shims thick side is pointing forward. I'll see if I have a picture of it.
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LMM: Vibration in rear
- Thread starter buildingup
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Best picture I could find. Shows the shim though. In the next couple weeks I'll look into removing it and seeing if it helps with the angles.
Yeah, remove the shim's and the trac bar on the bottom. If it goes away, those are all jacked up.
The thick side should only be on the forward side on an axle over configuration. With an axle under spring configuration, you have rotated the pinion down. Looks like that arm under the axle was added to help. Someone else is going to have to chime in, I don't know what side of the axle the shackle is on, so I don't know if that Tq arm could also be adding to the angle problem.
The thick side should only be on the forward side on an axle over configuration. With an axle under spring configuration, you have rotated the pinion down. Looks like that arm under the axle was added to help. Someone else is going to have to chime in, I don't know what side of the axle the shackle is on, so I don't know if that Tq arm could also be adding to the angle problem.
Do not know this and can't find a picture for this. Will be back by the truck friday and get this information for you.
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its hard to see the shim unless your talking about the silver block. if your talking about the little plate under it, thats not enough shim to get you at the right angle. what i find odd is the thick side pointed toward the front of the truck. Normally when you lift a truck with springs or a flat block, the pinion is pointed too much toward the ground and your trying to raise it back up. this is why most lift blocks are tapered and the larger side of the taper goes toward the back of the truck.
If you take the shim out based on everything you have given us, your vibration and pinion angle will become worse. you need a thicker shim in there to point that pinion flange down more.
can you get us a few pics of the leaf springs, shackle, and back side of the block as well? i just want to be 100% sure your text is matching what is on the truck. Absolutly no offense to you as im sure you know what your talking about but what makes sense to you dont always make sense to me cause im stuck in 110* heat all day
. pics speak 1000 words :hug:
its hard to see the shim unless your talking about the silver block. if your talking about the little plate under it, thats not enough shim to get you at the right angle. what i find odd is the thick side pointed toward the front of the truck. Normally when you lift a truck with springs or a flat block, the pinion is pointed too much toward the ground and your trying to raise it back up. this is why most lift blocks are tapered and the larger side of the taper goes toward the back of the truck.
If you take the shim out based on everything you have given us, your vibration and pinion angle will become worse. you need a thicker shim in there to point that pinion flange down more.
can you get us a few pics of the leaf springs, shackle, and back side of the block as well? i just want to be 100% sure your text is matching what is on the truck. Absolutly no offense to you as im sure you know what your talking about but what makes sense to you dont always make sense to me cause im stuck in 110* heat all day
Totally understand. I will get done better pictures for you guys. But the shim is just below the block and would say is about 1/8" thick on the forward side of the axle.
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I agree it sounds like you need to get a thicker shim under there to rotate the pinion down some.
See, I don't think the pinion should be rotated down. The carrier was pointed slightly down toward the axle, shouldn't the pinion slightly point toward the carrier then? I'm quite sure the angles need to be close. If the carrier is pointing 10 degrees down, the pinion should point 10 degrees up. The exception is if a double cardon joint is used, then you want the pinion pointing at the cardan.
I'm basing it off of the pictures, which may be deceiving. But it looks like the pinion-driveshaft angle may be dead straight 0° or even a bit more pointed up. I agree that usually when you lift the rear suspension the diff is usually rotated up slightly. But judging by the combo of lift springs/blocks/shims the diff pinion is pointing up way too high.
Basically it looks like the carrier is too low and the pinion is too high. But like I said pictures can be deceiving.
Basically it looks like the carrier is too low and the pinion is too high. But like I said pictures can be deceiving.
You need to leave the carrier out of it and think at the t-case angle and pinion flange angle. the ujoint at the carrier should have 0* between either side of the driveshafts where they connect at that center u-joint at ride height. Ignore the carrier for the time being, the only reason its there is because you can not make a single driveshaft that long as it needs support. if the T-case is tilted with the output shaft down at 5* past a horizontal 90* (which i think is close to stock), the pinion should be pointed 5* up past a horizontal 90*. the total angle of the driveshaft is not a worry unless we are maxing out the angle the u-joints and flanges them selves can take.
Once we get the pinion angle to match the t-case output angle, you can start messing with the carrier drop to get that back centered and correct.
Remember how you were saying a single u-joint at both ends pushes and pulls? thats why its so important the joints are "in phase" and the angles are correct so this push/pull can happen without inadvertanly causing harmonics or oscilation to a certain extent. without that, you get a vib like the OP is describing
it plays a good part in the vibration end of things but if your "base" setup is not correct, nothing after it will fix it if that makes sense
thaaaaaat explains it lol
. spin the shim 180* around. should fix you right up. If your really enthusiastic, take the shim out first, test drive and see how it feels, if still some vib left, put shim in with thick side toward the front of the truck. That should fix the issue. your carrier has a hair too much drop to it but when you twist the pinion flange down it should straighten it up more. i have much more off angle on my carrier bearing than you with no vibs but that will change when i put smaller blocks in the rear this weekend