Drive Shaft Angles In Question
 

Hey Guys,

I have been doing a bunch of research on the subject, but would just like a few other more experienced opinions.... I lowered by C10 by doing the rear axle flip (leaf spring rear end). I had the drive shaft shortened due to the axle flip and the LS swap. New U joints and a new carrier bearing as well as drive shaft balancing was all done at the same time. Drove the truck daily for about 3 months and now the carrier bearing is shot. it was pushed completely through towards the rear of the truck (rubber isolater was completely torn). There was no vibration at all until all of a sudden it must have blown out and the vibration was horrible. I have drawn up the angles for the rear end, rear shaft, front shaft, and transmission. I also drew up the slip yoke in the center showing the slip yoke to shaft overlay.

Please take a look and let me know if there is something that I am missing. Are the angles usable or should I shim something? Is there enough overlay between the rear shaft and the front shaft? Is there too much of an angle at the carrier bearing? Could the carrier bearing just be defective?

I have to decide if I need to alter the shaft lengths or change the angles (currently added a 3" spacer under the trans tail to achieve shown angles, which may be too much of a spacer).... I already have a new carrier bearing ready to install. Thanks for looking!!

Re: Drive Shaft Angles In Question
 

I'm not an expert on this but I had a similar experience when I did my axle flip.

From your numbers, your angle are too high. You don't want more than 3 degrees difference between each flex point, but you need at least 1 degree of angle so that u-joints are moving during each rotation, you don't want them perfectly straight. And you want the rear end angle to match the front drive shaft angle.

I would remove the spacer from transmission and see what the angle is at proper bolt torque (if it has rubber mount).

Then adjust the carrier bearing support to get the angle between the front shaft to transmission between 1 and 3 degrees.

With that set, I would adjust the rear end angle to match the front drive shaft.

From here, your angles should be good.

I would guess that since the front shaft was at 6 degrees that it was putting a severe angle load on the bearing and caused it to fail.

If you do a search, there are many posts here that have links to more technical discussions.

Re: Drive Shaft Angles In Question
 

If you have an iphone , a handy app is the tremec app , one feature is driveline angle finder , its free , may not work with a carrier bearing , I assume you took all the angles with the suspension loaded , factory engine / transmission angels are 3 degrees down . your rear angles look wrong to me , they should be equal and opposite , not both pointing up

Re: Drive Shaft Angles In Question
 

The operating angle between the first and second joint is too high. You should try to be no more than 3* difference between 2 shafts. Currently you have 11* (6*+5*) at the second ujoint. Your first joint is operating at 5* (1*-6*) so your operating angle between the first and second ujoint is 6* (5*-11*). As stated above me you need to bring the tailshaft of the transmission down more (Around 5*) to take some of the angle out of the first shaft. This will in turn allow you to lower the operating angle between the first and second shaft. It will correct both the bearing issue and u joints getting chewed up way to often. Because the second and third joint had operating angles within a degree of each other would explain why no vibration was likely felt.

Re: Drive Shaft Angles In Question
 

do they make a trans shim kit or one for the carrier bearing also?

Re: Drive Shaft Angles In Question
 

There are two mounting locations for the carrier bearing mount. You can also shim with washers between the bracket and carrier bearing.

Re: Drive Shaft Angles In Question
 

Id raise the carrier bearing a lot. Angles won't push the rubber out of the carrier bearing. Did you give the driveshaft shop all of your measurements? Sounds like the rear shaft is too long or the slip yoke is locked up or full of grease.
Youtube "driveline angle trainer" for the why and it looks like you have how to fix the angles pretty much figured out.

Re: Drive Shaft Angles In Question
 

Thank you all for the responses. The first thing I am going to do is get rid of that transmission shim (or use a smaller shim) to get the transmission and rear end parallel. I will have the new carrier bearing install this week as well and get that all bolted back in. Then I will recheck all the angles and raise the carrier bearing to reduce angle between the two shafts. Hope this gets rid of the problem!! Thanks again. I will post results as soon as I get it all back together.

Re: Drive Shaft Angles In Question
 

Just replace the rubber on the carrier bearing. Ask the guys who worked on the shaft if they have an extra.

Re: Drive Shaft Angles In Question
 

So I just wanted to give a quick update to the driveshaft issue. I had a local drive shaft shop install a new heavy duty carrier bearing. I also shimmed the carrier bearing up about 1 inch. I haven't been able to drive it too much since it is winter here in Wisconsin, but the little bit that I did drive it, I did not notice any vibrations nor bottoming out of the slip yokes. Here is a picture of the final drive shaft angles. Thanks again for all the input!

For some reason, no matter how I save this image it shows up upside down so I am sorry about that.