4WDrive - - Contents - Words and Pho­tos Courtesy Tom Smisek

COM­MUT­ING TO TOWN IN MY 2003 JEEP SAHARA, I be­gan to no­tice a lit­tle front-end shud­der at cer­tain speeds above 60 kph. It would come and go, so I wasn’t re­ally con­cerned, but within a cou­ple of weeks the vi­bra­tions got worse. It soon be­came an in­ter­mit­tent vi­o­lent shak­ing, and I was con­cerned it may be caus­ing dam­age, or worse, I could lose con­trol of my Wran­gler and crash. I hob­bled it over to my lo­cal tire shop and told them about the shimmy and asked that they bal­ance both front tires. They did. The tires were a slight bit out-of­bal­ance, but not that bad. When the ser­vice guy re­turned from a test drive he pulled my Wran­gler on to the rack and called an­other me­chanic over as they be­gan check­ing the front sus­pen­sion. After a few min­utes they gave me the bad news, my Jeep had “Death Wob­ble”, a prob­lem that can only be cured by re­plac­ing sus­pen­sion bush­ings and the track arms. They of­fered to order the parts, but I told them to hold up.

I did some re­search on the In­ter­net and found that “Jeep Death Wob­ble” is a com­mon prob­lem with ve­hi­cles that have a solid front axle and coil springs. The Wran­gler falls into this cat­e­gory. The wob­ble is a har­monic res­o­nance re­sult­ing from loose or worn parts in the steer­ing and/or sus­pen­sion, and is usu­ally set off by hit­ting a bump at a cer­tain speed. I also dis­cov­ered that Death Wob­ble is ex­tremely dif­fi­cult to di­ag­nose and fix, be­cause it is ac­tu­ally caused by slop some­where in the sus­pen­sion or steer­ing sys­tem but not by just one com­po­nent.

There were a lot of dif­fer­ent rec­om­men­da­tions on how to iso­late the of­fend­ing el­e­ment - from tires to steer­ing sta­bi­lizer to spe­cific link­age bush­ings. The more I re­searched, the more var­ied were the opin­ions on the ac­tual cause and how to fix it. One was worn and de­te­ri­o­rated bush­ings, so I de­cided to up­grade my sus­pen­sion sys­tem with ure­thane com­po­nents from Prothane. They have a kit for Jeeps that re­places all fac­tory rub­ber com­po­nents.

The bush­ings in the Prothane kits are avail­able in red or black ure­thane, and are su­pe­rior to OEM rub­ber as they are im­per­vi­ous to grease and oil, which tends to rot rub­ber, but more­over, ure­thane is a denser com­pound that pro­vides a firmer, more sta­ble ride in rugged off-road con­di­tions and high­way speeds. I also found out that the orig­i­nal fac­tory rub­ber bush­ings are bonded to con­trol arms, so you can­not just order re­place­ment bush­ings; you have to buy new con­trol arms. With Prothane you re­tain the orig­i­nal metal parts and just re­place the bush­ings, sav­ing money.

In­stal­la­tion of the Prothane To­tal Kit will take a skilled me­chanic about 8 hours, and I had mine pro­fes­sion­ally in­stalled. There are a few “tricks” that I will ex­plain as we go along. For the do-it-your­selfer plan on a week­end and if you have a buddy, it can go a lot eas­ier. The in­stal­la­tion process en­tails re­mov­ing all of the OEM rub­ber parts and re­plac­ing them with ure­thane bush­ings.

Re­moval and in­stal­la­tion is best done with the ve­hi­cle sit­ting on all four tires and you must sup­port the frame and take load off the axles to re­lax sus­pen­sion ten­sion. A driveon rack al­lows the ser­vice tech to stand, while back­yard me­chan­ics may use ramps to al­low ac­cess un­der the ve­hi­cle.

Be­fore re­mov­ing the front con­trol arm, mark the po­si­tion of the cam­ber bolt to as­sure the fron­tend will be close in align­ment when re­assem­bled. Front-end align­ment will be re­quired.

To re­move the bonded rub­ber bush­ings from the con­trol arms, heat the shells with a torch. The bush­ing will be­gin to smoke and bush­ings will be ex­pelled with a great pop. Cau­tion must be ex­er­cised, as these bush­ing may fly out. Clean the in­side with a wire brush and al­low it cool be­fore in­sert­ing the ure­thane re­place­ment.

Prob­a­bly the most dif­fi­cult pro­ce­dure is re­mov­ing the Up­per Con­trol Arm bush­ing from the front dif­fer­en­tial. Slow steady heat is ap­plied and prob­ing the rub­ber out will take time. How­ever, a much sim­pler task is re­mov­ing the end link bush­ings by cut­ting away one of the flanges.

Be­fore re­assem­bly clean all bush­ing cav­i­ties and lu­bri­cate with the Prothane spe­cial lubri­cant pro­vided in the kit. Use rub­ber gloves as the sil­i­cone lubri­cant will stick to your fin­gers and be dif­fi­cult to re­move. All sur­faces that are in con­tact with ure­thane need to be lu­bri­cated to avoid any squeak­ing that may oc­cur if lube is not ap­plied. This in­cludes hous­ings, bush­ings and sleeves.

Prothane bush­ings and sleeves can only be pressed into place us­ing a bear­ing press or a C clamp. A sim­ple tech­nique is to place a con­trol arm or link on a clean sur­face of the floor and press down with the heel of your shoe. Do not use a mal­let or ham­mer as im­pact­ing them will not work.

Re­assem­bling con­trol arms may re­quire a pry bar or winch strap to align mount­ing holes. Once all com­po­nents are bolted in po­si­tion, go back and torque each bolt to fac­tory spec­i­fi­ca­tions. A pro­fes­sional me­chan­ics trick is to mark the head of each bolt with a marker or dab of paint as they are torqued, to as­sure you do not miss any.

As my Wran­gler was be­ing re­fit­ted with Prothane parts, I ex­am­ined each of the orig­i­nal rub­ber bush­ing to try and iden­tify which of the many bush­ings was the cul­prit and caused my Death Wob­ble. I could not iso­late it to any one or two parts. As re­search had shown, it was a col­lec­tive de­te­ri­o­ra­tion of many parts that con­trib­uted to the con­di­tion. After the in­stal­la­tion a test drive val­i­dated that it was in fact the failed rub­ber bush­ings that caused the prob­lem. Now my Jeep handles bet­ter and has a more sta­ble ride.

A gear puller is used to re­move the end link

Mark the trail­ing arm cam bolt

OEM bush­ing

Cut­ting bush­ing

To re­assem­ble con­trol arms may re­quire a winch strap to align mount­ing holes

Sleeve in­sert

Rear up­per con­trol arm

Rear end link in­stalled

In­stal­la­tion com­plete

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