1970 K20 Axle Swap 3/4 to 1 ton CUCV

[jeffahart]

I completed swapping out my Dana44 drum and Eaton with CUCV Dana60 and Corporate 14Bolt.

I took on the axle swap because I wanted disc brakes and I needed to rebuild Axles anyway. So after trying to locate d44 with discs and looking into rebuild costs... The old front drum 44 and eaton did not seem like a good idea to put money into based on parts availability. And for cost of d44 axle with rebuild I decided to get a setup I would really be happy with. I purchased axles as 16,000 mile take outs from Boyce Equipment.

The truck rides much better, almost like new. The brakes are almost touchy, a little more sensitive than I would like.

Here's the rundown on how it went.

FRONT d60:
Front bolted in with no axle mods. Truck has a 4" lift so I bought a 2" drop pitman arm from Off Road Designs. I also purchased front soft lines from ORD. I pulled the Residual Check Valve out of the front reservoir. I also purchased a steering stabilizer. And I had to purchase 32 9/16 lug nuts. That was pretty much it for the front. I put new bushings all around. The 9/16 lug nuts had to be the long ones because the extra thickness would not allow my thin wall socket to fit in the rim slot.

I will hang my head and admit I made a bone head mistake. I ordered the ORD soft lines for 3/16 lines. No biggie right, just get a 3/16 to 1/4 adapter! Well, that worked on the passenger side. But guess what, on the driver side there is an inline T in the frame rail. It is one of those crazy ones with the banjo bolt. So what happens is the banjo bolt bottoms out in the adapter before pressure is put on the copper washers. I got fatter copper washers and there was very little thread left for tightening. I went for it anyway, it leaked. I tightened more and it stripped, luckily the adapter stripped not the bolt. So I stacked the original brake line on the ORD line with the adapter. So it's drivable. I need to get rid of the old T and get a new one.


REAR 14ff:
Rear axle bolted right in with only a minor Axle mod needed, which was to grind off original shock mount tabs and weld on new ones.
I bought the shock tabs from Barnes. I purchased the soft line from ORD. I also purchased a shackle flip from ORD and a zero rate leaf. I purchased a Driver side e-brake cable for a 1985 K3500 to put on passenger side because the driver side has a shorter cable. Almost worked but the free ends of the cables are about 4 to 5 inches longer than the eatons'. I used cable clamps to shorten on the passenger side only. I now have a rock hard e-brake. Yes I am keeping the drum brakes so I can have an e-brake. I put new bushing all around. Biggest problem with the rear was I used the 1970 style bolt from top U bolts and bent the cheap Rancho Plate http://67-72chevytrucks.com/vboard/s...d.php?t=638867 . So I ordered new over the spring bolts from bottom and used the 1985 style bolting. Now torqued to 150 ft lbs.

The truck sits level and no longer squats in the rear with the shackle flip and zero rates.

All in all I am happy with the results. Here's some pics. First one below is with squatting rear end prior to swap with shackle flip and zero rates.

[ryanroo]

Very nice. good looking truck!

[Bigdav160]

I like!

[ERASER5]

Nice job!

[SunSoaked]

Nice. I have done a similar swap in my 69. I had a CUCV chassis and ended up swapping the axles and springs over. Since I got the parts for free, I stripped everything including hangers/brackets and perches (front and rear), so technically its now a 1 1/4 ton? It lifted the truck about 2 inches and kept it level without a lift kit. I expect it to ride pretty stiff but I'll deal with that when the time comes.

Nice truck you have. Thanks for sharing!

[SunSoaked]

Oh, I forgot to ask. What modifications/changes did you have to do with your driveshafts?

Thanks

[jeffahart]

Rear:The distance from yoke to yoke is 5/8" shorter and that is with moving the axle back using the zero rate 1" hole.

Front: I didn't even bother checking anything prior to install because the axle configurations are so close.

I need to calculate the pinion angles. I just bolted in without the shim that was originally in. I don't notice any vibration. But the, general, old truck ride could be masking any issues. Even thought I don't notice anything I will check this weekend and get proper shims so it doesn't thrash itself apart.

Keep me posted on the ride of the CUCV springs. 2" is tempting in lieu of 4".



One thing I did not mention above is that I have to re-route my tail pipes due to the shackle flip dropping the springs in the pipe location.

[Former member Yoder213]

I recently found a dana 44 eith discs and swapped everything from the hubs out to make my d44 have discs. went well and they feel great.

I did although choose to keep my eaton ho72, even though I got a 14bff with the disc'ed
d44. My eaton had a factory Detroit locker and the gear ratio is right about where I want.

I am curios as to why you swapped the eaton out. I still have the 14bff and matching d44 and maybe I can learn something from you that makes it worth doing the swap when I put new springs on.

[jeffahart]

My decision was based on a few things. Main two items were to move to disc brakes in front and rebuild the axles. They both have 180k on them. Ball joints funky sounds from the 44 when locked. Probably just a u joint but all needed to be gone through.

I looked into getting a later disc dana 44 for my truck and buying parts to rebuild. First It proved hard to locate one. I just got sick of trying to go to the junk yards and find a decent axle. Going to wrecking yards aint what it used to be for me. Too much hassle and I only speak English. Lots of miss communication.

I spent about a year on and off with this brake/axle issue and finally decide to put the gavel down.

I opted to go with a platform I would be completely happy with and can get parts for and is, my favorite thing, a bit of overkill for what I need.

Why loose the eaton then, it's a great axle. Well, the corp 14ff basically came with the 60 in package deal from Boyce. CUCV is 4.56 my 44 and Eaton are 4.10. Wrong side of the carrier break for me. See how that goes. Make the 60 a 4.10 or make the eaton a 4.56 or take the corp 14 and hang with 4.56 for awhile.

So I figured with a 16,000 mile axle set that's a platform I really like, just swap everything. I dropped these axles in, even the brakes still have plenty of meat. When I spoke with Mark at Boyce he said he knew these axles and they were on a vehicle he went through and that I could bolt them in and forget about them. And so far, it's been true.

I liked the eaton but I won't miss it.

Because now when I go to the mall in my mall crawler( I love this mall crawler saying), all the soccer moms will say "Wow" look at that mans big axle. aaahhhh hahahahah.

[ryanroo]

Parts are less easy to find or downright impossible in some cases for the eaton. they are a beefy axle, no doubt. but, the 14 bolt is a very common unit and you can buy parts for an 80s chevy about anywhere. i did a 60/14ff swap in my yellow K20 as well. beefcake axles and parts are readily available. was much easier than trying to chase down all the crap i needed to replace on the 44 and HO52.