Disc brake conversion - The 1947 - Present Chevrolet & GMC Truck Message Board Network

JimKshortstep4x4 · 10-11-2002, 07:05 AM

I want to do a disc brake conversion on a 70 4x4 K10 and it looks like the 71-72 spindles would bolt up in place of the drum brake spindle. Has anyone ever done a conversion like this or do you have to get the 71-72 axle?

Any input would be appreciated.

Jim

6869704X4 · 10-11-2002, 11:20 AM

If you can find an entire axle it would be easier to swap that in. A 44 out of any Chevy should work. Even a 3/4 ton but lugs and U joints are an issue there.
I went the parts and pieces route and you will need everything from the knuckles on out. Plus the axle shafts. So you can see its less hassle to swap the axle.
Im using a master cylinder from a 72 and proportion valve from a 75. Then you have to get the brake lines to the calipers.
Good luck. If you have any more questions Ill try and answer them.

JimKshortstep4x4 · 10-11-2002, 01:09 PM

So the knuckles are different, it sounds like. I have located a complete front end, but I was hoping for an easier swap. I know what I have to do and I appreciate the information.

Jim

breeh · 10-11-2002, 06:23 PM

It seems to me that the knuckles were the same when I did this swap but everything else that was stated earlier needs to be swapped. Someone will correct me if I am wrong but I believe the axles did not need to be exchanged. Good luck!

6869704X4 · 10-12-2002, 10:02 AM

My hubs wouldnt go together right untill I swapped knuckles and axle shafts. This is what a guy at the boneyard told me but I tried anyway. He was right. Its the length of the shafts i think. Did this 5 years ago so my memory is kinda foggy about it.
Not saying this goes for every axle because there are sutle differences in them.
Another reason to swap the whole axle.

**jerry moss** · 10-20-2002, 10:28 AM

the knuckles are different but will work, there's no place for the little 1/4 inch bolt that is on the disc backing plate. by the time you buy a part here and a part there it's usually cheaper to buy a complete assembly. if you want to swap all the pieces over to your existing housing then it would be a perfect time to replace all the ball joints, the little needle bearings in the spindles and the axle shaft u-joints--- if needed.
i always swap in 73 or newer parts as they are much easier to find and cheaper too. just don't try to mix 72 parts with 73 parts, the spindles and axle shafts must match each other otherwise you won't get a good seal where the shaft goes through the back side of the spindle. 72 and older uses a pound in seal in the rear of the spindle and 73 on up use a rubber flap on the axle shaft itself. the shafts are totaly different.

JimKshortstep4x4 · 10-21-2002, 07:26 AM

Thanks for the replys. It will be next spring before I change out the axle. In the meantime, i will keep an eye open for a 73 axle, (73 throught 78?).

Jim

**jerry moss** · 10-21-2002, 10:12 AM

Jim,
i'm not sure what year the cut-off was, i think you are correct on 1978. after that , they used a corperate 10 bolt front. my 79 blazer has the corp front in it.

JimKshortstep4x4 · 10-21-2002, 10:27 AM

Thanks Jerry,

The yard where I go every weekend is bound to get one sooner or later and I will grab one. They have lots of parts so I was hoping that parts would be sufficient. We have (5) 4x4's in our collection, and we have upgraded the axles to the 73 up style with the newer seals. The older axle tin dust shields don't last up here in Michigan! The 4x4 that I am working on will be #6.

Jim

Pont · 10-21-2002, 02:55 PM

Jim, I think you are safe sticking to the 73-78 years for an axle swap, mainly because of brake lines. In 79 or 80, the disc brake calipers have a metric fitting at the caliper. The Dana 44 I'm using came out of an 80 Blazer but I can't confirm this was the original axle in that blazer. The calipers on my Dana 44 have metric fittings so I also had to change front brake hoses. Other than that, it was an easy swap.

red450ih · 10-22-2002, 03:14 PM

I thought there was a width difference between the 67-72 and 73-87? Anyone have the WMS to WMS measurements for both?

Thanks,
Keith

JimKshortstep4x4 · 10-23-2002, 06:56 AM

I can't answer the length question on the 67-70 axles, but on the 71-72 4x4 front ends we have changed out (5) sets of the 71-72 axles to the 73 up style. The 73 up axles are beefier and they have a forged labrinth shield in lieu of the thin metal shields on the 71-72 axles. They are a direct replacement if you use the seal setup on the spindles.

I will try to measure the 70 and compare to a 71 and will post the result.

Jim

10-11-2002, 07:05 AM	#1
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Disc brake conversion I want to do a disc brake conversion on a 70 4x4 K10 and it looks like the 71-72 spindles would bolt up in place of the drum brake spindle. Has anyone ever done a conversion like this or do you have to get the 71-72 axle? Any input would be appreciated. Jim Last edited by JimKshortstep4x4; 10-23-2002 at 06:41 AM.

10-11-2002, 11:20 AM	#2
6869704X4 Registered User Join Date: Jul 2002 Location: SE NM Posts: 769	If you can find an entire axle it would be easier to swap that in. A 44 out of any Chevy should work. Even a 3/4 ton but lugs and U joints are an issue there. I went the parts and pieces route and you will need everything from the knuckles on out. Plus the axle shafts. So you can see its less hassle to swap the axle. Im using a master cylinder from a 72 and proportion valve from a 75. Then you have to get the brake lines to the calipers. Good luck. If you have any more questions Ill try and answer them. __________________ The more I learn about women, the more I love my truck.

10-11-2002, 06:23 PM	#4
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	It seems to me that the knuckles were the same when I did this swap but everything else that was stated earlier needs to be swapped. Someone will correct me if I am wrong but I believe the axles did not need to be exchanged. Good luck! __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

10-12-2002, 10:02 AM	#5
6869704X4 Registered User Join Date: Jul 2002 Location: SE NM Posts: 769	My hubs wouldnt go together right untill I swapped knuckles and axle shafts. This is what a guy at the boneyard told me but I tried anyway. He was right. Its the length of the shafts i think. Did this 5 years ago so my memory is kinda foggy about it. Not saying this goes for every axle because there are sutle differences in them. Another reason to swap the whole axle. __________________ The more I learn about women, the more I love my truck.

10-21-2002, 07:26 AM	#7
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Thanks for the replys. It will be next spring before I change out the axle. In the meantime, i will keep an eye open for a 73 axle, (73 throught 78?). Jim Last edited by JimKshortstep4x4; 10-21-2002 at 10:22 AM.

10-11-2002, 01:09 PM	#3
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	So the knuckles are different, it sounds like. I have located a complete front end, but I was hoping for an easier swap. I know what I have to do and I appreciate the information. Jim

10-20-2002, 10:28 AM	#6
jerry moss Born Psycho Join Date: Feb 2001 Location: brentwood,cal,usa Posts: 4,943	the knuckles are different but will work, there's no place for the little 1/4 inch bolt that is on the disc backing plate. by the time you buy a part here and a part there it's usually cheaper to buy a complete assembly. if you want to swap all the pieces over to your existing housing then it would be a perfect time to replace all the ball joints, the little needle bearings in the spindles and the axle shaft u-joints--- if needed. i always swap in 73 or newer parts as they are much easier to find and cheaper too. just don't try to mix 72 parts with 73 parts, the spindles and axle shafts must match each other otherwise you won't get a good seal where the shaft goes through the back side of the spindle. 72 and older uses a pound in seal in the rear of the spindle and 73 on up use a rubber flap on the axle shaft itself. the shafts are totaly different. __________________ jerry moss 72 cheyenne super K20- tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,tow hooks,bumper guards,toolbox,aux. fuel tank,posi front and rear,plus other goodies!!! SOLD 69 suburban K20-tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,4 inch all spring lift,4 speed, 14 bolt full floater, dana 44 HD,warn winch,posi front and rear,tow hooks,plus other goodies. 73/80 chevy/gmc K20 SB400,turbo 400,205,tilt,a-c,gas hog. 77 K/5 cheyenne blazer-daily driver/beater. SON HAS IT NOW BRENTWOOD,CALIFORNIA

10-21-2002, 10:12 AM	#8
jerry moss Born Psycho Join Date: Feb 2001 Location: brentwood,cal,usa Posts: 4,943	Jim, i'm not sure what year the cut-off was, i think you are correct on 1978. after that , they used a corperate 10 bolt front. my 79 blazer has the corp front in it. __________________ jerry moss 72 cheyenne super K20- tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,tow hooks,bumper guards,toolbox,aux. fuel tank,posi front and rear,plus other goodies!!! SOLD 69 suburban K20-tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,4 inch all spring lift,4 speed, 14 bolt full floater, dana 44 HD,warn winch,posi front and rear,tow hooks,plus other goodies. 73/80 chevy/gmc K20 SB400,turbo 400,205,tilt,a-c,gas hog. 77 K/5 cheyenne blazer-daily driver/beater. SON HAS IT NOW BRENTWOOD,CALIFORNIA

10-21-2002, 10:27 AM	#9
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Thanks Jerry, The yard where I go every weekend is bound to get one sooner or later and I will grab one. They have lots of parts so I was hoping that parts would be sufficient. We have (5) 4x4's in our collection, and we have upgraded the axles to the 73 up style with the newer seals. The older axle tin dust shields don't last up here in Michigan! The 4x4 that I am working on will be #6. Jim

10-21-2002, 02:55 PM	#10
Pont I need another Barley Pop Join Date: Feb 2001 Location: Grants Pass, OR Posts: 1,629	Jim, I think you are safe sticking to the 73-78 years for an axle swap, mainly because of brake lines. In 79 or 80, the disc brake calipers have a metric fitting at the caliper. The Dana 44 I'm using came out of an 80 Blazer but I can't confirm this was the original axle in that blazer. The calipers on my Dana 44 have metric fittings so I also had to change front brake hoses. Other than that, it was an easy swap. __________________ 67 Short Fleet 4x4 04 Honda CRF450R 89 Toyota 4-Runner 34 Ford 2 door sedan - Long term project ---------------------------------------------- There is a very fine line between "hobby" and "mental illness"

10-22-2002, 03:14 PM	#11
red450ih Registered User Join Date: Mar 2001 Location: Nashville, Tennessee Posts: 225	I thought there was a width difference between the 67-72 and 73-87? Anyone have the WMS to WMS measurements for both? Thanks, Keith __________________ GMC

10-23-2002, 06:56 AM	#12
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	I can't answer the length question on the 67-70 axles, but on the 71-72 4x4 front ends we have changed out (5) sets of the 71-72 axles to the 73 up style. The 73 up axles are beefier and they have a forged labrinth shield in lieu of the thin metal shields on the 71-72 axles. They are a direct replacement if you use the seal setup on the spindles. I will try to measure the 70 and compare to a 71 and will post the result. Jim



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.