Have you ever considered swapping your 35-plus year old transmission for a modern unit that is more efficient and delivers overdrive? Silver Sport Transmissions (SST) has fully prepped five- and six-speed manuals, and its A41 automatic overdrive kits that will improve the performance of your classic. But, does the task of installing one of these transmissions into your valued hot rod seems overwhelming?
If you take time to contact the SST officials and share information about your project, the installation should progress smoothly. However, even with proper guidance from SST, mistakes can be made, which results in additional calls to the SST customer service line. With an interest in what questions are asked, we contacted SST’s customer service line to find out the top-five most common questions asked about the installation of an SST transmission.
When the Silver Sport Transmissions’ service line technicians receive calls about vibrations or excessive noise, the first question a tech asks is, “what are the bellhousing dial-in measurements?” This is a crucial step in the setup of the transmission, and if it is skipped, a multitude of problems can occur, including transmission failure. A handful of enthusiasts think if they install a brand-new steel scattershield, they don’t have to perform the dial-in procedure. This video shows how to complete the task.
When performing the dial-in procedure on the bellhousing, the check isn’t to verify the quality of construction of the bellhousing, but to measure how well the bellhousing and the crankshaft align. When the acceptable variance is less than 0.005-inch, it does not take much to require an adjustment with offset dowel pins. The SST techs help customers dial-in their bellhousings on an almost daily basis, and they are happy to help prevent future problems or catastrophe. Failing to dial-in the bellhousing will void the warranty of the transmission, so it is crucial to follow SST’s recommendations.
Hydraulic Bearing Cushion Measurement
The SST service line often receives calls about how to properly adjust the hydraulic clutch. This system utilizes a firewall-mounted, hydraulic master cylinder with remote reservoir, and a combination slave cylinder and release-bearing assembly. The combination bearing is known as the Concentric Slave Cylinder (CSC). It is designed to constantly contact the pressure plate fingers. With the pressure plate fingers at rest, the CSC is compressed. When the clutch pedal is depressed, the master cylinder forces fluid into the CSC, causing the CSC to expand and depress the pressure plate fingers, thereby releasing the clutch.
The CSC must be far enough away from the clutch to allow it to fully engage, yet close enough to completely disengage the clutch. This range of motion is called the CSC cushion. Different hydraulic systems have their own way of measuring for this cushion, so following the manufacturer’s directions will provide the best results. The measurement procedure requires a little math, but the SST tech department is willing to help customers through the process. This is another important step that if skipped, could lead to damage.
Driveshaft measurement is an area of the vehicle that many feel they can perform without following the directions provided by SST. The customer must follow SST’s directions exactly, even if it’s not the way your local driveshaft shop performs the measurement (if you threw the instructions away, SST will provide an additional copy free of charge). While there is more than one way to measure a driveshaft, it is important the driveshaft measurement be consistent for accuracy and efficiency. Some customers may question why they have to perform these measurements, but with SST assembling hundreds or even thousands of kits for the same car over and over, they have the data to back up the reasons for the measurements.
SST has found some vehicles, such as certain years of Corvettes, are very consistent. This consistency is a result of the suspension arrangement of the Corvette and how it is designed. With these Corvettes, SST can send a driveshaft with the kit, knowing it will fit properly. However, with other product lines, there will be a driveshaft-length variance that is too great to be considered within an acceptable tolerance.
What causes this inconsistency? Some vehicles came from the factory that way, and the specs were within a permissible tolerance for the manufacturer. Additionally, vehicles age and things start to sag and shift. Lastly, a previous owner may have modified the engine mounts or swapped rear axles, which could result in a driveshaft measurement change. SST requires its instructions be followed to the letter, so a custom-built driveshaft will fit your vehicle perfectly.
If the bellhousing was properly dialed-in and is within specs, but vibrations and noise are still a concern, the driveline angle needs to be verified. According to the SST techs, “there’s a sweet spot where the engine is tilted within spec and the driveshaft is at an angle not too extreme or too flat.” If the vehicle operated fine for years and has recently begun to vibrate, SST recommends checking the rear axle housing-to-driveshaft angle as it could have changed due to the springs sagging over time. Silver Sport Transmissions’ CEO, Jack Silver, developed an app for Android users, and TREMEC has an app for iOS and Android. Both apps will help the customer to measure the driveshaft angles and offer adjustment suggestions.
There are a variety of problems an enthusiast can encounter with a clutch, which can be caused by a variety of factors. A clutch unit can experience chatter due to the misalignment of the pressure plate to the flywheel during installation. The lack of parallel clutch fingers could result when an improper bolt tightening sequence is used. This could result in one side of the diaphragm dropping lower while the other side stays in place.
One sign your clutch was improperly installed is irregular wear on the clutch fingers. If the wear isn’t consistent on all the clutch fingers, the clutch wasn’t properly seated on the flywheel, or bolted down securely. An additional outcome may be a series of hot spots on the pressure plate.
The pressure plate must be suitably seated before securing, and the pressure plate bolts must be tightened finger tight in a crisscross pattern before using a torque wrench (in a crisscross pattern) to secure the pressure plate to the flywheel. While it may be tempting, never use an impact gun to torque down pressure plate bolts.
After the pressure plate is torqued, check that the plate fingers are parallel. You can use a 0.0015-inch feeler gauge to ensure the cover is seated against the flywheel after being properly torqued to spec. If a problem exists, SST’s tech experts can help troubleshoot the concern and find the underlying cause.
Read And Understand The Manual
After talking with the SST representatives, it turns out the five most common mistakes made by customers can be resolved by taking the time to read (and understand) the instruction manual that accompanies each transmission. The instructions and supplemental online tech articles and videos (available on SST’s website) will provide the vital pointers to dial-in the bellhousing, measure hydraulic bearing cushion, properly calculate the driveshaft length, check the driveshaft angles, and provide the proper torque specs for the clutch. If the instruction manual is followed and the proper tools are used, an error-free installation should result. But, if an oversight occurs, give the techs at Silver Sport Transmissions a call. They will have your ride catching rubber in all gears in no time.