Dakars and axle wrap...

Does anyone with Dakars on a second Gen experience any, or less than stock, axle wrap? I've got a 2" AAL and am getting a shudder when accelerating from a stop. I was hoping a Dakar leaf pack would help this by lessening the pinion rotation which causes the shudder.

 

Haven't noticed it with mine

 

X2, but I have a lot of other vibes...so once I get those to go away I'll make another assessment

 

I have it. Just put on the full ome with dakars 2 weeks ago. I'm looking to get under there this week and check all of the angles. It is annoying but after yesterday's excursion it has lessened some. Got vibes from around 20-25 mph and again around 50-65 mph.

 

Vibes and axle wrap are two different things

The OP was asking about axle wrap , do you feel that sensation ?

 

Yeah from a stop I get what he was describing, plus the vibez

 

Check the torque on the U bolts

 

Not enough???

We didn't have a torque wrench.

 

Yeah. Axel wrap has a thump, not a vibration.

 

The FSM , Chiltons , Haynes all have a typo stating the U bolt torque at 37 ftlbs , they should be at 90 - 100 IIRC

 

This ^^

it feels like the rear end catches up to the rest of the truck a bit late , resulting in a bump feeling

 

I'll check it out. I know we tightened the hell out of them because we had heard that 37lbs was in the book also. And thought that was way too low

 

I just thought I'd throw this out there. I had a ton of misc vibrations and the take off shudder with my 2" aal and i finally got it corrected with a 3 degree shim and a few washers to lower the carrier bearing. After the springs settled a little i got worse take off shudder and the 60mph vibration went away completely. I removed the washers from the carrier bearing and the take off shudder got much better. I was never happy with my aal and I finally shelled out the 400 for Allpro standard leaf pack, best 400 I ever spent!!! Installed the leaf packs with no shims or cb drop and they ride excellent! Best part...zero vibes! I think the allpro springs moving the axle back 1" helped the vibe by decreasing the angle because its extended. It also eliminated the take off shudder almost completely, very very slight under hard acceleration. Seriously ditch the aal and you'll never regret it! I am so pissed that it took me a year to get a good leaf pack. Sorry for the rant, but get a good pack and be done with it. My .02

 

the take off shudder (Axle Wrap) is from the weak rear springs. Your pinion angle should be a negative measurement because the rear end torques upward under power. Its very hard to get everything right with the crappy toyota spring pack. Many tacomas have the shudder straight off the lot brand new!

 

The shudder that I'm experiencing from axle wrap is caused by the rear pinion rotating up too much under acceleration from a stop. This is when the most torque is applied to it. The diff pinion should be equal and opposite of the transfer case pinion. When it rotates up too much, the angle of the pinion becomes off enough, in relation to the TC pinion, that the shaft vibrates at the rubber donut that Toyota calls a carrier bearing. Even if you use axle shims to compensate for the rotation it still doesn't help. I've also found that in 4WD I don't get any shudder,and no this isn't the front diff bearing issue that people are having. I've got that to and am installing a new ECGS bushing soon to fix that issue. When in 4WD, less torque is applied to the rear which means less pinion rotation resulting in no shudder. The thunk people are experiencing is also a common symptom of axle wrap but generally due to under torqued u bolts on our trucks.

 

This is exactly what I'm thinking...

 

Takeoff shudder is typically an angry Carrier Bearing in the driveshaft, usually too high in lifted trucks.

An easy way to diagnose this is spend $3 or $4 at Lowes for 10 or so grade 8 washers. Shim the carrier bearing down 1/4". See if the vibe lessens. If so, shim another 1/4" and see what happens. I got rid of 90% of my shudder with 1/4" shimming. A one piece drive shaft got rid of all of it.

Axle wrap (which I also have thanks to these shit springs Toyota uses) is a definitive bump in the ass, usually after coming to a complete stop. Spring clamps help. Stiffer leaf packs help. The golden fix is a traction bar.

A way you can baby your truck a bit on axle wrap is to slow to about 5 or 6 mph then briefly come off the brake completely at a slow roll. This will release the driveline to rotate back into position with minimal driveline torque on it. You may still feel a small thump, but less severe. From this slow roll to a complete stop, feather the brake pedal, on and off a couple times, to continue slowing the truck while letting the rear axle gently re-align.

 

The carrier gets angry if you don't have the first and second shaft equal (within a degree of each other) which I do have by shimming, or the diff pinion and transfer case output pinion are not equal and opposite. I feel the soft stock springs are causing the latter and creating a shudder.

 

3º shims added to axle last night. Shudder is barely noticeable @ 4-7MPH and no vibration.

 

I eliminated 90% of the axel wrap thump by clamping the leafs exactly 1.25 inches in front of the axle. The added bonus was firmer rear suspension which helped with body roll and overall ride quality. Might also help load carrying too but I have not tested that yet.