904657-8 – Short Couple Driveshaft – 1710 (1.938 x 6.094) Series – 12.380″ Flange To Flange

904657-8 Short Couple Driveshaft — 1710 Series, 12.380" Flange to Flange, 7.380" CL to CL

The 904657-8 is a 1710 Series short-couple driveshaft assembly with a flange-to-flange measurement of 12.380" and a centerline-to-centerline U-joint distance of 7.380". The 1710 Series U-joint uses a 1.938" cap diameter and 6.094" cross width, placing this assembly in the heavy-duty commercial truck torque range. This assembly is designed for Class 7–8 tandem-drive trucks as an interaxle (jackshaft) shaft connecting the forward-rear and rear-rear axles, and for other applications where the companion flange gap measures 12.380". The assembly ships factory balanced.

The 904657-8 has a shorter flange-to-flange dimension (12.380") than the 904657-9 (12.620") and 904657-12 (13.380"), but its CL-to-CL of 7.380" is notably longer than the 904657-9's 6.620" CL-to-CL. This dimensional relationship reflects different yoke body lengths at the flange ends — the 904657-8 uses yoke bodies that produce a longer CL-to-CL for a given F-to-F dimension, affecting the operating angle geometry at each U-joint position. When comparing variants, use the flange-to-flange measurement as the primary selection criterion since that is the installed dimension in the vehicle.

Specifications

• Part Number: 904657-8
• Series: 1710 (1.938" cap x 6.094" width)
• Flange to Flange: 12.380"
• CL to CL: 7.380"
• Application: Heavy-duty commercial truck tandem axle, interaxle shaft

Fitment & Installation Notes

The selection between 904657-8 and adjacent variants (904657-9 at 12.620", 904657-5 at 11.620") depends entirely on the measured flange-to-flange gap in the vehicle. Measure with the axles loaded at operating position — suspension travel affects axle position and therefore the gap. The 1710 Series requires 1710-rated companion flanges; the yoke bore is machined for 1.938" cap diameter caps, and U-joints from the 1610 Series (1.875" caps) will not properly engage the 1710 bores. Companion flange pilot diameter and bolt torque must be confirmed per the axle manufacturer's service manual.

The 1710 Series is the standard for tandem-axle Class 7–8 trucks operating at 80,000 lb. GVW and above. Short-couple interaxle shafts in this series are not adjustable for length — the fixed 12.380" flange-to-flange dimension requires an exact match to the chassis measurement. The factory balance ensures the assembly operates within vibration limits for commercial vehicle speed ranges. If the vehicle has been involved in an incident that changed axle positioning, remeasure the installation gap before ordering the 904657-8 replacement.

The 904657-8 is one of the stepped-length variants in the 904657 1710 Series short-couple family. All variants in this family share the same flange yoke design and U-joint series — only the assembly length varies. Companion flange bolt pattern, pilot diameter, and retention hardware must be sourced from the axle OEM's documentation. Explore related Short Couple Driveshaft assemblies including the full range of 1710 and 1610 Series length variants for tandem and single-drive axle configurations.