Washer Mod Help Needed

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Dec 22, 2015
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Hi all! Looking for some assistance/advice for doing the washer mod on the rear axle of my LJ78 Prado to correct the pinion angle. My rear driveshaft angles are out of whack after an engine swap, transmission modification and lift and are causing bad vibrations and eating the rearmost u-joint. If anyone has done this modification for caster correction and would be willing to lend a hand or give some useful tips on how to go about it that would be fantastic!
 
Joined
Apr 27, 2014
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Hi all! Looking for some assistance/advice for doing the washer mod on the rear axle of my LJ78 Prado to correct the pinion angle. My rear driveshaft angles are out of whack after an engine swap, transmission modification and lift and are causing bad vibrations and eating the rearmost u-joint. If anyone has done this modification for caster correction and would be willing to lend a hand or give some useful tips on how to go about it that would be fantastic!
Never heard of the washer mod but aren't LJ78's set up in the rear with radius arms like an 80 series front is. Couldn't you just buy 80 series castor bushings and install them so that the pinion angle is better? Or some castor plates
 
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Dec 22, 2015
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80-series caster correction bushings would fit, but I need about 5º of correction and I haven't heard good things about the longevity or ride quality of bushings. The washer mod is essentially weld-on caster plates, because of the sway bar mounting points on my rear axle I can't use readily available plates. Here's what I'm working with:
IMG_3853.jpg


IMG_3855.jpg


Basically I need to elongate the hole for the rearmost bushing bolt downward 15.5mm or about 5/8", weld some plates on the sides to beef it up again, and make spacers to move the sway bar brackets out away from the radius arm. Unfortunately all my fabrication tools and facilities are about 300 miles away in the Flathead valley.
 
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I was able to use my landlord's shop over the weekend, and got most of the project knocked out. Correction plates are fabricated and fitted, pinion angle is right where it needs to be now. The vibration is better, but not gone. Does anyone here have experience or tips about diagnosing driveline issues? The vibration starts faintly around 55mph and is worst between 62-70mph. The pinion u-joint has just barely noticeable endplay, the transfer u-joint has none. There is some play in the slip joint too, but I don't know how much is acceptable.
 
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Yes, u-joints are in phase and rotate smoothly. I had the driveshaft shortened by 1.5" due to the engine swap and transmission modifications, and supposedly the driveshaft shop balanced it at the same time. There is some rotational and runout type play in the slip joint spline, the manual specs a maximum of 0.031" of runout in the driveshaft but I don't have a way to measure it.
 
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Driveline Express in Belgrade is the single best driveline shop I have ever experienced. I usually do all my own work but I will gladly drop my junk off at this shop, they are old school awesome. I couldn't recommend them more... I'd drop if off with them and they'll knock it out. I had a u joint going out on the 100 series and pulled the rear shaft and couldn't for the life of me get the old u-joint out, they had it out and pressed in the new one in less than 20 minutes. They charged me $15 for labor and I supplied the new u joint. I am now a customer for life.
 
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Apr 27, 2014
Messages
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Driveline Express in Belgrade is the single best driveline shop I have ever experienced. I usually do all my own work but I will gladly drop my junk off at this shop, they are old school awesome. I couldn't recommend them more... I'd drop if off with them and they'll knock it out. I had a u joint going out on the 100 series and pulled the rear shaft and couldn't for the life of me get the old u-joint out, they had it out and pressed in the new one in less than 20 minutes. They charged me $15 for labor and I supplied the new u joint. I am now a customer for life.
I second this.
 

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