Knuckle rotation contemplation

[DrMoab]

Jeff, with your lift, did you ever decide how many degrees you would have to knock the knuckles back to get the right caster and also get the pinion pointed in the right direction?

Since I have a 30 laying around to put under Stink III, I'm really warming to this idea.

 

[XJEEPER]

I'm currently running 10.5* of pinion angle with 6" of lift, which puts my caster at 2.5*. Handling is not as bad as I thought it would be, but in no way ideal for daily driving my XJ. It's tolerable at 75 on the freeway though, considering how far out of spec it is, but I know that the front dshaft is still off a little because it gets really "vibey" at 73 and gets worse from there. Any speeds below that, the vibes are fine. Steering is a little sloppy too, so I need to get the knuckles rotated soon.


OK, that out of the way........based on measurements from my rig and the experience of others who've BTDT, I'll need to rotate my knuckles back 3 to 3.5 degrees to net the desired castor of 5.5 to 6 degrees which will also allow me to dial in the pinion angle to 10-11 degrees, with my 6" lift.

http://www.naxja.org/forum/showthread.php?t=907435&highlight=rotate+knuckles+to+correct+caster

 

[jwtrapper]

Have you done this yet. I was thinking about pulling mine out and cutting and rotating them back to where they should be.

 

[XJEEPER]

Nope, still driving it with 2.5 degrees of caster........I don't like it, but prolly won't get to rotating the knuckles for a few more months. Got a couple of higher priority spring projects that are "must do".

 

[rcmf5525]

What will happen if you have negative caster? Will it dart all over the place? I have heard that negative caster makes turning big tires at slow speeds a lot easier... Dont have any first hand knowledge though...

 

[corbinafly]

What will happen if you have negative caster? Will it dart all over the place? I have heard that negative caster makes turning big tires at slow speeds a lot easier... Dont have any first hand knowledge though...

You'll probably kill yourself and whoever's in the way the first time you take it above 30 mph!!:dunce:

 

[rcmf5525]

Sweet! So I guess its a go right?:gee:

 

[rcmf5525]

Holy Balls!!! I just finished turning one of my inner Cs! It took like 4 hours! The Dana 44 is out of a '76 F250 and the welds were DEEP! The shop I am working in has a MAC tools angle grinder and a cut off tool. The angle grinder is slow and wasn’t much help. I did the whole job with the cut off tool. Went through 3 wheels on one knuckle! Not to mention I had already installed the TnT truss (I know Im a dumb ass). This is a full width swap so the truss had extra steel past the coil perches. I had to remove the extra so I could get to the top side of the weld. One of my most miserable days in the shop ever. Got it to turn though. I thought the shop had an angle finder but they don’t, so I have to go pick one up before I can weld them back up. I just couldn’t believe the knuckle was that hard to turn. The only tech I have read here was "...grind the welds off and hit it with a BFH..." LOL.

 

[XJEEPER]

The only tech I have read here was "...grind the welds off and hit it with a BFH..." LOL.

Not sure where you read that, there's lots of tech from folks who've done it. Thanks for the feedback though. Still kicking myself for not doing this while I had a bare housing.....:twak:

 

[rcmf5525]

Not sure where you read that, there's lots of tech from folks who've done it. Thanks for the feedback though. Still kicking myself for not doing this while I had a bare housing.....:twak:

Show me a thread where the person did not cut the knuckle off the tube before turning it... That is the only wright up I have seen. Every other mention of turning the Cs involves a BFH, no pics or more info...

 

[rcmf5525]

Got the other knuckle turned... Only took about 2 1/2 hours this time. They are set at 4 degrees. My daughter left the digital camera at her grandmothers house (9 hours away) so I cant take any pictures... Sorry...

 

[jwtrapper]

Got the other knuckle turned... Only took about 2 1/2 hours this time. They are set at 4 degrees. My daughter left the digital camera at her grandmothers house (9 hours away) so I cant take any pictures... Sorry...

Whats your pinion angle at? Did you remove the spring buckets off of the axle first or did you have room to work around it?

 

[rcmf5525]

Whats your pinion angle at? Did you remove the spring buckets off of the axle first or did you have room to work around it?

The pinion angle is at 10 degrees, maybe a little under, but no less than 9.5. I had room to work with out removing the buckets because this is a full width swap. There is about 4" (have not measured) of distance from coil bucket to inner C. I had to remove the ends of the truss though. I should have done this before I welded up the truss, but I was being hard headed and did not think it would be that much of an issue until I drove another guys XJ that had negative castor and it sucked!! Very minor movements in the steering wheel were major movements in the vehicle. Not fun to drive on the road! He had hydrolic assist steering which did not help the problem.

 

[XJEEPER]

OK, I'm sick of daily driving my rig with 2.5* of caster. It's acceptable at speeds below 60 mph, but I spend so much time on the freeway outside that range, I'm done.

Taking Friday and Monday off, so I'll start stripping the housing down Thursday night in prep for knuckle rotation.

This procedure will be documented.

 

[corbinafly]

OK, I'm sick of daily driving my rig with 2.5* of caster. It's acceptable at speeds below 60 mph, but I spend so much time on the freeway outside that range, I'm done.

Taking Friday and Monday off, so I'll start stripping the housing down Thursday night in prep for knuckle rotation.

This procedure will be documented.

Pretty simple really. Just takes a BFH, some cut off wheels, and time.....

 

[XJEEPER]

Got the passenger knuckle rotated yesterday, along with a few other projects. Finished grinding the drivers side this morning and got it rotated.
Time to weld.....

 

[Mosephus]

sweet, i'm lookng forward to pics!

 

[XJEEPER]

Been a pretty busy week, so I'm finally getting around to the knuckle rotation project update.

First, assess the tools that you'll need to complete this project. I made sure that I had plenty of 3" and 4" cut-off wheels and grinding wheels, plus some 18 tooth blades for my Sawzall. Not show are: face shield, ear plugs, 10 lb sledge hammer and patience.

I unbolted everything from the inner axle C's out and took some pre-rotation measurements. My static measurements were 3.9 on each side. My goal was to rotate the knuckle back 4 degrees, so my new target was 7.9 degrees.
I decided to leave the D30 housing installed, as the suspension would act as a support stand that would keep the housing from flopping around when I started beating on the knuckles to rotate them. Don't forget to plug the axle tubes to keep the junk out.

Also checked camber too, just so I had a reference point. Note that this isn't true camber, as my housing was not sitting perfectly level on the jackstands.

I had to remove my lower C gussets, which I will replace with new ones. I just torched them off, then got to grinding......and grinding.......and you guessed it, more grinding.

 

[XJEEPER]

Another shot, from above. Cutting through the weld on the top of the knuckle was a little tricky, so I used my Sawzall to handle a short section that was hard to get at with the grinders.

The placement of my lower shock mounts impaired my ability to run the cutoff wheel on my 4" grinder all the way around the knuckle, so I used a 3" wheel on my air grinder to handle this section. I probably should have just cut them off and reinstalled them afterwards.

You'll wind up with lots of this to clean up.

Note, some key points in this process:

• You'll want to cut into the knuckle approx. 1/16" with your cutoff wheel. If you just cut through the weld where it mates the knuckle to the axle, you'll not cut through the area where the stock weld penetrated the knuckle.
• When cutting through the welded area, you will be able to see a fine, circular line appear in your cut, on the knuckle side.This is the exposed metal of the knuckle/axle joint. When you see this, you will know when you have cut enough on the outer side of the stock weld.
• Be aware of the depth of your cut, if you cut too deep, you could cut through the axle tube.
• Too narrow of a cut will not allow you to penetrate the void with a good weld after you've rotated the knuckle.

I have no shots of me smacking the knuckle with my hammer to rotate it, sorry. I was surprised at how easily it rotated, without the need to heat up the knuckle. Just a few solid smacks and I had the knuckle rotated back 4 additional degrees. I decided to set both sides at 8 degrees, so technically I rotated them back 4.1 degrees. Based on the pre-measurements of my pinion angle and caster, my goal was to be able to run with 5-6 degrees of caster, instead of 2.8.

Once I had both sides set, I verified that my camber was unchanged and then tack welded the knuckles to the tubes at 4 points, alternating top to bottom, front to back, and then rechecked the caster and camber measurements. Nothing moved, so I welded them up solid, using a pulse method and alternating from side to side, allowing cooling between passes. I actually made two passes around the knuckle, overlapping the welds to be good coverege and penetration. May have been overkill, but it made me feel better.

I also fabbed a couple of new lower C gussets ( glad I made a pattern the first time ) and welded them up.

With both sides welded up, I installed new balljoints. The old ones were less than a year old, but I decided just replace them while I was here.
As luck would have it, the local Six States only had one Spicer BJ kit, so I snagged a Crown BJ kit for the other side from Carl at TeraPlus. This way I can compare the durability of the Crown parts VS Spicer, for future reference.
Crown kit pictured on top, Spicer kit below.

Since we've had a long and snowy winter, the road salt had taken it's toll on the paint on my axle, so I gave it a fresh coat of Rustoleum while I had it torn down. Then on to reassembly.

Note that I chopped off my swaybar mounts at the beginning of this process, as I have a Currie's Antirock Univeral setup on order and will rework the mounts with that install. (Stay tuned.....)

I also took this time to relocate my steering stablizer, as I didn't like the way the bushing was binding by mounting it on top of the trackbar axle bracket and draglink. I snagged another bolt-on shock mount and drilled a hole in the lower trackbar bracket and moved the stabilizer down to the tierod.

I dialed in my pinion angle to match my driveline to take care of the vibes, and would up with a net caster of just over 5 degrees. It handles very well on the freeway and I can relax with a couple of fingers on the wheel, even in a cross-wind.
Rotating the knuckles is not difficult, with the proper tools. It's a time-consuming process, but well worth the effort.

(My coils are slightly bowed forward, but due to the bracketry rework and gusseting that I did on my LCA mounts/coil pads previously, I decided not to mess with rotating them back, as others have suggested. I have another idea to resolve this issue, which I will address when I decide if I'm going to add airbumps or not.)

 

[Goatman]

Nicely done, Jeff. Glad it handles better.