Free Horshpowa(well almost)

[Powerstroke Racer]

How many of you have played with pinion angle?

I realize pinion angle is very important for a race vehicle but on a DD it doesn't ever seem to be a point of interest.

Let me tell ya, it should be a very important part of any truck with decent power, I lowered the back on Amanda's truck a few years back and had about 1/2 degree at normal drive height and always noticed a slight vibration when heavy on the throttle but not a big enough vibration to warrant looking into it at depth. Well fast forward, we buy a tongue pull toy hauler (7100lbs empty weight) and I immediately noticed the vibration was constant and power was lacking as compared to when I pull my race truck on the goose neck.
So checking it with the trailer attached netted a positive 2 degrees.

So today I changed it to 5 degrees negative and boy what a surprise, a whole different truck, you can feel a performance gain all the way around. Ideally you want 0 degrees for maximum efficiency but not possible with a leaf spring setup and high horsepower/torque, plans are to drop truck another 2 inches so I should end up with 3 degrees negative at a stand still when all is said and done.

 

[PTSUPERD]

Nice! You have bags?

 

[Powerstroke Racer]

Nice! You have bags?

Nope.

 

[JMart]

When I lowered my truck I didnt adjust the pinion angle. I couldnt get over 80 at all. From 75 + the vibration was pretty bad. After I adjusted it, I dont have any problems. I put a 3 degree shim in to correct my problems.

 

[patrickke]

How much of a drop warrants the need to shim?

 

[cj45lc]

where do you put the shims & where do you get the shims from ?
can you put a pic of the shim in the truck ?

I get the driveline shudder when I've got my gn horse trailer hooked up & I've already greased the slip-joint & replaced 2 bad u-joints. When I hook up the trailer it drops the back of the truck about 1 1/2" so I'm pretty sure it changes the angle enough to cause the shudder.

 

[JMart]

where do you put the shims & where do you get the shims from ?
can you put a pic of the shim in the truck ?

I get the driveline shudder when I've got my gn horse trailer hooked up & I've already greased the slip-joint & replaced 2 bad u-joints. When I hook up the trailer it drops the back of the truck about 1 1/2" so I'm pretty sure it changes the angle enough to cause the shudder.

Here is the ones I used. I think I used a 6 degree now that I look back at the options. They fit in between the axle and the leafs.
http://www.stylintrucks.com/parts/pinion_shim_kits_by_djm/3355.aspx

 

[patrickke]

Jason,
Would just a drop shackle kit warrant the need for these?

 

[Jason]

It's funny, when I lifted my truck it vibrated like crazy, so I shimmer it and got rid of the vibe, I lowered my truck back down and never touched the angle again...no vibe at all, loaded or empty. I forget how much I shimmed it, but it's crazy how what worked for the lift, worked with it being lowered also.

 

[JMart]

Jason,
Would just a drop shackle kit warrant the need for these?

I wouldnt think so, unless you put weight in the bed. IIRC you only come down about an inch with a drop shackle kit. Anymore then that and you would probably need at least a 2 degree. Im no expert just speaking from my experience. When I lowered my truck I went down 5 inches in the suspension plus pull one of the leafs out. With the 6 degree my axle now lines up straight with the drive shaft, instead of putting it in almost a severe bind when I roll on the throttle. Look at your drive line angle and then remember when you roll hard on the throttle the axle will twist upwards creating more tension on the u joint. If you have a good set of traction bars there shouldnt be as much twist, but mine will almost twist enough I thought it might pull the drive shaft out. I was able to watch mine for a little while because I didnt have a bed on it.

 

[Hotrodtractor]

Yep - pinion angle is pretty important and often overlooked - I know I need to shim the axle on my sister's Colorado about 6 degrees since we lifted it - its never had a vibration (that I am aware of...) but it is eating rear u-joints to the tune of about 1 every 15K miles. Maybe I can get that done in the next couple of weeks.

 

[cj45lc]

Here is the ones I used. I think I used a 6 degree now that I look back at the options. They fit in between the axle and the leafs.
http://www.stylintrucks.com/parts/pinion_shim_kits_by_djm/3355.aspx

Thanks Jason, I'm gonna have to look into doing this

 

[patrickke]

Anyone have an idea on how much I will need with just a 2" drop in the rear

 

[patrickke]

Bump

 

[SouthFlstrokin']

Anyone have an idea on how much I will need with just a 2" drop in the rear

Shouldn't need any...

You usually add shims when you drop the truck 4" or more because of the drastic pinion angle change

 

[JMart]

Anyone have an idea on how much I will need with just a 2" drop in the rear

If you aren't getting any drive line vibration then I wouldn't worry about it.

 

[patrickke]

Problem is its not on the truck yet

 

[cj45lc]

I just get the shudder on take off with the trailer on do yall think the 2 deg would be enough ?

 

[Powerstroke Racer]

I just get the shudder on take off with the trailer on do yall think the 2 deg would be enough ?

you have to check to see where it is at now.

 

[AKHILF]

hey guys i dont know much about suspension things. But when i did my 4" lift i put a piece of 2x2 square tube in there to drop the carrier bearing and that got ride of most the shack but I think i still have a little at start off. The tube fixed 75mph and over. What should I do?