Pinion Flange Swap/Pinion Flange Drilling

[danthemanx07]

Anyone swapped out a rear pinion flange or drilled a new bolt pattern in a pinion flange?

Why might one want to do this? I believe the 1st gen Tacoma and 3rd gen 4Runner e-locker thirds will drop into the 4th gen 8" rear axles, but the bolt pattern on the pinion flange may not mount up to the drive shaft. Doing this opens up some re-gear opportunities that would be a little less pricey than going with new gears and installing an ARB or another type of locker.

A few different folks sell double or triple drilled pinion flanges to remedy this problem, but if you remove the pinion nut, you should technically reset/confirm the pinion preload which requires tearing the rest of the third down some. One might be able to get away with torquing the pinion nut back to the same setting it was when pulled off or marking the pinion nut and turning it back tot he same spot.

Another option would be to drill the 4th gen driveshaft bolt pattern into the 3rd gen pinion flange. Seems there are a few ways to skin this cat.

Anyone ever tried or looked into either of these options?

And yes - if money were infinite I would just regear with an ARB or buy a geared e-locker from ECGS.

 

[Inv4drZm]

The 3rd gen 4runner pinion bolts up I'm pretty sure, no idea on the Taco but it's probably similar. Some 2 gen Tacomas and FJ's came with elockers too, those will work.

 

[RonJR]

If you're going to re-drill the flange, you need to be meticulous about getting the holes centered in the right place. Just a few thousandth's will make the drive shaft vibrate at highway speeds. My guess is it would be difficult to do it accurately enough with home shop tools. Just finding the center of the flange (which is in free space, since it's hollow) would be a trick. You'd probably have to install a tight fitting dummy shaft for measurement purposes.

 

[danthemanx07]

The 3rd gen 4runner pinion bolts up I'm pretty sure, no idea on the Taco but it's probably similar. Some 2 gen Tacomas and FJ's came with elockers too, those will work.

Well that would be awesome! I hope you are correct. Maybe I am misinformed. I am aware of the FJ and 2nd gen Tacoma options. Those are much rarer, pricier, and the gear options are less desirable. Compatibility with the 3rd gen stuff opens up more options.

If you're going to re-drill the flange, you need to be meticulous about getting the holes centered in the right place. Just a few thousandth's will make the drive shaft vibrate at highway speeds. My guess is it would be difficult to do it accurately enough with home shop tools. Just finding the center of the flange (which is in free space, since it's hollow) would be a trick. You'd probably have to install a tight fitting dummy shaft for measurement purposes.

So - I have read a little on this (note I have not done this and don't claim to be an expert). There should be on the drive shaft flange a centering ring that will fit into the "hollow space" on the pinion flange - this much I am fairly sure of because it was like that on both my 1998 4runner and 2002 Tacoma, so centering two pinions may not be that hard. Mating that up should cure any concerns on getting the two lined up. Second - if you ruin the pinion flange with off center holes that cause vibrations - then you end up back at square one and just buy pre-drilled pinion flange.

Also - a third option I forgot to mention is a pinion flange adapter. This would be the least desirable option in my mind because it is essentially a spacer with several patterns drilled in. I am not sure I want an extra 1/2"-1" in my drive line.

 

[RonJR]

Now that you mention it, I think you are correct about the centering flange, so it should be possible to clamp the two together and mark the holes properly. Then you just need a solid drill press that doesn't wobble.

 

[danthemanx07]

Now that you mention it, I think you are correct about the centering flange, so it should be possible to clamp the two together and mark the holes properly. Then you just need a solid drill press that doesn't wobble.

I was thinking a little more adventurous - under the truck with third installed using the driveshaft flange holes as a guide...