Specifications

DRIVELINE MODIFICATIONS
Rear “leaf spring” (too low).
Will not rise enough for C.V.
Front “leaf spring” (too low).
Gets worse under load.
Front “4-link” (correct).
Good example.
Rear “4-link” (correct).
Good example.
20
driveline modifications
On all 4WD vehicles, you will find a front and rear driveline. Whenever possible, we design the conversion components to
eliminate the need for driveshaft modifications. However, several conversions will still need to have both front and rear
drivelines modified to accommodate the new engine location. We recommend that driveshaft modification requirements be
determined after the engine and transfer case locations have been finalized. There are numerous combinations of
transmission and engine conversions, and it is nearly impossible to relate every application as to driveline requirements.
Normally, vehicles equipped with a 6 cylinder engine or 304 V8 engine can change to the newer Chevy V8 without driveline
modifications. The transmission that you are selecting, whether the original or a new aftermarket transmission, will make
the biggest effect on driveline requirements. For specific applications, we suggest you contact our sales department for
further information.
When removing your existing driveshafts, it is a recommended procedure that you mark the relative positioning of each
driveline component to the appropriate connection. This procedure will prevent any unbalancing of the drivetrain system. This
same procedure should be followed if the driveline is to be shortened or lengthened.
Driveshaft modifications can vary in cost between $100-$250. The cost is greater if the shafts are going to be extended since
new material is going to be added. We have used both professional driveline shops and regular machine shops for doing
driveline modifications. Whenever possible, we recommend a qualified driveline/machine shop that has the proper balancing
& driveshaft equipment. Always make sure that the driveshaft is properly balanced.
Jeeps have used several different types of Universal yokes and driveline
components. It is critical that the driveline Universals be run at a slight 2 to 3
degree angle. The angle will make sure of proper bearing lubrication. When
driveline angles are excessive, it may be necessary to space the transmission
and transfer case down slightly to improve the angle. It is also possible to angle
the differential housing upward to com-
pensate for a better angle to the transfer
case. This adjustment can be performed
by the installation of a degree shim be-
tween the axle housing and spring mount.
With the introduction of suspension lifts,
we are constantly seeing the rear driveline
angle exceeding the limits of a normal driveline bearing and cross assembly. We have
had several customers install a C.V. joint at the transfer case location in order to
provide the necessary angle required to reach the rear differential. On short wheel
base vehicles such as CJ5s, the driveline angle can even be worse due to the short
driveline required.
Once the conversion is completed, a visual inspection should be made regarding driveline angles & clearances. New &
unwanted noises are most often related to poor driveshaft angles. C.V. driveshaft combinations must be set so that the
differential yokes are in line with the driveshaft under normal operating load. Non-C.V. driveshaft combinations must be set
so that the pinion yoke angles match the transfer case output angle under normal operating load. Remember to allow for
spring wrap when your vehicle has leaf springs. The front pinion will dive downward under load, and the rear pinion will rise
upward under load. There are many different spring rates on the market, so this may take some adjusting to eliminate poor
driveline conditions.
For certain early model Jeep conversions
that require additional front driveshaft clear-
ance alongside the automatic transmission
pan, we recommend using a special Jeep
yoke and bearing assembly. The special
small diameter yoke was used in Jeep
vehicles 1966-71.