Toyota 4Runner Topsites

TRD Supercharger Drive System


This is the original pulley plate with the two idler pulleys. 

The original TRD supercharger kit came with a pulley plate that had two idler pulleys to guide the drive belt.  Very soon after the release of the first batch problems started to surface with drive belts coming off or failing.  TRD as a fix modified the pulley plate so that it only had one idler pulley.  It is hard to believe, but fewer guide pulleys seemed to work better.

This the later pulley plate with the single pulley

The problem was setting the proper tension of the drive belt.  The newer flat ribbed belts require much higher tension then the old V belts to work properly.  There is a gauge called a belt tension gauge that you should buy to properly set the belt tension, but they are expensive and sell for around $100.  Belt problems seemed to always plague the supercharger because people just would not spend the $100 for the proper tools and it seems that the dealers that are supposed to have them many times don't.  If the belt is to loose it will slip, wear out faster, and may jump off the pulleys.  If it is to tight then it put excessive load on the bearings in the supercharger nose drive, idler pulleys, and alternator.  There is a very fine line between to tight and to loose, neither is a good thing.

Here is the new TRD "Dynamic Tensioner" installed.

The latest kits are now including a spring loaded supercharger belt tensioner.  The tensioner is available as an upgrade for the older kits.  In the past you needed to obtain a belt tension gauge that can cost as much as $100 to properly set the belt tension.   In theory the new tensioner handles this problem for you.  However, the installation guide still says that a belt tension gauge should be used to set the initial tension of the belt.  The alternator can be moved in and out to adjust the belt tension on a stock engine and if it is to far in or out it will prevent  the new tensioner from holding the proper tension so it must still be initially set using the gauge and from then on it should be fine.  I found that with both of retrofit dynamic tensioners that I installed on my 4Runners I did have to use the belt tension gauge to properly set the tension to 80 Lbs-Ft of tension.  This was even with the tension properly set with the pulley plate.

The tensioner comes with two brackets, one if for relocating the
wire harness that is behind the tensioner, and the other is to relocated
the oil dipstick tube.  You will need a torque wrench to install the tensioner.

I have obtained a retrofit dynamic tensioner and installed it.  It is a very nice unit, however I think I see potentially a serious problem with it.  On the original kits a steel pulley plate was bolted to the engine block and the nose of the supercharger.  This served two purposes.  One it held the guide pulley or pulleys for the belt depending on which version you have; and two it supported the nose of the supercharger.  This plate is removed with the dynamic tensioner and now the nose is not supported.  The belt puts a high load on the nose of the supercharger along with the weight of the supercharger assembly its self.  The mounting points on the manifold are in cast aluminum.  The mounting point is a fair distance from the load.  It is a matter of leverage here.  I am convinced that the mounting points are not strong enough to carry this load and the mounting bolts will eventually pull out of the cast aluminum.  The bolts are only torqued to 13 lb-ft to prevent them from stripping so they can't be very strong.

I took my old single pulley plate and cut it along the line and removed the pulley part.
This worked great for supporting the nose of the supercharger and provide enough room
for the new dynamic tensioner pulley.


As you can see in these pictures my modified bracket supports the 
front of the supercharger nicely.

Out of concern for what I believe to be a problem I cut up my old pulley plate so it will clear the dynamic tensioner and installed it so that it still supports the nose of the supercharger.  This may or may not be a problem, but I have always said "careful never hurt nobody."

The single pulley plate is available from TRD through your local dealer.  It is surprisingly cheap for a TRD part and is much easier to get one and cut it then to make your own supercharger support.  You may want to act fast because they may stop making and stocking them with the release of the dynamic tensioner.