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Unread 02-29-2008, 01:44 PM   #1
dandiv
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tech questions, bumper/frame strength.

I have a 98 sport and Im building a really tough brush guard for it. Im wondering what kind of hit the unibody will be able to take seeing as brush guard ties into it, and will not bend or flex at all.
also I have stock shocks on it and Im wondering if its weight (75-80 pounds) will hurt my shocks.

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Unread 02-29-2008, 01:49 PM   #2
mpwal099
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Are you simply adding a brush guard onto the factory bumper or building a whole new bumper? If a new bumper, build tie in brackets that will allow you to add more strength by giving more mounting points for your bumper. Instead of just the 3 stock mounting holes, you wind up with 6. Going that route will add a lot of strength to it and more rigidity against bumps and pulls.

Also your shocks should be fine. Springs may sag a bit, but not much. maybe 1/2" at most.
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Unread 02-29-2008, 03:41 PM   #3
dandiv
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im actually building the brushgaurd around the bumper. it mounts with the same holes the bumper does, then comes under the bumper out and up to cover the front of the jeep. i figured i would try tying in the same hole that the tow hook mounts use, thats a little farther back, but it looks a little tricky to do without mounting it on the jeep first.
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Unread 02-29-2008, 03:52 PM   #4
mpwal099
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From my understanding of how you are doing it, your brush guard will be no stronger than your stock bumper. And the weight you are talking for just a brush guard seems pretty high to me. My JCR winch bumper is less weight then that.
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Unread 02-29-2008, 04:34 PM   #5
dandiv
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what makes you say it wont be stronger? is it only where i mount it that matters? your right it is a lot heavier than a normal one because i designed it to be a lot stronger than most, so when you say it mont be any stronger than the sheetmetal its concerning lol.
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Unread 02-29-2008, 05:49 PM   #6
mpwal099
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I just think it is not going to provide the strength you think it will because you are using the stock mounting holes. Your bumper will only provide as much protection as those holes are strong. Kind of like the weakest link in the chain idea. The metal that the stock bumper attaches to is thin as it is. Put a heavy addition on it, and maybe hit something and those mounts are going to give out.
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Unread 02-29-2008, 05:57 PM   #7
CJ7-Tim
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Quote:
Originally Posted by mpwal099 View Post
The metal that the stock bumper attaches to is thin as it is.
X2

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Unread 02-29-2008, 05:59 PM   #8
mpwal099
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Quote:
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X2

.

perfect example.
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Unread 02-29-2008, 06:08 PM   #9
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Quote:
Originally Posted by CJ7-Tim View Post
X2

.
Nice shot. Do you know the story behind this pic? I kind of picture an xj sucked down in a mudhole and some maniac in a 3/4 ton with 10 feet of slack in the tow strap trying to "snap" it out of the hole... ugly.
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Unread 02-29-2008, 07:24 PM   #10
dandiv
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well im glad you pointed that out while im still in the process of building it lol. where are the holes you suggested i use?
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Unread 02-29-2008, 08:07 PM   #11
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Do you know the story behind this pic?
Cherokee owner gets cheap off-road bumper that only attaches using the three stock bumper bolts. Cherokee gets gets stuck on the trail. Friends attach tow strap to bumper and yank. Bumper flies completely off, pulling loose on both sides.

If you are going to build something solid, safe and useful, use this diagram --> http://www.twisted-halo.com/digicam/xj/Bumper%20mount.pdf




.
Original factory brackets are item #9 and the bolts attach to the angle bracket on the front crossmember.



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Unread 02-29-2008, 08:13 PM   #12
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Or, just order these: http://www.jcroffroad.com/Merchant2/...egory_Code=XJB
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Unread 02-29-2008, 08:37 PM   #13
mpwal099
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That's the best bet right there. Really beefy and lots of tie in points. The driver side uses the 3 stock bumper holes plus the steering box bolt holes. Passenger side uses the 3 stock hole plus 3 others you can tie into.
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Unread 03-01-2008, 03:26 PM   #14
dandiv
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the first diagram you showed me is actually what i was planning on doing, aside from the angle bracket. whats funny is after i saw that picture i went down to the jeep to see what else i could do and i came up with exactly that, only i figured id use more bolts on the cross member.
as far as those brackets go what i might just do is weld a piece of steel onto my existing brackets (theyre 1/4 in plate) and drill the holes in the same locations.
man i cant tell you how much i appreciate your help. the torn mounts look difficult to fix and im real glad i didnt mess up my jeep. thanks.
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Unread 03-01-2008, 05:33 PM   #15
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Check out UkraineTrain's custom mounts over on NAXJA (pic about half-way down the thread):

http://www.naxja.org/forum/showthrea...=935716&page=2

I just ordered a set of the extended ones. I am going to use them to mount my ARB bumper in a bit more secure fashion than the stock mounts (three bolts per side) provide.
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Engine: 4.0 HO, Sealed canister filter, 3 core CSF steel radiator, CatCo cat, Dynomax Turbo Flow muffler.
Electronics: Remote start/locks, Pioneer DEH-P7800MP w/XM, Polk Audio speakers, Garmin Nuvi 660 GPS, Cobra 148 GTL P&T w/Wilson 1000.
Suspension: Old Man Emu 3" lift+OME AAL, JKS adjustable trackbar, QDs, LCAs UCAs, A.C.O.S., DPG Offroad adjustable bumpstop plate, Daystar poly bumpstops.
Steering: Currie HD steering, C-ROK steering box reinforcement, OME stabilizer.
Armor/Recovery: T&T Custom belly skid, Mopar gas tank skid, JKS LCA mini skids, Rock Lizard Super Skink Sliders, Mopar 2" receiver, ARB Bull Bar/Ramsey REP 8.5 winch.
Drive train: D30 front axle w/Superior Chromo D30 axles & outter seals, D/S 4.56 R&P, ARB locker, Ruff Stuff cover. Ford 8.8 rear axle w/Superior Super 88 kit, Ford Motor Sports 4.56 R&P, ARB locker, SOLID cover, Russell stainless lines. Front and rear Tom Woods HD drive shafts, 242 x-fer case w/Tom Woods SYE.
Tires/Wheels: 33x10.5x15 BFG Mud Terrains on Alcoas.
Misc: Garvin Wilderness rack, Safari Snorkel, Redline Tuning hood lifts.
Awaiting installation: Autometer A pillar gauge pod, oil, water, & tranny temp guages, PIAA driving lights, Goferit tie-rod flip bushing, '95 Brake booster and M/C, M.O.R.E. Motor mounts, TnT Custom 1.5" Shackle.
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