Caster Fix for Death Wobble

[Gurr]

Wuddup Mud. Been awhile.

I've been attempting to finish my degree with the intent on keeping my FJ60 and not working on it until after my finance absorbing schooling era is over. I've come close to selling her with the way prices have gone up and how tight the budget is...but at the same time, I can't. Luckily, my friend did.

Last summer I picked up my friends FJ62 "Rose" with the intent on doing a little fix up and sell as he didn't really want to take the time do it. Long story short, another friend was looking to get something that he can take down to Central America on his 4 month adventures. I told him I will make sure this thing is a solid rig before selling it to him.

A few small things to get done is just the odometer/speedo cable, maybe the radio, adjust the valves...

However, the main issue is the death wobble. Rose has an Old Man Emu 4.5" lift kit, I believe, with a shackle reversal installed by some previous owner with no paperwork.

Starting with the simple things: I checked the suspension and everything is tight, so I decided to pull off the steering stabilizer...feels good too. Next step is checking the alignment. Caster reading is +5*...so 10* off of where it should be. Kind of a bummer. Shims come out at 2*, 4* and 6*. Another bummer. After talking to Bryce at Cruiser Outfitters, the proper fix is to cut and turn the axle with this big of an angle.

If that's what has to be done then it looks like that's what's going to happen. I would like to explore all of the options here though.

Would it be possible to cut the front leaf spring mount shorter or get a longer shackle to achieve the proper caster angle? Thinking about this a bit more also makes me realize this would have the same effect as adding a shim. The front driveline angle would be too steep, and the T-Case would have to be lowered to counteract this fix...

 

[White Stripe]

I would install a 6 degree shim and a high angle driveshaft. I don't know if I would trust a fj62 in south america unless in was in pristine mechanical condition.

 

[stevebradford]

I would put the shackles back the way they were meant to be and add castor shim. but that's just me, I don't like shackle reversals.

 

[Gurr]

Hahaha! Ok, that took an unexpected turn. I guess I should elaborate on my buddy.

Majored in Spanish and works as a vendor touring music festivals throughout spring and summer. During his off-season he goes down there doing all sorts of s*** with the locals, he's a personable dude. I can understand concerns involved with Central America, especially with s*** like scopolamine and the gang violence out there...but he'll still go, whether he's hitchhiking or driving a cruiser. However, I can recommend otherwise to him.

That being said, the issue is the caster. It still has to be fixed whether I sell it to him or someone else if I want to sleep at night.

 

[lcwizard]

+2 degrees caster is about stock. +5 degs in itself won't cause wobble. Most often death wobble is a tire balance issue. Next is worn steering parts and toe in. Caster is only a problem in the negative range. -5 degrees would be an issue (think shopping cart). Too much caster will result in extra steering effort standing still. If you set a tape measure at the ground, extended to the hood line and have someone turn the wheel lock to lock, you'll see the truck rise and fall. The more caster, the more rise and fall. I had a Nissan truck that Flying High built up with custom Dana 44s that the owner couldn't steer unless he was rolling. It had 14 degrees of positive caster. It tracked fine but the steering box had to lift the weight of the truck 3 or 4 inches going center to lock. Added with 12" wide tires, the Nissan box didn't have the hydraulics to move the wheel at rest. I set up lots of front ends +4 degrees. The only effect is really stable highway tracking.

I'd have the tires balanced first and look for tread separation in the tires. Age and sitting can cause this. No sense spending time and money
on expensive parts until you cross out the simple things.
If the tires are good. loosen the tie rod clamps rotate the tie rod one revolution and drive down the road. If it gets worse rotate back to start and add another revolution. If it gets better either way you can add another half or full in that direction. Don't assume textbook alignment numbers are always going to the best settings for all tire and rim combinations

 

[LAMBCRUSHER]

I've had steering issues self resolve more than once after a matching set of new tires

 

[lcwizard]

I've had steering issues self resolve more than once after a matching set of new tires

Once you've been around long enough and gone through enough off road tires you realize none are immune. From my first sets of bias plys
in the 70s to state of the art (?) modern radials eventually the tires will not run like new. I've had Maxi Tracs, Norsemans, Desert Dogs, Buckshot Mudders and nearly every brand of radial radials at least once in the last 40 years. It's almost always tires. Some of the bias plys were sensitive to pressure. We had 38" Swampers that ran true at highway speeds as long as the toe was 1/2~1 degree out and the pressure was never over 8 lbs. Any more tire pressure and the front end felt like it would break all the u-bolts and take off on it's own. Sometimes getting the last 25~40% of a tire is all about fiddling with alignment and frequent balancing. It gets worse if you do frequent off road air downs

 

[Gurr]

Thanks for the detailed response wizard.

I see that I mistakenly said +5*...but I meant -5*. The "10* off" that I was also referring to was from this thread: death wobble where +4 or 5* seemed to be the recommended number.

I used to work at a tire shop doing alignments for a few years. I wish this was as simple as a tread separation, but maybe I should describe the symptoms a bit for a better understanding and my logic with the diagnostic. I really do hope it's something simpler.

It doesn't happen every time I am rolling(rules out tread separation being a constant issue), as a matter of fact it can be a bit of a rare occurrence. However, sometimes when I am starting off from a stop or cruising at just the right speeds and maybe I hit a bump in the road(generally around 15 - 30 mph ruling out tire balance which gives a shake at about 60 mph) the front end starts to shake violently. I've stuck my head out of the window to take a look and I could see the tires wiggling like crazy! The only way to stop it is to slam on the brakes down to 5mph.

As for the toe reading I don't have the exact reading(I seem to have lost it somehow) but I remember it wasn't that far out when I had them check it not that long ago.

I could try rotating the tires to see if it does anything. I don't drive this thing a lot though...you can see the spiderwebs

 

[lcwizard]

Thanks for the detailed response wizard.

I see that I mistakenly said +5*...but I meant -5*. The "10* off" that I was also referring to was from this thread: death wobble where +4 or 5* seemed to be the recommended number.

I used to work at a tire shop doing alignments for a few years. I wish this was as simple as a tread separation, but maybe I should describe the symptoms a bit for a better understanding and my logic with the diagnostic. I really do hope it's something simpler.

It doesn't happen every time I am rolling(rules out tread separation being a constant issue), as a matter of fact it can be a bit of a rare occurrence. However, sometimes when I am starting off from a stop or cruising at just the right speeds and maybe I hit a bump in the road(generally around 15 - 30 mph ruling out tire balance which gives a shake at about 60 mph) the front end starts to shake violently. I've stuck my head out of the window to take a look and I could see the tires wiggling like crazy! The only way to stop it is to slam on the brakes down to 5mph.

As for the toe reading I don't have the exact reading(I seem to have lost it somehow) but I remember it wasn't that far out when I had them check it not that long ago.

I could try rotating the tires to see if it does anything. I don't drive this thing a lot though...you can see the spiderwebs

That SR kit came with a 4 degree caster shim. What's odd is without the shim it shouldn't have a -5. I've had one on all my 60's and after the shim it settles around 2+. It could be the springs have the center pitched at an angle. The manufacturers then adds a caster shim. Why they don't just redesign the spring is beyond me. Here's an image of such a spring set where the design flaw requires a caster shim. The bad part is
that company only puts an 8degree shim required to bring it back to a 0~1/2 deg caster, stock for a 40 series. I replace it with a 10 degree
to get a +2

 

[lcwizard]

The quick way to check caster on a 60 is off the pinion flange. A 60 series typically has 2 degrees of positive caster when the pinion flange is
pointed up 6 degrees. It's a very well thought out relationship between pinion and caster. A 40 series pinion is flat with 0~1/2 degree.
This creates problems with u-joint bind with lifts. Up to 5~6" lift you probably don't need a cut and turn but you may need a higher angle
u-joint like in the 80 series front shaft

 

[Gurr]

Fantastic, this is the kind of answer I am looking for.

I looked into it a bit and I did not come out disappointed. I found a thread(Shackle Reversal?) which had a post from a past wizard.

You can run it front or rear. It works well in the 40 where driveshaft lengths get very short with v-8/automatic swaps. Joint Fuji sells the slip yoke kit. Part #FTL-35050x. It's called the "Prop shaft 5 piece kit"
This kit has an 8" slip yoke assembly ( male and female ) FJ80 flange and u-joint,
and the steel dust cover/boot like you see on all cruiser driveshafts. All Pro is the only one I've seen with pics on their site. These have the same tube diameter as all cruiser driveshafts so it's a simple swap. The slip assembly in this kit is actually a couple inches longer than the stock 80 front The 80 has a 6" slip, this is an 8".
The 60's vary from 2 3/4"~3 14"

Drivetrain | All-Pro Off Road

My next question involved where to source some of this stuff, but it was answered with this post. Would this be the same kit you recommend? Only issue now is that it seems they have changed their part numbers and names for the parts. I was wondering if you might be able to guide me a little further on which kit it is if this seems to be the way to go: Welcome to JOINTFUJI.COM

Maybe shims will work out after all after reading that thread.

 

[Gurr]

Welp. Installed those fat-ass shims. Can't say I'm entirely warm and fuzzy with that steep angle. I'm going to drive it up and down the street and check the driveline angle tomorrow.

 

[lcwizard]

Yes, Joint Fuji does make the D/S kit. That's a bigger shim than I'd expect to need. I hope the center pin passes through

 

[Gurr]

Yeah, I don't necessarily like just how large it is...and now that I think about it and how this wobble was only an occasional thing...a smaller shim along with the toe adjust would probably be sufficient. s***. I'll probably swap it out for a smaller block and see how it sits along with the driveline angle. Previously it was at 12.5* now it's at 16* where the front flange sits at 4.5*

New center pin can be seen in that last picture. It was pretty long so I cut it shorter.