Torque Converters: Single-Disk vs. Multi-Disk Lockup
Today we're diving in to the often debated & sometimes mysterious topic of single disc vs. multi disc lock-up torque converters for use in common OEM-based overdrive transmissions.
To begin, we need to understand the purpose of a torque converter clutch (TCC). TCC's were first incorporated by the OEM's decades ago. The purpose of the TCC was originally intended to help improve fuel efficiency & reduce emissions through additional reduction of engine RPM by virtually eliminating torque converter slippage at normal steady state cruising speeds whenever the TCC was commanded to apply by the on-board vehicle electronics.
That intention of the OEM's still holds true today when it comes to incorporating a TCC into a torque converter. As years went on & horsepower has steadily increased, particularly with aftermarket engine modifications & power adders, the aftermarket identified a need for increased overall TCC durability & longevity as the single TCC simply was not providing satisfactory results in high-HP applications. Enter the multi-disc TCC design.
So, this leads us to a common question we are frequently asked by customers; which is better? Well, the answer to that is multi-faceted. Without the TCC applied (converter unlocked), you're basically going to get the same overall functionality & performance characteristics between a single disc & a multi disc converter assuming we're comparing identical converter builds other than the TCC design. In this scenario of an unlocked converter, one isn't really better than the other.
When the converter is locked, the multi disc option takes advantage of significantly increased surface area in the TCC design which allows for substantially more holding power & durability of the TCC. That being said, the multi disc option isn't always an absolute necessity in a high-HP application, either.
So, which one is right for you? The answer to this question is pretty simple. A good methodology to use when deciding between a single or a multi disc converter for your vehicle is to base your selection on a couple of factors:
1.) Will the TCC be applied at wide open throttle?
2.) In truck or SUV applications has the engine been heavily modified for increased HP & torque output **and** will the vehicle be used to tow or haul heavy loads?
If you can answer either of these questions with a "yes" then a multi disc torque converter is generally going to be the right choice for your application.
If your answer is "no" to either of these questions then you can generally select a single disc torque converter for your combination, although a multi disc converter can still be used without any issues if desired.
Ultimately there are several caveats to the scenarios listed above, so your final decision is best made with the assistance of one of our sales staff members if you still aren't 100% certain which option is best for you.
One of these caveats would be an instance of a high-HP naturally aspirated combination that employs WOT TCC apply. Some of these combinations can still successfully employ the use of a single disc torque converter if desired. Factors like vehicle weight, transmission ratios, rear axle ratio, rear tire dimensions, & torque output all play significant roles in such a scenario when deciding which option is most viable for a given combination.
Contact us today to get a customized torque converter recommendation specifically for your combination!