1970 4x4 Blazer Disc brake conversion

[HvyChevy]

I have a 70 4x Blazer and looking to install disc brakes on the front. I was told that a 1977 front axle parts will swap over. Not the whole axle because it's slightly wider, but from the knuckles out will work.

Has anyone tried it? Or is there a better way?
(thanks!)

[Yukon Jack]

Just swap over the whole axle assuming the gear ratio is correct. Width is the same and spring perches are placed correctly. I'm putting a 78 3/4 ton front axle under my K5 for the same reason.

Oh, welcome to the board and that is one sweet K5!

[HvyChevy]

Thanks YJ, that sounds easier.

Thanks for the compliments, it needs a little work. I just bought it a few weeks ago. The front springs are way too stiff (don't know what brand), it has a Mark IV a/c unit that I'm trying to get working, maybe a cross over steering set up in the future? Needs a roll cage too. A little rust on the bottom of the doors.....what fun would it be if it was perfect, right?

I guess there's always going to be a list of things to do to it...

Your truck looks cool...

[Jason915]

Sweet 70K5, I too am getting ready for the disc brake conversion on mine. I have a 1975 D44 from a 75K5 with 3.73's ready to go into my K5. The cool thing about the newer D44 is that it has a factory sterring stablizer. My question is what brake lines will work. I know I have to change my master cylinder out.

[meathead95]

welcome from nashville! that is one awesome rig

[Jason915]

Oh yeah for your suspension I would suggest Skyjacker Softride they kick butt in overall ride quility.

[bouncytruck]

Welcome from the Pacific NW. Nice lookin' rig (I'm partial to Orange with a white top!). I've heard the Rough Country is one of the stiffest lifted springs. I've had Rancho Lifts on three of my Blazers and it was stiff, but driveable. The tires make a huge difference too.

[HvyChevy]

thanks guys!!! I look forward to working on it.
I'll be sure to take pics and keep ya'll posted with the results.

[pound41]

I have a 70 that I bought that has a newer disk front swapped in it. It was a factory power drum. To me it didn't stop as well as I would like with the old master and prop valve. I got the correct master and valve but had to do some engineering. Different size threads etc. You might want to consider the whole 3/4 booster swap. That is what I am doing.

[LUV2XCLR8]

From West TN

[krue]

Welcome to the board from South Mississippi! That's a very nice Blazer you have!

[Chevyman63]

Welcome from Michigan, the home of rust. Nice looking ride.

[Southedisto]

Welcome to the board, and I would go with a complete axle swap instead of the knuckles out swap.

[Livrat]

Welcome to the board!!
Since 1970 is the first of the open knuckle dana 44's and the last of the drum brakes.. All you need to do is change from the spindles out... just pull off the calipers, remove the rotors.. then remove the spindles, pull out the axles from the 77.. and put it all in yours... Thats the easy part.. next is the brake lines.. the 77 stuff is not compatible... the easy way is to find a 71 or 72 chev 4X4 and use the brake lines.. the 70 lines drum brake lines come thru the frame behind the axle and the 71/72 comes out in front of the axle and uses different hoses.. you will need to drill the holes in the frame for the lines to come thru.. and use the hoses from a 71 to 80 4X4.. You will also need to change the master cylinder and booster to a "disc brake" one.. it does not matter if its from 2WD or a 4X4 as long as its from a 71/72 1/2 ton...
Hope that was not too confusing.. if you have questions.. feel free to PM me or email me directly.. Livrat@aol.com

[69TowRig]

'69 and '70 Blazers had open knuckle D44s. My '69 was not closed knuckle like everyone says it should have been, and I have not seen a '69 K5 with closed knuckles.

The problem with a spindle swap is that drum-brake knuckles have the six bolt holes clocked differently than the disc knuckles do, so a straight spindle swap is not quite so simple. The disc-brake backing plate will put the caliper in contact with the knuckle itself. You *could* grind away a lot of material and make the caliper fit, or swap the entire knuckle off.

If you do the knuckle swap, you can use any 1971-later D44 or Coporate 10-bolt for donor parts. It is closest to "bolt-on" if you use the matching outer axleshafts from the donor axle.

I did the knuckle swap last year on mine. I pulled the knuckles from an '84 K5, bought reman calipers and paid up for a set of Crown brake lines through xtremecrawlers.com. I re-used my original outer axleshafts but was not able to install the retaining clip for the shafts under the lockout. If you go the same route as I did you end up needing 1" long 7/16"-20 bolts with fender washers to retain the axleshaft from moving back and forth (the ends of the shafts are threaded)

The knuckle swap will cost you some $$$, I had to replace the balljoints, an axleshaft u-joint, and a couple wheel bearings too. Lots of time invested. In the end you get disc brakes but still have the smaller u-joints ('73+ have larger axle u-joints). The spring perches are the right distance apart on the '73+ trucks, and it is a straightforward swap if you go that route. A bonus is that you automatically get the lower mounts for a swaybar if you want to add one of those to the truck as well.

Overall, with the power booster and discs up front the thing stops way better than it ever did before, and the effort is worth it.

[jakeslim]

My drums on front axle will stop on a dime............well maybe 4 dimes Welcome to this habit. Warning we may see ya on that show "Intervention" for a bad parts habit.

[HvyChevy]

Thanks for the welcome, compliments, and info!!!

I found a 1980 4x4 front axle (well parts of one anyway....lol)

So, I'm going to give it a shot. I guess I need to try and find some beefy axleshaft u-joints.
Off Road Unlimited sells a cross over steering kit comes with a passenger side flat top knuckle, 2 wheel drive steering box, etc.....kinda pricey though. Well see.

Here's some pics of my parts pile.....Oh yeah, best part.. I found a '70 tilt column too...

[69TowRig]

Good luck, PM me if you need any pointers. Looks like you didn't get the shafts so just "run what you brung". You will need to do the setup with the bolt I was talking about, but you will figure it out when you put it together.

BTW, sweet column, where'd you find that?

[HvyChevy]

Originally Posted by 69TowRig

Good luck, PM me if you need any pointers. Looks like you didn't get the shafts so just "run what you brung". You will need to do the setup with the bolt I was talking about, but you will figure it out when you put it together.

BTW, sweet column, where'd you find that?

Maybe I can still get the shafts. I picked up the parts before I read your post. I'll probably be pm'n ya. Thanks!

I found the column (after searching a few yards) at Truck Parts Co. a dismantler in Baldwin Park, CA

[69TowRig]

Hmm, thinking some more if it was from and '80 then it was a Corporate 10-bolt. The inner shafts won't work because they are 19-spline instead of 30-spline like the Dana units. Not sure if there is a conversion joint for the axle u-joints either. You may just have to use what you have.

[HvyChevy]

Originally Posted by 69TowRig

Hmm, thinking some more if it was from and '80 then it was a Corporate 10-bolt. The inner shafts won't work because they are 19-spline instead of 30-spline like the Dana units. Not sure if there is a conversion joint for the axle u-joints either. You may just have to use what you have.

Hmm....good thing I don't have to drive it everyday...I guess I'll start wrenching and see what happens. (Oh, the fun....lol)

[ohboy321]

Originally Posted by HvyChevy

I have a 70 4x Blazer and looking to install disc brakes on the front. I was told that a 1977 front axle parts will swap over. Not the whole axle because it's slightly wider, but from the knuckles out will work.

Has anyone tried it? Or is there a better way?
(thanks!)

The only parts that will bolt in on a 70 D44 would be from a 71. They increased the axle and u-joint size starting in 72.

Duckduckgo the BOM (bill of materials) for the D44 and you can see the axle part numbers are different between 71 to 72, while 70 to 71 are the same. Sorry I don't have a link for the BOM, but the info is out there.

My K10 has a 70 Blazer D44 front axle, and I hope to convert to disk some day.

[hemi43]

You do realize you're replying to a 15 year old post?

[K5Fan]

As are you. Now I.

[jjzepplin]

Me too! haha!