7.5" open to limited slip conversion?

[CraigK]

I have a plain vanilla 44 (Ford?/Dana?) open 7.5" 3.73 rear axle on my stock '87 Bronco II 4WD AT. I can get stuck in winter in my gently sloped driveway, and would like to upgrade to a limited slip rear end for snow and poor traction situations. I do not plan competition or intense off-road use. Cost and ease of conversion are critical. What options are available? I am new to this site, and looked in the tech sections, viewed archives, ran searches and was not able to find info on what I thought would be a common upgrade. Any insight will be appreciated. Thanks.

CraigK

 

[Twizzler09]

I'd avoid running limited slip in snow and bad weather, mainly because if your right-rear loses traction, your left-rear quits moving, which means you lose forward momentum. With snow especially, losing forward momentum when your trying to get up a driveway is a bad thing. Personally I'd go with a locker or something running positrack. I know your running 4x4, but I'd rather keep all 4 tires moving, then having one cut out, and then I lose all rear-power.

Thats my suggestion/opinion, others may feel differently about it.

Have to wait for someone else to come in though, they know more so than I do where to find decent parts and such.

 

[kunar]

I'd avoid running limited slip in snow and bad weather, mainly because if your right-rear loses traction, your left-rear quits moving, which means you lose forward momentum.

No, no, no....thats how an open diff works and thats why he has the problem he does. if you have a l/s rear, it *should* keep both rear tires spinning even if one looses traction, but only in low traction situations. on a dry road, it will allow them to spin at different speeds (think cornering) having a l/s rear over an open will be a significant improvement. i would recommend hitting up your local junkyards and looking for an entire axle assembly thats the setup you want. it is a fairly easy swap, even for the backyard mechanic, and the entire thing can be had for around $100, at least in my area. another option would be a locker, which could go in your current axle/carrier but youre gonna pay more for it and its overkill for (and actually more dangerous in) snow or rain. hope this helps...

 

[AllanD]

And the rear axle in an early ranger isn't a dana anything, 44 or otherwise...

The rear axle is a ford 7.5" and limited slip diffs ARE available.

Limited slip IS the same thing as "posi" (GM's name for limited slip)

what is being described as one wheel spinning is the behavior of an OPEN diff.

AD

 

[MAKG]

Also FYI, a worn out limited slip diff behaves EXACTLY like an open diff.

Though it's relatively easy to rebuild these in MOST cases. On 7.5s, some gear ratios (I believe 3.73 and numerically higher) become complex, as the side gears won't come out of the carrier with the ring gear installed.

 

[dirtraider]

I'd avoid running limited slip in snow and bad weather, mainly because if your right-rear loses traction, your left-rear quits moving, which means you lose forward momentum. With snow especially, losing forward momentum when your trying to get up a driveway is a bad thing. Personally I'd go with a locker or something running positrack. I know your running 4x4, but I'd rather keep all 4 tires moving, then having one cut out, and then I lose all rear-power.

Thats my suggestion/opinion, others may feel differently about it.

Have to wait for someone else to come in though, they know more so than I do where to find decent parts and such.

I'd suggest you don't give your opinion when you don't know what you are talking about...

That being said, its going to be a lot more work to swap in a L/S because there are no insertable L/S's out there (opposed to an insertable locker like a lockright or something). I'd suggest you either use 4wd more, or upgrade to an 8.8 L/S axle....

 

[kunar]

or upgrade to an 8.8 L/S axle....

although i do believe the only *bolt in* for his b2 is another 7.5 form a b2. fairly certain the frame is slightly narrower so spring pads will need to be moved to use an axle form a ranger. (there never were 8.8 stock in b2's was there??)

 

[Twizzler09]

dirtraider, I also stated that others are more knowledgable than I am, therefore warning him that my information may be incorrect. One more thing, dirtraider, just because I may not know as much as you or others do, doesn't meant I can't share my opinion. If someone asks a question I will answer with the knowledge I consider to be true. When I'm wrong (as I *know* I will be) everyone FEEL FREE to correct me. But please don't be a dickhead about it, theres no reason to talk down to others that are still learning.

How would you feel if you answered someone's question and then someone else comes in and calls you a retard (metaphorically speaking, of course) and tells you to quit talking? *Most* people would say the same thing as I just did. Its a free country, I'll post up what I think is true, if I'm wrong, so be it, correct my mistake, but don't be all pissy about it. I'm not a dickhead to anyone else on here, including you, so show some respect and don't talk down to me, eh? Help the newer people to learn this stuff properly, and maybe there'd be less incidents like this.

Now, back to Limited Slips.

The reason I said what I did about l/s is because the 8.8" on my Ranger is supposed to be Limited Slip, but it behaves absoluetly nothing like the "definition" says its supposed to. Under low traction conditions you say both tires are supposed to spin... mine don't. As far as I've ever known, this is how all Limited Slips run. Under any low traction condition, if my right-rear tire loses traction, the left tire quits spinning altogether, unless I'm rolling forward, and the right tire sits there and spins for eternity. Its been like that for ages, ever since I bought it, actually. You say L/S isn't supposed to do the One-Wheel-Peel, yet my L/S does nothing BUT the one-wheel, time for a rebuild/new rear-end then? Thanks for the corrections though, everyone. I wouldn't have been able to make the distinction between open and l/s otherwise.

 

[dirtraider]

How would you feel if you answered someone's question and then someone else comes in and calls you a retard (metaphorically speaking, of course) and tells you to quit talking?

I'd feel pretty dumb, so i'd make sure i knew what i was talking about before i said anything.

The blind leading the blind doesn't make the world go round....

Nova, it doens't "split" the power persay, it locks the axle up so they get the same...however it does ratchet around corners making it a little more driveable than a spool.

However as with insertable lockers, they allow the drive shaft to move about 15 degrees before engaging the axles, so if the truck is a standard it'll become a pain to drive.

 

[CraigK]

Firstly, thank you to ALL that have replied. There seems to be a wealth of knowledge among posters on this site, and I appreciate the information and the learning.

I will probably not go to a "locker", as this just doesn't seem consistent with my 95%+ normal street driving use.

So my options appear to be:
- get a stock L/S Bronco 7.5" 3.73 axle (wrecker)
- get a stock L/S Ranger 8.8" 3.73 axle (wrecker)
(may be spring plate, shock mount and other issues?)
- get a stock open Ranger 8.8" 3.73 axle and add an after-market L/S kit
(may be spring plate, shock mount and other issues?)

Does this sound right? (No open-to-L/S kits available for the 7.5"?) The first option would likely be easiest, but I imagine these axles will be scarce.

Are the end flanges and flange bolt patterns that the brake components bolt to identical on 7.5" and 8.8", and on Bronco II and Ranger axles?

Any guidance on what I should pay for a L/S 7.5"/8.8" axle in reasonable shape?

Thank you.

CraigK

 

[MAKG]

IMO, limited slips offer a nice compromise between the 100% locked locker solution and the 0% locked open solution. Having locked axles has some highly significant consequences -- it becomes much easier to break an axle because you can shock load one side, and the rear end of the vehicle will "kick out" under power (as it tries to center the drive wheel).

Limited slips do both of these to a much lesser extent.

And frankly, that in a 7.5 (from a Bronco II) is all that is necessary for street driving. He's not rock crawling.

I'd go looking for a 7.5 in the wrecking yard, with a torque wrench. Try the breakaway torque test. Put the wrench on a lugnut set for 25 ft-lbs. Have a buddy hold the other wheel. Put the transmission or (preferably) transfer case in neutral, or disconnect the driveshaft. Crank the torque wrench. Click = good. Make sure the parking brake is off....

Not only are Bronco II rears a different width; they also have different offsets in the "pumpkin."

Do make sure the replacement rear has the same gear ratio (read the axle tags or count ring gear teeth) as yours or you'll need a front pig as well to use 4WD.

 

[dougs3.0L98]

my 98 ranger had an open 7.5 and i swapped in a L/S 7.5, i have 3.73 geas as well.

that extra 25% (or less cause i got my parts used) on the tire that has more traction helps out. if you flex it out it will still go to one tire spinning and one tire not moving at all but it was worth it to me. worth the money in my case.

my truck wouldn't back out of my driveway when it was wet and now it will with a lot of spinning haha.

 

[Evan]

I would personally recommend a No-Slip.

EDIT: The No-Slip will be very smooth on the road and will also give you 100% power to each wheel off road.

 

[Hahnsb2]

I would personally recommend a No-Slip.

EDIT: The No-Slip will be very smooth on the road and will also give you 100% power to each wheel off road.

They're not made for the 7.5...

 

[Hahnsb2]

Isn't that a locker? No slip sure sounds like one.

Yes, it's a very smooth and streetable lunchbox locker.