Intalled 1 inch front Diff Drop today...

badass98z

New member
I was wondering what the purpose was for doing this? I received it in my toytec kit so just decided to install it but didnt know what it is for. Do pros out weigh the cons if any?
 
Register to hide this ad
No cons and I swear it has to be easier on cv boots if not the.cvs as well , there's debate as to if you really need it , but there's no debate in if you got it no harm in using it .
 
The Diff Drop Debate!

I did the diff drop. Do I NEED the drop? Probably not. I think it is cheap/easy insurance. It should prolong CV life.

I dropped my skidplate and did an oil change. I didn't remove my diff drop and measure but as others have said you aren't dropping the whole diff, just rotating it. The rear, driveshaft side, mount is 6" from the axle centerline. The front, where the drops go in, is 7" from the axle centerline. There for when you drop the front 1" the actual axle centerline only drops .462" (~15/32") Just under 1/2". It's hard to tell what strain it takes off the CVs when wheeling and you have full droop.

Is it worth it? That is up to you. I'm leaving mine in.
 
I'm not planning to do any wheeling where I'd need flex or stress the CVs too much so I think I'm gonna put my 40 bucks elsewhere for now. I'd put it in if I could, for sure, though. It certainly can't hurt.
 
the kit also came with two 1x1 squares that are about 1/2 in thick. Any ideas what those are for? The kit was a gift from my GF and there are no install instructions?
 
Cool so it actually a kit then lol , I think I like their stuff more and more !

Yessir..when the diff drop spacers are installed, it pivots the front of the diff down, now the skid plate mounts don't quite reach the sub-frame, those 1/2" spacers provide just the ideal kick out for the skidplates to be attached properly, and that's also why the kit comes with two new longer bolts for those spacers..

I just trimmed parts of the skid plate framing off on mine and I was able to use the existing bolts.
 
You mean you just cut those "nubs" off where the bolt goes through ?

Been to busy working on mine to wheel so I just left it off, haha
 
You mean you just cut those "nubs" off where the bolt goes through ?

Been to busy working on mine to wheel so I just left it off, haha

No just the part of the skid plate frame where the differential mount and diff drop bolt hits..

drop.jpg~original


The Toytec 1/2" skid plate spacers go on top of the bolt holes to compensate for that amount of diff drop to eliminate the grinding and trimming I did as on the photo.
 
Here's the con.


Drive Shaft Harmonics
DRIVELINE/UNIVERSAL JOINT CANCELLATION
By Jim Clark, Hot Rod M.D.

What: Solving the problem of driveline vibration. Driveline geometry. The process that can be used to address a condition called driveline/universal joint cancellation, often referred to as adjusting pinion angle. This process can be used to eliminate the vibration and premature wear caused by improper orientation and phasing of the driveline.

This condition is caused because every U-joint that operates at an angle creates a vibration. It creates that vibration because the U-joint cross rotates with the shaft in a circular motion while also moving from front to rear. That rocking back and forth motion as it rotates causes the cross in the U-joint to accelerate and decelerate.

If you could view this as rotating around the face of a clock with the cross rotating in a counterclockwise motion it would show the U-joint when at a horizontal position (3 to 9 o’clock) as traveling in a circular motion. As the yoke arm at 3 o’clock travels counterclockwise towards 12 o’clock and tips to the rear of the vehicle it accelerates. Then decelerates as it continues counterclockwise towards 9 o’clock as it rocks forward again returning to center. Now again accelerates as it continues rotating counterclockwise from 9 o’clock to 6 o’clock and rocking towards the front of the vehicle. Finally completing one rotation as it travels counterclockwise from 6 o’clock to 3 o’clock decelerating as it returns to center. Because the U-joint is connected to the driveshaft and accelerates/decelerates through this full rotation, the driveshaft speeds up and slows down during each revolution. This creates what is called excitation torque.

U-joint_Harmonics.jpg


When viewed from the end, the path taken by the bearing cups is an ellipse, rotating forward and backwards as well as in its path around the centerline of the shaft. When viewed from the side, the path taken by the bearing cups would look like an angled line rocking back and forth while rotating around the centerline of the shaft

To cancel this excitation torque, the U-joint at the other end of the shaft needs to rotate at an equal but opposite angle in relation to the U-joint up front. By using U-joints in pairs and in phase, and the angle between the driveshaft and the equipment at both ends is the same, the acceleration/deceleration cycles tend to cancel each other.

These U-joint angles should always be at least 1-degree to avoid wearing out the yoke bearings.

How: When you build a chassis and position the driveline components, you need to orient them so that the angle of a line drawn through the center of the transmission exiting through the output shaft (A) and a line drawn through the center of the driveshaft (B) is equal to but opposite the angle of a line drawn through the pinion shaft in the rear differential(C) and the line drawn through the center of the driveshaft (B). The accompanying drawing illustrates how the lines drawn through the transmission and pinion shafts (A&C) are parallel to each other, though not in the same plane.

Driveshaft-5.jpg





So in other words - A diff drop is not a drop but a tilting of the diff changing the original factory pinion angle. The will lead to vibration and wear on the drivershaft and front pinion bears and seals.
 
If the 4runner had CV joints instead of U-joints on it's driveshafts, you could tilt the diff in any angle and not have any issues.
 
Here's the con.



So in other words - A diff drop is not a drop but a tilting of the diff changing the original factory pinion angle. The will lead to vibration and wear on the drivershaft and front pinion bears and seals.



i would believe that after lifting the truck the points of those components have already changed and rotating the diff with a drop should bring it back closer to nominal. how much closer who knows, is it enough to matter, maybe maybe not.
i think your assumptions would be right if based on installing a diff drop on to a stock/non lifted truck.

not really thinking it through but that's my first impression.

it just seems very few people who lift their trucks the standard 2-3 inches have geometry/drive line problems.
 
1” Diff drop

I was wondering this myself, as I bought a 3” lift kit from rough country about a year ago and I had to replace 3 cv axles since then from torn boots. So, I assumed it was the angle of the cv axles that were causing the problem. I’m planning on getting a diff drop kit soon to lessen the chance that another boot rips.
 

Members online

Forum statistics

Threads
278,308
Messages
3,554,057
Members
248,016
Latest member
Advally Service

Trending content

Back
Top