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View Full Version : 3/4 ton axles over 1/2 ton?



STIgary
10-17-2010, 05:29 AM
Here is the deal. I got a 78 k5 with stock everything, including axles, gears etc. I have the opportunity to buy an 81 suburban for like $200 and the only real thing wrong with it is that its got a bad motor. I plan to take ANY pats i can and dump the rest of the truck but my main question is this. Would it be worth it to swap in the 3/4 ton axles/leafs over the stock k5 axles/leafsprings(no d44 up front)? and would the gearing be any better in the 3/4 tons than the 3.72s that are in there now?

I am running a t350 tranny and an 8" lift w/37s. thanks gang
-Gary

bmpskir
10-17-2010, 03:26 PM
well, it sounds like it would be well worth having a burb short of an engine for $200... there should be plenty for your K5... check to see if the gearing codes are in the glove box or pull the covers and look for the markings on the ring gear... that will tell you if they are higher than 3.73s... but if you have straight stock stuff are you sure they are not 3.42s or have you already upgraded or did you get lucky?

GREY-GHOST
10-17-2010, 03:33 PM
The only thing different between a 1/2 ton and 3/4 ton front is that the 3/4 is 8 lug. The rear could be either a 14sf or a ff. Both are better than the 10 bolt thats back there now. It might have lower gearing, but check before you swap. The rear springs will not fit because they are 56s, the blazer springs are 52.

STIgary
10-17-2010, 05:03 PM
Well, my grandfather swears up and down its got 2.72s so...

70-K5
10-17-2010, 05:17 PM
Your first post said 3.72's, I think I remember a while back we figured out you had 2.72's. If that is the case AND you're running 37's, damn that thing must be a slug, or you've got one hot motor in there...

I think 3.73's with 37's and a th350 would be a pretty good match, 4.10's would be better. 4.56's would be a bit high for fast driving on the freeway.
Got any pictures?

STIgary
10-17-2010, 05:51 PM
It's actually not driving yet because we keep running into new issues like broken leafs, seriously stuck bolts inside the bushings ferrels, missing parts from rough country. They told me I didn't need to drop the tcase for a 6" lift but it turns out I do. They said the "reccomend" extended brake lines but turns out they are "required". Not pleased with them at this point. Still don't see how this drop transfer case bracket will work considering the tcase goes directly into the tranny

STIgary
10-17-2010, 05:55 PM
Plus, even though the ass end isn't together yet, I'm pretty sure it's going to sit lower than the front (6" springs in front, 2"add a leafs & 4" blocks in back). To me, I don't see how these add a leafs will add 2"

70-K5
10-17-2010, 06:08 PM
Did you go through Joey for your lift kit?

Also, it sounds like you are confused on your t-case drop. It is really easy to do and you don't need to purchase anything to do it. The spacers are already on your rig.

STIgary
10-17-2010, 06:31 PM
I had already purchased the lift from RC but I will end up getting new gears and such. How do I drop the tcase with said kit? Any way around the extended brakelines?

70-K5
10-17-2010, 06:38 PM
For the brake lines you can move the hard line below the frame rail and just use your stock length ones, I tried this before I swapped the axles and it didn't work too well... New brake lines are really the way to go.

As for the t-case drop get on your back and look at the cross-member. You will see there are four bolts that are holding it to the frame. Now look at the top of the frame rail and you will see that the bolts are 2" long and there is a spacer between the top side of the frame and the nuts. Throw a floor jack under the cross member, take these four bolts out, lower the jack an inch or so, replace the bolts but this time put the spacers between the cross member and the frame, viola! t-case is dropped.

You can also get some blocks with the holes drilled in the right place.

STIgary
10-17-2010, 06:45 PM
Huh, interesting. And this 1inch drop is enough for 6" of lift? Thx again for your help

elecdust
10-18-2010, 03:41 AM
Huh, interesting. And this 1inch drop is enough for 6" of lift? Thx again for your help

No, it's not going to be enough for the 6" lift. I have a 4" Rough Country full spring with a Rancho add-a-leaf and I get some hum from the U joints. I think 6" will be some major hum from the joints.

Skin-K5
10-18-2010, 03:44 AM
Drop will be enough but you may need to shim the rearend a degree or two to get rid of the hum. Another trick is to drop a CV joint in your driveline.

WARWGN
10-18-2010, 04:13 AM
does the suburban have rear A/C, if it does I will give you $200 if you let me rob all the stuff related to that off of it. I would drive over to you and pull it all myself!!

Ahays000
10-18-2010, 05:03 AM
I have a 6" lift on mine, I dropped the t-case 1.5" using the tough country kit (about $30) and it is working out well with the correct pinion angle.

My brake lines are stock, just moved under the frame. They do work, but I noticed when the suspension is flexed they are pretty tight so I am going to replace those soon with longer ones.

as for the rear add a leafs, they really will give you 2" of lift, I used them on an 86 k10 before. Not only do they add almost an inch in thickness but they re-arch the springs to give it more lift.

Have a little faith in rough country, with a few tweeks everything should work out just fine for you.

STIgary
10-18-2010, 05:49 AM
Thanks gang.
Warwgn, if you say 200 is fair, ill trust ya and it's yours. However, the burban is 60 miles away from me and I don't even know if it's got it but I will check and pm you with details.
Back on topic a little bit, anybody want sone 3/4ton axles for cheap?

WARWGN
10-18-2010, 04:05 PM
Thanks gang.
Warwgn, if you say 200 is fair, ill trust ya and it's yours. However, the burban is 60 miles away from me and I don't even know if it's got it but I will check and pm you with details.


Thanks, I guesstimate that is close to half of what it would cost to get new parts from LMC and pick a parts combined??

STIgary
10-18-2010, 04:06 PM
Well, I'll find out if it's got it and if it works. If it does, it's all yours. I'm located in monument Colorado.

Ahays000
10-18-2010, 04:46 PM
dude you should definitely keep those 3/4 ton axles for your truck... especially if you have 2:72 gears!

bmpskir
10-18-2010, 04:56 PM
yeah - isn't that the main reason why you are picking up the burb?

WARWGN
10-18-2010, 05:31 PM
Thanks gang.
Back on topic a little bit, anybody want sone 3/4ton axles for cheap?

think he meant "1/2 ton axles for cheap"?

STIgary
10-18-2010, 05:40 PM
If it was worth it to swap axles, then yes. But I might just throw the gears in.

STIgary
10-18-2010, 05:42 PM
I gotta find new wheels again if I swap in the 3/4 ton axles too.

bmpskir
10-18-2010, 06:03 PM
well, if the rear is a sf or ff 14 bolt, the gear will not work in the 10 bolt you have - way too big... and it is much easier to swap axles than gears...

STIgary
10-18-2010, 06:41 PM
Well, maybe I'll do that then. Are they stronger than the stockers on there now?

bmpskir
10-18-2010, 06:56 PM
yes - definitely! especially the rear, but you need to change both so your gearing will match... and you will need 8 lug rims that will come on the burb... but yeah - the axles are going to be one of your biggest upgrade options for getting the burb...

70-K5
10-18-2010, 07:21 PM
I'd think it would be way cheaper to use the Burb's axles assuming they can be run as-is (no rebuild needed) and find new wheels and tires than to re-gear your current axles.

Ahays000
10-18-2010, 07:30 PM
won't the brakes be bigger too?

bmpskir
10-18-2010, 07:42 PM
on the rear but not on the front... which is a good thing, no?

WARWGN
10-31-2010, 01:23 AM
well how is this project going? and does it have rear a/c on that burb? Did you figure out if your gonna get those axels?

jackedjimmy72
10-31-2010, 03:46 AM
First off 4.10's would bring you closer to stock grearing. I'm running 38" swampers with 4.56's and my speedo is back reading what it should. 3/4 ton swap is easier than changing gears. Front big hub 44 from that burb does have bigger bearings and hubs that the 1/2 ton 44 that you are running. Second the rear 14 bolt does have bigger brakes that will help ya as well. That 4" block with 2 add a leafs will ride like crap. I'm running a 6" block and a add a leaf and its level with my front 6" springs. Your truck will be sagging in the rear. Oh and my 6" block makes it ride like crap too. Also like all else were saying driveline angles will be a little off. Do the tranny/tcase drop and you'll probably need to shim the rear end as well so that the pinion angle matches the angle the driveline is coming out the back of your t case. Do those extended lines in the front to be safe or the drop brackets. Oh and your drivelines might be a little too short but you'll find out after you do the lift. You can deal with the front but the rear needs to be good length or it'll vibrate and probably overextend. Find a driveline from the rear of a short bed chevy k20 or k10 and get the 1310-1350 crossover u joint if you need the conversion.

GREY-GHOST
11-01-2010, 01:27 AM
I'm running a 6" block and a add a leaf and its level with my front 6" springs. Your truck will be sagging in the rear. Oh and my 6" block makes it ride like crap too.

You aal is making it ride like crap, not the block.

Skin-K5
11-01-2010, 05:04 AM
Maybe he has those air blocks and they are pumped up to tight....

Ahays000
11-01-2010, 05:09 AM
I have a 6" block in mine and other than axle wrap it rides pretty nice... I had a k10 with add a leafs on all corners and damn was it harsh!

jackedjimmy72
11-01-2010, 02:50 PM
Guess I'll have to eliminate both since removing the aal will make the ass sag. What you guys don't have the air ride blocks? Jeez get with it haha.

Skin-K5
11-02-2010, 04:10 AM
Damn Coasties anyway....

jackedjimmy72
11-02-2010, 07:28 PM
Hah no doubt. Always joked well we're here instead a college so that says something...Old joke about the Army. When you look down at your blouse and read US ARMY upside down. Yes My Retarded Ass Signed Up, dude that left the Army for Coast Guard told me that one.

monsterbowtiev8
11-11-2010, 07:31 AM
i would stick with half tons if you dont want to take all the work to swich to 3/4ton...i would just change 10 bolt rear out to a 12 bolt heavier duty axles but still half ton....the 3/4 ton is only different in the rear...14 bolt is WAY!!! heavier duty than half ton....BUT on other hand front 3/4 ton is just a half ton with bigger spindals and the dana44 has just a little bigger axles...im running 12 bolt and d44 and no probs with 38s...4 speed no prob with t350 you would have no prob with half tons breaking them unless running like 400hp and doul cases

STIgary
11-12-2010, 02:26 AM
Thanks. I was really hoping to find out it had a 14bolt and a d44 with 4.10s but it looks it's got the same as the blazer.... Bummer

jackedjimmy72
11-12-2010, 05:05 PM
Well if you ever need to re gear the truck it's cheaper to find a set a axles with the gears you want than to pay someone to swap out your gears. Takes a day to swap em with 2 people. Run yours till you break em!

STIgary
11-12-2010, 06:03 PM
I would bug I'm likely to break something else running 37s with 2.73s in there.

jackedjimmy72
11-13-2010, 06:32 AM
2.73's? Man you must get good mileage. You go lower and it'll feel like a new truck.