VRaptor SpeedWorks "You Dream It, We Build It!"

LS Serpentine Belt Tensioner Complete Kit

March 22, 2016  by Shane

As many GTM builders can verify, there are several issues with the serpentine belt set-up on the GTM.  If you are trying to set up the automatic tensioner on an LS7, you know that the back of the tensioner assembly hits on the vacuum port at the front of the intake manifold and you either need to relocate the tensioner, modify the tensioner or modify the intake manifold to make it fit.  The provided bracket for the tensioner from FFR is not very rigid and flexes as the engine revs and increases the tension on the belt…..causing the belt to go out of alignment.  Also, where FFR has the tensioner placed, the belt is being pulled over the alternator pulley and idler (which can bend the unsupported idler pulley down and bend the pulley support permanently) and the belt is being “pushed” over the waterpump.  This combination of push-pull and flex and belt alignment causes all sorts of problems….at best, the belt just queals.  At worst, the belts gets thrown off completely or partially….or one edge of the belt gets “eaten” by the misalignment.

To solve these issues, we’ve created a manual tensioner that offers several advantages:

  1.  It’s lower profile by about 1″ compared to the FFR unit.  Once the car is assembled, the stock tensioner pulley ends up almost touching the “waterfall” interior cover.  This tensioner will provide approx 1″ of clearance between the tensioner and waterfall.  This means you will have more room to install insulation on the bottom side of the waterfall to prevent heat and noise in the cockpit.
  2.  It holds constant tension on the belt.  If you watch the stock automatic tensioner as you rev the engine up and down, you will see that the tensioner moves…..unloading and loading tension on the belt.  This tensioner holds constant tension on the belt.
  3.  The bracket is supported at the waterpump bolt bosses (just like the FFR bracket), but is also bolted to the opposite head, which prevents the bracket from flexing under load as the engine revs.  This keeps the pulley in constant alignment.  Constant and consistent belt alignment and tension means no squeaky belt, no belt jumping off the pulleys and reduced belt wear.
  4.  This bracket clears the LS7 intake manifold with no need for modifications.  It also clears LS1 and LS3 intake manifolds.

This kit comes with the following:

Main Tensioner Bracket

Pulley bracket

Jack screw and nuts for adjusting belt tension

Spacer and bolt to attach main bracket to the LH cylinder head

Bolts to hold the tensioner pulley on and to lock your adjustment down

Shims to place behind the tensioner pulley to adjust your tensioner pulley to be in alignment with the crank pulley.

Tensioner pulley/bearing

Serpentine Belt


The brackets are made from 3/16″ steel and are not painted.



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