The only thing not mentioned that I can think of is check the pinion angle. If you recently installed a new housing there is a chance the pinon angle was not checked, its very possible that the spring perches are angled different from the original housing. If the pinon angle is wrong it needs to me shimmed with wedges to correct it.

 

Thanks for the reply. Well I would expect a company like Currie to know what they were doing with building a 9". I talked to a couple different builders and told them stock everything but I guess it could still be possibility. What is stock pinion angle and where do I need to measure it from?

 

Learned something new today!

 

If you don't understand I suggest reading this...

Drive Line Specialist

 

Nice. Sounds like could definitely be a possibility according to the article. It stated more vibration under acceleration (pinion tipping up) a less under coasting. Ours is just the opposite; more under coasting (pinion tipping down). I'll check it. Thanks.

 

So not much of an update really. I had CalTracs build us a kit for the truck which should help us with initial off the line traction. But I know I need to measure the pinion angle before I get the kit installed. I originally thought I could use the kit to dial in some pinion angle and John at CalTracs said that wasn't at all what the kit was for. Then he informed me that I should be looking for about 2° negative pinion angle.

Is that what most trucks are running for appropriate pinion angle for 2wd?

 

I had two experiences of such. The first case was a case of improper balance and a bent wheel (it was the spare tire) The second was a little more serious, a bent driveshaft. In that case, the previous owner's kid like to jackrabbit start and hot rod it, pop the clutch, etc. Of course I didn't know about this until after I bought the truck. After a junkyard replacement, it was fine.

 

If the vibration only starts at 45 and is not at lower speeds, then it should not be your pinion angle. A pinion angle vibration would be detected at all speeds. It is still a good idea to make sure your pinion angle is set correctly. Do a google search for "pinion angle" and select the images link for it. You will get all kinds of pictures showing how to set it up based on the type of drive-shaft you are running.

In order to find a vibration, I always recommend removing the front drive-shaft and go for a drive, if the vibration is gone, then it is located in the front end somewhere, if its not gone, then re-install the front drive-shaft and remove the rear drive-shaft and go for a drive. If the vibration is gone then it is located in the rear.

Once you know where the vibration is located, start looking for worn, bent, broken components. Usual suspects are: u-joints, drive-shafts, axle shafts, bushings, bearings.

If the vibration remains when the front drive-shaft is removed and also when the rear drive-shaft is removed then you need to look at the transfer case, transmission, their respective mounts, tires, rims, etc.

I know this was long, but the basics are to remove the drives-hafts one at a time to determine if the vibration is in the front or back. Do that and then let us know the results.

 

That sounds like a great idea except if I remove the driveshaft, the truck won't move. It's a 2wd.

 

So I found this. I think it's pretty telling.

 

That's what I get for assuming you had a 4 wheel drive.

Time to start checking for loose, bent, or broken components.

 

No harm done. I appreciate you taking the time to write the post. The ideas that I have are the pinion being at the wrong angle, a bent axle flange, a worn transmission mount or a worn tail-shaft bearing in the trans.

 

This has been on my mind lately for some reason but I haven't had a chance to get under there and check the angles with the truck being at my dads. So when I do get a chance to do some angle measuring, what are the angles at the pinion flange and trans output shaft am I looking for?


The tech at CalTracs said I should be shooting for 2° negative on the rear end pinion flange. Does this sound like the most common measurement?

 

Yes...1 - 3 degrees down-angle is about right, presupposing the trans output shaft is close to the same and in phase. You could try flipping the driveshaft 180 degrees to see if the vibration goes away...