Driveline angles

[planewrench]

With just a 3 1/2" Duff's lift I wound up with some pretty extreme driveline angles. After cutting up and rewelding the front axle and shimming the rear axle with wedges at the spring pads most things are under control. What remains is a fairly severe angle at the double cardan joint at the rear of the transfer case. I've dropped the crossmember about as far as it can go, but that's not enough. Any ideas other than a high pinion rear? (Can't afford that). Thanks in advance, George.

 

[bmc69]

that seems odd...with 5.5" lift on my '69, the CV joints were happy with the resulting rear driveshaft angle. I'm running a high-pinion 44 in the front so I can't really comment on how it would have worked out with the stock 44. What do you mean by 'severe' angle? I have the body off of mine at the moment for some mods and I could measure up the CV angle prety quick for comparison..

 

[elemetal]

I only needed a shim at the axle to get my U-joint on the rear aligned, haven't had an issue with the cv joint (3 1/2" spring lift). If you take some measurements you can tell if you're pushing it or not. High angle drive lines will accomodate up to 25 deg at the cv joint. What tranny and t-case? has it moved your t-case yokes aorund? I haven't heard of people needing to do what you're doing with only 3 1/2" lift.

 

[tabascom16]

On my 5.5" lift I have the back axle rotated up with shims so it makes pretty much a straight line with the drive shaft. The CV joint does not have that bad of an angle. Are you running a doubler or something that makes the back driveshaft real short? If you angle the rear pinion up you should almost have a stock driveline angle with a 3.5" lift.

 

[planewrench]

Thanks for the replies, guys. I don't know why I've had all these problems with just a 3 1/2" lift. The trans is a NP 435 with the stock Dana 20 transfer case, nothing unusual here. The angle at the double cardan joint is about 20 degrees. The problem is vibration. I was told by the driveline shop that balanced my driveshaft that this is too much angle even for this type of joint.
They said it's just two U joints in a row and a U joint doesn't want to see more than about 7 or 8 degrees max.

 

[TJK74]

Thanks for the replies, guys. I don't know why I've had all these problems with just a 3 1/2" lift. The trans is a NP 435 with the stock Dana 20 transfer case, nothing unusual here. The angle at the double cardan joint is about 20 degrees. The problem is vibration. I was told by the driveline shop that balanced my driveshaft that this is too much angle even for this type of joint.
They said it's just two U joints in a row and a U joint doesn't want to see more than about 7 or 8 degrees max.

Not sure how much this will help but here is my driveline angles with a 3.5" lift. Have no vibration problems with the angle its at. Not sure what degree they are at either.

 

[NeverSatisfied]

I'm not real sure what my driveline angle is on my 70 Bronco, but it has 3.5" lift and same driveline length as you (stock). I would be more concerned with the angle of my driveshaft to the yoke on the 9in. The general consensus is to have the yoke angled down ~2 Deg off of a direct 90Degrees with the driveshaft. This will allow for a small amount of axle rotation so you are near a perfect 90 degrees when driving at constant speed.

 

[SaddleUp]

It sounds like the angle at the pinion is off. The driveline should be in almost a straight lin with the pinion when a CV joint is used. (The pinion itself should be about 2 deg. lower)

 

[76Broncofromhell]

Lower your transfercase down a little bit. I have perfect angles on mine with a 5.5" lift and a ZF with a 31 inch rear shaft.