Drive line angle advice

[AndyG]

03 Rubi.

Transfer case drop

Stock rear shaft

3.5" rear springs

If you raise the moter to adjust the transfer case output angle, what happens with your front pinion angle .... especially if it needs adjustment and you are happy with your caster?

Or do you do a CV driveshaft in the rear if that's the best choice to avoid pushing the rear track bar into the gas tank skid with the adjustable contr arms?

Needing to learn

Thanks ,
Andy

 

[cpwolf]

Or do you do a CV driveshaft in the rear if that's the best choice to avoid pushing the rear track bar into the gas tank skid with the adjustable contr arms?

Needing to learn

Thanks ,
Andy

I’m not sure I follow this part.

I thought that when you Add the CV rear, and then use adjustable control arms to make the pinion point at the TC, then you have a problem with the track bar and need the angled bracket and and adjustable track bar.
If you stay without the CV then the track bar doesn’t have an issue, but maybe I’m off.

 

[AndyG]

I’m not sure I follow this part.

I thought that when you Add the CV rear, and then use adjustable control arms to make the pinion point at the TC, then you have a problem with the track bar and need the angled bracket and and adjustable track bar.
If you stay without the CV then the track bar doesn’t have an issue, but maybe I’m off.

With a CV shaft the pinion has to point directly at the shaft...no angle or just 1-2 degrees down at most for torque movement.....a CB shaft does not require the angle of both ends because the double joint cancels out the change.... My situation is I'm considering the CV shaft because I don't want to push the axle any further back as a rotated to get the pinion in the same parallel plane as the transfer case output you would with the stock shaft.

I guess it's all give and take and I'm just wondering what guys do when they do a motor mount lift change and it changes things on the front angle...and they don't want to lose caster to dial it in.

It's easy to see why the interconnected design makes it where these things aren't as simple as people think to modify.

 

[freedom_in_4low]

If you raise the moter to adjust the transfer case output angle, what happens with your front pinion angle .... especially if it needs adjustment and you are happy with your caster?

The front output yoke isn't very far longitudinally from the point you're pivoting the engine around (the transmission mount) so it doesn't change much at all in elevation, and therefore doesn't change your front pinion angle much if at all. It does add to the CV joint operating angle but again, shouldn't be enough to matter.

 

[Jason from SoCal]

Coming back to your first question:

"If you raise the moter to adjust the transfer case output angle, what happens with your front pinion angle .... especially if it needs adjustment and you are happy with your caster?"

Raising the motor has very little impact on the height of the transfer case's front output shaft which is set by the rear transmission mount (T-case drop). It simply rotates the T-case to point up slightly (and rear shaft points down slightly). The hight of the transfer has a large impact on drive shaft angle. The minimal change in hight means that there is minimal impact on the front drive shaft angle which should leave it aligned with the pinion angle (CV front drive shaft). Therefore there is no real impact on your front axle or caster. As Andy pointed out, the angle between the driveshaft and the transfer case is not important because the CV joint handles the angle.

However, in the rear, with a non-CV drive shaft, the relative angle between the T-case output shaft and the rear pinion is important. Therefore the motor-mount lift allows for the rear axle to be set at steeper angle. If your rear axle is already properly aligned, then adding the motor and adjusting the rear axle accordingly will raise the pinion and push the track bar closer to the gas tank (not further).

If you were to switch to the CV shaft, then you would need to rotate the rear pinion up even further to be in-line with the drive shaft, which would require you to rotate the axle back further and make the track bar situation worse. Because of the location of the transmission/T-Case mounting point relative to its rear output shaft, raising the motor mount will give you some decrease in absolute height of the rear T-case output shaft and therefore a slight rear drive shaft angle reduction and allow you to slightly rotate the diff back forward.

Generally speaking, increasing the motor mount height helps to compensate for rear pinion angles that are too high with non-CV rear drive shafts. Many of the lift kits provide longer lower control arms that are longer than stock and rotate the pinion down to alleviate this issue.

 

[freedom_in_4low]

Or do you do a CV driveshaft in the rear if that's the best choice to avoid pushing the rear track bar into the gas tank skid with the adjustable contr arms?

you do a rear CV driveshaft when you don't want a TC drop or a TC drop isn't enough to get a vibe-free operating angle in the non-CV u-joints.

When you're doing a CV driveshaft, you get upper AND lower adjustable control arms and an angled track bar bracket along with your CV driveshaft to keep the track bar and diff cover out of the gas tank skid. Getting only adjustable uppers and not lowers is what gives people gas tank interference problems.

 

[Jerry Bransford]

you do a rear CV driveshaft when you don't want a TC drop or a TC drop isn't enough to get a vibe-free operating angle in the non-CV u-joints.

When you're doing a CV driveshaft, you get upper AND lower adjustable control arms and an angled track bar bracket along with your CV driveshaft to keep the track bar and diff cover out of the gas tank skid. Getting only adjustable uppers and not lowers is what gives people gas tank interference problems.

X2, this right here.

 

[AndyG]

Awesome. I'm generally on the right track then . Thanks to each of you.

I'm in a situation where either would work, and have upper and lower adjustable control arms so I'm rotating it back up for the CV, since it's being made ...but I'm keeping my old shaft if that backfires.