Adjustable Rear Upper Control Arms

[97 _SR5]

So i have installed my Frankenstein lift with Rancho shocks and OME 891 rear coils with spacers. I added the spacers because front lift ended up being about 3.75" and with 891 in the rears, it did not look good, so I added a 1.5" rear spacers. Now truck measures 24" in front from center hub to bottom of fender and 24.5" in rear. I have installed an adjustable rear trac bar with drop bracket, but I have researched quite a bit about about the change of the rear pinion angle... I have not measured anything in regards to angle yet, however I have found out that the adjustable rear upper controls adjusted about 1/4" longer will help return the pinion angle closer to stock geometry. With that being said how do i correctly adjust the arms to know I am actually improving things. I have no experience with adjustable rear components. Thanks for your help

Rafal

 

[csp]

Unless you're experiencing driveline vibrations you really don't need to mess with pinion angle.

You would adjust the arms so that the pinion is moving the direction, either up or down, that it needs to go to be in the correct alignment with the output of the transfer case.

To bring it up you make the upper arms longer and vice versa to pull the pinion down.

 

[97 _SR5]

Unless you're experiencing driveline vibrations you really don't need to mess with pinion angle.

You would adjust the arms so that the pinion is moving the direction, either up or down, that it needs to go to be in the correct alignment with the output of the transfer case.

To bring it up you make the upper arms longer and vice versa to pull the pinion down.

No vibrations yet... put 250 miles on the new lift so far. As far as what you have said about the adjustment is pretty much exactly what I have read when researched, I was looking for something more specific as to maybe what angle the pinion/driveshaft should really be at... I don't want to start going through u-joints too often and I'm trying to make the suspension dependable for years to come. Thanks for the response.



Ok so I have found this that is closest to answering my question :
http://www.toyota-4runner.org/1699516-post4.html
But am I correct in thinking that as long as I keep the driveshaft/pinion in a straight line, the actual angle doesn't matter?

 

[MStudt]

No vibrations yet... put 250 miles on the new lift so far. As far as what you have said about the adjustment is pretty much exactly what I have read when researched, I was looking for something more specific as to maybe what angle the pinion/driveshaft should really be at... I don't want to start going through u-joints too often and I'm trying to make the suspension dependable for years to come. Thanks for the response.

Why are you wanting to adjust the pinion? If you don't have drive line vibrations I won't touch it. You're going to spend money on something that you claim isn't an issue.

We've got DC joints on the rear shafts. There is no simpler shaft to set-up than these. You can run a straight line from the pinion up the shaft and that is considered a perfect angle. However, I'd allow for around 1-2 degrees of the pinion pointing down to help with the springs settling over time.



As stated before. I won't go messing with it if you don't have issues. So many people try to fix things that need to be fixed.

 

[97 _SR5]

Why are you wanting to adjust the pinion? If you don't have drive line vibrations I won't touch it. You're going to spend money on something that you claim isn't an issue.

We've got DC joints on the rear shafts. There is no simpler shaft to set-up than these. You can run a straight line from the pinion up the shaft and that is considered a perfect angle. However, I'd allow for around 1-2 degrees of the pinion pointing down to help with the springs settling over time.

As stated before. I won't go messing with it if you don't have issues. So many people try to fix things that need to be fixed.

I understand what you are saying. But since the lift is relatively new, and if down the road vibrations develop (truck has 390,000 miles on it) and the bushings on about everything in the suspension are getting pretty worn. I'm just trying to figure out what is involved if this need to be done down the road really. I'm not going to mess with it right now, but at the same time, I would like to be more proactive about this.

 

[MStudt]

I understand what you are saying. But since the lift is relatively new, and if down the road vibrations develop (truck has 390,000 miles on it) and the bushings on about everything in the suspension are getting pretty worn. I'm just trying to figure out what is involved if this need to be done down the road really. I'm not going to mess with it right now, but at the same time, I would like to be more proactive about this.

If you're feeling it not you won't in the future. I would say your lift is at it highest point right now. This would put your pinion in the worse angle it's going to see. Once your springs settle down, your pinion will also come back down.

 

[Flatulento]

The original question posted is a good one. Also the image in Mstudts post is from a very good write-up on driveline angle.
Tom Wood's Custom Drive Shafts - Driveline 101
However, something this article doesn't address is how the angle of the pinion changes as the suspension compresses or extends. The 3rd gen rear suspension set-up is basically a 4-link mechanism. Depending on the difference in the length of the arms (top vs. bottom) and the difference in the spacing between the pivot points (front vs. rear), the pinion angle will change as the rear end travel through its arc. So, with that being said if the factory difference in arm length and pivot spacing is designed to keep the pinion in line with the driveshaft through the full arc of travel, then no adjustment should be necessary. The question is: was the suspension set-up to do this? Has anyone observed the degree to which the angle between the pinon and the driveshaft changes as the suspension cycles between compression and extension?

 

[T4Ryota4life]

I had to replace both front inner cv boots after my lift. I am sitting at 23 center of hub to fender. Just a heads up.

 

[97 _SR5]

I had to replace both front inner cv boots after my lift. I am sitting at 23 center of hub to fender. Just a heads up.

When I put the front spring/strut assembly on, I replaced LBJ, inner/outer tie rods, both cv shafts with new ones, and installed high angle boots on both shafts. Still have Upper Control Arms to swap up as my stock bushings are pretty much gone...

Rafal

 

[kammando808]

So i have installed my Frankenstein lift with Rancho shocks and OME 891 rear coils with spacers. I added the spacers because front lift ended up being about 3.75" and with 891 in the rears, it did not look good, so I added a 1.5" rear spacers. Now truck measures 24" in front from center hub to bottom of fender and 24.5" in rear. I have installed an adjustable rear trac bar with drop bracket, but I have researched quite a bit about about the change of the rear pinion angle... I have not measured anything in regards to angle yet, however I have found out that the adjustable rear upper controls adjusted about 1/4" longer will help return the pinion angle closer to stock geometry. With that being said how do i correctly adjust the arms to know I am actually improving things. I have no experience with adjustable rear components. Thanks for your help

Rafal

So I assume your 891 are sagging? Do you have pics with and without the rear spacers?

 

[97 _SR5]

They sagged about 1". No pictures without the spacers, but here's a quick one currently with spacers. The 891 would have been OK with only a 3" lift in the front.

 

[kammando808]

They sagged about 1". No pictures without the spacers, but here's a quick one currently with spacers. The 891 would have been OK with only a 3" lift in the front.

Yah I have a 3 up front but my 891 sags more then a old grandmas ass lol, hopefully soon but I'm really considering upgrading to the toytec superflex/adj panhard bar and drop bracket, don't really think I need the rear uca as much as I want it

 

[Cree]

Just installed 891's with no packers. Measured the angle tonight and it looks like there's roughly a 5 degree split between d/s and pinion. No vibration, BUT there is a little noise that I'm assuming is coming from it being slightly bound.

It seems like this is something most people ignore or write off as a non issue. I'd wager a guess that if everyone measured after a lift that their pinion angle is wrong. Maybe it's not a big deal, maybe I'm wrong. But I'm not going to bet tearing into a 3rd member to replace a worn bearing on it. I'll be ordering some Toytec upper arms next week. Wish I had looked into this a little more before I ordered everything instead of having to spring the extra spending on the CFO (aka wife).

 

[csp]

As long as that five degrees is with the pinion lower than the driveshaft you're probably ok. It really isn't good to have zero degrees at the pinion as there needs to be a little angle for proper lubrication in the ujoint caps. It also helps with avoiding brinelling between the needle bearings and the cap.

The pinion will also rise a little bit under power.

 

[Cree]

Any guess what the factory spec is?

 

[csp]

There won't be a published factory spec for pinion angle because it isn't adjustable.