Matt16

...on 4Runner. Trucks have a different rear driveshaft.

The angle on between the IFS diff and the T case is pretty minimal, it looks like its less than the rear DS- T case angle, yet the front gets a double cardan, the rear only a single. I believe Tacomas have a rear double cardan

Is the front a carry-over from the pre-'85 solids axles? I can see the angle being fairly steep when the passenger-side tire was fully drooped.

4x4YOTA

iTrader: (2)

I have always wondered the same thing... the wheel base on my pick up is short enough I almost need one in the rear

GSGALLANT

I'm just guessing here, but on the 2nd gen 4Runner, it could be because the front driveshaft is so short (for the same amount of front diff droop, the angle of a shorter driveshaft will be more than the angle of a longer driveshaft).

On the 3rd gen 4Runner, the double carden is on the rear driveshaft, and not the front driveshaft, and I'm just going by memory here, but I believe the 3rd gen front driveshaft might be longer than the 2nd gen front driveshaft was. Again... this is only my best guess!

Flash319

I think it is because the carden is used for smoother transfer of power not more angle. Actually less angle, but it holds tension on the shaft through the whole rotation so vibration is minimal. They do the same thing on the back shaft of a extra cab truck with the 2 piece shaft (hanger bearing setup). When the angle is not very steep it makes sense and last longer.

toyminator2000

96 and up Taco's and 4Runners have a double cardan on the rear shaft from the factory. I've got one from a 2000 4Runner for my 89 pickup.

GSGALLANT

Yes. The point is to reduce vibration, but the question is why on the front of a 2nd gen 4Runner but on the rear of a 3rd gen 4Runner.

Vibration will be more prominant when the shaft is bent at a joint. The higher the bend angle, the higher the vibration (mostly due to angular velocity differences between input and output shafts, which is constantly changing, and it is not linear.) The double carden, with both joints phased correctly, helps to cancel out the changing angular velocities, and turns it into a "almost" constant velocity joint, which reduces the vibrations.

4Crawler

iTrader: (3)

All depends on how the drive train was designed. In the earlier trucks/4Runners with the front CV, that was dictated by having the front pinion flange angled up to point at the transfer case front output, so a CV shaft was the ideal setup. Since the front flange on the t-case is facing somewhat upward due to the rearward slope of the transmission/t-case, with a single cardan shaft up front, you would need to have the front pinion flange angled downward (since it faces to the rear) at an angle matching the upward angle of the front flange. This would increase the angles on the u-joints, especially on the front solid axle trucks.

Haven't looked to closely at the setup on the newer trucks, but they probably went to the rear CV for a smoother/quieter ride. Not sure what the story is on the front end, but likely they were able to modify the angles and possibly fit in a lower cost single cardan shaft. Not sure if they use a high pinion front diff on those trucks, but that would help with the shaft angles.

iamsuperbleeder

that's a bolt on? intersting...


I too kinda wandered the same thing last time I was under my truck hitting the grease fittings...