driveshaft and pinion angles
 

I just got done reading an article over at airridetalk.com about pinion angle which was very good, but I'm still not sure about my setup. Perhaps somebody here can help. I'm at the point where I just set my ride height and want to do some welding on my rearend, but I'm not sure if the pinion angle is correct. Everything is still connected (rearend to driveshaft to tranny), so I took angle measurement of everything. This is at ride height: (I've got a two piece drive-shaft) The tranny points down 4 degrees, the first driveshaft points down 8 degrees, the second driveshaft points up 8 degrees, and the pinion points down towards the front of the truck 5 degrees. Is this OK, or do I need to change something?

Heres the link to that article if anybody is interested:
http://www.airridetalk.com/articles/...-joint-enigma/

Re: driveshaft and pinion angles
 

Heres some very help full info on this SITE IMO it's one of the best rear suspension pages I Have read.

Re: driveshaft and pinion angles
 

I disagree, however maybe thats because I used to run bagginit.com and no longer do and know its going down the ****ter. ;)

OP: Here's what I'm getting from your post: The operating angle between your tranny and first shaft is 4° and the operating angle between the first and second shaft is 16° (pretty extreme... anything over 8 will cause joints to wear more quickly over time). Taking the larger number from the smaller, we get a total operating angle of 12°. That means that the operating angle between the second shaft and pinion needs to be 12°. You have a second shaft pointing up at 8° and your pinion pointing down 5° towards the front of the truck. Subtract them, and you get 3° all together. As you can see, 12 and 3 are pretty far apart. In order to correct that, your pinion would have to tilt down around 20°, which is pretttttty extreme.

I would highly recommend that you look into shimming up the transmission and the carrier bearing as well. This will decrease the angles between the first and second shafts, and will thus require a smaller angle between the pinion and second shaft. What kind of drop or setup do you have on this truck? At what height are you trying to set this up at?

I guess the biggest misconception that a lot of people have is that it all revolves around the angles of the objects to mother earth, but its really about the angles between the different objects and how they interact (their operating angles, which you saw me mention).

Something else I should ask, on your two shaft setup, do you have single joints connecting everything, or are they double cardan joints (which would make life hell of a lot easier)? :)

Re: driveshaft and pinion angles
 

I was talking about the document not the company I didn't even know that they were a company.I thought it was just an informative web page, oh well live and learn. are they related to AIM if they are I agree stay away.

But then I barely came into the bagging scene around a year ago.

Re: driveshaft and pinion angles
 

Hey matt, thank you so much! Just the man I wanted to hear from.

Anyway, your math is exactly what I came up with after reading your article, so because of the extreme angles, I knew something is wrong. The truck is currently on jack stands, level, and at ride height. I read a bunch on s10forum last night and came to the same conclusion as you did: The carrier bearing needs to be moved up and possibly the transmission. As far as I understand, all the connections look like they are single U-joints.

I'm surprised that I've never read about this issue on this site. I always see people notching their cab and assumed those were only people with a one-piece driveshaft. Is there anybody else out there that have a two-piece shaft and slammed? Matt, fyi, there are pics of my truck in a thread called "progress pics" Should be close to the top of the suspension forum.

Thanks for your help. I've never shimmed a tranny before. Any comments or suggestions?

Re: driveshaft and pinion angles
 

I have a 2 piece drive shaft and the first shaft is straight from the trans to the carrier bearning, then the secong shaft has a slight angle down to the rear end. My rear end is square with the back half of the drive line.

I was going to have a solid drive shaft made ($300), but the shop I took it to said there was no need for it since the angles were good and I wasn't running a whole ton of power.

Re: driveshaft and pinion angles
 

By 'run', I mean that I ran the website, updated it, kept it alive, made sure info was up to date, etc, etc. Its not a company just a website. Its not related to AIM either. Its just another website out there that sits with no updates now. Now all the good stuff is in the link in my signature. :)

jlaird: Shimming the tranny is fairly easy, as long as you have the room under the cab for it (which you should). Take a look under the transmission and you can see that it is bolted to a rubber mount, which is then bolted to a crossmember. Normally there will be two bolts holding the tranny to the rubber mount. You simply have to make or buy some shims to go between the tranny and that rubber mount, and you may have to get some longer bolts as well. Don't use washers, as I've seen some other people do. I took some 3/16" steel plate, cut it with the grinder, notched it for the bolts, then put in as many shims (ended up being 3) as I needed to get the angle up.

Re: driveshaft and pinion angles
 

there was a thread going in the 73-87 section.i'm not sure how to insert a link to that thread.i think hiway started it search threads started by him or my threads i chimed in a few times.i had a similar problem . my truck is 79 swb. 5,7 lowered,with 2 peice shaft.that had screwed up angles.had it up on the rack and exhaust guy suggested taking out about 2 inches of length in my carrier bearing bracket above the bearing itself..i'm not sure what yours looks like if thats possible,but he welded it back together.and the first part out of trans is level.and second part at a acceptable angle,works great,no vibes.no shims.although i'm looking into a 1 piece.

Re: driveshaft and pinion angles
 

I worked on the driveshaft angles today. I ended up having to move the carrier bearing a couple inches up. Does anybody see an issue (mechanically) with rotating the carrier bearing 180 degrees so the mounting bracket is on the bottom?

Re: driveshaft and pinion angles
 

thats kinda what i did. reduce total height of bearing holder bracket,it sucked up closer to frame and reduced angles big time.

Re: driveshaft and pinion angles
 

Boatpuller, I was going to cut down the height of the carrier bearing and mount the carrier bearing higher up on the crossmember, but I realized it would be easier to rotate the carrier bearing 180 degrees so the mounting plate is on the bottom and move the bracket to the bottom to hold it up.

What exactly did you do?

Re: driveshaft and pinion angles
 

Any chance you guys can post up some pictures? I'm curious to see what you're working with here. :)

Re: driveshaft and pinion angles
 

here is a pic of what I plan to do. I dont have any pics of the stock setup, but you can tell by the holes in the crossmember where the bracket used to be with the carrier bearing rotated in its original location.

Re: driveshaft and pinion angles
 

yeah,that's kinda what i thought.your series of trucks have a different carrier bearing than 73-87.my driveline doesn't go thru crossmember like that,i don't think what i did will work for you.i'll post a pic and you can see what i mean.

Re: driveshaft and pinion angles
 

Jlaird, that would work.

Re: driveshaft and pinion angles
 

here's what i was trying to explain and couldn't...the perch that the bearing mounts to,used hang down about 2 inches lower than it is now.he welded in a flat plate and bolted bearing to it.works great for 73-87.no shudder at launch and cruise at 80 on interstate no vibration at all,when bearing goes,i'll swap to a single. jlaird,i also think your idea will work.your doing the same thing only different. and if it doesn't.. your not out much,then do a single.

Re: driveshaft and pinion angles
 

thanks guys. Off to the garage!

Re: driveshaft and pinion angles
 

Old post but Thanx Guys ..I think I found my fix!!

Re: driveshaft and pinion angles
 

Thanks for searching! Weird how the search option actually does works huh?

Re: driveshaft and pinion angles
 

yea I went though alot of posts to find it to bad its not a sticky

Re: driveshaft and pinion angles
 

Stickey I doubt, but it could be made into a FAQ article.

Re: driveshaft and pinion angles
 

Kool I'm going to do mine as soon as it stops snowing maybe I can add a pic or two

Re: driveshaft and pinion angles
 

I know this is an old thread and the OP has since resolved their issues but since it's still helping others I'll add my $.02 to it. The important thing with multiple drivelines is to set the true angle (operating angle) of the first universal joint at ~1*-1.5* and since in the OP the trans was down 4* and the first driveline down 8* (4* operating angle as previously stated) the first driveline could be moved up either 3* or 5* (both would give the u-joint a 1* operating angle, up or down doesn't matter) lets say we went up 3* that puts drive shaft # 1 at 5* down (8*-3*=5*) and with the transmission still down 4* it gives us our 1* operating angle on u-joint #1. Now setting the rear end we want to set it up 5* so that the centerlines of drive-shaft #1 (not the transmission) and rear end pinion shaft are both parallel with each other. That makes the operating angles of u-joints 1 & 2 equal which is what I refer to as 0 pinion angle here's a chart on operating angles and life expectancy of u-joints and some goo reading in the link..
http://www2.dana.com/pdf/J3311-1-DSSP.pdf

Re: driveshaft and pinion angles
 

so you are saying that ther could be up to 2* diff from the trans to the axle...so I could split up the bad angle that would result from the trans not going up high enough ( I'm conserned about carb angle by liftting the tailshaft to much)

it would kinda make the drive shaft look like it was flat on the floor and you lifted one end it would bend in the middle until you where at 2* then you could have 2* more on the trans and 2 in the oposite direction on the axle?? or would the axle have to be at 4*

I think I have a brain cramp??

Re: driveshaft and pinion angles
 

It really depends on what your angles are. In the diagram below lets assume that the transmission is sitting down 4* and we want a 1- 1.5* operating angle on u-joint #1 we can set drive-line #1 down either 3-3.5* or 5-5.5* that gives you some flexibility. Lets say we go with 3* down, now in relation to the transmission drive-line #1 is going uphill but thats OK because u-joint #1 now has a 1* operating angle (4*-3*=1*). The rear ends pinion angle needs to be set at 3* up so that its centerline is parallel with drive-line #1's centerline this makes the operating angles of u-joints #2 and 3 equal, this is what will cancel out vibration. To calculate the operating angles of u-joints 2 and 3 subtract the angle from drive-line #1 from the angle of drive-line #2. I hope that makes sense.