What a great site, just found it. I was a tad disappointed however, as several posts made it evident that I don't have a ls differential. I recently purchased a 2000 F-150 4x4 with Offroad 4x4 Group. And you can call me stupid (as this is my first truck but I should know better) but I assumed that was part of it...Seems like a reasonable marketing person at Ford would have thought of that. I mean someone who needs skid plates and heavy duty shocks...hmmmm...let's leave the limited diff out! I just can't understand that. Maybe they should leave out the 4x4 shifter/knob unless you actually request it.
Anyway, as I am not the greatest mechanic in the world, could someone tell me how difficult would it be for me to have the Ford dealership (maybe at 30k when I have to take it in anyone) swap out the diff? Seems like it shouldn't be that hard, I mean the axle doesn't have to removed, does it?
Also, regarding lockers, maybe someone should tell me whether I should blow by the ls and get a locker (after all, limited slip means just that - slip, then limited slip). Are Detroit Lockers and the like actual differentials, or devices that just lock the pinion shafts/gears so the side gears are locked to the case? Could a Ford dealership install that for me or do I have to find a truck speciality shop (I always worry about taking autos to places like "Crazy Cooter's Truck World" for serious jobs - would rather go to the dealership).
P.S. I'm sorry about the long post, please bear with me, as I don't have a clue, and you guys seem to have all the answers.
Could someone please help? Also, if you don't mind, maybe you could provide your email address so if I had to ask more specific questions I wouldn't have to bore the other members.
It would be alot easier just to replace the whole rear axle if you want to go from factory open to a factory ls. Dont know on your truck but many factory open and ls pumpkins are differnt inside. You really dont need lockers unless you are going to do some serious off-road driving. When the axle is locked both wheels will spin at the exact same speed. If you try to make a sharp turn while locked you will get alot of hopping.
buckdropper- You don't need to change gears to change a open differential to a posi unit. Do you really know people with 4X4s that only change rear gears; just curious?
cpadpl- If you change the whole rear end, you risk getting one that whines or a damaged unit; with a very substantial investment. You simply need a qualified installer to change your differential. There are several good units in the 8.8", but if you have the 5.4L/9.75", then you're limited to the OEM LS or the new Auburn unit. It is a perfect time to change the gear ratio if you prefer a different one, as the rear is torn down to that exact level. On a 4X4 though, you will also need to budget the front ratio change as well.
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2000 F-150 XL, RC, LB, 5.4L, 4R70W, 4.10LS,
Class III tow, Payload #3, & Convenience pkgs.,
4-wheel disc/ABS, Chestnut/Parchment 40/60,
Ford bedliner w/Paintsaver & gas/wheel/spare locks,
K&N F.I.P.K. w/Outwears pre-filter, Superchip,
Dynomax ultra-flow welded 3" cat-back w/ 3" Y-pipe,
Hellwig front & rear anti-sway bars, Rancho RS 9000s,
Pirelli Scorpion Zero 275/60/16s, Mobil 1, K&N oil filter.
thanx a million for the info. I have a 4.6L v-8 2000 4x4. As I'm sure you know, I have the 3.55 8.8 diff.
Let me ask you three more detailed questions:
1) Are the ls' really worth their while as far as functioning and reliability? Obviously, clutches wear out, I presume they can be "burned" out or overstressed. And as someone once said, "more parts means more to break." I know it sounds stupid, but at least with an open diff. I know what I've got so to speak (does that make any sense?)
2) Is there a safety issue with wet driving? I live in Florida, constantly drive through deluges, and every once in awhile get caught were I am throttling around a corner and one rear wheel will slip. With a ls, I believe I would be sideways, as the ls would cause the other rear wheel to over-torque and break loose.
3) I do know that you have to gear up if you go to a certain larger size tire. I have the offroad 4x4 package, with 265/70 R17 tires. How big can I go before having to gear up? How big can I go before I have to lift my truck higher (forgive me, this is my first truck so I may seem naive)?
Location: Kansas City, Pothole Capital of the US, maybe the Western Hemisphere.
Vehicle: 1999 Ford F150
Posts: 108
cpadpl,
Max has it right. As long as you don't change ratios, you can change out the open for ls without touching the front.
Your thought process is correct about getting ls rear-end with all the off-road goodies, but remember, unless you order it, they won't fork over anything for free. When I ordered mine with tow-pack, offroad-pack, skid plates, 5.4, 17" tires, and then ls rear-end, the only ratio I could get was the 3.73. Apparently the 3.55 is too weak for that setup (at least Ford thought so in '99).
I don't have any problem driving around on wet roads and fishtailing when I turn, but I don't get on it when it's wet, either. It will break loose on wet pavement EASILY under even moderate acceleration.
I really think that ls is better than open. Rear-wheel drive vehicles with open rear-ends can get stuck on a postage stamp sometimes. As for wearing out, I can't speak to that, but make sure that you get some of Ford's Friction Modifier Additive, even if you have the dealer do it. I had my diff's fluid changed by my dealer at 30,000 miles, and they didn't notice my ls rear-end. You'll develop a vibration if you don't add the stuff. As for ratio, if you decide to go up a gear ratio, skip the 3.73 and go to a 4.10. There isn't that much difference between 3.55 & 3.73, and I think you would have a 3.73 in your truck if you had ordered limited slip. If you do anything, make sure whoever changes your rear-end knows what they're doing. There's quite a bit to it, and if its not done right, you'll know it as soon as you drive away.
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1999 Lariat 4X4 SuperCab Flareside 5.4; Auto, Tow Pack, Offroad Pack, 3.73LS, Factory Step Bars, 17" Chrome Wheels, Oxford White/Silver, Graphite Leather, Keypad Mod., Airaid, SuperChip, ARE LSII Bed Cover, Alpine CDA-855/JBL AMP, Polk dX7's, Custom cat-back exhaust.
thanks for the insight. As of now I'm leaning toward a manual locker for the following reasons (but I could switch back, I'm wishy washy on stuff like this):
1) I don't want to loose the handling that I've got now with my open diff. As I understand it, ls diffs have the most pronounced effect on shorter wb trucks like mine. I also feel like I have enough of propensity to go sideways just from the standpoint that i have a truck, I don't think I want something that increases that possibility
2) The ls diff will eventually wear, the manual locker won't.
3) My offroad situation is 99% interstate concrete and 1% pure wilderness hell so when I need traction I need absolute traction. i.e. I spend most of my days commuting to work, but then have occasions during vacations/trips up North where had I not had a winch, a shovel, 4x4, etc. etc, I would have been spending a night (or two) stranded in a blizzard. It's amazing how fast weather can do things like knock out cell phone towers, etc., and it's essentially man against the environment.
4) My firearm analogy - If I want to take the time to look for and spend money on a gun, I'd either buy a 9mm (i.e. non-ls diff), or a .45(i.e. a locker) , but not a .40 (i.e. ls diff). It's kind narrow-minded thinking, but why would I want to go middle of the road even if it is cheaper? Kind of a carryover philosophy from my father, "Do it or don't do it, but don't do it half-a$$." Had I been wise enough to have the ls diff put in when I ordered the truck, that would be a different story. But here we are talking about me taking time and money out of my schedule to have a modification done to my truck, due to my stupidity.
Would you agree or disagree? Also, any recommendation on lockers? Are there any electronically activated solenoid ones?
1)Yes, LS clutches eventually need to be replaced, but only after a long service life. Other posi units don't use clutch packs. The Auburn unit uses a non-replaceable cone clutch. I have a Detroit Locker that's 30 years old with many high HP miles. That's your call.
2)I find a posi unit much more useful in the dry, rain, and snow; it's just a variation of necessary driving skills. I've never liked open rears; I will search far and wide for a posi, and haven't owned but a few opens. Some work much better than others; like the Torsen unit. The OEM LS works quite well for daily driver applications. You can swing the rear out very easily on the slick roads, but on most roads you get very good traction even while peeling out of your initial track under heavy throttle.
3)Any greater tire height makes your gear ratio higher (lower number); the variance is directly related to the amount changed of course. A moderate increase in tire height will not bog you down or require a lift. Exact calculation would need exact size changes. There is a ton of great tire/lift info in several areas here, and many 4WD guys here much more experienced in exact modifications than me.
Driving 99% concrete interstates you will be fine with a open rear. It is a hassle to tear everything down. I searched many lots/trucks and found few LS rears. If I wanted a posi, and wasn't changing the gear ratio, I would look into one of the Powertrax systems, as it's installed utilizing only a rear cover/axle removal. It doesn't remove the gears, differential, or change the backlash. You should also make sure if you do change the differential that the one that interests you has ABS exciter ring compatibily, this is why many choose Auburn units.
Okay, you've got me back on the ls track (as opposed to lockers), especially if there exists a ls that doesn't need clutch replacement (I presumed the only other type of of ls diff was a viscous coupling).
Anyway, explain to me that Powertrax thing you mentioned, as I don't understand, you mean the axle shaft comes out and you install it that way? I thought you had to do something to the diff so the side gears could lock to the case (i.e. mess with the gears or case).
That Auburn unit sounds nice, I checked out the site. How do you suggest I would get something like that installed? Would a Ford dealership install an aftermarket product? If I can't go to a Ford place, I'm not sure how I would find a place I could trust.
Yes, a Ford place "can" do it. Shops that specialize in aftermarket/4WD accessories or drivetrain only commonly have better experience with aftermarket differentials/gears. Setting up a rear end for a quiet,long life does require a good technician. I would suggest asking friends or members here for recommendations in your area. I should have been more clear on my powertrax description. The differential, gears, backlash/setup, and driveshaft stay in place; this is the beauty of it(especially if you don't want to change gears). You simply remove the rear cover, pull out your axles (to allow the modification), and install the product in the factory differential while it's still factory installed. The parts convert the open to a locking type differential by using a coupling system with cogs. The no-slip unit is the more advanced product. Go here for more information www.powertrax.com
what did you have done? For some reason, that Auburn gears ls is appealing to me. Are you familiar with any ratings that have been done re/torque transfer? I'm wondering how much more efficient the Auburn cone clutch one is compared to a Ford OEM.
One interesting note, on the FAQ page on Auburn gears website, it states not to use synthetic oil (and to add friction modifier), however I believe my front and rear axle are sealed "for life" (or 150K) with synthetic oil and have some bladder system to allow for expansion/contraction..
Does that mean no no to Auburn ls in my rear axle?
The Powertrax thing was interesting, I checked it out. Too involved for me, although I understand the installation instructions.
If increased traction with marginal effect on normal handling is my goal, ls would be the way to go, correct? A locker would give me the traction, but not the smooth handling I assume the ls would.
My truck has the OEM LS. It came with 3.55, I just replaced the gears. Due to the clutch design of the Auburn, it can produce a higher torque bias than the OEM unit. I don't have exact figures on either one. The HP unit is considered to be an improvement for not much more cash, and even more so in the pro series. The reason why your factory setup has extended maintenance intervals is due to the synthetic fluid. If you go with the Auburn you simply use what they recommend in that axle and it's fine (yes, to the additive too; Auburn or OEM LS). The front will stick with it's original recommendation. I wouldn't even run the synthetic that long as it's the mechanism's life-blood. The Auburn will work fine. The powertrax is extremely simple actually; similar to other posi differentials without the hassle. Lockers ?? Who is making this locker that will accept the ABS exciter ring? All 3 units will give improved traction: the OEM LS works fine, the Powertrax has installation ease w/low cost (labor), and the Auburn has higher performance than the OEM LS. It's not like any of these units will have you uncontrollably fishtailing all over the road. You just take it easy on the most slippery surfaces/corners and every other condition is just improved.
Like I said before, thanks a million for the help. Sometime during the work week I will stop by a 4x4 performance store. I don't mind being only half-way knowledgeable about things (as that's usual - its been a long time since I did something like replace a clutch assembly), but I hate being completely blind about things, and you have given me great information to think and ask about.
And correct me if I'm wrong, but the Powertrax is in fact a locker, like a Detroit EZ? I'm leaning towards the Auburn. The drawback to the OEM to me was the marginal traction increase (which is better in the Auburn according to you) and the fact that the clutches wear out, you don't know when, and then you have an open diff (another issue nonexistant with the Auburn according to you).
So, I'll chalk this up as one of my more successful weekends (although my girlfriend might argue that point), and do some in-depth research.
You're very welcome. Yes, the Powertrax is of the locker design. Both the OEM LS and the Auburn will eventually wear out. They have a long service life when properly maintained. What I meant was that the Auburn doesn't have the rebuildable clutch packs. If I had your same setup I would: leave it alone, buy the powertrax, or step up and get the Auburn. If I can help you in any way, don't hesitate to ask. Happy Truckin'
cpadpl, noticed your post, I dont get here very often, but I also bought an F-150 4x4 with an open differential. I couldnt pass up the deal, it was a 97, and the 98's were taking over the lot.
Back to your question, I had a friend who put an Auburn in his F-150, had the truck for six more months and decided to buy a light duy F-250. I bought his Auburn for a song and him and I installed it in about 2 hours.
We used a dial indicator to check backlash and side to side movement on the ring and pinon, then we installed the Auburn unit and remeasured. No change in tolerances to speak of.
The only thing different we had to do was add two bottles of Friction Modifier in the rear end when adding the gear lube.
That said, he has an impressive array of tools and an oven to heat the ring gear, of course we had to install my anti-lock ring on the unit, but it was pretty straight forward. I have a Lock-Right in my Jeep, which is awesome, but the LS unit in my truck has given me no problems in two years, and it has very good street manners also.
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Swapout of open diff for limited slip
Linear Mode
