Do you own a 1999-2006 Harley Davidson with a Twin Cam motor and are wondering about these cam chain tensioner issues everyone is talking about? If so make sure to read on. If you own a 2006 and later Dyna model or a 2007 and later Softail or Touring model you don't have to worry about these issues but you can keep reading if you'd like. Twin Cam engines have two camshafts with timing chains and chain tensioner assemblies, one on the front of the cam support plate and one on the backside of it. Unlike the Evolution motors which only had one camshaft with four lobes the Twin Cam has two camshafts with two lobes on each camshaft that are held by a cam support plate in the cam chest with an internal oil pump, whereas the Evolution and earlier motors had an external oil pump outside of the cam chest. The cam support plate is a system where it's used to distribute oil to critical components of the motor using a bypass valve and pressure chamber system by using oil pressure from the oil pump. The early Twin Cam motors had spring loaded chain tensioners that keep tension on the timing chains therefore are under tension at all times. In 2007 (2006 Dyna models) they upgraded to hydraulic cam chain tensioner assemblies which are controlled by oil pressure. Since it is controlled by oil pressure it isn't under full tension until the oil pressure goes up as the motor revs up, and at idle when the oil pressure is lower it's under less tension. What is dangerous about the spring-loaded style tensioner is that since it is under tension at all times and isn't controlled by oil pressure the tensioner pads or shoes tend to wear out prematurely and can cause metal on metal from the spring tensioner and timing chain wearing on each other causing metal debris to get pumped throughout the motor causing extensive damages that can result in having to completely rebuild or in worst case scenario replace the motor. But you're in luck! There is a way to upgrade the tensioner assemblies to hydraulic or completely eliminate the tensioner and timing chains entirely. To upgrade the tensioners to hydraulic tensioners you will have to purchase a new cam support plate and oil pump set up, Harley Davidson offers a Screamin' Eagle upgrade kit with a high flow cam plate and oil pump or you can go with an aftermarket set up from S&S or Feuling. Which ever one you go with is a personal preference as they are all good options. You can eliminate the tensioners by going with gear driven camshafts which like I mentioned earlier eliminates the timing chains and tensioners completely, but in order to have gear driven cams the recommended or ideal pinion shaft runout spec should be under 0.003" although you can get away with up to 0.004" or 0.005" but you will be pushing the limits, so make sure to check the pinion shaft runout before deciding if you should go with hydraulic or gear driven cams. This is also a good excuse to upgrade your cams and get more juice out of your 88 cubic inch motor or even bump up the cubic inch and turn it into a hot 95" or can even go up to 100 cubic inches and potentially get over 100 horsepower and torque if you pair it with a good set of camshafts, air cleaner, exhaust system and some cylinder headwork. If you have any other questions or want to inquire about upgrading your cam chest assembly give our team a call at Denco Cycle or stop by the shop and we can get you sorted!
