LC4LIFE
Supporting Vendor
When I measured mine, I just jacked up one wheel, put the TC in neutral, spun the tire so the TC and/or Pinion flange was where I wanted it and then set it back down prior to measuring it. It is a very quick process.
Castor/pinion angle question for de-grring
- Thread starter hammerheadfistpunch
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
When I measured mine, I just jacked up one wheel, put the TC in neutral, spun the tire so the TC and/or Pinion flange was where I wanted it and then set it back down prior to measuring it. It is a very quick process.
Thank you, I will try that tonight.
@digitalmarker, post a photo of your front pinion with driveline installed show as to show the angle at which the two come together. Also, place an angle finder across the two bolts on the top trunnion pin and post that reading. Do this on a level surface with vehicle fully on the the suspension.
Those Slee arms correct castor angle more than you need for a 3” lift. My bet is that you have been on the verge of front vibes the whole time and dropping the front just 1” broke the camels back.
And unless your 80 is very heavy all the time, Slee heavies had lifted your rig more like 5”.
Those Slee arms correct castor angle more than you need for a 3” lift. My bet is that you have been on the verge of front vibes the whole time and dropping the front just 1” broke the camels back.
And unless your 80 is very heavy all the time, Slee heavies had lifted your rig more like 5”.
Thanks, will investigate this.
My 80 is fairly loaded, but depends on what your definition of heavy is. I have a Slee bumper and a winch in the front, and a 4x4 labs bumper and a 24 gal LRA tank in the rear. I actually installed a 20mm spacer in the front after installing the 4" kit to level out the front and rear.
What's interesting is my buddy has the exact same setup on his 97 (same bumper, winch, suspension, and tires) and does not have the front or rear vibes. He is running the Slee arms as well.
I will report back with results once I get it back on the ground and measure, and shorten the UCAs a bit to compensate for the 1" of lift I just lost.
Phil you've never been in a 80 that is totally vibration free? I'm just not that experienced with what's considered somewhat normal on a 80 series. Only 80 I drive is my own. Mine has dshaft vibration at like 90mph. If it's fairly normal then I will leave it alone.
Were the Slee springs heavies or mediums? What are the new slinky’s, heavies or mediums?
The Slees were medium, Slinkys are heavy (just heavy, not extra heavy). I unfortunately don't remember the exact amount of lift I got o Slees, but I am going to measure the Slinkys vs factory height today. I was told that Slinks actually result in more than the 70mm they are listed at.
Today I got the front and rear axles centered within 1/8" and got an alignment. I then adjusted the UCAs to make them shorter by 3 full turns.
Took it for a test drive, and while there is still some vibration happening (around 40-45mph), although it is much improved from where it was the day before where I was getting a lot of vibes from 25 to 55mph.
What's strange is that the angle on the rear TC flange is at 3*, while the angle of the diff flange is now 0.5*. Cristo at Slee told me these angles need to match. But it looks like changing the angle at the rear diff helped get rid of a lot of vibration, even though the angles don't match.
The other somewhat concerning news is that the caster increased from 3.8* to 5.8* by virtue of decreasing the lift height by roughly 1.5". The target range is 2* to 4*, so 5.8* seems kind of high. The good news is that the truck handles well at low and high speeds, and my camber is finally in spec and matches on both sides (my old axle housing was bent and installed a brand new one, which got rid of an annoying pull to the right). The bad news is that some vibration is still there at 40-45 while accelerating.
Thoughts on these stats/numbers? What is the potential downside of having such a high caster value?
PS - I have a DC front drive shaft and leading arms from Slee. Don't have the 7-pin mod/switch yet, it's on order, so can't pop off the front DS just yet to check if is the front or rear causing the vibes.
Last edited:
That’s a lot of caster up front. I’d pull the ft drive shaft and see if that helps.
If you don’t have a cdl switch put the truck in low range and once the center diff locks turn off the truck and pull the fuse for the lickers. Now it will stay locked even when in high.
Now you can pull each drive shaft out independently to narrow down the source.
If you don’t have a cdl switch put the truck in low range and once the center diff locks turn off the truck and pull the fuse for the lickers. Now it will stay locked even when in high.
Now you can pull each drive shaft out independently to narrow down the source.
Thanks, I have the CDL button on order from Delta VS, coming later this week. So I will pull the DS over the weekend once I get it in and do the test.
Any thoughts/input on the pinion angles? I found it surprising that the further away I got away from the rear DS pinion angles matching the TC, the less vibration I felt. This is directly contradicting everything I have read and heard in terms of getting the TC pinion and diff pinion angles to match.
Another thing that's weirding me out is the instructions in this thread that someone posted earlier:
forum.ih8mud.com
According to this, the pinion angle at the diff has to be within 1* of the angle of the shaft body itself. In my case, I am seeing a 3* angle on the diff pinion, and a 11* angle on the shaft. So according to this thread I am way out of range. Am I reading that correctly? Or is the 1* threshold for non-lifted trucks?
DC-Shaft pinion check
I've had a few questions about vibrations and whether or not a DC shaft is the solution/problem. So I decided to post up how I evaluate the pinion angle to confirm if the pinion is aligned correctly for a DC shaft to operate without any vibrations. The technical aspect of this is that a DC...
forum.ih8mud.com
According to this, the pinion angle at the diff has to be within 1* of the angle of the shaft body itself. In my case, I am seeing a 3* angle on the diff pinion, and a 11* angle on the shaft. So according to this thread I am way out of range. Am I reading that correctly? Or is the 1* threshold for non-lifted trucks?
the 1* threshold is for the DC shaft itself regardless of lift. Beyond that and it's likely to vibrate and make noise. The end of the instructions is to subtract one reading from the other and that will give you the operating angle of the u-joint. 8* is well outside of the limits.
5.8* castor is just a number. If you like how it Drives and your tires wear well, then that’s fine. Mine is closer to 5* than 4* and it has been fine and much better than when I had .5*. Unfortunately, 5.8 castor means that your front pinion angle is not close to where it should be for a DC shaft, this is why I requested a photo. My rig has been lifted over 4”, closer to 5”, for a long time. I went part time in the transfer case so I don’t have to be concerned with my front driveline. Ever since I installed the delta 6” lift front arms, my front pinion angle is way off for a DC shaft and my standard shaft is even worse when run with hubs locked on the street for testing.
You should have zero vibes in the rear. My transfer case output is 2* down. Did you measure on level ground? Garage floors usually have something like a 1* slope. I would adjust the rear pinion to match the T-case output flange and if it vibrates consider new U-joints especially if yours were running at the previous angles for a long time.
Post a photo of you front driveline and axle from the side. Removing one tire would make this come out better.
You should have zero vibes in the rear. My transfer case output is 2* down. Did you measure on level ground? Garage floors usually have something like a 1* slope. I would adjust the rear pinion to match the T-case output flange and if it vibrates consider new U-joints especially if yours were running at the previous angles for a long time.
Post a photo of you front driveline and axle from the side. Removing one tire would make this come out better.
Here is the best pic I could quickly get of my DS and the diff.
I did another reading of the pinion and DS angles, and they are at 3.1* and 11.55* respectively.
I have a CDL button on order, arriving in the next day or two, so I am going to pull the front DS once it gets here and confirm the source of the vibration. Based on what I have read here, it is likely coming from the front.
Aside from going part time, are there any other options for getting the angles right in the front?
A local shop here suggested I could install OME caster correcting bushings into the slee arms in reverse, which would reduce the excessive amount of caster and possibly get my caster back to 4.5* range. But it would be a bit of a guessing game as far as what the caster would end up being and whether it would get the pinion angle just right and actually reduce vibrations.
There is definitely a misalignment of the front driveline and the pinion shaft. Theoretically, for a dc shaft to run smoothly, the drive shaft must be within 1* of running directly into the pinion shaft as if they are one.
Once the CDL switch is installed you can narrow it down.
Once the CDL switch is installed you can narrow it down.
That's what I figured. Will confirm this weekend assuming the switch installs without issues.
Would shorter radius arms solve this issue? Apparently Slee's arms are designed for a 6" lift, but worked with a 4" lift (which was probably higher than 4") as well.
Delta's radius arms come in 2" and 4" sizes, which are 4* and 8* of correction respectively. But since I don't have stock arms, I don't really have a way to test how much correction I need.
Ultimately, the question is - would getting the right size radius arms address the vibration issue and get the angles right?
First I would identify for sure the vibration is coming from the driveshaft or not. If it is the driveshaft then I would make sure the ujoints are fresh and shaft is balanced and true with run out that is within spec and that your slip yoke isn't worn. In regards to the front angles of the tcase and pinion, I have no idea what Toyota was thinking here. For a broke back driveshaft setup, if your front tcase output is up 3 degrees, then the pinion should be up 3 degrees of which you can be 2 degrees off. That's what my driveshaft shop told me. However in Stock form the pinion is not close to 3 degrees up. If people are using a CV driveshaft of which really eliminates all vibration, I would follow that formula. My guess as to why that is needed for larger lifts is that the ujoints are running beyond their rated operating angles. 5.8 of caster is high and is likely bowing your coils, not a big deal except the bump stops probably bind in the coils. So I would shoot for 3 degrees ish.
What his the measurement from the center of front wheel hub to the underside of the fender flare. This will give you an idea of how much actual lift you have.
Also that drive shaft seems to short based on how much the slip yoke is extended.
Also that drive shaft seems to short based on how much the slip yoke is extended.
FWIW - You can lock your CDL without a switch by engaging the CDL and removing the fuse.
I have delta arms and think they are a great product. They actually correct castor to the higher side of spec. If you know exactly how may degrees of castor the Slee arms induce, you could more easily choose a set of Delta arms with their guidance. Before you contact delta know the vertical distance between your front upper and lower track bar mounts, they will ask. But first, troubleshoot by removing the front shaft and locking the CDL.
Which ones do you have? They have 2" lift/4*, 4" lift/8* and 6" (not sure what degree this level is) options.
The challenge is I don't know what amount of caster correction I actually need with a Slinky 3" kit, because I no longer have stock radius arms. I only have Slee arms which are apparently designed for a 6" lift, so they are over-correcting the caster for my amount of lift.
So I don't have a baseline to measure against to figure out which height kit I actually need, unless I get a hold of a set of factory radius arms and get an alignment reading to figure it out.
Even then, I am not 100% convinced that getting the right amount of caster correction will address the diff pinion angle/driveshaft vibration issue.
