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Why That Shake Could Be a Bent Tailshaft 

A tailshaft doesn’t need to be obviously twisted to cause serious damage. Even 1mm of bend is enough to throw your whole driveline out of sync - leading to vibration, bearing stress, gearbox strain, and costly repairs.

Book a driveline inspection or explore our tailshaft repair services if you're noticing vibration at speed or uneven wear.

What Causes a Tailshaft to Bend?

Tailshafts are designed to rotate perfectly along a central axis. But when they take a hit or bear too much strain, they can bend just slightly - and that’s all it takes.

Common causes include:
  • Off-road impact or bottoming out
  • Overloading or towing stress
  • Accident or kerb contact
  • Poor-quality aftermarket parts
  • Incorrect installation or tailshaft angle

The Chain Reaction: What a Bent Tailshaft Damages

Even a mild bend causes imbalance. That imbalance creates stress across the driveline, leading to:
  • Premature U-joint wear
  • Damage to centre bearings and differentials
  • Transmission or gearbox misalignment
  • Reduced torque delivery and driving smoothness
  • Fatigue cracks in the shaft if left unrepaired

How to Spot the Warning Signs

A bent tailshaft often mimics other issues, which is why it’s frequently misdiagnosed. Watch for:
  • Vibration at speed (especially consistent at certain RPMs)
  • Noises under load or when cornering
  • Leaking seals at the centre bearing or transmission
  • Uneven rear tyre wear
  • Visible wobble or distortion when viewed under the car

How GJ Diagnoses a Bent Tailshaft (And What Others Miss)

Plenty of workshops blame vibrations on diffs or gearboxes — but GJ Drivelines goes deeper. Here’s how we find the real issue:
  • Runout testing using precision balancing machines
  • Visual and laser-based inspection
  • Checking tailshaft angle, centreline alignment, and yoke condition

It’s not guesswork. It’s proper mechanical diagnosis — and it makes all the difference.

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Repair vs Replace: What’s Safe (and What’s Not)

If the bend is minor, we may be able to correct and rebalance the shaft.

But if there’s any structural compromise or significant deformation, it’s safer to replace the tube or full shaft. GJ Drivelines can:
  • Fabricate new tailshafts to exact spec
  • Match yokes, flanges, and powertrain needs
  • Improve strength and reliability for future load handling

For high-torque, heavy-duty, or performance applications, custom tailshafts are often the better long-term solution.

Don’t Wait for the Shake to Break Your Car

A bent tailshaft won’t fix itself — and the longer it’s left, the more damage it does.

Contact GJ Drivelines in Keysborough today for a proper diagnosis and repair before it turns into a gearbox rebuild.

Enquire With Us today

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ALL YOUR TAILSHAFT AND DRIVESHAFT NEEDS

  • CUSTOMISED TAILSHAFT MANUFACTURING
  • TAILSHAFT REPAIR, RECONDITIONING AND STRENGTHENING
  • DIGITAL BALANCING
  • REPLACEMENT OF TAILSHAFT COMPONENTS
  • DIAGNOSTIC DRIVING AND VIBRATION ANALYSIS
  • SUPPLIER OF TAILSHAFT COMPONENTS
  • DRIVESHAFT REPAIR AND MANUFACTURING
  • DRIVESHAFT CENTER BEARINGS
  • UNIVERSAL AND CV JOINTS
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Identify Transmission

Chrysler – Dodge
727 – 30 Spline 1 11/16″ Seal Diameter
904 – 26 Spline 1 9/16″ Seal Diameter

Ford
C6-T56 – 31 Spline 1 11/16″ Seal Diameter
AOD & C4 & T5 – 28 Spline 1 1/2″ Seal Diameter
4 R 7OW – 28 Spline 1.598″ Seal Diameter

General Motors
T-350 700R4-4LLOE – 27 Spline 1 1/2″ Seal Diameter
T-400-4L80E – 32 Spline 1 7/8″ Seal Diameter

Note: Transmission slip yokes are manufactured with various U-Joint Series. It is important to match Horsepower and Torque requirements to U-Joint Series. For aftermarket transmission applications usually a spline count and seal diameter will identify slip yoke required.

Identify Rear U-Joint

diagram-d

If Pinion Yoke has Placement tabs that retain the U-Joint, measure inside tabs. See Diagram D.

diagram-e

If Pinion Yoke does not have Placement Tabs that retain U-Joint, measure from flat of yoke inside to inside. See Diagram E.

diagram-l

If 4 bolt Flange is used on pinion, measure Pilot Diameter and center to center diagonally bolt hole to bolt hole. See Diagram L.

diagram-a

Universal Joint Size. There are hundreds of U-Joint sizes or “Series” to accomodate many different applications of power and desired longevity for your automotive, 4×4 truck or auto racing requirements, these 4 series of joints cover most needs.

1310 Spicer Series: 1 1/16″ Cup Diameter (Dim C – Diagram A) 3 7/32″ length (Dim B – Diagram A) Certain Ford applications have 2 cups 1 1/8 Diameter. Appropriate horse power range is up to 500 in circle track or road racing, small tire drag racing and 4×4. Also available: Performance Dynamic Cryo Joint.

1330 Spicer Series: 1 1/16″ Cup Diameter (Dim C – Diagram A) 3 5/8″ length (Dim B – Diagram A) Certain Ford applications have 2 cups 1 1/8 Diameter. Slightly stronger than 1310, Used in 5.0 Mustangs. Also available: Performance Dynamic Cryo Joint.

3R Saginaw Series: 1 1/8″ Cup Diameter (Dim C – Diagram A) Retained with internal clip 2 5/8″ (Dim B – Diagram A). Most common GM joint. Horse power range up to 700 in road racing and circle track. Solid drag racing U-Joint can accomodate most sportsman classes. Also available: Performance Dynamic Cryo Joint.

1350 Spicer Series: Manufactured with OEM tolerances and treated with our Cryogenic Process to yeild the strongest U-Joint available. For drag racing applications a solid non-lube design U-Joint is recommended because of the tremendous initial shock load, or short duration of high torque the joint must be able to withstand.

 

Driveshaft Measurements

diagram-n

If PST is supplying you with transmission slip yoke, Pinion yoke and driveshaft yoke measure Dim W. See Diagram N.

If PST is supplying you with transmission slip yoke and driveshaft measure Dim X. See Diagram N.

2 Piece driveshafts use Dim Y + Z. See Diagram N.