Early Harley-Davidson® twin cams were plagued with cam-related issues and you’ve probably heard of at least someone who’s experienced a problem with one. From 1999-2006, these motors are notorious for cam chest problems and we’ve repaired our fair share of them over the years. From the tensioner shoes wearing prematurely, to the inner cam bearings failing, to low oil pressure- they can present with a multitude of shortcomings related to the cam.
Own one of these years and left wondering, “Should I upgrade my Harley to gear drive cams or hydraulic tensioners?” or “What happens if I don’t?”. Read on to learn more!
Symptoms
We find that most affected models present with audio indicators first, often described as a “whirling” noise. This can be a sign of the shoes or bearings wearing out, and the “whirl” sound heard is actually the metal pieces rubbing together. If left untreated for a period of time, these bikes will eventually also experience low oil pressure. When an excess of tensioner/bearing debris is ran through the pump, it becomes damaged and is no longer able to sustain the same level of pressure. Our worse one yet, as detailed below, presented with the engine quitting entirely. It had catastrophic failure that caused the cam chain itself to break, resulting in significant and costly damages.
Causes
There are two main reasons why these failures occur. First, the inner cam bearing used on the early models (’99-’06) had a cage that commonly fails. This allows excessive cam play, and debris from said cage to flow free through the motor. The purpose of the cage is to space out the rollers in the bearing. This was factory corrected in later models by using a new bearing design with no cage and double the rollers.
Another cause we sometimes see is the cam chain tensioner shoes wearing out. The incredibly strong spring they used on these models kept a significant amount of pressure on the chain, resulting in premature wear and the same debris outcome as above. In 2007, Harley-Davidson® corrected this by changing the tensioners form spring loaded to hydraulic.
We’ve yet to see these same failures in bikes with the new style bearings and hydraulic tensioners.
Treatment
Always check to see if a remedy has already been performed when purchasing a bike of these years. If it hasn’t, consider the financial burden these repairs will have in the future and factor it into the price you’re comfortable paying for the bike. With this specific scenario, we always recommend preventative versus retroactive treatment. If owners wait until symptoms present, they’ve often already caused more damage and therefore incurred more costs to repair.
DO I HAVE GEAR CAMS?
Unfortunately, the only way to tell if a bike has already been upgraded is to remove the exhaust pipe, foot boards, and cam cover. This process takes about 1 hour labor in a shop setting.
TWO RECOMMENDED REPAIRS (EACH APPROPRIATE AT DIFFERENT STAGES OF THE PROGRESSION):
- GEAR DRIVE CAM CONVERISON KIT
Our preferred method. Recommended before obvious symptoms, not after. The reason we prefer this method is it converts chain-driven cams to gear-driven cams. This eliminates the need for tensioners and chains altogether. The most cost-effective of the preferred methods. This method retains the existing cam support plate and oil pump.
- COMPLETE CAM CHEST UPGRADE KIT
Recommended after symptoms present or damage to other parts has begun. The same as above, but with additional parts (cam support plate, oil pump, tappets, etc.), and therefore additional costs. This is the best option when damage to the support plate or oil pump has already occurred.
Both of above options are considered more permanent as they don’t reintroduce wear items (tensioners).
TWO REPAIRS WE DON’T RECOMMEND:
- HYDRAULIC CONVERSION KIT
Although it is not a bad option, it is not one we recommend. This option converts spring tensioners to hydraulic tensioners. This isn’t our preferred method because the bike is left with chains and tensioners. Any time there are more moving parts, there are more opportunities for future failure.
- BEARINGS / TENSIONERS REPLACEMENT
Simply replacing the bearings/tensioners might be the least expensive option, but in exchange offers little peace of mind. In this scenario, these parts need checked about every 20K miles and replaced in the range of every 30-50K miles. After paying for this job twice, you’ve invested about the same amount that the gear drive conversion would have cost the first time without all of the extra headache. Not to mention the excess debris that gets ran through the motor.
Both of these options are considered less permanent as they include wear parts (tensioners) that are known to eventually fail.
An important distinction is that all four methods require roughly the same amount of labor (within 1-2 hours of each other). What changes considerably is the price of the parts involved for each.
One of the worse cases we’ve seen to date was this 2004 Harley-Davidson® FLHRC that presented with engine failure. It was not running on the front cylinder and sounded like a “big single” (think: Thumper). We removed the pushrod tubes and noticed that the front two pushrods were not moving. At this point, we knew the bike had big problems.
We then removed the cam cover and the issue was obvious. The front cylinder’s inner camshaft bearing had gone out, allowing the camshaft to “walk” around. This chewed up the tensioner and eventually caused the chain to bind and break, resulting in damage to the oil pump, engine cases, lifters, and tensioners. We replaced all parts in the cam chest with a complete S&S kit and it is now a healthy twin again!
This bike sounds great now that it’s repaired. Check it out here!
Questions about your twin cam? Reply to this email or call (740) 747-2299 during normal business hours!
