73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Brakes and Braking Systems => Topic started by: LTZ C20 on January 27, 2015, 10:08:19 pm
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Hey all, I was just doing some poking around and found a conversion kit for the gm 14 bolt commonly found under the 3/4 and 1 ton square bodies.
Here is a link to the info I found.
http://www.fourwheeler.com/how-to/transmission-drivetrain/129-1103-14-bolt-disc-brake-conversion/
Has anyone used this kit? If so does it work well? Is there any other kits that members know of that are very good and reasonably priced.
I need to rebuild the brakes on my 73 C20. This kit looks like it would be a better way to go.
Thoughts and opinions welcomed and encouraged. Thanks all!
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I can't see how it would be cheaper than a new set of shoes but if you have to replace the wheel cylinders she and drums it might be
Lots of threads for disc conversion on pirate4x4
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Oh ok I'll check it out. I think the cost probably will be about the same, maybe a conversion just a little more. Cost isn't really the issue here, it's the upgrade factor. I'm gonna have it all apart anyway.
The only thing I've noticed is that there is no ability to keep the parking brake. Anything that doesn't have a parking brake will not be used, loosing the parking brake is not an option.
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I'm not for certain here, but I've heard that the proportioning valve in a drum setup is somewhat different from a 4-wheel disc setup. Therefore if you change the rears to disc, the power division may be different from what you expect
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I been looking the disc conversion for my 87. I have picked up a 4:10 FF 14 bolt for $100. I want to do the disc conversion on it before I put it on the truck. From what I've discovered, there are complete kits out there that are rotors calipers and brackets. Some of the kits that include the same rotors and calipers that the front wheels use. I don't really want to go this route since it doesn't have e-brake capabilities. There are other complete kits that do have e-brake calipers though. I guess the 89 Eldorado rear brakes have the same bolt pattern the brackets use. This is probability the route I will go. I have heard of some drive line brakes and some tranny/transfer case options but I don't know a whole lot of these options.
Yes you do need a proportioning valve. The amount of force that is sent to the drums to get adequate braking in the rear will cause the disc to lock up every time you press the brake pedal. The proportioning valve steps down the force being sent to the rear so that doesn't happen. I believe the proportioning valve goes in the master brake cylinder.
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The typical conversion uses the same disc and caliper as the D44 front brakes! So...if you have a D44 front and 14-bolt rear...just get what you have on the front. You are correct in that you lose the parking brake. Options include: 1) Using the eldorado brake calipers with the integral parking lever, but...beware that you have to use the parking brake frequently because the calipers do not self-adjust, it is built into the parking brake mechanism and activating it adjust the pads. 2) utilize a driveline parking brake setup. They actually work much better than the typical wheel-end parking brakes! There is mechanical advantage though the differential that gives you much higher parking brake force. And 3) (which I feel is the most elegant, but takes more fabrication skills) is to use the AAM 14-bolt disc brake/parking brake setup off of a 2001 and newer truck! This has the parking brake mechanism built into the rotor hat.
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Tim, your right about the proportioning valve.
Ehjorten, could you elaborate more on your options 2 and 3.
The driveline brake interests me, as does the 2001 newer truck option. Option 3 I'm more interested in as I work a dealer so I could probably get one of the guys to help me if that's the way I go.
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This company has been making them for 14 bolts for over a decade.. http://www.tsmmfg.com/2630e.html (http://www.tsmmfg.com/2630e.html)
With parking brake calipers (need to be used as Erik stated)
You could also use a line lock for the parking brake...
The disc/drum combination valve delivers LESS pressure to the rear not more. This is the proportion part of the combination valve.
You can gut them and remove this portion effectively making it a distribution block.
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I put discs with 3/4 ton front calipers on the rear of several 73~87 K30 4x4 trucks.
I have NEVER had an issue with using the hydraulic system as-is. No one I have built rear discs for have reported any proportioning issues either.
Before spending money on some tricky, non-factory, braking gadget try using the stock system first.
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Thanks for the link Capt. I think I have come to the conclusion that I think I can build this kit my self for the most part.
I will get rotors, pads, braided lines, a distribution block, fluid of course and new axle seals from local auto parts stores. The website that Capt provided states that most times you don't need to change or get an adjustable proportioning block, only if they lock up. Is this true?
The only thing I would need to get from a kit manufacturer would be the brackets and the calipers with the parking brake built in. Are the calipers with the park brake built in the Eldorado calipers they talk about or is that another option. Some say that the Eldorado set up requires adjustment frequently and I would like to avoid that.
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Ehjorten, could you elaborate more on your options 2 and 3.
The driveline brake interests me, as does the 2001 newer truck option. Option 3 I'm more interested in as I work a dealer so I could probably get one of the guys to help me if that's the way I go.
Option 2 - Driveline Brake:
Looks like this
(http://highangledriveline.com/images/1350cv/Copy_of_205_e-side.jpg)
Typically they are mounted to the output of the transfer case, but can also be mounted to the input on the axle. High Angle Driveline has probably the best setup for purchase, but it is spendy. If you have fabrication skills you could put one together yourself and save some cash.
Option 3 - AAM 14 bolt:
There are 2 versions: 11.5 AAM and 10.5 AAM. The 10.5 AAM is really just a factory disc brake 14-bolt. It is used on the 2500 with gas engines as far as I know. The 11.5 AAM is just that an 11.5" ring gear instead of the 10.5". It is used on the DMax. Dodge uses the same axles since like 2003.
Here is a good thread on them with pictures for identifying them:
http://www.gmc4x4.com/topic/298-aam-14-bolt-rear-axle/ (http://www.gmc4x4.com/topic/298-aam-14-bolt-rear-axle/)
The only thing that these axles don't have that the original 14-bolt had was the pinion support bearing, but these axles do have a larger pinion bearing to start with.
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Thanks for the info again. So with the AAM 10.5 and 11.5 axles, I don't have to use the whole axle right? I can just pull all the brakes stuff off and swap it onto my 14bolt. I don't want to change the whole rear end.
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You could fit it to your axle, but it will take some cutting and welding on the housing to get the mounting geometry for the caliper and dust shield. I haven't done it myself, but I know it has been done.
http://www.pirate4x4.com/forum/chevy/887663-disc-brake-research-14b-ff-compatibility.html (http://www.pirate4x4.com/forum/chevy/887663-disc-brake-research-14b-ff-compatibility.html)
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Oh ok. I see. I don't want to hack up or butcher my rear end, that's why I was looking for something completely bolt on. It looks like I will most likely be going with the Eldorado set up. I wanted to use the 3/4 ton 4x4 caliper setup but with no provisions for a park brake, Eldorado it is. A trans brake or line lock is pretty much out too as it will require more parts along with the disc brake conversion parts. As long as the Eldo calipers are reliable and effective I don't have an issue with using them. Do you guys know if the actually mounting of the Eldo calipers are the same as the 4x4 calipers? As in, the measurements are the same, just the caliper itself is different. Do the 2 sets of calipers use interchangeable brake pads?
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Was talking to our suspension and brake expert here at the shop, he said that the Eldo calipers are somewhat small. The pads on the front of the truck are about the same size as the calipers for the Eldo. He said it would stop the truck ok but not be sufficient in stopping anything that would be towed or hauled.
I don't know tow much but when I do its usually pretty heavy. I have a 30 ft camper, a boat and the shop trailer, last time I towed that it had a another squarebody on it.
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I was gonna say I dont see how a eldo caliper could be anywhere near the braking of the stock 14 bolt drum
Nothing wrong with drums in the back
Drums are not enough for the front
But on the back they are fine
Especially the huge ones on the 14 b
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Yes. After much consideration, research, price comparison and the intended use of the new brakes versus the old brakes, I have decided not to convert. It should be cheaper to rebuild than upgrade, they are not going to have the stopping power and I loose the factory park brake, so I would have to find a solution for that as well.
So when it's time, I'm just gonna rebuild the front and rear brakes and not worry. She's been stopping like that for 40 years and will be just fine for another 40. Plus they are good when towing.
Thanks all for your opinions and help!
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I really liked the link that was posted earlier for tsmmsg.com and noticed the dual piston option, and a parking brake option.
http://www.tsmmfg.com/2630x2.html
The part I am not sure about is stopping power. How did you determine that rear discs do not have as much stopping power as the original drums?