UUC's 'Double Shear Selector Rod'
Info from UUC...
Increases the precision and smoothness of ALL shifters -- OE and
aftermarket! Whether you have a factory stock shifter or
aftermarket short shift kit, this Dual Shear Selector Rod (DSSR)
will dramatically improve it.
The goal.
While producing a "short" shifter, our more important goal in
improving the BMW shifter assembly is to increase the precision and
smoothness of the overall operation.
The problem.
One significant wear area that has never been addressed previously
is the wear and ovalization of the linkage connection points at the
transmission and the shifter's lower pivot.
In the original BMW design, the connection at both ends has a large
injection-molded plastic bushing. We already know how badly plastic
wears in an automotive application, and these areas are not an
exception. The design of the selector rod has a pin at 90° to the
main rod, which exerts a tremendous amount of leveraged force on
the selector joint bushing from one side (known as a
single
shear force). The result is a steady deformation of the
bushing, resulting in looseness and slop in the entire mechanism.
(see photo at right) The image shows a selector joint that has
approximately 25K miles of use.
The looseness and slop are magnified by the leverage-multiplication
effect of the shift lever itself. The result is an in-gear shifter
"free play" of 3/4" and up to 1" in either direction, over 35mm
total.
The cure.
A temporary fix is to simply replace the selector joint.
Unfortunately, this is only a temporary fix as the new joint's
bushing will exhibit the same rapid deformation. To permanently fix
this, a change in the fundamental design of the pivot is required,
changing the assembly to a
double shear system with the
UUC Double Shear Selector Rod (DSSR).
The DSSR redistributes the torsional forces from the pin/bushing
interface to the complete face area on both sides of the selector
joint. By taking advantage of the strength of steel in the DSSR and
the body of the joint, the problem of deformation is eliminated and
the movement of the selector rod correlates directly to movement of
the selector joint - the only "free play" movement remaining in the
shifter assembly is from within the transmission itself.
In-gear "free play" is reduced to approximately 10mm total
when used with a UUC EVO3 shifter.
The original BMW shifter and all other aftermarket shifters (except
UUC which uses deformation-free bearings) contain a plastic bushing
similar to the selector joint, and the exact same wear and
ovalization causes those shifters to get sloppy. The DSSR
permanently fixes these shifters also.
The DSSR is compatible
with all brand shifters, whether original BMW or other-brand
aftermarket. When used with the original BMW shifter or other
aftermarket shifters, the amount of "free play" will be greatly
reduced but varies by shifter (flexation of the shifter shaft
contributes to the total "free play" travel).
- E30 M3 1987-1991 (installs like OE)
- E30 325, 325e, 325es, 325i, 325is 1982-1991 (requires use of
1989 or newer BMW selector joint)
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