14 bolt conversion to disc questions/options
 

Not sure if this is the best place, but I am looking for info on disc brake conversion on a GM 14 bolt, 8 lug, semi float rear end. I just can’t seem to get the drum brakes right, so I’m thinking of a conversion.

Can I buy just the bracket for the calipers and rotor, or do I need to buy a kit?

Are there any other options for a parking brake? All the kits want to add $200 for the parking brake calipers. Are there parking brake calipers from other cars that would work?

When’d did the rear ends (3/4 ton) start getting disc brakes? 1999?

Any help would be greatly appreciated. I’m sure there must be somebody out there that has done this.

Re: 14 bolt conversion to disc questions/options
 

ruffstuff probably has just the brackets.

Re: 14 bolt conversion to disc questions/options
 

the vans got a disc semi-float 14 bolt in 03.

Re: 14 bolt conversion to disc questions/options
 

Here is my opinion….

Since you have a semi float and since you want a working ebrake. I would swap in an full float factory disc axle from a newer gen truck.

Personally it all comes down to cost. I think the ebrake calipers are junk. They were junk back when cadi used em on the eldo. I ran them on my conversion at first but now have a deive line ebrake and am running regular calipers.

Coat me
Ruff stuff brackets
Rotors
Calipers
New lines
Brake pads
Drive line ebrake kit from TSM

A newer axle from a 2500 or 3500 would have cost me
Perches and shock mounts from ruff stuff
Axle from bone yard or CL
Ebrake cable mods?

Re: 14 bolt conversion to disc questions/options
 

What is a driveline brake? Do they have kits available?

This one from Lugnutz is $379 without the ebrake calipers.
https://lugnut4x4.com/product/14-bolt-semi-float/

What is so bad about the ebrake calipers? Is the regular braking affected, or just the parking feature?

Re: 14 bolt conversion to disc questions/options
 

I believe 1977-1987 Chevy K20 front calipers, pads and rotors will work on the rear of the 14 bolt rear ends.
And the 76 Cadillac Eldorado.

Can anyone confirm?

Re: 14 bolt conversion to disc questions/options
 

Thats what i used on my 14 bolt FF. I know i used eldo calipers not positive they were 76 model year.

Is your project 4x4 or 2wd?

A drive line brake puts a disc or drum brake on your output yoke. When you set it it will keep your drive shaft from turning. Common on med duty trucks.

I used a driveline brake on the back of my NP205 transfercase.

High-angle drive line makes them too.

https://www.tsmmfg.net/np205-transfe...ing-brake.html


Really it all boils down to what you use your truck for. For me i offroad alot and wanted to ditch the heave 13.5 drums that would get mud packed. I also wanted to be rid of ebrake cables that caused me problems. If i could of used a lever lock or line lock as an e brake i would of gone that way. But for inspection i needed a mechanical e brake.

If i was towing i would of kept the 13.5 drum brakes.

With the eldo calipers i could not get a good adjustment for the caliper and park brake. I got tired of messing with them and sold them. With the regular front sibgle piston calipers and a few other mods i got a great pedal.

I also installed:
1978 c3 corvette master cylinder ( equal fluid capacity. More fluid moves with calipers then cyl)
Disc/disc proportioning valve. ( a must in my mind altho many don’t)

I was having problems with rear brakes locking up and the proportiobibg valve fixed that.

This swap has been done a zillion times on the FF. People have different takes on it. Keep in mind what components your changibg and how the system was designed to work.. i highway drive my truck on 39 inch tires and was glad i took the time to go through the system when a tour bus cut me off..

Re: 14 bolt conversion to disc questions/options
 

And the 1500HD's got the SF 14 in 2000. Most yards sell these complete for less than the cost of a kit, then Rockauto for all the wear items.

Re: 14 bolt conversion to disc questions/options
 

The GMT800 2500HD had 14bolt AAM full floating axle with rear disc brakes. They have full two shoe drum parking brake inside the disc brake hat.
The semi floating 9.5" 14bolts are lighter duty all the way around. They have the same ring shoe parking brake friction liner as my 2009 Impala.
I believe The AAM 10.5" rear disc setup was installed from 2003-06 but it might've been a few years earlier.

Re: 14 bolt conversion to disc questions/options
 

I spoke with Ron at Ruffstuff, he said they have a weld on bracket that I can use for the semi float. I can order the entire kit with the weld brackets, calipers, rotor, hardware, etc. $364 + tax and shipping. The bracket alone is $53.95.

I thought I could maybe procure all the other parts, however, in the end, I’ll probably spend that much or more getting all the parts.

He also confirmed the parts for the K20 and 76 Eldo.

Re: 14 bolt conversion to disc questions/options
 

I chose to use a 02 silverado 2500hd rear in my crewcab, so I had a good ebrake. works great, and other than moving perches was a drop-in. It takes the same gears as any FF 14bolt.
I don't understand swapping on a old rear anymore when you can pick these rearends up for less than the swap parts usually. but everyone does it their own way.
I have the old bracket setup on my offroad truck, but I don't have the ebrake functional on it.

Re: 14 bolt conversion to disc questions/options
 

I’m still considering swapping in another rear end, just wish I could find one that has gears taller than 4:10. Seems like all the 3/4 ton rear ends are geared low.
And, my truck is a 63, so some of the newer ones might be too wide.

Re: 14 bolt conversion to disc questions/options
 

there was some adapters to put the newer disc/ebrake setup on the older axles, but they were not cheap, around $200 just for the brackets. haven't seen any lately, don't know if they still make them.

Re: 14 bolt conversion to disc questions/options
 

The 14bff is one of the easiest axles to regear. The pinion preload can be preset before installation, and the carrier does not require shims.

Re: 14 bolt conversion to disc questions/options
 

I had my local cnc machine shop Build a set of backing plate mounts to run the 01+ disk setup on my ‘89 V30 14 bolt. They were rough cut on a water jet out of 1/2” plate then finished on the CNC. They are pure beef and set me back about $250. I already had the 01+ axle to rob brake parts from. It may have been easier to re perch the 01+ axle but I didn’t want to go that route as I have a matched set D60/14 bolt from the same square body 1 ton that I’m building for my 72 K20. The old style hubs that capture the drum behind the hub have to be machined slightly to center the rotor on the hub as well.

I’ve been peeking in on this thread a bit but wasn’t really sure my setup would help much with the semi floating axle.

Re: 14 bolt conversion to disc questions/options
 

The more I think about it, the more apparent it becomes that I will be better off swapping in a new rear end. Hoping I can use a later model with disc brakes and 3:73 gears; still concerned about width.

Would these work?
https://orangecounty.craigslist.org/...317962388.html

Re: 14 bolt conversion to disc questions/options
 

There are at least two AAM 14bolts in the left rear of the picture.
They were available in 10.5" on the 6.0L & 11.5" on the dirtymax trucks.
If you can use a squarebody or 67-72 axle in your 63 you can use a T800 axle.
3.73 gears are easy to swap into a 14bolt. No shims at all. The pinion housing bolts into the nose of the axle so you assemble the pinion in the pinion housing and pick steel gaskets between the housing and the diff housing to set the pinion depth. The carrier bearings are set with threaded rings.

Re: 14 bolt conversion to disc questions/options
 

I agree with Hatzie. You likely don't want the massive 11.5" 14-bolt that came behind the 8.1 and 6.6 diesel engines. The 10.5" is the one you want, and it was found in the 6.0 trucks.

Some of the early-2000's 10.5" 14-bolts came in 3.73 gears. You might get lucky and find one. Most were 4.10's though.

If you're running a conventional slip-yoke transmission or transfer case, grab the driveshaft to go with that rear axle. It will likely be too long, but it's cheap enough to shorten it. That way, you won't have to swap out the pinion yoke on the rear axle or run a conversion u-joint. From my experiments, all the slip yokes from the 1980's through the 2010's were identical. The early 2000's 2500hd trucks with a 10.5" 14-bolt have a 1410 u-joint.

Re: 14 bolt conversion to disc questions/options
 

For now, I am going to do the disc brake conversion on the 14-bolt.

So far, I have this:
Caliper mounting brackets
12.5 rotors from a 73-87 K20

Debating on which calipers to buy, parking brake style or regular ones.

And, not sure if the ones from the 76-77 are different than the ones from 80-85.
These two on ebay:

https://www.ebay.com/itm/32204212340...kAAOSwpDdVS8Kf

https://www.ebay.com/itm/12375051254...4AAOSw3TFcxw-O


Is there any other way to setup a parking brake, instead of using those Eldorado parking brake calipers?

Re: 14 bolt conversion to disc questions/options
 

Depends on the kit. Depending on the year calipers Wilwood D52 calipers are a good swap too. There light weight with dual pistons.

If you do the swap. You need a adjustable proportioning valve. Otherwise the rear brakes get touchy, and lock up a bit to easily.

Re: 14 bolt conversion to disc questions/options
 

Well, I’m not buying a kit. I purchased the rotors from Rock Auto and the bracket from Ruff-Stuff. I just need calipers and pads.
Didn’t really want to go with the parking brake calipers, but they seem like the only option if I want a parking brake. Pretty sure the later ElDorado calipers won’t work; probably need to find the 76-77 calipers.

No other options for parking brakes - bummer.

Re: 14 bolt conversion to disc questions/options
 

The mid aughts GMT800 6.0L Silverado 2500HD axles are plentiful and very easy to install. 2001ish through 2005 at least. I think they went back to drums in 2006 or 2007 to save money.
They're the same 10.5" GM Corporate 14bolt full floater as your truck but manufactured by AAM using the GM design.
The discs are massive with two piston calipers bone stock.
The parking brakes on those axles are rock solid. The parking brake drum is the inside of the hat of the rotor. The parking brake shoes are essentially slightly scaled down, and I do mean slightly, good old fashioned drum brakes. Probably about the same diameter drum as a 4 banger S10 but the shoes are quite a lot wider.

Re: 14 bolt conversion to disc questions/options
 

Hatzie's post is entirely accurate, as far as I know. I'm working with a 2005 2500hd axle myself, and will be installing it on my squarebody. The spring perches need to be moved. I'm using a driveshaft from the same donor truck, and will have it shortened a few inches to fit. The slip yoke is the same exact size as the original 1987 driveshaft, so it will fit the same np208/np241 transfer cases.

The main thing I wanted was 4.10 gears. It was going to be very expensive to regear my original 14bsf axle, so I started looking at different options. A parking brake on my manual transmission truck was a non-negotiable-- I had to have one. The '05 axle seemed to be the best way to get a solid parking brake, a strong axle, 4.10 factory gears, and the lower unsprung weight of disk brakes all wrapped in the same package. As a bonus, I don't have to keep track of a lot of different vehicles when ordering parts for my rear axle. Everything is factory correct for a 2005 2500hd with a 6.0 engine.

Re: 14 bolt conversion to disc questions/options
 

You guys are probably right, that would be a good option. Right now, I don't know if I am up to it.
Not sure if I could even find one.Maybe something I will do in the future; it's just right now, I have almost all of the parts. for just the brake conversion.
I'll think about it.

Re: 14 bolt conversion to disc questions/options
 

Depends on how far you're willing to drive. There are some huge salvage yards just off Glenoaks Northwest of the Intersection with Sunland Blvd in Sun Valley. I used to drive past them on my way to work at the LACMTA transit garage in that area. It's been a decade and a half but they're still showing on the Satellite maps.
Sun Valley is around an hour and a half from San Clemente. There were a few big yards in the Riverside San Bernardino area but not like the ones in Sun Valley.

Re: 14 bolt conversion to disc questions/options
 

Also, if you're thinking of pulling an axle at a junkyard, the trickiest part is lifting the back of the truck enough to remove the axle without dropping the truck on yourself. On one axle I pulled, the truck was sitting on the side of a hill(reality in Virginia salvage yards!). I was lifting the truck with a handyman jack under the rear bumper. The whole truck kept scooching sideways, and threatening to pin me under it.

The disconnect procedure is simple enough. On mine, the u-bolt nuts came right off with a large breaker bar. The driveshaft unbolts easily, and the shocks come loose easily as well. The brake lines and parking brake cables need a good sharp bolt cutters. A cable cutter would be better, but I didn't have one. Once everything is disconnected, then lift the truck, and roll the axle out from under it.

Take the driveshaft and the spring u-bolts along with the axle. They can all be reused to one degree or another.

Remove the spring perches and shock mounts, and clean up the axle tube. Purchase new perches and mounts from OffRoadDesign. Loosely assemble the perches on the axle, and bolt them to the leaf springs. Don't weld anything yet. Adjust the pinion angle until it's correct, then tack weld it in place. Get the new driveshaft shortened to fit(the driveshaft shop can tell you how to take the measurements), and install that.

Drive the truck gently up to speed to check for driveline vibration, and if all is correct, have a skilled welder lock the perches to the axle. There is some risk of warping the axle tubes when welding on the spring perches, so make sure the welder takes proper precautions.

Re: 14 bolt conversion to disc questions/options
 

Find some tires on steel wheels to use as cribbing under the frame or bring some actual 2' timbers to use as temporary cribbing. Timbers will be an operation to get to and under the vehicle.
I make sure it's supported underneath with some kind of cribbing so you can disconnect the propshaft and parking brake cables.

At least one of the yards I frequent has a double A Frame on wheels with an I beam between the A frames and a chain fall hoist. It's for lifting engines and transmissions out of a rig and into a cart. You can attach it to the frame with your own chains or straps and lift the whole shebang after you have the axle is free of the springs, propshaft, cables, and brake line. Then you pull it out using chains or straps without getting underneath.


If the parking brake cables are in serviceable shape I'd keep em. SoCal is unlikely to have the rust we have in the Northeast. If you're in the rust belt they're unlikely to be in good shape. If they are... Chah ching...
You can keep the T800 parking brake cables in one piece by disconnecting from the frame and the pedal cable. I usually nip the sheet metal disconnect cage in two and then pull the rear cables out of the brackets and wire tie them onto the axle tubes. You can usually slide a box-end wrench over the cable and turn slightly to fold in the ears to get the cables out of the holes in the brackets/frame.
It's more work but those cables aren't cheap.

I usually go to a heavy truck spring and axle joint to get new spring pak U-bolts. Not worth re-using them unless they're perfect.
They'll ding you at the counter for the propshaft but it's probably worth getting as long as they didn't bend it with the forks on the loader.
Bring some tape to wrap around the Universal joint caps to hold them on assuming it's serviceable.
Assuming the U-joint yoke straps or U-bolts are in good shape, put em back in the yoke on your axle.

One more piece of shopping advice. Look on the Service Parts ID tag in the glovebox.

• A 2500 with an LQ4 engine will have the 10.5" 14bolt. The LB7, LLY, & LBZ will have the 11.5" 14bolt axle. You don't want the 11.5" AAM axle.
• G80 is limited slip on the T800 trucks. Useful information to have later on.

The other G code will be the axle ratio.

• GT4 : AXLE REAR, 3.73 RATIO
• GT5 : AXLE REAR, 4.10 RATIO

The other RPO code you'll be interested in is the Brake code. If you find a JBx or JDx it's a Disc/Drum truck. Not worth looking any further.

• JH5 : BRAKE, HYD POWER, 4-WHEEL DISC, 7200 LBS
• JH6 : BRAKE, HYD POWER, 4-WHEEL DISC, 9900 LBS

Re: 14 bolt conversion to disc questions/options
 

One other thing that I wanted on a gmt800 10.5 14bff axle is the infamous 'gov-lock' differential. These are usually considered a detriment, but most folks who hate on them are doing stupid stuff that the truck wasn't designed for. Burnouts and severe offroading aren't very kind to the gov-lock design.

I'm building a daily driver truck, and not something that I'll be beating on. Because of this, the gov-lock should last a long time for me, and actually be quite useful in low-speed slippery conditions. This gov-lock comes with a "G80" code on the glovebox sticker.

Re: 14 bolt conversion to disc questions/options
 

I'm not sure the T800 G80 code diff is an Eaton Gov Loc.
It may be an actual limited slip diff.

Re: 14 bolt conversion to disc questions/options
 

Just fix whatever issue you've created with the original brakes. They have worked just fine for GM for decades.

Re: 14 bolt conversion to disc questions/options
 

I thought about that too. My biggest problem is trying to figure out what parts are correct. Not sure what year the one I have is.

Re: 14 bolt conversion to disc questions/options
 

Download the parts and illustration books and take a look at the blowups.

The Axle Quick Req I scanned is useful as well. It shows where to find the axle Ident numbers on the corporate 14 bolt axles. Look in the manuals thread.

Re: 14 bolt conversion to disc questions/options
 

Help!
The rotors I purchased won’t fit over the axle. Does anyone know the part number of the correct rotor for converting this 14 bolt?

Do I need to pull the axles and mount the rotors on the inside??

That means, every time I need to change rotors, I gotta pull the axles?

Re: 14 bolt conversion to disc questions/options
 

Supposedly the Dana 44 8lug front rotors will work but i haven't tried it.

Re: 14 bolt conversion to disc questions/options
 

So, my issue seems to be wheel studs now.
The axle flange has holes for .61 knurl studs, the rotors have holes for .65 knurl studs. So, I need to find a stud with a .65 knurl, but a short shoulder (1/2" or less).
This is due to the fact that the rotor will sit behind the axle flange.
I guess there was no other way to do this... to have the caliper fit behind the wheel without hitting the inside of the rim. I did not realize this.

I guess no one here has ever used a semi float 8-lug axle before. Hoping I can be the first to be successful. I sent an email to the guy at TuffStuff, hopefully he will have some answers for me. Thought I would save some money by buying the parts myself - not always that easy.

I already have the parking brake calipers (76 Eldorado) and rotors and brake hoses; hoping I don't have to try and return this stuff or sell it on eBay. Such a major pain to replace the whole axle, especially now that I don't have a truck to get one with.

Anyone have a good source for wheel studs?

Re: 14 bolt conversion to disc questions/options
 

lugnut4x4.com might be a resource. I think he sells kits for the semi-float axles. I've purchased parts for my full float conversion from him and he seems to be a pretty good guy (I think he'd sell you just the parts you need vs an up-sell).

Re: 14 bolt conversion to disc questions/options
 

I think I have a few things figured out.

Got the correct wheel studs and the brake calipers have arrived.

Just got to find the time to get things assembled.

Re: 14 bolt conversion to disc questions/options
 

Has anyone replaced the bearings in a semi float rear axle?

Special tools required?

Re: 14 bolt conversion to disc questions/options
 

Axle bearings, carrier bearings, or pinion bearings?

Re: 14 bolt conversion to disc questions/options
 

Axle bearings.