THE Driveshaft Video. The Nature of U Joints. Suspension Basics Ep. 06

what if I told you that your drive shaft without you knowing it could speed up and slow down twice on every single rotation hey garage fabbers I've talked a lot about pinion angle pinion angle pinion angle pinion opinion pinion angle on this channel but today we're finally going to talk about why pinion angle is so important especially on vehicles with air suspension and it all starts with a drive shaft or more specifically the universal joints in a drive shaft sometimes referred to as Cardon joints this is a CV joint what does it have to do with a universal joint nothing and that's why I bring it up CV stands for constant velocity velocity can roughly be translated as speed the CV joint uses ball bearings in machined grooves to allow a rotating shaft to bend while maintaining a constant speed in other words if a motor turns this part of a CV joint at a constant speed this part will also rotate at a constant speed well duh I'm sorry any joint connected to a motor will turn at the same speed as the motor right [Laughter] there must be a reason the constant velocity joint was named the constant velocity joint and that reason is the U-joint the U-joint is not a CV joint by that I mean a U-joint doesn't always rotate at a constant velocity instead of ball bearings like the CV joint the U-joint uses a cross to allow Flex because of that cross even when attached to a motor that's turning at a constant speed a bent U-joint drive shaft is out here doing its own thing speeding up and slowing down and speeding up and slowing down and it's happening really fast if your suspension isn't set up properly this will shake you to death and destroy your drivetrain I built a machine to help me demonstrate the sorcery honestly I borrowed the idea of this machine from some other videos I've seen but mine is way better because mine as a parallel link setup to show real-time changes in a drive shaft as a modern suspension moves up and down I've attached this thingy to my motorized bead roller which will resemble your vehicle's transmission making the other end the differential on this drive shaft there are three bicycle sprockets those are noise makers they will allow you to hear any variation in speed one is attached to the transmission tail shaft another on the center section of the drive shaft and the last one on the differential to start notice our entire drivetrain is in line with no bends and because of that there's nothing interesting to see or hear [Applause] that's because things don't get weird until you bend a U-joint so let's extend our suspension fully as if we're lifting our vehicle that's a nice Bend right there and now check this out the transmission is still turning at a constant speed but the drive shaft so you're the pitch change this bent U-joint is causing the drive shaft speed to oscillate isn't that crazy and the oscillation is going straight into the differential can you imagine a car with this bent U-joint installed I'm gonna go grab some milk an important thing to note is that this speed oscillation increases and decreases as the U-joint angle increases and decreases so if the drive shaft speed only oscillates when the U-joint bends then the obvious answer is to just keep the drive shaft straight right in theory yes that would be great but as the suspension moves up and down in a vehicle the U-joints are going to bend and in a vehicle with adjustable height suspension the U-joints are going to bend a lot luckily we have a fix you can actually cancel out the speed oscillation of this U-joint with a second U-joint to do that there's two requirements one the second U-joint needs to be installed in Phase that's a fancy term for saying that these yoke ears are in line or put another way the second U-joint is positioned as a mirror image to the first that's interesting because a mirror reverses stuff and that's exactly what we're trying to do reverse this wacky speed oscillation requirement two is the angle of that second U-joint remember that the speed oscillation increases the more the U-joint bends so in order order to reverse just the right amount of speed oscillation the angles of both U-joints need to match I'm going to zero out my angle finder to the transmission side sprocket and then adjust the differential side sprocket to match now the shaft inside the transmission and the shaft inside the differential are parallel and because of that the front and rear U-joints are bent at the same angle let's try it out and see what happens the transmission is still turning at a constant speed the drive shaft speed is still oscillating because of this Bend and the differential after the second Q joint is back to constant speed I don't know about you but when I first learned this it was absolute magic so now you know the rule pinion angle should be parallel to the transmission shaft angle let's mess things up on purpose say someone tells you hey buddy hey you're going to want to set that pinion angle at three to five degrees down oh okay why a brief tangent pinion angle refers to the angle of the input shaft inside the differential in this video I will be saying that the pinion angle of a differential in this position is down and this position is up some folks will disagree and they will be right their argument is that the shaft angles should be determined from the front of the vehicle to the back so if this transmission is angled down and this drive shaft is angled down then the pinion angle is also angled down I agree however visually that can be confusing to someone that's just learning this stuff and as always it's more important to me to help you understand than it is for me to sound smart so visually this arrow is angled up this symbol is angled up this pair is angled up and this pinion angle is angled up in the end when you're working alone in your garage terminology he doesn't matter much if you truly understand the system so let's continue understanding the system so you do as you're told and set your pinion angle to three to five degrees down the problem is that person never bothered to ask you what your transmission angle was which in this case it's pretty much in line with the drive shaft at zero degrees what have you done I'll tell you what you've done you've created a single vent U-joint and a nasty vibration on the freeway here's something interesting that guy that told you to point your opinion angle down three to five degrees may have been right Once Upon a Time back in the day muscle cars had leaf springs High horsepower engines have the ability to twist those leaf springs a little causing the axle and differential to rotate backwards some under heavy acceleration maybe even three to five degrees backwards so on Leaf sprung Vehicles built strictly for the drag strip it would actually make sense to point the pinion angle down knowing the torque of the engine would pull the pinion angle up into alignment during the race then the vehicle would go home with a misaligned pinion angle on a trailer with that in mind let's add to the pinion angle rule pinning angle should be parallel to the transmission shaft angle as often as possible that's an important addition because with many suspension designs pinion angle isn't fixed pinion angle change is really common on production vehicle suspensions both my wife Caroline's Forerunner and my Mustang have similar Link Bar rear suspensions with long lower bars and shorter upper bars this setup increases traction on acceleration but the uneven length bars causes a pinion angle to change as the suspension moves up and down see suspension Basics episode 2. so why isn't this a problem because the Forerunner and the Mustang are both static height vehicles in other words they have a constant ride height the manufacturer set the pinion angle parallel to the transmission shaft angle at that ride height because that's the height the vehicle will see most often the vehicle will probably hit a bump or a dip at some point and the ride height will change momentarily when that happens the pinning angle will also be misaligned momentarily but it's likely so minimal and so brief that you wouldn't notice it and it certainly wouldn't cause any parts to fail it's not until we custom car enthusiasts start messing with things that problems arise say Caroline decides to lift her Forerunner six inches and I decide to drop my Mustang into the Weeds now that our ride heights are different our likely misaligned pinion angles are permanent now you might feel the vibration at higher speeds and you will also start wearing out the drive shaft U-joints more quickly so what would be the fix with the vehicle resting at its New Height not on a lift you should check to see if your pinion angle matches the transmission shaft angle if it does great leave it alone if it doesn't you might need to install either aftermarket adjustable length link bars or some wedge-shaped blocks between your leaf springs and Axle that will allow you to put your pinion angle back into alignment I want to install air hydra products on my truck it's going to be sweet how do I set my pinion angle I am glad you asked if you haven't noticed air suspension is my favorite topic if your vehicle will be able to drive at a one inch ride height a 10 inch ride height and everything in between pinion angle is something you're really going to want to pay attention to if you're bagging something with unequal length bars like the Forerunner or even some aftermarket Link Bar kits pinion angle misalignment is going to happen and managing it is going to be a balancing act you can approach it two ways one you can determine what your total travel will be and set your pinning angle to the correct position at half travel this will minimize the pinion angle misalignment at both maximum and minimum ride heights two or what I would suggest install an air management system that will allow you to set the desired ride height adjust your pinion angle to that ride height and stick to that ride height this will operate the same as the factory setup except now you can drop your vehicle on the ground when you park and the occasional drag sesh probably won't hurt anything if you want to bag something that came with leaf springs like the Mighty Max you're probably going to want to ditch those leaf springs and install some link bars instead and this is your opportunity to never have to worry about pinion angle again if you install a parallel four link or a triangulated four link that uses the parallel four link principles once you set your pinion angle it will stay at that angle at all right Heights you can see that magic in my video suspension Basics episode 2 or you can see it right now because there's a parallel link set up on my doohickey watch how the equal length and parallel bars cause the differential to maintain the same angle as the transmission and even though the speed of the drive shaft varies the speed of the differential does not hopefully things are clicking for you because things are about to get confusing inevitably somebody is going to hit me up in the comments and ask what about the double card and Joint so I'll be proactive and install one on my machine people often call this a constant velocity joint I realized I just went on a tangent about how terminology isn't important but this is a CV joint not this a double card and joint is exactly what the name says it is it's two Cardon joints or two U-joints put together a double Cardon joint takes all the magic that we just learned about and puts it in a neat little package the speed oscillation is still there it's just confined to the center section which is essentially just a really short drive shaft a double card and joint is Handy on vehicles with rapidly changing pinion angle like on vehicles with a two link suspension think old Chevy c10s and NASCAR with a two link the rear joint on the drive shaft will maintain relatively straight while the front joint bends again not a big deal with minimal movement of a static height to link but a very big deal if you decide to increase the amount of travel with airspray Rings because a single bent U-joint equals vibrations since only the front joint bends on a two link installing a double carton joint on the front of the drive shaft would prevent any vibration so should a double card and Joint be installed on every adjustable suspension definitely not a double card and Joint both creates and eliminates its own speed oscillation but it does not eliminate the oscillation from other bank U-joints on the drive shaft for example on a parallel four link the front and rear joints of the drive shaft will be bent at the same angle the singular U-joint will create an oscillation but if you install a double carton joint on one side that joint will create and eliminate its own speed oscillation but it does not eliminate the oscillation from other bank U joints think of a bent U-joint as a light switch that turns on and off vibration if you add a single bent U-joint you just flip the switch and turned on the vibration add a second U-joint bent to the same angle to turn it back off if you add a third bent U-joint you just turned on the vibration again and so on that said an even number of equally bent U-joints is necessary to prevent driveshaft vibration an odd number of bent U-joints just might vibrate so on that vehicle with one card and joint and one single U-joint that's technically three U-joints and a potential vibration maker yo Humpty got a Tacoma with a two-piece drive shaft and three singular U-joints how come that one don't wiggle because with a two-piece drive shaft the first U-joint doesn't bend the transmission is fixed and the carrier bearing is fixed which keeps the first U-joint straight and a straight U-joint doesn't oscillate the second piece of the drive shaft however moves up and down with the rear suspension and both of the rear U-joints Flex about the same amount which again creates and eliminates the speed oscillation before it gets to the differential here's a quick side note for those of you considering using a double Cardon joint on their project some people think that the two U-joints in a double Cardon joint will allow a drive shaft to flex more it does not there's less Flex actually the front and rear flanges in a double Cardon joint are connected in the middle that ensures the two U-joints Bend an equal amount because remember equal bends are needed to prevent vibration but this connection also greatly limits the movement of a double carton joint so remember my friends when building your suspension plan to keep your pinning angle and your transmission Mission shaft angle parallel as often as possible and keep moving forward seven months ago I was feeling a little overwhelmed okay a lot overwhelmed and I decided to take a break from YouTube during those seven months I received a bunch of messages from people to encourage me to take as much time as I needed but that they miss the garage Fab content in that time off seven thousand more people subscribed even though there wasn't any signs of new material coming that's a total of 20 000 garage Fab subscribers it was a bit of an eye-opening realization that people really care and they value what we create here so I'm glad to be back at it a very genuine thank you to all the viewers for your support and the much needed motivation to continue my friends garage fabbers I'll see you in the next one

Channel: Garage Fab

Views: 386,724

Keywords: Driveshaft vibration, u joint vibration, air suspension problems, cv joint, 2 piece drive shaft, 4 link, parallel 4-link, coilover, air ride, air suspension, panhard bar, pickup, suspension, suspension design, suspension geometry, airbagged, air bagged, bagged, 4link, how to, air suspension book, air suspension design book, automotive suspension, custom cars, watts link, Garage fab, triangulated, mini truck, Double Cardan Joint, Operating Angle, Pinion Angle, Off-road

Id: YgNZfIR-8Ng

Length: 19min 20sec (1160 seconds)

Published: Mon Nov 07 2022