Short Shifter Kit


The UUC Motorwerks EVO3 Ultimate Short Shifter

Nothing that can make every drive more satisfying like the "snick-snick" feeling of a precision shifter. Too bad BMWs are not known for that, and that is where UUC Motorwerks steps in.

The UUC Ultimate Short Shifter is unique, completely different than anything else available.Their design starts with the finest materials: T-304 stainless steel, self-adjusting and lubricating primary pivot bearing, sealed lower pivot bearing, and the finest-grade silicone vibration absorbing material. They use their own precision-machined pieces, all "massive overkill" designs, race-tested to ensure they easily surpass the rigors of street use.

What makes the UUC Motorwerks short shifter kit so good is the engineering and attention to fine details, many different points that add up to tremendous differences in how the unit works and feels. Their products are not modified BMW components, and they are not "one size fits all" as with lesser offerings.

The unique characteristics of the design include:

• height adjustment via upper-section length change. Simply loosen, slide lever to preferred height, and re-tighten.
• CNC-machined stainless steel lower section features integral pivot ball and self-adjusting primary pivot bearing. No welds, no plastic.
• flex and rotation-free lever construction with full-length vibration-absorbing internal silicon damper.
• linkage geometry perfectly corrected, with self-adjusting primary pivot bearing that permanently retains lubrication and precision (some models).
• zero-tolerance lower pivot bearings that never require lubrication and eliminate significant mechanism friction. These do not wear or ovalize like solid-metal or plastic designs with expanding tolerances.
• 100% compatible with BMW illuminated shift ****.

UUC's in-house manufacturing tolerances are "mil spec" using the latest CAM-controlled machining and milling equipment. Their ongoing dedication to quality and ultimate precision would tolerate nothing less.


Double Shear Selector Rod


UUC Motorwerks Double Shear Selector Rod

The goal.

While producing a "short" shifter, their 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. (figure 1)


figure 1

In the original BMW design, the connection at both ends has a large injection-molded plastic bushing. They 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 degrees 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. (figure 2) The fig. 2 image shows a selector joint that has approximately 25K miles of use.


figure 2

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. (figure 3)


figure 3

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). (figure 4 and 5)


figure 4


figure 5

The DSSR redistributes the torsional forces from the pin/bushing interface to the complete face area on both sides of the selector joint. (figure 6)


figure 6

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. (figure 7)


figure 7

In-gear "free play" is reduced to approximately 10mm total when used with a UUC EVO3 shifter. (figure 8)


figure 8

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).


Other solutions?

While there are other replacement selector rods sold in the aftermarket (including "no tolerance" brass and "heavy" selector rods), none of them will get rid of the slop and "free play" in the BMW shifter assembly. These alternate products are not actually improving the shift feel at all, but are simply rods with alternate geometry (either bent or twisted), an accommodation to make the "universal fit" aftermarket shifters fit properly.

These other aftermarket shifters, even with their "heavy" selector rods, will still be as sloppy as the original BMW shifters they are replacing. While the throw may be shorter, the precision of the assembly is no better than a new BMW part, and will develop the same slop within a few thousand miles. (figure 9)


Figure 9

For more information on one or both of these parts, click the product pictures or the links below. As always, don't hesitate to message us with any and all questions.

 

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