2990-1839B – CV Double Joints Heads – 29×52 ISR 1510 SER’ – Blank Flange for Toyota 1.810M Pilot DKTHB | 1.142 x 2.047

2990-1839B UDS 1510 Series CV Double Joint Head — Blank Flange, Toyota 1.808" Pilot

The 2990-1839B is a UDS 1510 series CV double joint head with a blank flange end and a 1.808-inch pilot diameter designed for Toyota applications. This constant-velocity joint assembly connects to the driveshaft tube via the weld end — tube diameter 2.560 inches, wall 0.067 inches — and the blank flange end provides a machined pilot of 1.808 inches (male register) that centers the assembly against the Toyota companion flange or differential flange. The blank flange has no bolt holes drilled; the installer machines the bolt circle diameter and hole pattern to match the specific Toyota application.

The 1510 series designates the U-joint cap geometry used within the CV double joint head — the spider crosses inside the centering ball assembly are sized to 1510 series specifications. ISR (inside snap ring) retention is used within the joint construction; this affects service procedure if the joint is ever rebuilt. The blank flange approach provides flexibility: rather than stocking a flange drilled for every Toyota bolt circle, the 2990-1839B ships with a solid flange face that must be machined to the target application's bolt circle diameter and hole count. The butt diameter at the weld end is 2.440 inches; end-to-weld dimension is 5.75 inches. These are the reference points for the weld joint preparation and driveshaft tube cut length.

Specifications

• Part Number: 2990-1839B
• Brand: UDS
• Series: 1510
• Application: Toyota (1510 Series)
• Flange Type: Blank (no bolt holes drilled)
• Pilot Diameter: 1.808" (male register)
• Bolt Circle Diameter: Blank — machine to application
• Butt Diameter (weld end): 2.440"
• End to Weld: 5.75"
• Tube Diameter x Wall: 2.560" x 0.067"
• Retention: ISR (Inside Snap Ring)

Fitment & Installation Notes

Before welding 2990-1839B to the driveshaft tube, confirm the tube OD is 2.560 inches and wall is 0.067 inches — the yoke butt bore is machined to this tube OD. A tube with a different OD will produce an off-center weld prep that compromises balance and weld joint strength. Measure the Toyota companion flange pilot bore to confirm it accepts a 1.808-inch male register; if the Toyota flange uses a female (bore) register, this joint's male pilot will not center correctly. Machine the blank flange bolt holes only after confirming the bolt circle diameter, hole count, and hole diameter from the Toyota flange specification — drill and ream to final diameter.

CV double joint heads eliminate the angular velocity variation that causes vibration in single-cardan driveshafts operating at high angles. The 2990-1839B is suited for Toyota Land Cruiser and related 4WD applications where front driveshaft geometry or a lift kit has increased the driveshaft operating angle beyond what a conventional single U-joint can handle without producing speed variation. The 1510 series capacity is appropriate for the torque demands of these Toyota drivetrain applications.

After welding, the complete driveshaft assembly must be dynamically balanced. The blank flange machining operation must be completed before balancing — drilling holes after balance will alter the balance state. Confirm ISR snap ring installation is correct within the joint; misinstalled snap rings allow cap migration that destroys the yoke ears.

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