The Polar Bear - NP241 Upgrade

[downtowncb]

Good luck finding the vibration, hope you get that sorted out.
Congratulations on an amazing build, even if it had just a 360 the ZJ would be amazing! Can't wait to see how this thing performs in the rocks and on the street!

Thanks a lot man!

Well I put the transfer case in neutral and the transmission in drive and the vibration persists so that eliminates everything aft of the input planetary gears in the transfer case. I'm going to drop the pan in a bit and see if there is anything obvious to see.

[MineRunnerZJ]

We need an update!!! And a new video.

[MineRunnerZJ]

.....please

[ratmonkey]

Almost makes me want to ditch the 408 and go with one of the cheap and plentiful chevy power plants. Almost.

[Bama Installer]

Congrats on an Awsome Build! Ive been following you for several months and I really admire your patience and attention to detail . KUDOS

[ATL ZJ]

How are you liking your spring rates so far? Still running the 200 over 350?

I sold my 150 over 250 setup in favor of something stiffer, I've run the calcs but I figure our front ends are probably somewhat close in unsprung weight...

[downtowncb]

How are you liking your spring rates so far? Still running the 200 over 350?

I sold my 150 over 250 setup in favor of something stiffer, I've run the calcs but I figure our front ends are probably somewhat close in unsprung weight...

I've actually been up in Reno for the last couple of weeks so I haven't been driving it. From the somewhat limited use I have I think those rates are still a bit soft, they seem good for slow flexy crawling but I plan on going a bit faster. That transmission issue was still persisting. I'm driving back to San Luis tomorrow and on Thursday I'm going to throw my last ditch efforts into diagnosing the problem before I take it to a transmission shop probably the first of next week.

[downtowncb]

We need an update!!! And a new video.

Alright and for the update, I've got all the problems sorted out. I figured out what the source of the vibrations were coming from; when the transmission was in park or neutral the engine would rev without problem but when it was in reverse of drive there was this god awful vibration. It turns out that the torque from the motor being in gear was causing the engine to rotate just enough to make the exhaust contact the frame. This allowed vibrations from the motor to be conducted straight into the frame. I'm working on sorting it out but at least for now I'm glad it's nothing major this close to GSW.

Every day my list continues to get shorter for GSW. I'll have more stuff up in the next couple of days but for now here is a long delayed video; just a quickie around the block but you get the idea.

http://www.youtube.com/watch?v=a8Quz3-t2H4

[downtowncb]

Finished my ghetto ass steering box brace. I've been pounding my head against the wall trying to figure out how I was going to mount a steering stabilizer because it gets the occasional death wobble without it. I finally settled on piggybacking it on the steering box brace.





And look what UPS just dropped off! My $15 junkyard TJ pump wasn't quite the bargain so I bought a 1600 psi CB pump from PSC.



Only a couple more things for GSW!

[downtowncb]

Got the reservoir mounting brackets. The last thing to tidy up is the wiring, ugh.

[AgitatedPancake]

Damn man this thing is lookin sexxxay! The engine compartment is damn clean also man, everything is comin out awesome.

[downtowncb]

Thanks a lot man!

To fix the exhaust I went AP on it. It was the flange on the driver's side cast manifold that was touching the frame. I cut the flange off and tack welded it on where I wanted it, I then preheated it in my oven to 500º. I then did a two pass weld on beveled edges for full penetration, which I followed by post heating it in the oven at 500º for an hour. After that I lowered it about 50º every half hour. Hopefully it holds up fine.





Here you can see where the flange used to touch the frame, in the center of the soot is the bare spot.

[downtowncb]

Alright, another battle, this time death wobble. I know I'm beating a dead horse with this one but since everything up front is new/tight since I just built it; I think the source lies in my design/suspension geometry. The steering stabilizer helped prevent it from happening on every little bump but it still goes crazy on a pothole or big bump. I am sitting at 5º of caster, haven't measured my toe yet. My drag link is 35.125" long and my track bar is at 34.25" with the axle centered under the Jeep. They are 6º out of parallel.

I need to get this puppy performing well for my drive to Reno on Tuesday before we haul it out to Moab for GSW on Wednesday. Before I go cutting shit up I wanted your guys input. Is my imperfect geometry the likely culprit?

Facts:
Caster = 5º
Drag link = 35.125"
Track Bar = 34.25"
Difference = 0.875"
6º out of parallel

[Ted_Z]

Make sure you are a bit toe-in. I typically set it at 1/8" to 3/16" measured on the tire surface.

[downtowncb]

Just checked the toe, it came out to 1/16" or .11º. Spec is .04-.44º, so I'm within spec but half what you suggested. I was also wrong about the caster, it's at 6º. I'll play with the toe and caster a bit before I go hacking at it.

[Jeeptech01]

I was wondering if it had something to do with the bends in the dl. Maybe it is rocking back and forth across the travel of the tre's. I cant think of any factory app that has a bend in the dl. HTH I have been staring at the pic and your comment for like 20 min and that is all I can come up with.

[IndyZJ]

I would think that the difference in length/ angle would only contribute to slight bump steer and not have anything to do with death wobble. It looks like you could just drill a new hole in the frame side track bar mount to make everything parallel. They are close enough in length that that sould not be an issue. Your caster sounds good, too.

I'm guessing you've double checked all the hardware in the suspension and steering to make sure it's tight? How about the steering box itself and its mounts? I'd take a look at the box; if it checks out, add some toe and see how it does.

Going off of what Jeeptech said, it looks like there could be some slop in that goofy drag link adjuster. Otherwise, nothing looks like it would deflect enough to cause a problem.

[downtowncb]

So far I adjusted the toe to .217º, caster to 5º, lowered the frame side track bar bolting location a bit which brought it to within 3º of parallel and now I'm working on the axle side mount, I cut it off and am moving it up a bit to get it perfectly parallel. I know I said I didn't want to cut shit up but I figure after this much work I want it to function perfectly.

Thanks for your input guys. After rechecking everything, the only thing I found were that the bolts on the steering box weren't terribly snug and one brake caliper bolt was loose, thank god I caught that. Otherwise everything else, including my goofy adjuster on the drag link are all tight.

[downtowncb]

I removed the old 2.5" exhaust today. I recycled if from the old 5.9 and I could feel it robbing power so while I was in Reno after GSW I stopped by Summit Racing and picked up a Magnaflow muffler and 3" mandrel u-bend.





It is freaking tight fitting 3" pipe through there but I managed to clear everything, barely.



I also cut out and replaced the driver's door hinge pins and bushing. The old ones were really worn out, the door was sagging and made a god awful screech when opening or closing.

Also, can anyone recommend a good high temperature plastic adhesive? This stud that the engine cover bolts on to broke off in Moab and I trail fixed it with duct tape. I've tried two different brands of plastic epoxy and both have broken under the heat. I tried a high temperature plastic epoxy from Napa and it too broke again today. A vacuum leak that big is NOT fun when you're driving through town, I was standing on the brakes to not rear end the vehicle in front of me.

[faststang1]

try JB weld!!

[Jeeptech01]

My guess would be panel bonding adhesive. Whatever you use though hit the area with some sandpaper first so it has something to grab onto.

[311WJ]

what happened with the death wobble? I don't recall you mentioning it in moab and i forgot to ask.. did you fix it?

[ATL ZJ]

Just plug it and get rid of that poser cover

[downtowncb]

try JB weld!!

Forgot to mention I tried that too, it also didn't hold.

My guess would be panel bonding adhesive. Whatever you use though hit the area with some sandpaper first so it has something to grab onto.

I scuffed it up with some steel wool every time I tried a different adhesive. What is panel bonding adhesive?

what happened with the death wobble? I don't recall you mentioning it in moab and i forgot to ask.. did you fix it?

I think the ultimate cause was too much caster, I dialed it back to about 5* and haven't had an issue since.

Just plug it and get rid of that poser cover

Plug it with what No matter what I do I'll have to use some sort of adhesive, besides, I want everyone that looks under that hood to make no mistake it's a Chevy

[ATL ZJ]

Plug it with what No matter what I do I'll have to use some sort of adhesive, besides, I want everyone that looks under that hood to make no mistake it's a Chevy

I was mostly kidding but you could pop the TB off, lay a towel in there, and install a pipe plug... Then you'll have the most hood rat chevy/jeep on the block.

If you're going for obvious it'd be a good time to step in the direction of an LS6 intake...