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School me on axles please

MEMO43

MEMO43

1/2 ton status
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Mar 24, 2018
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Location
Gardenrville NV
So my son wants to convert his 14 bolt semi float and go 14 bolt full float on his rig. Something about carrying more/ hauling more etc etc an he says its safer as well.
His rig is an 86 k20 we swapped the engine to an L31, summit racing max efi system
front axle is 12 ( correction dana 44) bolt with 4:10 gears.
trans is a th400 he eventually wants to swap a 700r4, he already has an L29 lined up to swap in.
rear is 4:10 as well, he is running ko2 33x12.5r16.5
He doesn't tow yet heck he is still 17 almost 18.
It's his daily driver, he works at a local 4x4 shop
I dont want to discrouge him I just want to more know why the peak in interest.

Thanks in advance
 
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Thanks for the reply
Are there any real advantages to having a full float at all, I understand the whole axle shaft not being retianed by the C clips an what not.
is there a major strength difference.
What trans is best kepp the th400 or go something more modern an run a stand alone system if it's a 4l60e, 4l80e
 
The ff has better wheel bearings, and axle retention.
You 2 bearings per wheel. Instead of a U clip slipped on to the inside of diff to hold the axle, there are 8 bolts in the hub.
He would need to swap the housings. Not difficult or that costly.
 
FF is definitely heavier, heavier duty. One should ask if it’s a needed cost. Expect a drop in fuel mileage as it’s a less efficient axle

the first choice for me replacing a th400 behind an L29 would be the 4L80e that they often came with, which can be controlled by the L29 ECM
The 4l60e is a glorified th700, often supplied with 6 neutrals
 
If he does swap to a full float consider the later model AAM 10.5. Same basic axle except factory disc brakes with integral e-brake. Look for early 2000's 3/4 ton work trucks with a 6.0L engine. The diesels got the AAM 11.5, not what you want. I put the AAM 10.5 in my K5, its great. Cost me $200 for the axle, another $200 or so for all new brakes and I put in a detroit locker. You do need to move the spring perches, different frame widths. Lots of guys swap in a full float 14 bolt and then want to disc brake swap, which then leads to e-brake issues. You get it all at once with the AAM 10.5 and its a factory engineered brake package. I tend to agree that he doesn't need a full float but as a guy working at a 4x4 shop he will certainly want to do some upgrades. Its a worthy project, I have done it to several of mine over the years.
 
If you break an axle in semi float on the trail you are pretty much screwed. Bust an axle on ff remove the broken part and roll in out.
 
Ask how many have broken a 14SF, outside of some known (pinion bearing?) issues some of them had from the factory at one point.

Think I recall one person on here that's broken a 14SF.

It's definitely not 14FF strength, but the penalty in clearance and weight for the FF is pretty high, comparatively.
 
I beat the nuts of my semi float on 37's with a locker. Never had a problem. It's still living under my K5 with the same setup.

@Richcz28 broke an axle shaft on his semi float locked on 35's.... with a 6.2 and a manual. So. Depends on who you ask and what you're doing with the truck...
 
There are worse things your son could spend his money on. My 76 had a a 14 bolt FF and I beat the snot out of it, never had a problem one. And it was a 2wd and went places some 4wd had problems with. He's 17 and WORKING so if he wants to spend some of his hard earned cash on a possible upgrade... He's working at a 4x4 shop, it's going to be hard to not get the itch to upgrade something on his rig.
 
thanks everyone for the replies
I will show him this thread an see where he wants to go from there.
Like I mentioned earlier I don't want to ever discourage him from wrenching or learning. But more to show him different options.
I've always told him to build them for a purpose versus what someone else thinks I'd cool.
heck not so long ago he was wanting to do a 5.9 swap, now he wants to go the Big block route.

few pics of him learning how to do engine swaps an how amazed he was that once it was done over the span of 2 days in 40 degree temp and not all that complicated

20210313_123718.jpg

20210327_210511.jpg
 
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If potential customers come into the 4x4 shop asking about upgrades, its always nice to have some of the potential upgrades you are recommending on your own truck. If I was going to a shop and wanting to have upgrades done, I would ask the folks working there what they have done to their own trucks. Helps sell thats its a good upgrade that they should pay the shop to do for them.
 
I mean why not just send it lol. If the name of the game in 4x4's was practicality, the most practical thing would be to use the nicely paved streets we have crisscrossing the nation in little fuel efficient sedans :haha:
 
TJ1978 said:
The only axle I know of was in a crappy overplayed band that made a record in like 1987. Then another equally bad double album named use your illusion.
Click to expand...
They sucked in concert too. They came on way late, drunk and high AF. Good thing I paid for the other bands that opened for them
 
Joel Wilson said:
They sucked in concert too. They came on way late, drunk and high AF. Good thing I paid for the other bands that opened for them
Click to expand...
When appetite hit it was enjoyable for a bit. But every song is played to death on "classic" rock radio. To me, just an overhyped and entirely overplayed one album band. Axle sang like crap and his ego didn't do them any favors either. They've been coasting on that records success for 30 years.
 
Diving back into the axle debate. If the kid wants to swap it's a good project for a budding truck guy to do. There really isn't much downside to a 14bff other than the reduced clearance due to the massive housing. Strength is better as others have said. No worries of a wheel coming off if a shaft breaks.

Depending on what axle he finds he might have to move the spring perches and shock mounts which are good projects for the kid to do.

If he finds one with the wrong ratio he will get experience on gear setup too.

I say go for it!
 
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