Spungie Rear End

[Kiqman]

I have an 89 k5 with chevy's "wannabee Dana 44" in the rear. I'm guessing it came stock with 3.73 in there? I run a 3"inch suspension lift and 33" tires. For power I have a built 383 with the TBI. Anyway...when I step on the gas from a stop it almost feels like I'm getting tons of backlash from the rearend before the tires start to move. Aometimes around corners I swear theres slippage. Does this mean I need new gears? Can the rearend just be adjusted? Could it possibly just need to be filled with oil? All of the threads I'm looking at are saying, "don't open it up yourself". I've worked on a ton of stuff on my 4x's over the years but never been inside a diff. Really not sure I want to do the whole, "find a 3/4 axle from the junkyard" thing.

 

[R72K5]

find a 14 ff in the yard

youll be fine with it, no worries

im not sure what kind of slippage you mean

either is gonna be gear backlash slop or a u joint is worn out and slopped
one or the other

easy to check by hand just get under truck whit it parked level and yank on driveshaft near u joint in a couple different directions try to get slop movement out of the u joint
if nothing then grab drivesahft somewhere and try to rotate one way and then the other, if its slopped somewhat then its ok, if its slopped a ton back and forth then you have a diff problem

its probably a gov lok anyways so id be getting rid of it either way and go for a 14 FF or d60

14ff are had for 150 or 200 tops, dont give more than that for one, they are too common still.

find a parts truck for that much with axle and all and have a better deal overall, leave your name and number notes on houses where 3/4 or 1 ton 2wd or 4x4 trucks are parked, abandoned, bad or no plates, not running, whatever, etc, you would be surprised what you can end up with for real cheap, also go to all repair shops in town asking about any known unwanted trucks needing to be hauled off cheap,. and towing places arond town sometimes will sell parts for cheap, if you ask them right, most of the time a rig thats sitting can be had for less than 100 if the ppl just want to see them removed immediately


good luck

 

[Kiqman]

Swapping 10bolt to a 14 bolt

So I can just pull the whole rear axle out and replace it with a working 14bolt without any fab work? I think my 10bolt has 3.73...what would a 14bolt have? Running 33's what "should" I have? Do I have to swap out my 10bolt front axle too or can I run a 14bolt rear with a 10bolt front? The slippage I mention was called "waffling" by the last shop that had it in (replacing rear driveline U-joints). They made it sound like they could maybe adjust the rearend? When you step on the gas from a stop it's like the rearend has to break free from a frozen position...like it's really loose inside the diff. Is there any "middle ground" with a diff? Or when they act up at this age are they in need of replacement? Oh and what's the difference between a "ff axle" and one that's not "ff"?
I love this fricking site

 

[mikey_d05]

So I can just pull the whole rear axle out and replace it with a working 14bolt without any fab work? I think my 10bolt has 3.73...what would a 14bolt have? Running 33's what "should" I have? Do I have to swap out my 10bolt front axle too or can I run a 14bolt rear with a 10bolt front? The slippage I mention was called "waffling" by the last shop that had it in (replacing rear driveline U-joints). They made it sound like they could maybe adjust the rearend? When you step on the gas from a stop it's like the rearend has to break free from a frozen position...like it's really loose inside the diff. Is there any "middle ground" with a diff? Or when they act up at this age are they in need of replacement? Oh and what's the difference between a "ff axle" and one that's not "ff"?
I love this fricking site

If the 14 bolt is out of a 3/4 ton yes, if it is out of a 1 ton, no. 14 bolts can have pretty much any gears. I have 4.56's but they came from a military truck. I think a lot came with 3.73's and 4.10's. The gears you should have depend on what you're going to do with the truck. I have 3.73's and 33's on my DD and I like it a lot, it's a good compromise, but it's not for everyone. You don't have to swap out your 10 bolt front to use the rear, but a 14 bolt full floater will have 8 lugs, whereas your front axle should have 6. This can be fixed by either mixing rims or finding a 3/4 ton front axle with 8 lugs also. Remember too that you need the same gears front and rear to keep from having big problems when you shift the t-case into fun mode. If there's noticable slop in the rear end, there's really no adjusting you can do unless the gears were set up REALLY badly in the first place. In that case they would probably be damaged anyways so you'd need new gears. I would have leaned toward the u-joint explanation but it sounds like you already had that covered.

The ff that you often see next to 14 around here means "full float". It's a particular type of axle design that's much stronger than some other. Full float simply means that the axleshafts are transmitting torque and not bearing any weight. Semi-float is the other type, which means the axleshafts are carrying the weight of the vehicle as well as transmitting power.

 

[mini_mull]

Could this just be axle wrap? from 383+soft lift springs Or maybe I'm not understanding what he's trying to explain, or maybe I'm just in over my head and making a fool of myself?

 

[Kiqman]

How much is too much

"grab drivesahft somewhere and try to rotate one way and then the other, if its slopped somewhat then its ok, if its slopped a ton back and forth then you have a diff problem"

When I grab the driveshaft and try to rotate in “park” it turns quite a ways in both directions. It does come to a definite stop though where I can’t turn it further. I would say it moves a bit more than a vehicle should when it’s in “park”.

What causes this? Does this mean my rear-end is going to go out? It’s not making any noise? I’m afraid I’m going to step on the gas at a stoplight and leave my pinion on the pavement? Once I’m moving though it feels fine?

 

[dyeager535]

The open differentials I've seen that have a lot of play in them have tons of slop/wear in/on the pinion gears. Worn out thrust washers especially. They "walk" when the pinion is rotated resulting in quite abit of yoke/driveshaft movement before they "catch up" to the driveline input.

Only way to verify/check that is to pull the cover and look over the innards very closely.