Driveshafts

[Chevy350Ben]

I'm gonna try to make this short and sweet:

Im building my truck in stages. Almost done with Steering/suspension/axles.

One of the big hurdles I still need to cross is driveshafts. I have poured over the build threads here and in other sites, and cant find a good, comprehensive thread on driveshaft angle theory.

Specifically how caster/pinion angle are supposed to be set up.

Eventually, I will order custom shafts from tom woods, or high angle. But I don't really want to spend that money untill I get through with stage 2 (engine/transmission/wiring).

What I have gleaned so far:

Caster angle on the front axle should be about 6 deg. negative (top further back than bottom).

Rear axle pinion should be pointed at the transfer case output if using double cardan style ujoint. Or should be the same angle as the transfer case if using traditional single ujoints.

Problems:

• I don't feel comfortable cutting and re-positioning the inner C's on the front axle, and I cant really afford to have a shop do it. So, the only way I can get the correct caster angle is to use degree shims. Im probably just going to lengthen the shafts I have for now. And the stock front shaft has a double cardan. So what is the Ideal pinion angle for the front? I'm sure I wont be able to make pinion and caster angles happy, so what do I do here?
• As stated before, I'm just going to lengthen my stock shafts for the time being, until Im ready for custom shafts. Could be years before I have the drivetrain I want rebuilt, so this has to last a while. If I set up the rear axle for the stock shafts, then Im gonna have to re-do everything (shock mounts/spring perches/u-bolts etc...). But if I set it up for double cardan, then the stock shaft probably wont make it around the block.

Can anybody point me to a cheap/easy solution here? should I just trailer it to a shop and have them handle it? I really cant afford to dump another few thousand into this, but I'm kind of at a loss...

I did not succeed at making this short and sweet. Sorry.

 

[mechted]

Most of us have a compromise on front caster vs driveshaft angle. Usually you can get away with just front axle shims and still get decent steering. Kinda depends on how much lift, how much tire, what style of steering, and what vehicle speeds will be to determine the best solution. Shims are cheap and probably worth a try before investing in axle rotation.

Pretty much any company that makes driveshafts has an article on their website showing you how to set up / measure for replacement shafts. This will include angle information. Usually running near max angle on a joint just lowers the life of the joint and may cause vibrations at higher shaft speeds. Do you want to spend money once or twice is also a debate. It will be more to do it correctly now, but then its done. If you think you are dramatically changing things in a few years, maybe a cheaper option will work for now. You need to decide what will work best for your situation.

Pretty much the cheapest decent rep company I have found: http://fulltorquedriveshafts.com You can spec out different shafts and see what the prices will be.
If going to a Tom Woods / Adams / High Angle driveline / other premium name, I would expect the price to go up 30 to 50%.

 

[Chevy350Ben]

Sorry, yeah. I should have provided some critical stats:

1990 K5 Stock 350TBI and 700R4 trans/241 transfer case.

ORD custom leaf springs, shackle flip rear for about 6" total lift. on 40" tires.

Dodge passenger drop Dana 60 front, 14 Bolt FF rear geared to 5.38.

Mainly will be a trail rig. But I dont want to trailer it there and back, so it will see some highway miles too.

 

[Fastereddie]

6” lift on a K5= double cardan on the rear for sure. So you want your rear pinion pointing at your t-case output. But you still want it just a hair down. (like1 or 2 degrees) because of axle wrap. The front is a compromise like others have said. I’m only running 3.5 degrees of caster on the front and it drives fine.