I have a 1990 John Deere 420 I built, and am having some drive line vibrations. Now 90% chance it's the engine off center by a hair, I wanted someone to look into my driveshaft fabrication. I took it to a machine shop where I was told the 1" yoke is too small for their lathes, and they didn't know how they were gonna verify it. They suggested putting it back in the tractor and turning it by hand with a runout gauge, but I'll be damned if I can get the thing secured anywhere on the frame to be able to measure accurately. I've also seen people hold a hammer handle on the top to see how much it vibrates, and any at all is bad.
I'm almost at a loss here, I have no clue how to verify the DS is actually balanced and I can see the highlights at idle to know it doesn't seem to be running true. Anyone ever build one before that can assist? It uses 1" yokes from TSC, 1" solid bar, and the stub shaft from Honda.
I have a 420 and it's little brother 318 that started as fixer uppers.
Not like restoring a 1920 Dusenburg but still quite the journey and worth the trouble. This is my second set of these tractors. A 430 is on the wish list but have not tripped over the right one where the owner didn't think it was worth more than when it was first produced.
Observations:
1: Your offset engine concerns are needless. Driveshaft u-joints work and stay alive by being offset so the little needles will move a bit. If the joints were dead parallel in line the needles just rattle, brinell and die fairly quickly.
2: I will assume you have already replaced the u-joints. The yokes themselves tend to wear to the point that the joint cup itself is no longer a tight fit. The ID of the joint that slides on the shaft also wears, gets sloppy and moves around. That makes a difference. On one I wound up replacing the whole thing to get it right. As mentioned the joint cups should be on the same plane on both ends. (facing the same direction)
3: Have you looked close yet to determine if one of the engine mount feet is cracked or broken? I can attest that will create a vibration that will make you nuts. These are easily repaired by a competent TIG welder. Remove engine, drain oil, clean off well and take it to the welder.
Do not believe for a second that it can be repaired in the chassis. Throwing some weld on top of a crack does nothing but crack again in a short time.
The crack has to be opened up and filled back in with weld filler to be righteous.
4: I have also run across the engine mount bolts not being tight.
5: If you have a rear PTO the little bracket that keeps the pto from rotating in the chassis gets worn. It will create an annoying rattle and vibe.
Bear in mind these things are all solid mounted construction, everywhere. They will never be totally vibe free.
It seems previous owners treat these things like a throwaway push mower.
Maintenance was never spoken of or implemented
I always found that strange as these things were top to high dollar even when they were new.
