From drum to Disc brake - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Myride · 02-21-2005, 12:01 AM

I have a 1971 jimmy that has a dana 44 with drum brakes, what would I need to change it over to disc? Thanks

**JIMs70GMC** · 02-23-2005, 11:46 AM

Are you sure it's a 71? If it is then someone put a drum brake front under your 71. I'd say find an axle from a 71 and up GM truck and bolt it in, brake lines from frame to caliper will need to be replaced. Need to match year of caliper as some are standard and they switched to metric in the late 70s/early 80s. Make sure you match your rear end gear ratio.

Brimow525 · 03-05-2005, 03:14 PM

I did the same swap as you did on my 70 k20. It has a Dana 44 with drums and I converted it over to disc. This is what I used. I bought an 86 k2500 front end.(stock Corporate 10 bolt) took everything off and come to find out, all I needed was the dust covers that hold the brake calipers on. (For the actual swap to be complete) Naturally I bought brand new calipers, rotors, seals, bearings and so on. The biggest challange was finding the long enough rubber brake line for the front discs. The spindles are the same, even the steering knuckles are the same. Both the disc and drum spindles have the same bolt pattern to bolt to the steering knuckle. Be carefull, and replace the upper and lower ball joints. Get the special socket to remove the retaining nut on the top ball joint. Mine took a torch and impact to get it out.

I have pics. Just have to find them. Let me know if you need more help on this subject.

Gator70 · 03-06-2005, 01:58 AM

Brimow, do you know the appl that you got the brake lines from. Im just about to do this swap to my K10. I think that I have everything lined up but just trying to figure out the brake lines. How did you secure them at the frame.

Brimow525 · 03-06-2005, 09:59 AM

On the drivers side I used a T from napa and washers to keep the brake line secure. Still a little loose, but this was my first ever conversion/ truck project. Passenger side I did the same kinda thig but no t fitting. I am going to my shop today and will get pics of the brake lines for you. I'll reply sometime after 3pm. BTW, I have a proportioning valve from a 72 gmc 1500. I think its a little small but it is working for now. I will also see if I can get the part #'s off the brake lines. They were from napa.

Gator70 · 03-07-2005, 11:59 AM

thanks Brimrow,

Brimow525 · 03-07-2005, 10:58 PM

OK lets see if these pics will help...

Brimow525 · 03-07-2005, 11:01 PM

My digital camera isn't the best. Hope this helps. If you guys need other pics let me know. It may not be a 100% correct way to do it, but I don't take it off roading so I think it'll hold up for my applications.

Gator70 · 03-08-2005, 11:53 AM

Thanks Brimow, it gives me some ideas. By the way, if you know anybody looking for another snowplow. I have one taken off my '70.

Brimow525 · 03-08-2005, 12:43 PM

well I was looking for one and had no luck finding any so I had refab the one from my 83 gmc and made it fit.

6869704X4 · 03-08-2005, 06:09 PM

Just a heads up here Gator70. I did the swap on my 70 K10 and niether the spindles or knuckles were the same as the disc axle. So, check them close.

**JIMs70GMC** · 03-08-2005, 08:27 PM

I thought the same thing, the studs for the spindles are cocked on the drum front and I though their was interference between the disc backing plate and the drum style knuckle.

Brimow525 · 03-09-2005, 12:31 AM

Mine didn't. Now, there maybe a difference if you have a half ton front axle as apposed to a 3/4 ton corporate or dana front axle. Like I said, this is my first project and I am still learning, but I do know that I used my 70 dana 44 steering......no I didn't! Now that I think about it, I put the 86 K2500 steering knuckles on the dana 44 axle, BUT the spindle bolt holes are the same as the dana 44 and the 86's. I did however use the dana 44 original axles. I had new u joints pressed in. Either way, if you can find a 3/4 ton front axle for next to nothing to get major parts off of, its cheaper than buying a conversion kit out of the books. I'll have to see if I kept the old parts. I do believe that the dana 44 steering knuckels and spindles will work with just getting the dust or backing plate for disc conversion. Don't hole me to it, because the more I think about how I did it, the more I confuse myself.
I have to remember all kinds of numbers and years. Body is a 70 c10
Frame is a 70 k20
70 Dana 44 front axle
70 Eaton full floating rear axle with 4:10 gears
NP205 transfercase
Rebuilt TH350 tranny
350 goodwrench motor 1978
Rear drums are machined dana 60 drums to fit the eaton rear
front disc stuff is from 86 K2500

I don't want in anyway to act like I know more than anybody, I just know that it was easier than I thought to do the conversion, as far as major hardware goes. The harder parts where finding the right size brake lines and connecting them through the frame and making that work.

6869704X4 · 03-09-2005, 09:08 AM

The bolt pattern was the same for the spindle. The difference was right at the base. If you stand them up next to each other you can see it. I cant remember for sure if there was a difference in the knuckle, but I think there was. I was going crossover steering so I had to swap the machined knuckle anyway.

Brimow525, this very well could be a K10/K20 thing. As far as your brake lines, check them often. There is stress on the hard brake lines right at the fitting. As long as its not leaking you should be OK. A friend of mine's son did that and thats what showed up.

**JIMs70GMC** · 03-09-2005, 09:36 AM

Some good reading: http://77cj.littlekeylime.com/flatop_knucles.html

Brimow525 · 03-09-2005, 11:05 PM

I totally agree about the hard brake line where it is. As soon as I get some time I want to redo that part of the lines and do it right. Like I said, I don't use it for off roading. Just an old work truck. It plows better than my 95 k2500. Way better traction.

Gator70 · 03-14-2005, 02:07 AM

I was going to change the knuckles to the disc brake knuckles in my conversion. The ball joints are the same for both applications. Is this where you ran into trouble 686970,
My plan is to take off the donor the knuckles, caliper mounts ,spindles,stub shafts, hub/rotor, caliper, prop valve and master. basically the whole outer. and the tire rods and drag link assy.
I had figured this way everything should match with each other.
Is there issues with transplanting it this way or just when trying to use the drum knuckle assy??

Brimow525 · 03-14-2005, 08:20 AM

If you have a complete donor front axle, I would change(update) as many parts as I could. I was lucky enough to have a complete donor axle to get parts off of. What year is your donor parts. I wanted to use my 70 steering control arm and couldn't because tie rods were different size than the 86.

Gator70 · 03-14-2005, 03:37 PM

Im getting all of the stuff from a 87 Jimmy. My plan is too use as many of the new pieces as I can. I have ordered all new tie rods, drag links, calipers (anything that wears out) and replace it. I dont want to be under there replacing items every few months. If its new Im good to go. I will be keeping this truck as long as my Grandad kept it.(at least 30 years)

6869704X4 · 03-14-2005, 04:23 PM

Gator70, looks like your replacing everything from the knuckles on out. Once I did that there were no problems. I used 74 parts to a 70 axle. Dont know if there will be any difference in the 87 stuff. Brimow525 mentioned tie rod ends.

Gator70 · 03-14-2005, 05:09 PM

686970, do you happen to remember any particulars with your brake lines?? attaching or converting?

6869704X4 · 03-14-2005, 05:30 PM

I ran new brake lines. I came out this hole here.

7084Driver · 03-17-2005, 02:08 PM

How about using the dust shields and calipers off a 84 10 bolt front axle? Will they swap over to the 44 w/ drum brakes?

Brimow525 · 03-17-2005, 03:57 PM

I used an 86 10 bolt to do mine. I don't believe there is any difference between 84 and 86.

02-21-2005, 12:01 AM	#1
Myride Registered User Join Date: Mar 2002 Location: Pacific Northwest Posts: 292	From drum to Disc brake I have a 1971 jimmy that has a dana 44 with drum brakes, what would I need to change it over to disc? Thanks

02-23-2005, 11:46 AM	#2
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	Are you sure it's a 71? If it is then someone put a drum brake front under your 71. I'd say find an axle from a 71 and up GM truck and bolt it in, brake lines from frame to caliper will need to be replaced. Need to match year of caliper as some are standard and they switched to metric in the late 70s/early 80s. Make sure you match your rear end gear ratio. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

03-05-2005, 03:14 PM	#3
Brimow525 Registered User Join Date: Feb 2004 Location: Wrenchin' or Working in De., take your pick Posts: 51	I did the same swap as you did on my 70 k20. It has a Dana 44 with drums and I converted it over to disc. This is what I used. I bought an 86 k2500 front end.(stock Corporate 10 bolt) took everything off and come to find out, all I needed was the dust covers that hold the brake calipers on. (For the actual swap to be complete) Naturally I bought brand new calipers, rotors, seals, bearings and so on. The biggest challange was finding the long enough rubber brake line for the front discs. The spindles are the same, even the steering knuckles are the same. Both the disc and drum spindles have the same bolt pattern to bolt to the steering knuckle. Be carefull, and replace the upper and lower ball joints. Get the special socket to remove the retaining nut on the top ball joint. Mine took a torch and impact to get it out. I have pics. Just have to find them. Let me know if you need more help on this subject. __________________ Cuttin' Grass and Kickin' A** , and We're Running Out of Grass to Cut! Last edited by Brimow525; 03-05-2005 at 03:16 PM.

03-06-2005, 01:58 AM	#4
Gator70 Registered User Join Date: Oct 2004 Location: Turner Valley, Alberta Posts: 91	Brimow, do you know the appl that you got the brake lines from. Im just about to do this swap to my K10. I think that I have everything lined up but just trying to figure out the brake lines. How did you secure them at the frame. __________________ 1970 GMC K15 - Canadian built 2nd Owner truck 68k miles 2014 Denali 1500 6.2L

03-06-2005, 09:59 AM	#5
Brimow525 Registered User Join Date: Feb 2004 Location: Wrenchin' or Working in De., take your pick Posts: 51	On the drivers side I used a T from napa and washers to keep the brake line secure. Still a little loose, but this was my first ever conversion/ truck project. Passenger side I did the same kinda thig but no t fitting. I am going to my shop today and will get pics of the brake lines for you. I'll reply sometime after 3pm. BTW, I have a proportioning valve from a 72 gmc 1500. I think its a little small but it is working for now. I will also see if I can get the part #'s off the brake lines. They were from napa. __________________ Cuttin' Grass and Kickin' A** , and We're Running Out of Grass to Cut!

03-07-2005, 11:59 AM	#6
Gator70 Registered User Join Date: Oct 2004 Location: Turner Valley, Alberta Posts: 91	thanks Brimrow, __________________ 1970 GMC K15 - Canadian built 2nd Owner truck 68k miles 2014 Denali 1500 6.2L

03-07-2005, 10:58 PM	#7
Brimow525 Registered User Join Date: Feb 2004 Location: Wrenchin' or Working in De., take your pick Posts: 51	OK lets see if these pics will help... Attached Images __________________ Cuttin' Grass and Kickin' A** , and We're Running Out of Grass to Cut!

03-07-2005, 11:01 PM	#8
Brimow525 Registered User Join Date: Feb 2004 Location: Wrenchin' or Working in De., take your pick Posts: 51	My digital camera isn't the best. Hope this helps. If you guys need other pics let me know. It may not be a 100% correct way to do it, but I don't take it off roading so I think it'll hold up for my applications. __________________ Cuttin' Grass and Kickin' A** , and We're Running Out of Grass to Cut!

03-08-2005, 11:53 AM	#9
Gator70 Registered User Join Date: Oct 2004 Location: Turner Valley, Alberta Posts: 91	Thanks Brimow, it gives me some ideas. By the way, if you know anybody looking for another snowplow. I have one taken off my '70. __________________ 1970 GMC K15 - Canadian built 2nd Owner truck 68k miles 2014 Denali 1500 6.2L

03-08-2005, 12:43 PM	#10
Brimow525 Registered User Join Date: Feb 2004 Location: Wrenchin' or Working in De., take your pick Posts: 51	well I was looking for one and had no luck finding any so I had refab the one from my 83 gmc and made it fit. __________________ Cuttin' Grass and Kickin' A** , and We're Running Out of Grass to Cut!

03-08-2005, 06:09 PM	#11
6869704X4 Registered User Join Date: Jul 2002 Location: SE NM Posts: 769	Just a heads up here Gator70. I did the swap on my 70 K10 and niether the spindles or knuckles were the same as the disc axle. So, check them close. __________________ The more I learn about women, the more I love my truck.

03-08-2005, 08:27 PM	#12
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	I thought the same thing, the studs for the spindles are cocked on the drum front and I though their was interference between the disc backing plate and the drum style knuckle. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

03-09-2005, 12:31 AM	#13
Brimow525 Registered User Join Date: Feb 2004 Location: Wrenchin' or Working in De., take your pick Posts: 51	Mine didn't. Now, there maybe a difference if you have a half ton front axle as apposed to a 3/4 ton corporate or dana front axle. Like I said, this is my first project and I am still learning, but I do know that I used my 70 dana 44 steering......no I didn't! Now that I think about it, I put the 86 K2500 steering knuckles on the dana 44 axle, BUT the spindle bolt holes are the same as the dana 44 and the 86's. I did however use the dana 44 original axles. I had new u joints pressed in. Either way, if you can find a 3/4 ton front axle for next to nothing to get major parts off of, its cheaper than buying a conversion kit out of the books. I'll have to see if I kept the old parts. I do believe that the dana 44 steering knuckels and spindles will work with just getting the dust or backing plate for disc conversion. Don't hole me to it, because the more I think about how I did it, the more I confuse myself. I have to remember all kinds of numbers and years. Body is a 70 c10 Frame is a 70 k20 70 Dana 44 front axle 70 Eaton full floating rear axle with 4:10 gears NP205 transfercase Rebuilt TH350 tranny 350 goodwrench motor 1978 Rear drums are machined dana 60 drums to fit the eaton rear front disc stuff is from 86 K2500 I don't want in anyway to act like I know more than anybody, I just know that it was easier than I thought to do the conversion, as far as major hardware goes. The harder parts where finding the right size brake lines and connecting them through the frame and making that work. __________________ Cuttin' Grass and Kickin' A** , and We're Running Out of Grass to Cut!

03-09-2005, 09:08 AM	#14
6869704X4 Registered User Join Date: Jul 2002 Location: SE NM Posts: 769	The bolt pattern was the same for the spindle. The difference was right at the base. If you stand them up next to each other you can see it. I cant remember for sure if there was a difference in the knuckle, but I think there was. I was going crossover steering so I had to swap the machined knuckle anyway. Brimow525, this very well could be a K10/K20 thing. As far as your brake lines, check them often. There is stress on the hard brake lines right at the fitting. As long as its not leaking you should be OK. A friend of mine's son did that and thats what showed up. __________________ The more I learn about women, the more I love my truck.

03-09-2005, 09:36 AM	#15
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	Some good reading: http://77cj.littlekeylime.com/flatop_knucles.html __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm



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03-09-2005, 11:05 PM	#16
Brimow525 Registered User Join Date: Feb 2004 Location: Wrenchin' or Working in De., take your pick Posts: 51	I totally agree about the hard brake line where it is. As soon as I get some time I want to redo that part of the lines and do it right. Like I said, I don't use it for off roading. Just an old work truck. It plows better than my 95 k2500. Way better traction. __________________ Cuttin' Grass and Kickin' A** , and We're Running Out of Grass to Cut!

03-14-2005, 02:07 AM	#17
Gator70 Registered User Join Date: Oct 2004 Location: Turner Valley, Alberta Posts: 91	I was going to change the knuckles to the disc brake knuckles in my conversion. The ball joints are the same for both applications. Is this where you ran into trouble 686970, My plan is to take off the donor the knuckles, caliper mounts ,spindles,stub shafts, hub/rotor, caliper, prop valve and master. basically the whole outer. and the tire rods and drag link assy. I had figured this way everything should match with each other. Is there issues with transplanting it this way or just when trying to use the drum knuckle assy?? __________________ 1970 GMC K15 - Canadian built 2nd Owner truck 68k miles 2014 Denali 1500 6.2L

03-14-2005, 08:20 AM	#18
Brimow525 Registered User Join Date: Feb 2004 Location: Wrenchin' or Working in De., take your pick Posts: 51	If you have a complete donor front axle, I would change(update) as many parts as I could. I was lucky enough to have a complete donor axle to get parts off of. What year is your donor parts. I wanted to use my 70 steering control arm and couldn't because tie rods were different size than the 86. __________________ Cuttin' Grass and Kickin' A** , and We're Running Out of Grass to Cut!

03-14-2005, 03:37 PM	#19
Gator70 Registered User Join Date: Oct 2004 Location: Turner Valley, Alberta Posts: 91	Im getting all of the stuff from a 87 Jimmy. My plan is too use as many of the new pieces as I can. I have ordered all new tie rods, drag links, calipers (anything that wears out) and replace it. I dont want to be under there replacing items every few months. If its new Im good to go. I will be keeping this truck as long as my Grandad kept it.(at least 30 years) __________________ 1970 GMC K15 - Canadian built 2nd Owner truck 68k miles 2014 Denali 1500 6.2L

03-14-2005, 04:23 PM	#20
6869704X4 Registered User Join Date: Jul 2002 Location: SE NM Posts: 769	Gator70, looks like your replacing everything from the knuckles on out. Once I did that there were no problems. I used 74 parts to a 70 axle. Dont know if there will be any difference in the 87 stuff. Brimow525 mentioned tie rod ends. __________________ The more I learn about women, the more I love my truck.

03-14-2005, 05:09 PM	#21
Gator70 Registered User Join Date: Oct 2004 Location: Turner Valley, Alberta Posts: 91	686970, do you happen to remember any particulars with your brake lines?? attaching or converting? __________________ 1970 GMC K15 - Canadian built 2nd Owner truck 68k miles 2014 Denali 1500 6.2L

03-14-2005, 05:30 PM	#22
6869704X4 Registered User Join Date: Jul 2002 Location: SE NM Posts: 769	I ran new brake lines. I came out this hole here. Attached Images __________________ The more I learn about women, the more I love my truck.

03-17-2005, 02:08 PM	#23
7084Driver Registered User Join Date: Jan 2005 Posts: 21	How about using the dust shields and calipers off a 84 10 bolt front axle? Will they swap over to the 44 w/ drum brakes?

03-17-2005, 03:57 PM	#24
Brimow525 Registered User Join Date: Feb 2004 Location: Wrenchin' or Working in De., take your pick Posts: 51	I used an 86 10 bolt to do mine. I don't believe there is any difference between 84 and 86. __________________ Cuttin' Grass and Kickin' A** , and We're Running Out of Grass to Cut!

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