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Faqs By RennShift

What shift knob can I use on a RennShift

The RennShift has a smooth round outer surface of the stick to use the original knob and crush sleeve. The RennShift stick is also drilled and tapped on the end with 3/8"-24 internal threads. This allows the installation of our optional threaded knobs, or easy adaptation of universal knobs.

Does the RennShift come with a knob?

No, because of the variety of choices, including reusing your original knob, we do not make you pay for a knob (you may not use) when you purchase the shifter.

Which stick length do I want?

Stick length is determined by personal preference, your body type, and how you sit in the car. The shorter stick places the knob as the same position as the factory shifter. The 2 inch longer raises the knob and moves it back slightly. Many people enjoy the decrease in the distance from shift knob to the steering wheel afforded by the longer stick. The longer stick can also help from having to lean when reaching for 4th gear (901) or 5th gear (915). Others find the stock height just right, or want to maintain a more original look.

How do I install the RennShift?

The RennShift is very easy to install because it comes as an assembled unit. The base plate and shifter stick have to be bolted to the main housing. Remove your old shifter and set it aside, you won't need any parts from it. ------------------------------------------------------------------------------------------------------------------------- Install the RennShift by lowering the bottom bushing into the ball socket in the tunnel until the shifter is flat on the tunnel. and the shift rod bushing bracket is nested in the rear of the shifter plate. The shifter knob should be forward of neutral as though selecting a forward gear. -------------------------------------------------------------------------------------------------------------------------- Install the two new M6 screws through the lower base plate into the shift rod bushing bracket and tighten both (lightly for now). -------------------------------------------------------------------------------------------------------------------------- Install the three M8 mounting screws that attach the shifter base plate to the floor. If side force against the shifter springs is required to align these screws, then you know that an adjustment to the alignment (at the rear shift coupler) will be required. A minor alignment may need to be performed in almost all installations. -------------------------------------------------------------------------------------------------------------------------- Tighten the three base plate screws and completely tighten the two rod bracket screws (installed previously) at this time.

How do I align the RennShift?

A note about “adjustment.” The RennShift does not have any adjustments for the shift pattern - it uses the same shifter-to-transmission alignment needed with any 901 or 915. Fortunately, the RennShift’s self-aligning spring gates allow a much easier time of creating the alignment position than the factory shifter. Tight bushings and coupler are essential for a quality alignment. ------------------------------------------------------------------------------------------------------------------------- To access the rear coupler for adjustment, remove the cover plate on the tunnel just in front of the rear seats. ------------------------------------------------------------------------------------------------------------------------- To perform alignment at the coupler, make sure 3rd gear (915) or 2nd gear (901) is still selected. Under the rear cover plate, you will find the shift coupler attached to the transmission and the shift rod. Loosen the nut and bolt that clamp the rear of the shift rod onto the splines of the coupler. These are not really splines, but axial (sometimes radial for replacement couplers) knurls to afford clamping grip. With the clamp slightly loosened, the shifter can be moved without changing the position of the coupler (and therefore the transmission). Note: this alignment is quite a bit easier with our shift coupler clamp that features a single clamp bolt rather than the factory nut and bolt combination. ------------------------------------------------------------------------------------------------------------------------- Bolt the shifter down, noting that the shifter springs self-align to the transmission with the coupler loose. ------------------------------------------------------------------------------------------------------------------------- Now the shifter can move fore and aft along the center plane while sliding the shift rod in and out of the coupler. Position the knob (or knob location if it is not yet installed on the shifter) in the approximate position of 3rd gear (915) or 2nd gear (901) – about 2-1/2 inches forward of center (this distance is not exact and will vary depending on shift throw and stick length). ------------------------------------------------------------------------------------------------------------------------ Tighten the shift coupler clamp and shift rearward into neutral. If the side-to-side alignment (radial in shift rod terms) has been maintained, the shift lever will enter neutral and back into 3rd gear (915) or 2nd gear (901) with no change in lateral position of the knob. That is, the spring gates in the shifter are aligned with the shift gates in the transmission for the center gears. ------------------------------------------------------------------------------------------------------------------------- In neutral, the upper portion of the shifter stick inside the housing (where the reverse lockout makes contact) should stand straight up when viewed from the side. If not, engage the forward gear again, and repeat the alignment at the coupler until the fore-aft position is correct (straight up in neutral). ------------------------------------------------------------------------------------------------------------------------- After checking that all gears can be selected, again check that the center plane gears can be selected from neutral with no lateral motion of the stick. This is the key to the shifter alignment. ------------------------------------------------------------------------------------------------------------------------- Note: Do not attempt to perform an alignment by holding the shifter all the way to one side or the other. There is nothing in the shifter that relates the limits of the side travel to the transmission.