Rear End Diff

[Broncobill78]

and back to the other problem i am having trouble understanding is what is the point of unlocking your front hubs?
why wouldn't you just always have them, ready standing by waiting for the 4 wheel drive?

Well, it's an issue of wear. A lot of times you'll leave them locked for long periods during winter just so you're not jumping in $ out of the cab to lock & unlock them but basically it's to keep the wear down. Everything lassts longer if the tires are allowed to freewheel & only locked to the axle when you need to apply power. Letting them freewheel allows for less friction & somewhat better milage (although not a whole lot).

The old Blazers used to be full-time 4WD but most owners would retro locking hubs so they could unlock them & keep the wear down. You CAN keep them locked all the time if you want but if you do then you need to do maintenance on them more frequently as well as the front end U-joints. By keeping them unlocked most of the time you avoid putting the hours on the frone end parts.

JSM, Damn, you're right. It's been so long since I bothered to do it myself /emoticons/[email protected] 2x" width="20" height="20" /> I just assume most of the trucks that I wind up with are either open or so old the clutches are dead so I really don't worry about it until I install a locker & then I go back to not worrying about it.. I'll go back & edit the earlier posts. My bad for not cking first, that's what I get for relying on an aging memory.

 

[Justshootme84]

Here are a few good articles about open diffs, limited slips, lockers, etc. The links are available on Miesk5's Homepage as well:

http://www.off-road.com/offroad/article/ar...l.jsp?id=285534

http://www.drivetrain.com/difwhatthedif.html

http://www.technicalevolution.com/faqdiff.htm

The last one explains why the tires do indeed turn opposite directions on an open differential when both wheels are off the ground, JSM84

(I've copied this reply to a new sticky on "axle tech" for quick reference.)

 

[madmax]

i don't understand this part
if you have limited slip on the front you wouldn't ever be using it with out 4 wheel drive right? or am i missing something

i don't understand if the front is limited slip why wouldn't you need 4x4 as much?

all i was pointing out was that if you have a limited slip front then you almost definatley have a limited slip rear.

If youve got a limited slip rear then you don't need 4X4 as much, because you've got more traction, in 2 wheel drive than an open diff.

 

[jsomedaysoon]

all i was pointing out was that if you have a limited slip front then you almost definatley have a limited slip rear.
If youve got a limited slip rear then you don't need 4X4 as much, because you've got more traction, in 2 wheel drive than an open diff.

they are right about the extra wear on the front end when you leave the front end engaged. my 88 blew the rear drive shaft so i just took it out and locked in the front hubs and ran it as front wheel drive for like 6 months. pretty much everything in the front end went to crap in a hurry.

 

[madmaysey]

ok so i got my bronco, under the axle code it says H5 not I9 or H9

what?!?

 

[Broncobill78]

Well if it's an H5 axle then you are indeed a lucky man. H5 is the code for an 8.8" with 4.10 gears & a limited slip differential.

http://www.ford-trucks.com/article/idx/0/0...ode_Chart_.html

 

[madmaysey]

is the 4.10 more of a street gear set up than the 3.55?

and does the 8.8 have an signifance?

 

[Jersey]

while not totally useless 4x4 with out atleast one limited slip diff is kinda pointless isn't it?
and i have heard from multiple sources that confirm that on LSD's you spin one tire and the other spins the OPPOSITE way...open diff they spin the SAME way....sounds kinda backwards but i have seen it first hand

with the wheels off the ground, an open diff will spin the opposite way of the wheel you are turning. Thats just the way the spider gears react off load with no restrictions. With a trac-lock diff, technically they should spin the same way once the rotation of one tire exceeds the rotation of the other. Thats when the clutches kick in and "lock" the two together. Easiest way to tell is go in the dirt, mash on the gas from a dead stop, and see how many marks you leave. open is one, trac-lock leaves two. Unless the clutches are broken, which happens more often than not.

 

[Broncobill78]

The 4.10 is a much better gear if you ever run a larger tire. The 3.55 is the *standard* gear that 90% of the trucks come with. With 4.10's your truck is quicker off the line than the exact same truck running 3.55's and if you choose to run 33" or 35" tires you won't suffer any performance loss. In fact, if you're running small 30" tires you'll see an increase in your milage if you swap to 33" tires because the engine will be runing closer to it's "optimal" RPM's. When most of us swap to larger tires we have to swap gears as well because changing the tire size changes the final gear ratio and throws the engine out of it's optimal powerband. By changing to 4.10 gears you bring the engine back into it's best operating rev range and you milage and performance increase. If you're running 30" or 31" tires you truck is very quick off the line but by the time you get to cruising speed the enging is revving higher than it would in a truck with 3.55 gears. These extra revs cost you milage. To bring the engine revs down you can either swap to 3.55 gears (insane in my book) OR swap to a 33" or 35" tire. You can run the 33" tire stock without a lift kit or trimming the fenders but the 35" tire will put you closer to the optimal powerband. The bottom line here is that if you run a larger tire you will see your rpm's drop at highway speeds and this will translate into better gas milage because you aren't spinning the engine as fast. The 4.10 is a very coveted ratio *because* it allows you to run the larger 33" tires without suffereing any performance or milage loss and it actually results in *better* overall milage and performance.

The 8.8" has no real significance as far as you're concerned. It just means that you have an 8.8" rear axle which is the same axle that all modern Bronco's & F-150's have. The older trucks came with 9" axles but those were phased out back in 82'. All it means is that you have the standard axle.