Jeep Nathan and Tanja's 99 XJ Build up

[thenag]

Test fitting bracket




Painting the bar


Passenger side spot welded and bolted in


Almost ready for a drive. (more on that later...)


So part of the reason I haven't built this support before is that I couldn't decide the best way to attach it, make it removable, and make it compliant if the "frame" bends or moves a bit. This setup is not at all compliant to any movement. So if I have to remove it and it doesn't move, I will have to cut it and build up some plate or something to bolt through.

Also I should figure out a center axle limit strap to hang off that thing...

So that final picture was taken the afternoon of July 2nd. I installed the drag link and tires and re-checked the bolts, and re-checked the toe.

I drove it, I have a manhole cover that is close that has been real good at triggering death wobble.

It still wobbled after all this extra support.

(frowning face drank much alcohol that night...)

the next day for the heck of it I rotated the tires, the first DW started not too long after 2 new tires, maybe the balance is screwed up, nope still wobbled.

So I went down the DW rabbit hole on the internet.

I found so much good information on stock jeep wrangler axles that my head hurt.

I was so mad, I have this pretty friggen cool Jeep that is totally un-drivable.

There was only one thing that kept coming up that I had not changed, wheel bearings. But everything is written about wranglers with unit bearings, the d60 has old school tapered bearings. Well I was just throwing money at it now so I went to Napa and got some wheel bearings. (this axle is just getting old enough that parts are not as accessible, I ended up with Napa China bearings, I would prefer Temkins or something but they should be good enough)

I pulled on the wheels with the old bearings and there was no movement sideways or anything, they spun nicely.

The other thing that I was looking at was my axle side track bar bracket, it was angled back indicating more caster, so I looked through my old photos and it seemed to be more vertical in the old photos. Measuring off the bottom of the ball joint I was at 5 degrees. (again I can find a ton of places to put the angle finder on a wrangler axle, not so much for a ball joint 60 that the "C's" have been turned a bit) I also (conformation bias, my google search was "jeep death wobble caster") found a few guys online that swore just bad caster would cause DW even with no other worn/loose parts.

I also had added some spring spacers front and rear over the years to help with the sagging springs, so I wanted to remove those, because why not.

So I did three things at once, new wheel bearings, removed the spring spacers, set the caster at 3 degrees.

Drove straight to "my manhole cover"...

No wobble!

I have drove it a bit more including a pretty rough paved road and no wobble!

I am still to scared to try the freeway but I am optimistic, at least I made it better.

So I don't believe it was the wheel bearings but I like the idea that it was.

Lets look back in time a bit

So no death wobble

First death wobble was early May on the highway.

I looked at it, realized that my caster was negative 6, changed it to positive 6. It drove well but gave a wobble on the highway. It did NOT instantly wobble like after I installed the Heim steering.

Then I decided to change to Heim steering and install new ball joints, which requires removing and re-installing the bearings.
I also removed my hydro assist, hydro assist will prevent wobble since the tires cannot push the ram. I removed it for clearance reasons (for now).

Then it wobbled really easy, 35 mph manhole cover would cause full wheel jerking wobble.

Over the years I have had my alignment all over the place, and haven't had a wobble. Also I set the caster and it was driveable but with a random occasional wobble, of course smaller wobbles may have been prevented by the hydro assist.

As with many DW I didn't find a clear smoking gun, it may have been a combination of wheel bearing, caster, tire balance, loose trackbar frame bracket bolts, and removing the hydro assist.

Like I said it still makes me nervous I don't know that I will be hitting the spaghetti bowl anytime soon, but it seems to be better.

Nathan

 

[Gravy]

I'm not one to offer negative critique much but I'm confused why you made your cross frame bracket directly above your axle side track bar bracket? It looks like it will severely will limit up travel?
You could quite easily move the bracket 3 inches forward.

As far as death wobble goes I would definitely make sure your caster is spot on and that you as close to zero toe as possible. Erring on the toe in side.
Also pretty easy to check and see if you're power steering box has slop. You can pull it out with the adjuster nut and allen key bolt on top.
Best of luck.

 

[Kiel]

Avoid the temkins bearings, get the timkens

 

[thenag]

I'm not one to offer negative critique much but I'm confused why you made your cross frame bracket directly above your axle side track bar bracket? It looks like it will severely will limit up travel?
You could quite easily move the bracket 3 inches forward.

As far as death wobble goes I would definitely make sure your caster is spot on and that you as close to zero toe as possible. Erring on the toe in side.
Also pretty easy to check and see if you're power steering box has slop. You can pull it out with the adjuster nut and allen key bolt on top.
Best of luck.

My track bar has never gotten that close to my oil pan, I have so many other things that will hit before the track bar hits the support (I think). I guess I should cycle the suspension with the springs out...
37's and "up travel" on an xj is always interesting.
Also if the support bar moves forward I might have to worry about clearing the steering linkage.

Thanks for the ideas.

Nathan

 

[thenag]

*Warning horrible welding pictures ahead!*

I have always believed that the exhaust was undersized, it is 2.25 inch and has some smaller restrictions in it. I really didn't want to buy a bender so I looked into buying pre-bent sections and welding them up. I have a decent welder and am working on becoming an ok welder. The engine seemed like it didn't want to go above 3500 rpms, it is hard to explain. Hot rod rule of thumb is 2.25 is good for about 190hp, my stroker should be more like 225hp. So I got some pieces, some .023 welding wire, 20 some odd hours later, the Jeep runs much better! I am hoping that it will run cooler, but since it is December I will need to wait to see if that happens.

For the most part I just copied what I had but made it out of 2.5 inch exhaust pipe.

Using flanges, I was able eliminate the need to do more than just tack weld under the vehicle. (this also makes everything easier to work on, from experience the transfer case does not come out unless the exhaust moves a few inches out of the way)

I re-used the Cat, although it is 2.25, I stretched the inlet and outlet with a tailpipe expander.

My down pipe cannot come down where every pre 1998 4.0 comes down, the d60 yoke is way to close to the bellhousing, so our exhaust goes around the front of the oil sump (very close to the d60 truss..). I also have the 2000+ Banks header. Since it is a 1999 I do NOT require the two small catalytic converters right below the intake.

I paid $80 for this part just to use the 2 inlets, I welded some scrap on them to keep them in position.




Here is the Y pipe I picked up


Old and new downpipe to cat section


Pinhole leak testing


And... either my scrap pieces allowed the inlets to move, or the "cheap" Walker piece was not precise, which it wouldn't have to be since it would flex. I couldn't get the new piece to seal on the Banks manifold. BTW if you have worked on one of these you know the inlet bolts are really hard to get to, well I made the 2 center bolts really really really hard to get to. So I had a couple day delay fixing this little imprecision. Look at the top inlet it is off by almost 3/16th. (the OEM cast 2000+ manifold is 2 pieces so I had to clamp them to my table using the old down tube to figure out spacing)


After I go that figured out, and lucked out since I was able to fix it on the bench and not under the vehicle, I crusied along, I didn't take to many pictures along the way.

Here is the last section which slides nicely out the rear of the Jeep. The muffler sits outside the frame rail next to the gas tank, where the stock rear leaf spring was.





(Yes my welding is that ugly done on a bench...)

Nathan

 

[Hickey]

Don't sweat the welds. We've all gotta start somewhere. 👍