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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.

SOURCES
Lakewood Industries
Dept. CC
8700 Brookpark Rd.
Cleveland
OH  44129
Wenco Industries
15748 Arminta St.
Van Nuys
CA  91406
8-18/-785-0643
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