Critical Speed Chart

VMP Performance Speed Chart

Critical Speed is the RPM at which the driveshaft is computer projected to bend or whip. Exceeding Critical Speed can produce vibrations that can result in driveshaft failure.


The vibrations can also cause damage to the differential gears and bearings. The transmission extension housing, along with the torque converter and planetary gears can also be destroyed.


When you take a small piece of steel and bend it repeatedly, the stress will eventually break the steel. The same effect occurs on your complete driveline when no attention is paid to Critical Speed.

Identify Rear U-Joint

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Full Name

Position

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

VMP Performance Driveshaft diagram-d
VMP Performance Driveshaft 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.

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

VMP Performance Driveshaft diagram-l

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.

VMP Performance 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.

Driveshaft Measurements

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.

VMP Performance diagram-n

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