Substitution of Harley-Davidson Twin Cam distribution tensioners

The Twincam 88 engines, which appeared for the first time in 1999 are characterized by having 2 camshafts (hence the nickname "Twin-Cam") and in the same compartment a compartment oil pump of double eccentric rotor. The ciguëñal moves the oil pump through its axle, and at the same time using a chain moves the rear camshaft, and it in turn moves the front camshaft using another chain.

The tension of these chains is secured by 2 mechanical tensioners, that act by the force of a dock.

Depending on the type of driving and the oil used, as well as the RPM of the idle these tensioners reach the end of their useful life, since the friction material is wearing up and must be replaced. If this maintenance operation is not performed on time, they can be worn completely, breaking and letting the metal of the tensioner's body with the chain, producing strange noise and damage to the oil and engine pump in general.

This maintenance of the tensioners is not necessary to do it in the DYNA models from 2006 and on Twincam 96 from 2007, since mechanical tensioners were replaced (by dock) by other hydraulics, which last almost like the same engine, so they practically do not require substitution.
Therefore it is highly advisable to review the status of these tensioners every approximately 40,000 kilometers, to avoid major evils. If they are worn we can replace them with the same reference, or as in this case perform an update consisting of the installation of a screamin ’eagle kit. This kit turns our mechanical tensioners into hydraulic, and at the same time replaces the oil pump, with a more modern unit, with 8% more oil flow and 22% more return, increasing the life of the engine and the same time your performance.

Safety above all: before starting we will disconnect the negative battery terminal to prevent the engine from being shaped by surprise. To start the installation we will disassemble the fuel tank and the rocker covers, to release the rockers and release the pressure on the camshaft. We will do all this following the instructions of the kit and the manufacturer's service manual, which should never be missing in our toolbox.
Then we extract the cover from the camshaft, where we will have access to the distribution plate. With a specific user we will release the tension of the chain tensioner.

Following the instructions we extract this lid together with the oil pump and clean everything conscientiously. Already arrived, this point is highly recommended to replace the bearings that hold the camshafts in the crankcase; HD originals are manufactured by INA, but we can put some better in Torrington (currently Koyo), which have more rollers and work better.

The substitution requires the use of an installer-installer of bearings.

Before starting with the assembly of the components it is highly recommended to measure if the crankshaft axis rotates without deviation, operation that we will perform with a comparator clock and check the data manual data. Motor crankshafts that have been "squeezed" in excess can have decentralization, which could cause premature wear or oil pump break.

Once this verification is carried out, we proceed with the assembly of the components, always lubricating them with special assembly oil. Our service manual will guide us step by step throughout the process.
Special attention must be paid when aligning the pump with the crankshaft, pressing the screws in the indicated order while we turn the engine with the help of the rear wheel. After this we will check the alignment of the distribution pinions so that the chain rotates silent and centered.

We then proceed to the tightening of the screws that hold the pinions, and we can already install the lid with a new joint and proceed with the assembly of the rods of the pushers and the rocker. Tras montar la tapa de los balancines y el depósito procedemos a quitar los cables de las bujías y hacer girar el motor unas cuantas vueltas para cargar de aceite la nueva bomba. Instalamos de nuevo los cables, arrancamos y tras comprobar que en breves segundos la luz de presión de aceite se apaga y el motor gira silencioso ya podemos realizar una prueba en carretera.

Frank Burguera

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