Stock front axel on a K20??

[FLYNAVY30]

As I'm slowly plotting the eventual conversion of my C20 to 4wd, I've started compiling a parts list. At the moment, I'm leaning towards a Tremec TR-4050 manual 5speed with either an NP205 or Atlas transfer case. Ill probably use the B-52 mounting kit and spring from DIY4x for the front springs and retrain the stock Dana 60/trailing arms/coils in the rear.

My question is, what was the stock axel set up on the K20's and is that the best option for this application, or is there something from another year/model that would make more sense?

This thing isn't going to be a rock crawler, just a daily driver that I can take camping on trails and in the mud...and the big reason for the 4wd conversion, is so that I can pull a boat up and down the steep boat ramp at the end of our street.

Thanks for the input!!

[CG]

I always wondered if this would be a viable idea to anyone wanting to switch from 2 wheel to 4 wheel. Aren't all 67-72 4x4 leaf springs in the rear? I wonder how the trailing arms and coils would work? I feel like in your application they should be fine.

I wonder how low you can go in the front with that set up, not low rider low, but modern SUV low? I think it would be pretty cool.

You might consider having this moved to the 4x4 area of the board. Lotta really smart folks that might be able to help you out vs this generic Burb area.

[FLYNAVY30]

Appreciate the input! I've done a bunch of research on this....yes the factory 4wd trucks are leaf springs in the rear. That being said, if you're not doing heavy, technical off roading, the trailing arms with coils are just fine and will actually provide a better on-road ride quality.

As far as ride height, I would get the front set up the way I wanted it, then order rear coils to match the ride height. Once I had the truck sitting even, at ride height, I would order shocks....probably Fox, with a measured operating window to match the ride height.

I used the same process on my Corvette and got a really nice combo of ride height aesthetic, handling, and ride quality.

[Ziegelsteinfaust]

I am not the biggest 4x4 person but I am building a Willy's Wagon to do exploring.

Coils at all 4 corners will usually ride better, and do better off road typically. The down side is death wobble appears in linked front ends at a exceptionally high rate vs leaf spring front ends.

My TTB is fairly immune to it, but it will eat tires compared to a straight axle. Even with regulat rotation.

A Jeep Wrangler Unlimited I rented when my Silverado got hit got it at speeds above 70mph on bumpy freeways. Scary as hell. Theories suggest weak frame brackets or weak links allowing twist. As aftermarket arms rarely exhibit the trait unless lifted with large tires. Also Brand F and Rams have death wobble in fairly new trucks. But they have a 2 link front. A guy I know his uncle wrecked a nearly new F250 when it happened to him on the freeway. The wheel got away from him, and quickly ripped a link off the frame.

So what ever you decide. Do your research, and try to get the best kit you can.

[FLYNAVY30]

Yea, for my purposes and a relatively stock ride height (32s), I think a stock-ish 4wd set up in front makes sense from a financial, logistical, and spares availability stand point unless someone has an argument to the contrary.

From what I've read, with the Suburban's extremely long wheels base, the trailing arm rear will not be a limiting factor in my intended use. If I was going to go lifted, and do more serious off-roading, it would probably be prudent to switch to leafs in the rear.

Given that it will be primarily a daily driver, pulling double duty as a tow-rig, and lastly used for light duty camping.....gravel trails, logging roads, etc, I think the stock 4wd front with the stock 2wd rear will work just fine. Again, Im very open to input/criticism.

This is the height/stance I'm going for....

[Ziegelsteinfaust]

The only downside could be awkward handling.

Leafs at all 4 corners is typicly a very stable ride.

Leafs in the rear are typical left for weight carrying stability. Such as brand F trucks.

The worst case scenario if you feel Leafs in front, and coils in the rear is not how you like it. Swap to Leafs at your convenience.

[FLYNAVY30]

agreed....it would be easy enough to swap to leafs in the rear if my theory about the ride quality doesn't pan out.

[CG]

The pic you posted is a nice height. A little extra ground clearance and easy entry and exit for you and your passengers.

I am curious now how low you can go in the front with the 67-72 4x4 suspension. Obviously tire and wheel choice is a limiting factor. I wonder what else "hits" to limit lowness.

[Ziegelsteinfaust]

To increase the ride quality. If smooth is what your after.

Get a leaf with as many leafs as possible. A factory load 2 leaf pack will ride rougher then a 5 or 8 leaf pack.

Also make sure the shackle is vertical or slightly angled towards the other side of the leaf. Of the leaf is pushing the shackle all the way back. This will make the leaf buckle which reduces ride quality

[franken]

You need to match the diff ratios in front and rear, but I imagine you knew that.
I'd look in the scrapyards for a K20 front diff, springs, and frame shackle mounts. As to the diff used originally in a 72 K20, I can't answer.

[Richard]

The stock front axle in a K20 would have been the Dana 44. Later trucks, Suburbans and Blazers/Tahoe's would use a corporate 10 bolt. All the way into the 90's. As you are adding the axle year does not matter if complete. There are slight differences. You could step up to the Dana 60 which was used in one tons. The passenger drop D60's are getting really hard to find. I am having a new one built to my specs for various reasons. Do not think it is really necessary for your application. Stronger is always better, your call. Looking at what you have and want to do. If it was mine I would do coilovers in the back with air assist bags for load handling. Would require some custom fab work. You are probably going to need some custom fabbed coils for the rear in any case.
More leafs does not mean a better ride, sometimes just for load. Many thin leafs equal better ride, more spring movement and longer life. Sometimes the individual leafs are different thickness. That is what you get with the higher end spring manufacture's

[richard2717]

Originally Posted by CG

The pic you posted is a nice height. A little extra ground clearance and easy entry and exit for you and your passengers.

I am curious now how low you can go in the front with the 67-72 4x4 suspension. Obviously tire and wheel choice is a limiting factor. I wonder what else "hits" to limit lowness.

I would keep in mind oil pan to axle clearance as well

[FLYNAVY30]

Originally Posted by Richard

The stock front axle in a K20 would have been the Dana 44. Later trucks, Suburbans and Blazers/Tahoe's would use a corporate 10 bolt. All the way into the 90's. As you are adding the axle year does not matter if complete. There are slight differences. You could step up to the Dana 60 which was used in one tons. The passenger drop D60's are getting really hard to find. I am having a new one built to my specs for various reasons. Do not think it is really necessary for your application. Stronger is always better, your call. Looking at what you have and want to do. If it was mine I would do coilovers in the back with air assist bags for load handling. Would require some custom fab work. You are probably going to need some custom fabbed coils for the rear in any case.
More leafs does not mean a better ride, sometimes just for load. Many thin leafs equal better ride, more spring movement and longer life. Sometimes the individual leafs are different thickness. That is what you get with the higher end spring manufacture's

Thanks Richard, out of curiosity, who are you having build the Dana 60 for you?

[CG]

How would you handle the lift in the rear to level out the ride? I heard the DIY B52 kit your talking about gives a little bit of a lift. Actually have read conflicting info on the actual amount, two inch, four inch?

Back when I had 4x4's I tried contacting them via their website and never got a response. I tried calling and leaving a message but never got a call back. Could have just been bad timing on my part I suppose.

[Richard]

Originally Posted by FLYNAVY30

Thanks Richard, out of curiosity, who are you having build the Dana 60 for you?

East Coast Gear. I am getting a high pinion D60 for just a bit more than Boyce would have cost me for the standard version. Currie and Dynatrac are two times the cost and both were not interested in doing a passenger drop axle for me.

[Richard]

Originally Posted by CG

How would you handle the lift in the rear to level out the ride? I heard the DIY B52 kit your talking about gives a little bit of a lift. Actually have read conflicting info on the actual amount, two inch, four inch?

Back when I had 4x4's I tried contacting them via their website and never got a response. I tried calling and leaving a message but never got a call back. Could have just been bad timing on my part I suppose.

The DIY B52 kit itself provides about 1" lift when used with the 6" shackles (2" longer than stock). Lift is determined by spring. Many use salvage yard 52" rear springs which typically nets 4"-5" with the kit. Do not know of any off the shelf spring that would net a 2" lift.

[FLYNAVY30]

Originally Posted by Richard

The DIY B52 kit itself provides about 1" lift when used with the 6" shackles (2" longer than stock). Lift is determined by spring. Many use salvage yard 52" rear springs which typically nets 4"-5" with the kit. Do not know of any off the shelf spring that would net a 2" lift.

What off the shelf 52" spring options are available? It sounds like 1" higher via just the DIY B52 kit is where I want to be.

[CG]

This is where the conversation about the B52 confuses me. You get a one inch lift automatically via the 6 in shackles which are two inches longer than stock. Can you not use a shorter shackle with these like maybe 4 in? And lose the shackle lift and maybe even go negative by an inch (that sounds impossible lol)? Next pick up a set of totally stock, no lift built in, 52 inch springs and then be really close to the two inch overall height over the stock burb height?

I hope that made sense LOL!

[Richard]

Using optional 4" shackles (same as stock) would make the kit net 0" lift. To get an idea of what the length of a shackle does look at the aftermarket rear shackle flips. The new bracket and compression shackle drops the rear of spring a whopping 8" to get the 4" lift. Moving only one end of spring nets half of lift or drop.

Chevy never used a 52" spring in the front of consumer trucks. All the 52" are from the rear and will have more arch due to them using a tension style shackle. Stock rear replacements will still net 4" with kit and 4" shackle. Least expensive option would be to pick up a pair of salvage 52's, they have probably sagged. See were they sit. You can have them de-arched to fit your needs.

Other option is custom springs, probably $600-$800 pair. I think Ford did use a 53"-54" on the front of F250's, they are pretty flat. Used on TTB and straight axle. Might be something to look into. With the springs being a bit longer the rear shackle mount position would most likely need to be adjusted.

You are in the full custom category with what you want to do. Not much off the shelf will work.

[FLYNAVY30]

so it sounds like just going with a completely stock set up in the front may be the way to go. I was under the impression the 52 inch springs would ride better which is the only reason I was looking at the B52.

[CG]

This is one of those things Ive always wondered about. Look forward to seeing you do this. Soon right? LOL.

[FLYNAVY30]

"Soon-ish"....within the next year. In a perfect world, I'd just pull the body off the frame and slide a Roadster Shop RS4 frame under it....but I'm a little short of the $50K required for that evolution.

Given my intended use, I figure going with mostly factory K20 stuff is the best way to go. I'll probably post another thread over in the 4x4 section to pick up some additional traffic from the guys that dont frequent the Suburban board.

[Mike C]

Using 73-91 springs gets you a little more length. For what you are describing for usage is just run an 8.5” 8 lug 10 bolt in the front.

[Bmdully]

I’ve got a 72 K20. Dana 44 up front. If you need pictures of the rear setup let me know. I think it’s stock. Sits awesome. I know I can see the leaf spring part numbers up front, but haven’t crawled around the back lately.
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[FLYNAVY30]

Originally Posted by Bmdully

I’ve got a 72 K20. Dana 44 up front. If you need pictures of the rear setup let me know. I think it’s stock. Sits awesome. I know I can see the leaf spring part numbers up front, but haven’t crawled around the back lately.
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Thanks for the info....so dumb question...are all Dana 44s the same width, or do I need to ensure I find one (if I go that direction) from a 67'-72' K20 to ensure everything is in the correct spot?

I look forward to getting settled in Austin and meeting up with MikeC as he has much more experience building these old trucks with 4wd than I do!