Should I shim the rear axle on a reg cab?

*Long post alert* I just want to try and get out as many details as possible that might help diagnose potential problems. This may have been covered somewhere already but can't seem to find a definite answer to this question on the site. Is it necessary or okay to shim the axle on a Regular cab Tacoma with the one piece driveshaft?

Backstory: I didn't necessarily plan to lift my truck, it just sort of happened. I put on my camper shell a few months back and decided it was too level, almost sagging in the rear (I do have the TSB 4 leaf pack) I went with the Deaver AAL and it added almost 2 inches in the rear. It looked kinda goofy, too much rake. While driving around like that I noticed a very slight, not super noticeable vibration at around 55 mph give or take. Decided to shim the rear with the toytec 3 degree shim, I put the skinny end forward towards the front That didn't seem to do anything still slight vibe at 52 to 58ish...well I drove around like that, got tired of how goofy the truck looked so I got me some ucas and 884x front coils. Three weeks after lifting the front end, I started hearing that weird intermittent vibration which I have determined is the front diff needle bearing (goes away in 4hi) and I'm going to get that replaced next. The truck seems to drive pretty smooth but I'm still having that little vibration in the 55 mph ballpark and I'm wondering what it is.

So back to my question(s), do you guys think it's okay to keep that 3 degree shim in? I had a local mechanic as well as an off-road shop tell me that my driveline angles look fine. One shop said the 55 vibe could be the new u-joint angle since my u-joints are now wearing differently. I still have that minor vibration at 55 and then also at any speed above 55 when I let off the gas I hear this noise that sounds like a crosswind or slight grinding, I heard it was something to do with the slip yoke and isn't a big deal. Apparently some guys use a driveshaft spacer to remedy it but mines not that noticeable. Goes away with a couple hundred pound load in the bed. I haven't tried to see what my truck is like without the shim, it was such a pita to do the aal, then go back later and redo it all to add the shim. Should I try it without or just leave it be? Like I said truck is smooth other than that 55 mph vibe and the coasting noise.

Sorry if that's too much/unnecessary information. Just want to get some opinions or advice on if I need the shim or if it could end up being a detriment in the long run. The slight vibes I have don't bother me too much just want to make sure it's not a big deal using the shim or not. Thanks in advance!

 

This is what happened to most of us on here, you've come to the right place

I just put a 2.5˚ (maybe it was 3...can't recall) shim under my leaf packs a few months back, helped get rid of some driveline vibes I've had for awhile. I think it's a good idea if you lift the rear of the truck, even if you don't necessarily feel any difference. Lifting the rear changes the driveline angle and the shim helps correct it, can't really go wrong with that.

 

You could always just do this!



I'm of no help

 

You're telling me, I got bit by the bug, hard! Lol

Yeah the shim doesn't seem to be causing any trouble. I have read some very technical posts on here about how you should make sure not to screw up front and rear driveshaft angles. In a perfect world I guess they should cancel each other out. It does appear from just eyeballing my driveshaft, that the pinion/diff angle is a little more straight, while the transfer case angle is slightly steeper.

 

What finally convinced me to do it (probably later than I should have) was when I started noticing some gear oil weeping from the pinion flange on the rear diff, presumably from the sharper angle caused by my lift over time. Not enough to be considered a "leak" but eventually it will be, there's a seal in there that can wear out faster.

 

Good to know. It's definitely more inline now. It's less noticeable in my picture but Top is before. Bottom is after. Both of these are before I lifted the front end.

 

Wot in tarnation hillbilly hell is that abomination

 

I like it.

S runner dually, thats bad ass.

 

My truck has add-a-leafs and shims, but I'm not sure what degree they are. I will get a vibration from 64-70 mph once in a while but since I do very little highway driving, I haven't really looked into it. Most of my driving is under 50 mph and there is no vibe in that range. I still need to replace the needle bearing up front but that gives me the rumble strip effect around 20 mph so it's a separate issue.

Have you tried greasing the u-joints to see if it helps?

 

Very nice looking rig right there ^ yeah I have greased the u-joints since all this. I'm pretty good about keeping em lubed up. My truck is completely smooth everywhere above 60 mph it's like only between 52 to 58ish somewhere in there. And really it's not even much of a vibe but I notice it. Just harmonics are off or something. But yes I have the same rumblestrip vibes from the needle bearing but mine are like 30 to 45 maybe a little at 50. And that usually goes away once the truck warms up enough.

 

Do the needle bearing and see where you're at

 

Definitely. I don't know if that's what my 55 vibration is since it's been doing that since the aal but stranger things have happened. Before I got new tires my current ones were badly cupped and it sounded like a "wop wop wop" going down the road, they were loud! Also had a wheel bearing go out after getting stuck in the mud. I always assume its something worse than it is...