 the new pads.....so new calipers). Rear shoes looked good, original drums. The right rear arm that keeps the adjuster from backing off was bent up. So I took it off and bent it back. Rock Auto had a close out on a set for drums for $25 a piece, so I bought them. Drivers rear went on perfectly, passenger rear was a *****. where the shoes meet at the top, one side kept flipping up. you push it down and the other side flips up. Long story short.......I finally got the drum on. Adjusted everything till you hear a little drag then backed off slightly. Pedal feels much better.

Went on a couple hour trip a few days later with the family. Fill up gas when I found a cheap station. 8 mpg. Something is wrong. Get on the highway. Drums are not balanced. ****. Drive farther..............big vibration. Pull over thinking I have a flat tire on the side of the highway. All 4 tires have air. No idea. Get back on the highway and get off at the next exit. It starts to rain. Pull off in a hotel parking lot and do a walk around again. Lug nuts are all tight. Then I hear something sizzle. The rim on the right rear tire is hot. I then splash water on the right rear brake drum. Steam.

I then drive 3 miles down the road to a hardware store and buy a set a screw drivers to back off the shoes. Adjuster wont budge. In the process of laying under the truck in the rain I burn my shoulder on the exhaust. Shirt was wet, so its a steam burn!

I take the wheel and drum off and remove the adjuster completely. With transmission in neutral, I still hear something dragging inside, so I take everything off and put the drum back on. Bolt tire back on and go. Brakes feel just like they did before. Truck has more power. 14 mpg.

At this point I am ready to send this thing down the road. Wife and kids want to keep it. Besides the balance issue, I don't think I have a drum issue. Something is screwed up with the right rear brakes. Truck of this year are notorious for chewing through front brakes and hardly using rears.

My options are to send the thing to a local mechanic to figure out what's wrong with the rear or to put on disc brakes. ABS is currently unhooked, but I want to fix that (clean the front sensors). In a hydro boost application with ABS, where is the check valve? Is it in he master cylinder or the ABS control module box? I don't want the rear brakes dragging and I don't want to bypass the ABS either. I would install an adjustable proportion valve. I have done a net search and found nothing on the check valve. I want to do it right, or not at all.

tbshakie · 06-27-2015, 12:35 PM

I bought new pins and bushings for the front with the new pads. lubed them up with never seize. On one of the old calipers, the piston would not open up all the way (i.e. caliper with new pads would not go on the rotor). So I was forced to buy a new caliper (I replaced both instead of just 1).

I am talking about the 10 lb residual valve. its not a big deal leaving it in on a trail truck, but I don't want the brakes dragging on a street vehicle. if its in the ABS unit, i'll get the drums fixed.

I wouldn't install a 2500HD set-up. I would install the ORD brackets with Eldorado calipers. I have the 3/4 ton rotors sitting on a GM dana 60 front than I never ended up using.

I never thought about a bent backing plate.........

humpy · 06-28-2015, 10:26 AM

I don't think A 1999 is an aam I didn't think those came till late 2000??? If it's the older body style it should be 10.5"... Either way going from drums to eldorado caliper or even look into ruff stuff brackets and use 3/4 ton chev calipers I think would be an upgrade... Your gonna get 10 different people to answer and 17 different opinions.., try to find someone that has done the swap and will let you drive it so you can get your own info..

tbshakie · 06-28-2015, 11:02 PM

I don't know when AAM took over. Its the old body style truck. rear axle looks the same as in my 1993 3500 except for some extra ribbing on top of the axle.

blazerbrad · 07-02-2015, 09:59 AM

AAM and the GM Corporate Axle Division are basically the same thing as GM just spun it off as a separate company. Most differences between a newer "AAM" axle and older "Corporate" axle have more to do with normal product revisions versus being a different company.

Just like mentioned below the AAM 10.5" rear axle in my 2500HD is the same basic axle as the mid-80's era 14FF in my K5 with the exception of extra ribbing on the diff case and the factory disc brakes.

Speaking of the Eldorado calipers that have a parking brake, I have no personal experience with them but they don't have a very good reputation on the internet in regards to the parking brake working well (everything on the internet is true.....right?). However I don't know if it's more of a matter of improper setup or just how they function by design. Seems like all the factory stuff now uses the "drum in hat" style which has the completely separate mini drum brake for the parking brake.

tbshakie · 07-02-2015, 10:30 AM

I have the Eldorado calibers on the 14 bolt on my green jeep. parking brake does not work very well, but I think it is more of an adjustment issue.

I found a diagram of the Kelsey-Hayes ABS box. it appears the residual valve is internal. not 100% sure, but it does not look to be removable

06-26-2015, 08:59 PM	#1
tbshakie Join Date: Apr 2012 Location: Circleville Ohio Posts: 61	14 bolt disc brakes I know going from drum to discs on a trail truck is easy on a 14 bolt, but that's not my question: I bought a 1999 K2500 Suburban to haul the family and toys around, super nice shape. Brake pedal was kind of mushy, so I figured the rear drums may not be adjusted correctly. I put new caliper and pads on the front because the insides were wearing a lot faster than the others on 1 side (caliper wouldn't go all the way out 4 the new pads.....so new calipers). Rear shoes looked good, original drums. The right rear arm that keeps the adjuster from backing off was bent up. So I took it off and bent it back. Rock Auto had a close out on a set for drums for $25 a piece, so I bought them. Drivers rear went on perfectly, passenger rear was a ***. where the shoes meet at the top, one side kept flipping up. you push it down and the other side flips up. Long story short.......I finally got the drum on. Adjusted everything till you hear a little drag then backed off slightly. Pedal feels much better. Went on a couple hour trip a few days later with the family. Fill up gas when I found a cheap station. 8 mpg. Something is wrong. Get on the highway. Drums are not balanced. **. Drive farther..............big vibration. Pull over thinking I have a flat tire on the side of the highway. All 4 tires have air. No idea. Get back on the highway and get off at the next exit. It starts to rain. Pull off in a hotel parking lot and do a walk around again. Lug nuts are all tight. Then I hear something sizzle. The rim on the right rear tire is hot. I then splash water on the right rear brake drum. Steam. I then drive 3 miles down the road to a hardware store and buy a set a screw drivers to back off the shoes. Adjuster wont budge. In the process of laying under the truck in the rain I burn my shoulder on the exhaust. Shirt was wet, so its a steam burn! I take the wheel and drum off and remove the adjuster completely. With transmission in neutral, I still hear something dragging inside, so I take everything off and put the drum back on. Bolt tire back on and go. Brakes feel just like they did before. Truck has more power. 14 mpg. At this point I am ready to send this thing down the road. Wife and kids want to keep it. Besides the balance issue, I don't think I have a drum issue. Something is screwed up with the right rear brakes. Truck of this year are notorious for chewing through front brakes and hardly using rears. My options are to send the thing to a local mechanic to figure out what's wrong with the rear or to put on disc brakes. ABS is currently unhooked, but I want to fix that (clean the front sensors). In a hydro boost application with ABS, where is the check valve? Is it in he master cylinder or the ABS control module box? I don't want the rear brakes dragging and I don't want to bypass the ABS either. I would install an adjustable proportion valve. I have done a net search and found nothing on the check valve. I want to do it right, or not at all. __________________ 1976 CJ 5 1984 CJ 7 1993 K3500 GMC 6.5 TD

06-27-2015, 12:35 PM	#2
tbshakie Join Date: Apr 2012 Location: Circleville Ohio Posts: 61	I bought new pins and bushings for the front with the new pads. lubed them up with never seize. On one of the old calipers, the piston would not open up all the way (i.e. caliper with new pads would not go on the rotor). So I was forced to buy a new caliper (I replaced both instead of just 1). I am talking about the 10 lb residual valve. its not a big deal leaving it in on a trail truck, but I don't want the brakes dragging on a street vehicle. if its in the ABS unit, i'll get the drums fixed. I wouldn't install a 2500HD set-up. I would install the ORD brackets with Eldorado calipers. I have the 3/4 ton rotors sitting on a GM dana 60 front than I never ended up using. I never thought about a bent backing plate......... __________________ 1976 CJ 5 1984 CJ 7 1993 K3500 GMC 6.5 TD Last edited by tbshakie; 06-27-2015 at 03:31 PM.

06-28-2015, 10:26 AM	#3
humpy Join Date: Sep 2008 Posts: 573	I don't think A 1999 is an aam I didn't think those came till late 2000??? If it's the older body style it should be 10.5"... Either way going from drums to eldorado caliper or even look into ruff stuff brackets and use 3/4 ton chev calipers I think would be an upgrade... Your gonna get 10 different people to answer and 17 different opinions.., try to find someone that has done the swap and will let you drive it so you can get your own info.. __________________ S10 with a few air shocks..

06-28-2015, 11:02 PM	#4
tbshakie Join Date: Apr 2012 Location: Circleville Ohio Posts: 61	I don't know when AAM took over. Its the old body style truck. rear axle looks the same as in my 1993 3500 except for some extra ribbing on top of the axle. __________________ 1976 CJ 5 1984 CJ 7 1993 K3500 GMC 6.5 TD

07-02-2015, 10:30 AM	#6
tbshakie Join Date: Apr 2012 Location: Circleville Ohio Posts: 61	I have the Eldorado calibers on the 14 bolt on my green jeep. parking brake does not work very well, but I think it is more of an adjustment issue. I found a diagram of the Kelsey-Hayes ABS box. it appears the residual valve is internal. not 100% sure, but it does not look to be removable __________________ 1976 CJ 5 1984 CJ 7 1993 K3500 GMC 6.5 TD

07-02-2015, 09:59 AM	#5
blazerbrad - CORE Member - Join Date: Feb 2007 Posts: 831 Images: 6	AAM and the GM Corporate Axle Division are basically the same thing as GM just spun it off as a separate company. Most differences between a newer "AAM" axle and older "Corporate" axle have more to do with normal product revisions versus being a different company. Just like mentioned below the AAM 10.5" rear axle in my 2500HD is the same basic axle as the mid-80's era 14FF in my K5 with the exception of extra ribbing on the diff case and the factory disc brakes. Speaking of the Eldorado calipers that have a parking brake, I have no personal experience with them but they don't have a very good reputation on the internet in regards to the parking brake working well (everything on the internet is true.....right?). However I don't know if it's more of a matter of improper setup or just how they function by design. Seems like all the factory stuff now uses the "drum in hat" style which has the completely separate mini drum brake for the parking brake.