my lift idea.

[04desertrunner]

Okay so i planing on buying a lift kit for my 4runner, i called a couple of shops around my area for quotes. When i mention a diff drop for my runner alot of them have been saying i don't need one. Can someone clarify this. What i will be running is

front lift- blistein 5100 R.H.A on 2.5 setting

rear lift- ome 890, blisteins

i also been thinking of running the pro comp prorunners R.H.A shocks and im going to be running 265/75/16 bfg at

 

[spectre6000]

The more lifted you are, the more articulated the CV axles will be. They are designed to last forever(ish) at stock suspension height. When you lift the suspension, you are effectively running them at a height greater than they are designed optimally to be resulting in increased stress and wear. The decrease in life of the CVs may not be much at lower lift heights, but it is there. Generally, I've seen it suggested that anything over 2.5" benefits from a 1" diff drop; I also see people suggesting ridiculous things like deck plate and ISR mods, so I take it for what it's worth. If it were me I would absolutely drop the diff.

You'll probably run just fine for quite a while with the diff in its stock location and only a 2.5" lift, but you'll ultimately be better off with a diff drop. The question is: what is your desired return on vehicular investment? If replacing your axles XX% sooner/more often isn't worth the $100 or whatever a diff drop is running, don't do it. If the $100 (or whatever, it's probably cheaper and if you have any fab skills at all you can easily get by for under $20) is a price you're willing to pay to have your axles last some unknown percent longer, get the drop.

If you only drive the truck around town, and the odds of you breaking an axle somewhere inconvenient are nil, it may not be worth as much to you. If you drive off road a lot and don't mind swapping axles however often is necessary at the XX% degradation of performance, it's probably not worth it to you. If you're planning to drive the Pan-American Highway, it shouldn't even be a question...

Don't listen to people who don't drive your truck regularly and rely on it like you do (especially not on internet forums). Get the information (generally most easily found on internet forums) and make an informed decision on your own. The same goes with every modification and maintenance item you perform or have performed on your truck.

 

[AZTOY]

Like spectre said, research and make best decision for you. I researched for six months before I bought my lift. I decided not to use the diff drop. I have had it for six months with no problems. I also replaced a lot of front end parts at the same time for good measure and age. (CV, all ball joints, tie rod ends).

The fact that you got quotes for a lift install, tells me you may not want to or be able to fix your truck on the trail. Most places that are fun to off road, a tow truck can't get to. Something to think about.

Look at the stickys if you haven't already. Search " diff drop or no diff drop" and read the debates. There are strong opinions on both sides. Good luck.

 

[techno]

The biggest benefit from the diff drop is its effect on the rubber boots. When lifted the ribs on the boots sometimes contact each other more than usual, resulting in increased wear. If the boot fails and you dont see it, dirt and crap will get into the joint and cause excessive wear and increased chance of failure. CV's keep almost all their strength within the entire range of motion, but only as long as they are kept clean and lubricated.
I've been lifted for about 5 years with no diff drop and have never had a cv joint fail. I keep the boots stretched out to avoid rib rubbing and spray them down with wd40 occasionally. And after a day on the trails, clean the mud off asap.

 

[opie74]

Youll be fine with a 2.5" lift and no diff drop.

 

[rjaudi]

First, see if anyone local can help you install the lift. That way you may get some knowledge of your suspension first hand. Second, I would get the diff drop. It is minimal cost and easy to install. I have always recommended Tundra coils up front fitted to the Tundra 5100 Bilstein shocks. It produces a very good ride. Out back I have OME 890's with 95 factory landcruiser shocks. I have always liked how this rides and did not surprise me that Sonoran Steel no longer puts Bilstein's in the back with there kits. They use the factory Landcruiser shock.

 

[opie74]

The diff drop is a little misleading. It does not drop the entire diff. I merely rotates the front (rear) of the diff down. This also pulls oil away from the pinion bearing. The front diffs pinion is not force feed oil to keep it lubricated like the rear. It is a splash/oil bath. Now, there is some discussion on whether or not the new angle of the diff starves the pinion of oil, but with a 2.5" lift or lower, the CV's are not operating at any extreme angle and the boot ribs should not be touching. Yes they will be close, but not quite.

Since the diff drop merely rotates the diff down, the 1" spacers do not equate to a total 1" diff drop. IIRC, someone measured and the 1" spacers equal about a 3/8" drop at the output of the diff. Youre also changing driveshaft angles and this can cause premature bearing/u joint wear and vibrations.

 

[rjaudi]

The diff drop is a little misleading. It does not drop the entire diff. I merely rotates the front (rear) of the diff down. This also pulls oil away from the pinion bearing. The front diffs pinion is not force feed oil to keep it lubricated like the rear. It is a splash/oil bath. Now, there is some discussion on whether or not the new angle of the diff starves the pinion of oil, but with a 2.5" lift or lower, the CV's are not operating at any extreme angle and the boot ribs should not be touching. Yes they will be close, but not quite.

Since the diff drop merely rotates the diff down, the 1" spacers do not equate to a total 1" diff drop. IIRC, someone measured and the 1" spacers equal about a 3/8" drop at the output of the diff. Youre also changing driveshaft angles and this can cause premature bearing/u joint wear and vibrations.

People do have CV problems, but I have never heard of a front differential failure from not getting oil. The diff drop is not perfect, but it does help. Also the boots will always have to ride around at bad angles. If the driveshaft angle is made slightly worse it will only be a problem the few times 4wd is engaged.

 

[cougar428]

My advice would be to just get it. You're already planning on spending all this money for the lift so what's an extra 30 dollars. It's cheap insurance. Also, even if you do get it, there is a good chance the boots on your current cv shafts will still rip. This is because the rubber boots are old and hard and the cv's have been sitting parralel for all this time and then now it's at an extreme angle. once you replace the ripped boots with new softer ones you shouldn't have anymore problems. Hope this helps

 

[04desertrunner]

Thank you all for the advice on the diff drop. i do know how to install the lift my self but with college and work don't have time to do it, but seeing how orw is going to charge me 1200 for everything seems to much i thinking of requesting a day of work to do it. Still waiting for 1 more shop he's going to get back to me on monday.

 

[opie74]

People do have CV problems, but I have never heard of a front differential failure from not getting oil. The diff drop is not perfect, but it does help. Also the boots will always have to ride around at bad angles. If the driveshaft angle is made slightly worse it will only be a problem the few times 4wd is engaged.

I disagree. The marginal change in angles on the CV is not worth the cost. But thats just my opinion, on my rig. With 2.5" lift on the front, which is what the OP asked about.

 

[HellRazur]

Remember that on road the new shaft angles really dont make much of a difference, but off road you will be flexing at much greater angles and stressing the cv shaft beyond its intended deflection. I am not for or against the diff drop, just giving your food for thought.

 

[Singtoe]

The diff drop is a little misleading. It does not drop the entire diff. I merely rotates the front (rear) of the diff down. This also pulls oil away from the pinion bearing. The front diffs pinion is not force feed oil to keep it lubricated like the rear. It is a splash/oil bath. Now, there is some discussion on whether or not the new angle of the diff starves the pinion of oil, but with a 2.5" lift or lower, the CV's are not operating at any extreme angle and the boot ribs should not be touching. Yes they will be close, but not quite.

Since the diff drop merely rotates the diff down, the 1" spacers do not equate to a total 1" diff drop. IIRC, someone measured and the 1" spacers equal about a 3/8" drop at the output of the diff. Youre also changing driveshaft angles and this can cause premature bearing/u joint wear and vibrations.

If anybody cares. This is my thoughts exactly.

1" spacer equals 3/8" at the output. Not worth the money nor the effort.

You are changing your pinion angles. This will cause more wear. If the front drive shaft had a double cardan joint or a cv joint in it, it would be fine but running u-joints pinion angles need to be parallel with each other.