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November 2012 Your Jeep

Leaf Spring Shackles
Verne Simons
| Senior Editor, Jp
Posted November 3, 2012

Your Jeep Tech Questions Answered

I really need your help. I just “finished” the build on my ’91 YJ. I installed a Wagoneer Dana 44 in the front, an Isuzu Rodeo Dana 44 out back, a heavy-duty slip yoke eliminator, and a 4-inch Rough Country suspension. On my maiden voyage, I got stuck in a mud pit, winched myself out, and my front shackles were inverted. They had flipped backward pushing the front eye of the front springs against the frame. What caused this and how do I prevent it from happening again? I have a large off-road event coming up and really need to remedy this problem before then.
Craig Warner
Mason City, IA

The shackle inversion was probably the result of winching the Jeep out of the mud. It seems to me that the mud prolly pulled down and pushed backwards on the front axle as you winched the Jeep out. This would arch the springs and pull the shackles backwards. There are a couple of options you can use to prevent this. First you can build small snubbers that sit just behind the shackle and prevent the shackles from inverting or moving backwards too much. It’s important that these snubbers don’t hit the shackle during regular driving. They should be in a position to just hit the shackle if the suspension is unloaded. You can weld these to the frame, or bolt them in place if there are convenient holes in the frame. I have seen fancy versions of these with small polyurethane landing pads for the shackles to hit if it starts moving backwards to jagged rusty steel strategically welded to the frame behind the shackle. The second and maybe easier option is to buy and use anti-inversion shackles, sometimes called boomerang shackles because of their shape. These shackles don’t have straight sides. The sides are L-shaped or shaped like a boomerang as the suspension droops the L-shape prevents shackle inversion as it hits the frame before the spring can pop backwards.

Help, My Jeep Drools
I have a ’05 Rubicon Wrangler Unlimited with about 60,000 miles. Over the past year, I have noticed that when I fill it with gas it will routinely overflow before the gas pump automatically turns off, spilling gas down the side of the Jeep. I have done some research and the consensus is that the vent tube to the gas tank may be clogged which prevents the gas pump from sensing the tank is full and allowing it to shut off at the proper time. My questions are: Have you seen this problem and is this the likely cause, and if so, how can I clean out the vent tube hopefully without dropping the tank and taking it apart?
Rich Hunt
Albuquerque, NM

Rich, I agree with your diagnosis of a blocked filler neck vent hose. I would be willing to bet a very small sum that the vent hose is not clogged, but is instead kinked or folded and is thus blocked. There is not much room under there for the filler neck hoses to fit in certain spots. I fear that there is no good way to un-kink or clean out the vent hose other than by dropping the tank. You could pull the rear fender flare and the inner wheel well plastic liner and get some visual access to the tops of the filler neck and hoses, but I bet the kink is lower down towards the tank, and basically inaccessible without dropping the tank. If you find a kink or clear out a clog, your drooling problem…er, Jeep’s drooling problems…should clear up.

However, Trasborg’s girlfriend owns an ’06 Unlimited and here’s what he has to say about it:

My girlfriend’s Jeep does this and has done it for a long time. It seems a lot of ’05-’06 models do it. I read on the Internet that it wasn’t the filler hoses or anything else, but I was not convinced they were wrong, so I spent two days pulling her Jeep apart. The vent hose was not kinked or blocked. The lines coming off the vents were not clogged or blocked. The charcoal canister seemed to be flowing (not clogged). I inhaled a lot of fuel fumes and couldn’t find anything wrong in the system. Basically I narrowed it down to something internal in the tank. I talked to Tony Pellegrino at GenRight Off Road (, and he said he hears this complaint frequently. More on the ’05s and ’06s. The factory changed something in the tank, and we hypothesized that there is an over-achieving safety valve in the filler or an under-achieving vent valve in the top of the tank. However, Trasborg recently found out this isn’t the case, and the real cause and solution will be found in the Jan. ‘13 issue of Jp.

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