Vibration when using the go pedal
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Stopped at two different shops today. Both said it would be a minimum 2 hour charge to mill the blocks. Since it's a small job and they normally do bigger (quantity) jobs. That puts the cost just below new blocks.
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Right now my blocks measure 6 3/4" in the front and 6 1/2 in the back. After talking with the machine shops. I called pmf suspension about their lift blocks. Let them not what I had going on and they recommended a block with 2.5 degree taper.
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Went on vacation, but while gone I went ahead and ordered the PMF lift blocks. Got those installed over the weekend and still having the same vibration. Comes in around 35-40 and continues (comes in sooner if hard on the pedal) until til around 70-75 before calming down but just not as noticeable. When ordering from PMF I talked with him about what was happening and he recommended the 2.5 degree lift blocks. So I ordered 6.5" lift blocks with the 2.5 degree taper. Lift block height is 6 3/8 in the front and 6 5/8 in the rear. Since installing I have been trying different spacing for the carrier bearing as he said I would have to adjust that. Any changes in the spacing have not made any real difference. Currently have it spaced at 2". With that spacing I have the following angles T/C 7.2 Slip Yoke 10.1 and Rear Pinion 8.9. The front driveshaft angle is 10.2 and rear driveshaft is 6.9. Also what is the correct rear u-bolt torque? The info I found said 150ft lbs. Is this correct?
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Joined: Dec 2003
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From: Foothills of NC
The slip yoke angle you originally had was where it should be. The block you bought is not at the right angle. You are still off more than enough to have bad vibes with the new setup. That's why I suggested to have the old block machined to the correct angle instead of buying one. A guy on the phone who has not analyzed your angles with the old block will not know what block you need to buy.
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I can go back easily enough on the carrier spacing to get that angle back. I went with the new blocks since the shops in town wanted more then what the new ones cost. I guess trying to save money backfired on this one. But now with the blocks out I will take them in and see what they say. Before I was just describing to them.
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Looks like I need to remove .388 off the thick end of the old lift block to get the 3.7 degrees over the run of the lift block. Will stop and talk to a shop hopefully tomorrow about what they might be able to do. Wonder if a chop saw would work?
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Got the blocks cut down and installed. Still have a slight vibration mainly now between 50-70 mph. My angles measure at T/C 7.2 1ST SHAFT 8.3 SLIP JOINT 8.3 2ND SHAFT 8.7 REAR PINION 6.4. If these number are where you were thinking they should be please let me know and I will pull the driveshaft back out and take it back to the shop and have them recheck the balance. I have noticed on the shaft where they used a punch to mark the flanges and also the slip yoke. The slip yoke marks do not line up. But they did have the wax crayon marks on the driveshaft and those were in line with each other.
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Joined: Dec 2003
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From: Foothills of NC
What are you referring to when you say T/C?
If I'm seeing what I think, the carrier bearing should come up until there is between 1/2 to less than 1 degree difference in that yoke and the transmission yoke, with the carrier yoke being lower. 7.7 deg would be best.
By second shaft, I'm assuming you are speaking of the angle of the drive shaft.
The rear pinion is a little too low, enough to make some vibes, but, if you get the carrier yoke up to 7.5 to 7.7, the rear axle yoke will then be within tolerance. Basically, get the carrier yoke within 1/2 degree of the transmission yoke.
If I'm seeing what I think, the carrier bearing should come up until there is between 1/2 to less than 1 degree difference in that yoke and the transmission yoke, with the carrier yoke being lower. 7.7 deg would be best.
By second shaft, I'm assuming you are speaking of the angle of the drive shaft.
The rear pinion is a little too low, enough to make some vibes, but, if you get the carrier yoke up to 7.5 to 7.7, the rear axle yoke will then be within tolerance. Basically, get the carrier yoke within 1/2 degree of the transmission yoke.