1971 Pontiac Firebird - How To Replace Driveshaft Universal Joints
QUESTION
I have a '71 Firebird that sees a lot of street/strip action. It's got a hot 400ci V8 with a TH400 trans, 2500-stall converter and 3.73:1 rear gears. After cruising it for the past year or so, I've noticed that each time I put the car in gear, I hear a clang coming from somewhere underneath. Sometimes I even hear it clanging while I drive. The trans and converter are new, so what could the sound be? Lee Kerr Oil City, PA
ANSWER
By John Kiewicz
The loud "clang" noise is probably coming from the driveshaft universal joints. The noise is generated because the U-joints are severely worn and are moving around within the driveshaft yolk assemblies. This is extremely bad and potentially dangerous. The U-joints are shot and need to be replaced. If Lee's engine is as hot as he says, one good launch at the dragstrip will likely destroy the clanking driveshaft assembly. And if the Firebird doesn't have a driveshaft safety loop, a nasty crash will likely occur when the U-joints break.
Being that U-joints are an overlooked hop-up amongst street machiners, chances are that the units in Lee's '71 Firebird are stock. The stock units were medium-duty U-joints at best, which were not designed to handle the rigors of stout street/strip use. Upgrading the driveshaft with new U-joints is a step in the right direction, but what really should be done is an upgrade to heavy-duty units that can handle the hard-launching abuse inflicted by today's high-horsepower street machines.
Here, we follow along as the driveshaft experts at Wenco Industries show us how to install new heavy-duty Lakewood U-joints in Car Craft's project Cheap Street Chevelle. At the dragstrip our rig runs low-13-second times on slicks and 12.20s on nitrous. Our U-joints weren't making noise yet, but we wanted to replace them with heavy-duty parts before they started acting up. We advise that the driveshaft be balanced and checked for straightness while it's out of the car, and that's just what Wenco Industries did to ensure that our driveshaft performs properly for years to come.
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1. We ordered new driveshaft universal joints (PN 23013) from Lakewood Industries to repla
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2.Begin the U-joint swap by removing the driveshaft from the vehicle. Be sure to support t
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3. Use an old piece of pipe or a large-diameter socket as a low-buck U-joint removal tool.
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4. Using a pair of needle-nose pliers, remove the snap rings that hold the U-joint caps in
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5.Once the U-joint is removed, carefully inspect the driveshaft end for cracks and/or dama
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6.Carefully remove the U-joint caps, making sure you don't knock any of the small needle b
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7.Use a pair of needle-nose pliers to install the new snap-ring retainer clip. Rotate the
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8.To remove the front U-joints from the transmission yolk, begin by supporting the drivesh
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9.With the two U-joint caps pushed up, angle the yolk slightly and remove it from the U-jo
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10.Install the new Lakewood U-joint into the driveshaft (as shown with the other end of th
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11.Position the new U-joint end caps in the yolk and carefully tap the cap downward until
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12.Whenever you do driveshaft service work (such as installing new universal joints), it's
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13.Just as your wheels do, driveshafts use add-on weights to achieve proper balance. Howev
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14.While the driveshaft is out, it's a good idea to use a center punch to mark the positio
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15.Carefully inspect the end of the driveshaft yolk that slips into the tailshaft of the t
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Lakewood Industries
Dept. CC
8700 Brookpark Rd.
Cleveland
OH
44129
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Wenco Industries
15748 Arminta St.
Van Nuys
CA
91406
8-18/-785-0643
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