The Truth About Your Cam Chest - TMF Cycles

The Truth About Your Cam Chest

If you've been around Harleys especially bikes from 99-05, you know the first question that's asked when it comes to cams is, did you do the tensioners yet? That question spills over into even the newer twin cam motors as more and more new riders continue to modify their stock twin cam. In this post I'm goin to go through the most common questions I receive from customers. But first lets talk about the plates, pumps and issues.

99-02 - The problem with the early twin cam 88 was not necessarily the fact that they had a spring loaded cam chain tensioner. The problem that haunted most of these early twin cam models was the fact that the chains were made with sharp ridges on the outer plates that quickly ate away at the plastic tensioner. being spring loaded, there was always constant pressure on that chain, unlike newer models where the tensioners fill with oil. This caused the sharp ridges of the chain to dig with each rotation of the crank, the higher the rpms you hit, the more plastic was being chewed away.

03-05 - Although these bikes had the same spring-loaded cam chain tensioners, the chain issue had been addressed after multiple people got free replacements under warranty. The new and improved breathers were in the 03-05, which helped with overall efficiency, but they also made changed to the cranks in these year dynas and went away from the Timken tapered crank bearings. These cranks usually ended up having more run out that the earlier models but if you were easier on your bike, you probably got more miles out of the tensioners on it. The more run out the less consistency on the you cam chain tensioners tension (more pad wear)

06- Current - These bikes have the best all around stock tensioners, hydraulic oil fed with delrin style pads. These were the best mix because they are able top place more or relieve tensioner tension with each rotation because of the lighter preload put on the chain. Mix in the delrin pads, these are pretty much as durable as you can get. These models also offered the bearingless bushing style cams that took away any more potential chain tension issues that could have been caused by worn cam plate bearings.

(Left 99-05/Right 06-Current)

Upgrade Options

There are a lot of options out there to either convert your older cam plate to something like the newer hydraulic style, or upgrade your newer one to a high volume race plate. But what the right choice? I will break down my top options below.


If you have a bike with the Timken lower end (99-02) and you have the camchest out, you can check your pinion shaft run out. While Harley seems to be ok with .010 max run out, if you have plans of a high volume plate and pump, you should be shooting for under .005. A lot of the early bikes are some what blessed with less run out due to the tapered Timken bearings. If your bike has .005 or greater, it doesn't mean you cant upgrade the tensioners to a more bullet proof system. Although, I don't recommend spending the money on the high volume set up if you're sitting above .005 you can still safely run it as long as you check you oil each change for any signs of bronze or metal from the plate or pump. These high volumes plates are made to tighter tolerances so even the slightest amount of excess runout will begin to wear the components. That's why I recommend balancing the crank beyond .005 if you absolutely want the high volume set up, that goes for 99-17. If your bike has under.005 you can also consider a gear drive set up, but honestly that's more for a complete motor overhaul!

So what if you don't want to do the crank? On your early models you can take a plate and pump combo from a 06 up dyna and use either Andrews or Feuling conversion cams which will allow the newer plate and eliminate the spring loaded tensioners while allowing you to also update the cam plate to the non bearing bushing style outer cam roller. This will allow you to also upgrade to the newer hydraulic lifters. This can be done for under $500 and if your goal is just to fix the issue and ride this is my top choice. If you have .005 and higher run out Feuling also has a OE+ option that has looser tolerances which will work great for this conversion (priced around $499)

If you plan on balancing your crank the race options will help your camchest scavenge and run with more oil pressure/oil-flow. The options for that 

Feuling HP+ or Race Series

S&S Hi Performance Plate and Pump

Screaming Eagle Plate and Pump

all of these companies have done their homework to create a great product for you build. If you have more cubes going on up top, you may like the extra oil pressure to have your motor running smooth, but like I said unless your run out is under .005 you should really think about what your future plans are for the motor before you spend the money. If you just want to upgrade to say you did it, you could be asking for more problems down the road.

Either way I can get you set up with the best parts for you build, so hit me up with any more questions!