1.What is the biggest mistake owners make installing drive shafts?
Not remembering to grease the centering ball in the double cardan regularly after the initial install. Remember, your lifted Jeep’s shafts are running at steeper angles than they are really supposed to so wear life is a significant issue. Grease is the key, even though it is a pain in the ass to grease the center ball.
2. What is the most common mistake installing u joints?
Probably banging and damaging the areas around the bearing cap bore, specifically the snap ring groove. You must be careful not to hit the yoke near the snap ring because once that is damaged the yoke is essentially ruined. Another common mistake is not cleaning everything before installing the new joints. Joints and yokes require a very precise fit with each other and any dirt or debris that’s in the way will prevent the joint from being adequately installed. Plus, you don’t want dirt in your bearing caps.
3. How often do shafts need serviced?
I’m assuming by “serviced” you mean greased. This is such a nuanced question/answer. It depends a lot on how often the Jeep is driven and what type of driving conditions. For most people greasing the joints every oil change and the center ball every other oil change is going to be terrific. But let’s say you grease your shaft on a Friday then spend the weekend driving through mud holes and rivers. You should grease everything again as soon as you get home to flush out whatever contaminants might have gotten into the moving parts of the shaft. Even if the Jeep is going to sit parked for the next 3 months. Rust never sleeps and it is important to flush any/all moisture out of the shaft with clean grease as soon as possible.
4. What kind of grease is best?
The kind you are most likely to use. It is better to grease your drive shaft using non-ideal grease than it is to wait forever until you get around to ordering the optimal grease. That being said, we recommend grease with a calcium sulfonate additive. My understanding is that the calcium sulfonate grease has nearly the same temperature rating as lithium grease but has a much higher load rating. Which means you can apply more pressure to it, more times, before it breaks down.
5. What is your favorite driveline set up? CV or regular u joint at each end?
My favorite type of shaft is whichever type of shaft required by the specific application. From an Occam’s Razor approach to design, I prefer the simplest solution/design whenever possible. A single u-joint at each end has fewer moving parts, less things to grease (no centering ball), and less things to potentially wear out. But when a Jeep is lifted, and the angles are increased, a double cardan (CV) shaft is almost always required for smooth power flow. I recently created a flow chart to help people decide between a double cardan and a single cardan shaft. I’ll past that below.
6. What is the worst mistake you have ever seen made with a driveline?
That’s a tough one. I’ll list some of the most potentially dangerous mistakes I’ve seen.
When people think that they can build their own drive shaft with a hack saw, an angle grinder, and a mig welder. Welding skill usually is not included in this scenario. Drive shafts are big heavy things that spin very fast and are out in the open. It takes skill to do it right but it also takes special equipment. Even with all my years of experience I couldn’t build you a shaft that would be safe to run at highway speeds without access to the right equipment.
Similarly, sometimes people don’t understand that certain types of parts only work when mated to certain types of parts. For example, I’ve seen it where people think they can make a double cardan by just installing a cv housing and another joint to their single joint end of their shaft. I’ve also seen people try and force the wrong size joint into a yoke. Or the people who have argued with me online about being able to replaced u-joints in a staked yoke that does not have snap ring grooves. When it comes to moving parts things either fit together or they don’t you can’t force it.
Lastly, when people don’t understand that the stock size shaft is not adequate in a vehicle that has 5X the stock horsepower and is running huge tires and 1-ton axles. You gotta know when to upgrade.
7. What do you look for in a drive shaft build?
We try to remember that drive shafts are not a one size fits all thing. What type of shaft a person needs varies a lot depending on what modifications they’ve made to their vehicle and how they intend to use it. Usually if a customer calls asking us what type of shaft they should order we’ll first ask them about their motor, tire size, axles, lift height, and whatever other significant changes/upgrades they’ve made. We’ll also ask about the intended use, although the aforementioned modifications usually tell us a lot about the intended use. From there we will suggest the configuration that we think will best suit that individual. I’m speaking broadly here, for a Jeep TJ the best type of shaft is almost always a 1310 series double cardan (cv) shaft. From there we just make sure to use good quality components and procedures.
8. What else do we need to know about driveshafts and u- joints that we may be overlooking?
I could go on for hours, there’s lots of information in our General Tech and FAQ sections of our website, as well as our youtube channel. With more info pages and youtube videos to come, whenever I eventually get around to extracting the ideas from my head and putting them into video and tech page format. But to give you a more direct answer, a lot of people don’t understand the variability in drive shaft lengths in modified Jeeps. Drive shafts are designed to compress and extend but this is not so that they can be one size fits all, it is because they need to compress and extend as the axle moves up and down. Proper lengths are important and often unpredictable. More about that topic here
https://4xshaft.com/blogs/faq/why-do-i-need-to-measure?
9. Am I sexier than Blaine?
Yes, sorry Blaine.
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