1972 Chevy 4wd Longhorn Project: Never Ending Changes

[1985-GMC]

How much stronger do you think a D80 is than a drw D70, because im afraid I might brake mine after I do the cummins swap.

[Dieselwrencher]

Honestly, A LOT! The D70HD's in my mind aren't very strong. My brother broke 4 in his V30 with a 250HP VE 12v. I used to think they were strong, but not now. The D80's live in 650HP pullers for a long time. They have their weak links too, but I have seen them take a heck of a lot of abuse for what they are. 3rd gear boosted launches with 500hp+, many times over. I'd run the D70HD until you can find a D80. They are pricey but if you search you can get a good deal on one.

[1985-GMC]

Thanks, I figured your the guy to ask so I guess ill add a D80 to the list of things I will need. Ill try to swap it out before I brake it so I can make some money back on it.

[Dieselwrencher]

That's a good idea. Unfortunately my brother purchased what he thought was a D80 from a P-30 chassis camper for his V30 project. It is massive with huge disc brakes, 10 lug hubs, huge leaf springs, and a massive sway bar. The unfortunate part is, it is a dang D70HD! I've tried selling it with no luck, so I told him to use it until he either breaks it or can afford a D80. He wants 19.5's so he better take it easy this time. He purchased all 7 wheels and tires from the guy too.

[Dieselwrencher]

Today my U-bolt plates showed up as well as a different transmission dipstick. So with any luck this weekend I wil bring the truck to the shop and see about getting a different engine installed and redo my engine crossmember with any luck.

[hgs_notes]

Originally Posted by Dieselwrencher

with any luck.

If it weren't for bad luck I'd have no luck at all...

[Dieselwrencher]

Well the forecast was looking grim for this next week with a lot of strong winds. After I got some snow fence up for my mom, and picked up some junk out of the yard, I decided to see about getting a rear axle back under the Longhorn and get it inside. I noticed earlier in the day that my jack stands had started settling into the ground, and the truck was starting to lean over. I didn't want this thing falling over. I had my brother go get our neighbor's skid loader while I started cutting the leaf spring perches off the D80. What a PITA that was. I was running out of acetylene, but finally got them off. When I went to clean them up, I noticed I bent them while beating on them trying to knock them off the axle housing. I will just purchase new ones. We took the rear end out there with the skid loader and started getting ready to put it in. Then I realized the axle pads were wider than my u-bolts a long with my lower mounting plates. I drilled out the mounting plates and opened up the u-bolts in the vise. Next we went back out there and started putting it together. One more slight issue, the U-bolts are too short because this axle tube is much bigger and so is the new mounting plate. I removed the lift block and put it together. Once I got it on the ground back on tires, I'm getting the vibe that I might just remove the 4" lift kit altogether. The truck only sits maybe 2" lower in the rear now. Here are some pics in the shop again.

[Dieselwrencher]

Here is another issue, kind of. This rear axle is quite a bit wider than a stocker too. It puts the tires out of the body a bit. But, at least you won't be able to see the front tires sticking out at the rear. I always hated that about these for sure. I have the rear axle close to where it goes, but just put it in and eye balled it in to get the truck in the shop.




I think I can live with it due to the price to narrow it and my options for strong rear axles.

Now for the height issue. I was thinking about removing the 4" lift from the front, but that is more work. I'm thinking about getting a smaller block for the rear to level it out and call it good. I'm guessing 2" would be plenty. It is really hard to see the difference in these pictures, but here are a few more.




Hopefully this week I can get the engine positioned where I want it and try to get this truck running. That will be a big hurdle to jump!

[nickp51chevy]

She's lookin' good!

You said that you bend the leaf springs when you were trying to take them off the axle? That is crazy those are some huge springs.

[Dieselwrencher]

I didn't bend the spring, I bent the leaf spring mounting pad that is welded to the axle tube. You can kind of see it in this pic. There shouldn't be a gap in between the leaf spring and that perch.

[nickp51chevy]

Oh ya, that's not good.

[Dieselwrencher]

Man, that's a good idea! I just might have to try that. I'll have to see how much lift it needs and go from there.

[propanemudtruck]

I see people do it all the time with 2x2 .250 tubing, no reason you couldn't do 2x3 or anything else like that. Good Luck with your decision, I'm sure you won't under-do it!

[Dieselwrencher]

Thanks for the idea, I don't know why I didn't think of it. This will save me money by not having to purchase the spring pads and lift blocks. I was looking at some from ballistic fab so I think I'll try to model the ones I build off of them maybe.

[watahyahknow]

it will put more load on the springs twisting them when accellerating and braking
there a couple of guys here in holland that send the leafsprings out
the company replaces the top leaf with the mounting eyes for a longer one add one more leaf for height and arches the ones below a bit extra , its not realy expensive and a bit better resisting the loads put on it and gives about 2 inches extra lift

[Dieselwrencher]

Originally Posted by watahyahknow

it will put more load on the springs twisting them when accellerating and braking there a couple of guys here in holland that send the leafsprings out
the company replaces the top leaf with the mounting eyes for a longer one add one more leaf for height and arches the ones below a bit extra , its not realy expensive and a bit better resisting the loads put on it and gives about 2 inches extra lift

This shouldn't be an issue because I plan on installing a set of traction bars on it once it is drivable. And, I don't want to add to the spring pack it has already because it will ride bad enough.

And another thing, the taller perch should be stronger than a short perch and block due to the new perch being one piece.

[DirtyLarry]

Lookin good Ryan!

[Dieselwrencher]

While searching this board, I found a pic of another 4x4 to show what I mean by the rear tires sitting clear in the wheel wells on these years of trucks. The top pic is the opposite side of mine but you can get the idea. Notice how the front tires stick clear out on the white truck compared to the rears. That is just how these trucks are stock.

[DirtyLarry]

Yeah, the front track width has always been wider than the rear on SFA trucks. Even more noticeable on the ½ tons. Not too sure I like the wide Dodge D80 axle in the rear of an old GM truck though….too wide for my taste. I guess I am just too used to the goofy look of the wide axle in front

I wouldn’t mind using a late model GM 10.5 or 11.5 axle to gain rear disks along with the nifty park brake set up but I can’t live with the width issue. I am sure different wheels and fender flares would change the look a lot though.

Your truck is coming along great! Not too sure about that width of that rear axle though.

[Dieselwrencher]

I think I'll get used to it because the D80 is still stronger than a 14 bolt. Besides with it being this wide, I may eventually end up doing a DRW 4x4 conversion to make it like 72Freak's blue 68 truck he sold this summer.

[DirtyLarry]

Originally Posted by Dieselwrencher

I think I'll get used to it because the D80 is still stronger than a 14 bolt.

Oh, I don’t know about that. I work for a truck manufacturer and we see plenty of Dana 80’s break all the time. Much more so than we ever saw on the old Corp 10.5 14 bolt FF that later became an American Axle 10.5" 14 bolt FF. Everything from side bearing retainer bolts breaking to axle flange bolt heads popping off, shearing off, hubs cracking, etc. We never saw any of those problems on a 14 bolt FF.

Below is the most common failure I see on my fleets running D80’s. The axle shaft bolts shears off in the hub. I never understood why Dana builds this big beefy axle with huge shafts, etc then uses the same little tiny 7/16 bolts at the axle flange that they use on a D60 and 70. These little bolts are the fuse of the entire axle. Heck, the 14 bolt FF had ½ axle flange bolts! Compare them next time you have a chance. Ring gear wise, the D80 is a beast! Good stuff. I wouldn’t go as far as to say it is stronger than a 14 bolt FF though.

[watahyahknow]

shouldnt be too hard to remove that weak link by boring and tapping the holes bigger and mount stronger hardware

[Dieselwrencher]

I will agree the industrial hubs are a joke. We have those in our W700's at work. I'm pretty sure a long while back, we had a TSB to replace all the hub to axle mounting bolts because Dana had a bad run of them. The dodge hubs are a lot stronger than those. Granted these bolts will break in the dodge style hubs, but usually you will break an axle first. Try putting a 14bolt in a 550hp 1100ft lb diesel pulling truck and tell me how long it lives. Heck, put it in a pick up and go drag racing. I have done it, and they suck for that application. The pick up Dana 80's are much stronger than a 14 bolt. I have used 14 bolts in dodges to try to save money and all it did was waste my time and money. The axles didn't even last 2 complete pulls and a dana 70 from a dodge would make a atleast 6 hooks and I hate them too.

[Dieselwrencher]

Well I pushed the truck outside to make room for ford month. I have 3 fords to get going by the end of the year. My brother is coming home from California and wants to drive his 92 F-350 back home. I also have the 04 super duty to finish. Plus in between all the mayhem, I have to get my 95 F-350 drivable. It is closer to driving than the Longhorn is. Oh well, it'll get done sooner or later.

[Dieselwrencher]

I'm going to check into getting some rear wheels made to set the rear track a little closer in the wheel well. Right now it is just too wide, and I haven't fully commited to making it DRW. That is still an option though.