Need info on axle shims....have never used any

[RSchwarzli]

After I did the new springs on the 1990 (lifted about 2"), I have had a vibration. The vibration mostly goes away when I have a fair bit of trailer tongue wait. This tells me it is driveline angle.



Due to also having a gear Vendors ont he back of the getrag, and being the red cab, the driveshaft is fairly short.



How much would I need to angle the pinion up? Who makes good axle shims? What do I need to know about this?



Thanks!

 

[ZedMikey]

For driveshafts with two u-joints, theoretically, the pinion of the axle should be parallel to the output of the, in your case, gear splitter. This is supposed to make the motions of the u-joints effectively cancel each other out.

So, the techincal answer is measure your splitter output angle and pinion input angle and shim the axle accordingly.

Oh, that's assuming you don't have a carrier bearing. If you do, measure the angle of the carrier bearing and the pinion and shim the axle to make them match as closely as possible.

 

[JLEONARD]

This is supposed to make the motions of the u-joints effectively cancel each other out.

Yes this is true. However the larger the angles are, the greater the change in load on the ujoints as it rotates. Each axis accelerates and decellerates as it rotates. This creats a sinewave and if perfectly "in phase" the two ujoints will cancel out and there will be zero effect.



If the ujoint angles are different they will be out of phase which sounds like what you have when unloaded, and adding weight in the back makes the angles closer to being the same.



So different angles and steeper angles are both working against you here.

 

[cerberusiam]

Yep, shim the rear axle to get the angles to match. If that cures the vibration your good. Otherwise you have 2 options: bye-bye gear vendors, custom double cardan joints at each end of the DS.



There is a limit to shim the rear axle and you loose lube to the R&P but don't think you are high enough yet to worry about that.



Lift plus gear vendors plus regular cab equals drive line angle problems. Not as bad as Durango with 16" of lift but its getting close.

 

[ZedMikey]

Yep, shim the rear axle to get the angles to match. If that cures the vibration your good. Otherwise you have 2 options: bye-bye gear vendors, custom double cardan joints at each end of the DS.

There is a limit to shim the rear axle and you loose lube to the R&P but don't think you are high enough yet to worry about that.

Lift plus gear vendors plus regular cab equals drive line angle problems. Not as bad as Durango with 16" of lift but its getting close.

You'd really only need a double-cardan on the splitter side, then shim the axle to make the angle of the pinion match the angle of the driveshaft itself, i. e. point it up to minimize the angle of the single-cardan joint.

 

[ENafziger]

The best thing to do at this point would be to get the crew cab going. With the longer wheel base of the crew, you'll likely not have driveshaft issues. Put the '90 on the backburner, and research shims thoroughly first. The crew and rest of TDR will thank you.

But, just to try to be helpful, these guys make custom shims: 4Crawler Offroad Products - Custom Leaf Spring Shims

Or Pro-comp and others sell set degree shims... i. e. 2. 5°, 3­°, etc.

Or you can cut your leaf spring perches loose, rotate the pinion where you want it, and reweld the perches... thus, no shims involved.

Or, some people utilize an old leaf spring that has a tapered design at the end of the leaf. Simply cut a 4" section off the end of the leaf, drill a hole for the centering pin, and bolt it up.

Beware, some of the cheap shims are made out of aluminum. I wouldn't go that route.

There's also a variety here, but I don't care for this company for a variety of unspoken reasons... Leaf Spring Axle Shim

Summit Racing also carries a few: Rancho Leaf Spring Shims - SummitRacing.com

Or, here's a higher priced option: Degreed Axle Shims

Now, go think about this as you're working on the crew

--Eric

 

[DVolk]

If you lifted the truck did you check your front drive line ? my guess your CV is

hitting slightly ive had to grind the bosses of the cv to correct the issue and get it to a better work ible angle .

 

[RSchwarzli]

Thanks for all of the thoughts guys! That is great. I have a better understanding now.



And a few thoughts...

you have 2 options: bye-bye gear vendors,

That is not going to happen anytime soon so lets see whats behind door 2... .

Not as bad as Durango with 16" of lift but its getting close.

Oh I have got to hear this! :-laf

The best thing to do at this point would be to get the crew cab going. With the longer wheel base of the crew, you'll likely not have driveshaft issues. Put the '90 on the backburner, and research shims thoroughly first. The crew and rest of TDR will thank you.

And you. What to say other than I almost fell off my chair laughing so hard!:-laf



Yes, I suppose that is an option. Guess you wont like the comment on my shimming would be done in the very near future when I NV5600 the truck!



The getrag is slowly dying so..... And yes that will set me bck a few weeks on the crew and will also use up some of the funds that could have gone into the crew...



In saying that, the rear drivehsaft is going on another diet so the angle will be much worse! :{

If you lifted the truck did you check your front drive line ? my guess your CV is

hitting slightly ive had to grind the bosses of the cv to correct the issue and get it to a better work ible angle .

Very good thought. Will check into that. But I guess when I put the 5600 in and it gains 6", that would also help.....

 

[cerberusiam]

What??? And thought you had drive shaft problems!!



#ad






My eyes are bleeding... ... ...

 

[RSchwarzli]

On my god!

What actually happens here? Do you wake up one morning and say I just got this great idea for our car honey! It will done make us look purdy good compared to the neighbors new quad...

Or do you smack tour head off a post and this is what comes of it?

Like really! Wow.


Wonder if he is popular on the intrepid forums...

 

[cerberusiam]

Just a guess, but, have you seen Swamp People on A&E... ... ...



Now, if it was me I would have a light bar with 4 big KC's up there on the luggage rack. I wanna SEE what I am running over.



A welder and too much time on their hands does result in some innovative solutions. :-laf

 

[RSchwarzli]

Aaaaaahahahahahahaha.

Omg you are funny. I wanna see what I am running over... . :-laf