diff drop

[Singtoe]

im sure that could be an issue over time if we all drove around in 4wd constantly but at low speed off road the bearing cant build to much heat and in 2wd it isnt spinning. also the fill plug is lower than the pinion so the lubrication is from splash or gear climb. it is not relying on oil saturation

It looks like the oil fill plug is at the same level as th bottom of the pinion bearing. So if the front of the diff is lowered 1", all the oil is away from the bearing keeping it dry.

As for vehicular rake, in proportion to a 1" diff drop, the front of the truck would have to lower then rear by more then 1 foot to equate the same level of tilt as a diff drop.

 

[hartsgt]

well i guess this can be debated forever but in my opinion this is not a concern. i have never heard of a bearing failure from lack of lubrication. i do know looking at my vehicle the fill plug is lower than the pinion bearing. this is no different than setting the pinion angle on a straight axle set up with a lift. you always raise the pinion to correct the angle with the driveshaft and do not have pinion failure. once again 90% of the driving that we all do the pinion is not spinning anyway so there is no lubrication neeeded

 

[brian2sun]

@Singtoe, Your theory makes sense, but there are 3 big issues I have with your claim..

1) Like Toytec and I asked, Do you have any examples of this actually happening in real life?

2) Who says (besides you) that the pinion relies on oil saturation to function properly and that the oil that is splashed and brought up by the ring gear isn't enough? It's a "high-pinion" design meaning the pinion meshes with the ring gear on the top of the ring instead of the bottom. that means the pinion is much higher than a "normal" diff and I do not believe any hi-pinion diffs require oil saturation of the pinion bearing. Even without a diff drop, you're only going to be saturating a little piece of the bottom of the pinion anyways - if that.

3) Of all the bad things you said could happen by running a diff drop, I haven't seen or heard of a single incident in which it actually has. On the other hand, there are literally countless examples of people having CV issues all across the board (particularly torn and leaky CV boots) when they don't run a diff drop. I've had one for several years now and I can tell you I have had zero issues from it. I can also say that I have not had any CV issues since I installed a drop either, but I screwed a couple sets up before I put a drop in.

 

[hartsgt]

completely agree!

 

[maxspeed96ct]

Reason I asked about a diff drop doing damage on a small lift like the 1.5 " lift is because just 4 weeks after installing my lift and diff drop my passanger side axle started to spit grease, and my drivers side axle started to mkae noise.

Now I figured the truck is just old and has 122k so I bet thats part of the reason why the axles failed.

But It also made me wonder if maybe I should just get rid of the diff drop since im only running a 1.5" lift.

 

[brian2sun]

Reason I asked about a diff drop doing damage on a small lift like the 1.5 " lift is because just 4 weeks after installing my lift and diff drop my passanger side axle started to spit grease, and my drivers side axle started to mkae noise.

Now I figured the truck is just old and has 122k so I bet thats part of the reason why the axles failed.

But It also made me wonder if maybe I should just get rid of the diff drop since im only running a 1.5" lift.

Stock CVs just don't like new angles after sitting in one position for so many years. The diff drop didn't cause that, if anything it made your CVs leak less, but you'll probably need to replace your CVs soon regardless. New CVs shouldn't require a diff drop with only a 1.5" lift, but I would just leave it in if it was me.

 

[Singtoe]

I admittedly did not come with this synopsis on my own. I went to a meet and greet that ECGS had and talked to them about my Lincoln Locker idea and using the A.D.D. system to disconnect for street use. They obviously said it was not a good idea. The IFS diff is really weak and will most likely blow up. They recommend the arb air locker or if didn't have enough funds, to go with a lunch box locker as it has enough give for slip.

I had a thousand questions for these guys. I asked about the life span of front diff with a locker and they said it would lst a long time but they did mention that they are issues with diff drops. They said that is the number reasons why IFS Diffs get sent to them. The small pinion bearing is toast.

Since all they do is ring and pinions and differential work, I would tend to believe them.

 

[T4Rscott]

So, if older CVs do not like new angles, should I even think about lifting my 99 with 133K+?

 

[scottishb]

Hey, Singtoe, makes perfect sense to me. Who cares what the others say... I did my axles after the diff drop, and a ton of fluid came out.

 

[maxspeed96ct]

So, if older CVs do not like new angles, should I even think about lifting my 99 with 133K+?

that choice is up to you, but just a few weeks after lifting my truck both axles needed to be replaced, and both lower ball joints ..

Its a old truck, but everything looked great before the lift.

But I still love my mild lift even though its killing my wallet. :whipping2

 

[Gerdo]

that choice is up to you, but just a few weeks after lifting my truck both axles needed to be replaced, and both lower ball joints ..

Its a old truck, but everything looked great before the lift.

But I still love my mild lift even though its killing my wallet. :whipping2

Lifting the front isn't going to greatly shorten the life of your lower ball joints. I'm sure that they were going bad before the lift. I replaced my LBJs ~80k after my lift.

Lifting can cause the boots to leak. Mine didn't. Even if the boots start leaking, just have them re-booted. That doesn't cost that much. My boots tore at 210k. and ~100k of that was lifted.

As for diff drops, I'm keeping mine. The front diff doesn't spin when 2wd. When it is spinning, there is oil moving around inside. I have over 100k with my diff drop in.

 

[the great him]

the change of angle might be an issue in trucks that are awd, or full time 4wd, but like mentioned above, for most of us the only time that bearing is in use is when your in 4wd and off road, meaning that oil(gear lube) will be moving all around front-back, left-right as would be in off road conditions. i dont think that it sitting for a period of time with out off road use would "dry it out" as that would take years to happen. and even for the awd runners (01,02 limited runners i believe) they should see enough movement from day to day driving(gear sling, stop/go, and hills -parking garages, driveways, entering parking lots ect) to keep it lubricated enough. and as brian2sun stated the added benefits far out weigh the "possible" draw backs. id rather lose a seal over time than snap my 3rd cv joint on a trail run 12 miles out on a trail in moab and be dead in the trail... just my thoughts

 

[MTDewX8]

so after a week. I just noticed some grease on the outer part of the boot.
So, if I intstall my diff drop will the grease stop leaking. or will I need to get new boots?

if a diff drop will fix the leak then I would say there is good reason for the diff drop.

looking at the CV angles. what does stock look like? straight and level?

 

[durrell]

I'm wondering the same thing MTDew. If the diff drop fixes the CV leak I have, then I'm all for it. But if long travel boots would be just as good (Long Travel Outer C.V. Boot) then I will go that route.

 

[MTDewX8]

wellI wiped it up a bit to see if it continues.
still plan on the diff drop.

just little dark on how it all goes back together. I know its simple, but all I can see is two big bolts and where the spacer goes dont seem right.

maybe it will all make sense when I get it apart.

hate tearing into something not being to visualize it. but I can be slow too

 

[durrell]

I placed an order with ToyTec last night so I guess I will just contact them and see if they can add the diff drop to the same shipment. Might as well do it all in one shot.

 

[brian2sun]

so after a week. I just noticed some grease on the outer part of the boot.
So, if I intstall my diff drop will the grease stop leaking. or will I need to get new boots?

if a diff drop will fix the leak then I would say there is good reason for the diff drop.

looking at the CV angles. what does stock look like? straight and level?

The diff drop might stop them from leaking but I doubt it. Once they start, they usually keep on leaking unless you reclamp the boots or get new CVs. You shouldn't have to reboot them unless they are torn (or unless you want long travel boots). You could try just putting regular hose clamps right over and on top of the existing clamps and torque em down, but make sure the screw part doesn't rub the boot. But the best way is still to remove the old clamps (which you need to be really careful you don't tear the boots in the process) and get new clamps that you can get nice and tight.

I don't think stock angles are totally straight (but it's been a while since I've seen mine stock). The diff drop actually rotates the diff more than it drops it, but it does still help reduce wear and tear and on the CVs.

I agree with the kid about the "dangers" of the diff drop and being part-time 4wd too. That pinion bearing is only turning while in 4x4 which is relatively a very small percentage of the time. But I could see it being more of an issue in a full-time 4wd.

 

[Singtoe]

I have a spare front diff assembly and the fill hole is right even with the bottom part of the pinion bearing. The rear diff has a channel that is hollowed out directly above the pinion shaft. So just the nature of the ring gear picking up oil and sloshing it forward to keep the pinion bearings lubed up. The front diff has no channel. The gear oil needs to travel trough the big bearing to get the small bearing. With the Diff pointing down, even with all the sloshing going on, the large bearing acts as a shield preventing the gear oil from going up.

So, here is the situation, You drive around weeks at time in 2wd, then you proceed to use 4wd, The Small bearing is throughly drained and now you start spinning it under a load. How long will it take before you have an up hill climb to get oil on it? How much damage will occur running it dry, especially with all the preasures it has?

 

[brian2sun]

I think this is a good discussion and I can see your points. Here's a few thoughts...
When I got my front ARB locker, I found out that the carrier is bigger than the stock one. If you fill the diff with gear oil all the way up to the fill hole like normal, it will be too much once it builds some pressure in there because of the bigger carrier. What happens is the oil will climb all the way up the breather tube in the engine bay and the excess will leak out - even in 2hi. I researched this after I noticed gear oil running down my suspension and I found multiple articles and posts that said to fill the gear oil about .5" below the fill hole when you have an ARB. So my point is..

1) I have less fluid in there than a stock 4runner and I have a diff drop, and about an inch of rake, but I haven't had any issues. I'm also in 4x4 in my truck a lot more often than your average driver.
2) If the pressure that builds up in my diff is enough for oil to climb a couple feet up the breather tube and actually leak out a few ounces, I'm sure everything in that diff is getting oil. If nothing else, I think the pressure inside along with the sloshing motion will get oil to that bearing.

 

[MTDewX8]

good info,

I have the Sonora spacers (diff drop) and they are angled or beveled for something. did they do this to eleviate anything or just something different?