Rear Swing Arm (Chain Driven)

[Bugpac]

it may work, seems like the mounts are going to have to be large to compensate for the minimal attachment points....

[ChillItsGill]

Awesome, thanks for the replies. I'm gonna go draw this up. Any ideas on where to buy a quality u-joint?

[Bullnerd]

The TK is basically just a big swingarm,with a "floating"sprocket between the drive and driven sprockets.

I was trying to think of a way to do a 3 or 4 link,because i had heard the tks would "jack" up in the back under power.My idea was to copy a traditional truck link setup just using a belt inplace of a drive shaft.That way you could control the instant center and the jacking effect.

I think a harley belt with a good tensioner/guide on the lower side,so theres no room for the belt to derail,would work.They are quite flexible.

I also was thinking of using this for lower Hp toy not "busa" nonsense.

[ChillItsGill]

I'm gonna bump this thread, as I'm finally getting around to SW drawings. What's the average misalignment a U-Joint can handle before binding?

[nutz4sand]

Many people do not like to run them at more than ten degrees. But some of these severe angle guys (long travel) are taking a bit of your average large 4x4 front axle u-joints. Some use large 1 ton U-joints and can get over 30 degrees of angle plus. The driveshaft will be doing the flip thing (accelerating and decelerating each rotation and cause some vibration) But some claim they have high angle driveshafts and no vibrations. But there is gonna be some. *

Look at how tight a U-jointed 4x4 can steer. But high power and high speed at max angle can be touchy. I always thought that Ford ranger U-joints might be something for a lightweight machine with smallish tires. *Bill

[Gene]

OK. Reading back a few posts - U joints don't plunge, plunging axles with U joints and certain CV's do. I forget which type VW/Porsche CV's have more or less angularity but one style can go to 23* or so without binding. Front Wheel drive CV's can go to 40* or maybe a bit more.

My rear axle has FWD CV's with a plunging splined axle. The Cv's can go maybe 40 and are limited to perhaps 37*. The axle plunges about 1/2 inch according to Solid Works.

So the answer is how much do you want to spend and how much stress are you willing to place on the driveline. Some are believers in U joints and some not. Nutz points out some good considrations.

[nutz4sand]

I forgot to say that only one U joint in a shaft at an angle will make the vibration more noticable.
In a driveshaft with TWO u-joints IN THE SAME PLANE (I.E. *same angle as in flat to the horizon both must be. If ones level the other should be. If ones at a 10 degree angle the other end should be 10 degrees angle to.) This will help to smooth out the motion to where ever the power is going. An Easy way to think about it is the transfercase in a truck. Its normally level (on flat ground.) the rear end (pig) should be so that the pinion gear is at the same angle as the transfer case (level on flat ground) For the driveshaft vibrations to be minimal. Many times a person will have the transfer case flat and the rear end tilted up thinking they are doing a good thing when its actually very bad. They make a bit less angle on the rear U joint but the vibration this sets up will be far worse. Tilting a transfer case to the rear hurts the front driveshaft so what to do? Keep them all level and spend some loot on really good driveshafts that can deal with angles. Thats the best way. bill

[ChillItsGill]

Wow, awesome replies.

10* seems like a really small amount. I'll have to design the system and see how much travel I'm looking at with only 10*. Good idea with ranger U-joints, I'll price them out.

As for my price range, I would obviously like to keep it as small as possible. The engine I'm using is not all that powerful. I pulled it from a 250cc bike, so I'm not dealing with that much.

How much more are CV's over say a ranger U-joint?

[nutz4sand]

If you are only using one joint for angle I would go with CV no questions. It will not create any vibration or speed changes.

10 degrees is on the safe side. For major high speed stuff. They can go more and are put to far more all the time. But you have to make sure they are supported properly.

Also with a U joint there will be no give (plunge as Gene stated) Being that two of its points will NOT be in the same plane at any angle it will need a slip joint shaft. It simply cannot be held in a pivot point with no ability for ONE side of it to flex or plunge. *If you have ever tore apart an old VW swing axle and seen the "u-joint" it had the entire end of the axle flatened and it slid back and forth a little between two beveled pucks. This allowed the "plunge" it needed for a single joint. With a "typical" u joint there is no movement allowed so it must be accounted for somewhere or it will bind like all heck. Two will be the same way as in they need perfect suspension setup for free movement. If you ever bend anything it will bind. So a slip joint helps allow for all this. *Bill

[ChillItsGill]

Originally Posted by nutz4sand\";p=\&quot

If you are only using one joint for angle I would go with CV no questions. It will not create any vibration or speed changes.

10 degrees is on the safe side. For major high speed stuff. They can go more and are put to far more all the time. But you have to make sure they are supported properly.

Also with a U joint there will be no give (plunge as Gene stated) Being that two of its points will NOT be in the same plane at any angle it will need a slip joint shaft. It simply cannot be held in a pivot point with no ability for ONE side of it to flex or plunge. *If you have ever tore apart an old VW swing axle and seen the "u-joint" it had the entire end of the axle flatened and it slid back and forth a little between two beveled pucks. This allowed the "plunge" it needed for a single joint. With a "typical" u joint there is no movement allowed so it must be accounted for somewhere or it will bind like all heck. Two will be the same way as in they need perfect suspension setup for free movement. If you ever bend anything it will bind. So a slip joint helps allow for all this. *Bill

Awesome, thanks. I plan to use a "4-spline drive shaft" with 2 U-joints. I'll post up pics whenever I finish drawing it up.