I Might Just Know What I'm Talking About
Join Date: Sep 1999
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Re: \' 90 YJ rear CV type drive shaft
There are a few questions that can get asked here, and some more research you can do.
1) Do you get a vibration in the rear driveshaft now with the longer shackles? The rear driveline in a YJ is sensitive to even small changes as the driveshaft is so short. If you do have a vibration, it will eat ujoints more rapidly. Sometimes a slight transfer case drop (some washer spacers) or an angle shim in the rear is required to get the angles just right, even with a lift as small as you get with a longer rear shackle. Remember you are rotating the axle some when you lift with longer shackles, throwing off the angles. This is one of the problems with a shackle lift -- if you need an angle shim, you'll lose almost all of what you gained lifting it with shackles. [img]images/graemlins/crazy.gif[/img]
2) Do you have heavy-duty ujoints? There are a lot of different quality ujoints. I prefer the ones with the grease zerk fitting in the end of one of the caps. It is a stronger body without the additional zerk hole at the cross.
3) If you go with standard ujoints with the zerk fitting in the body at the cross, you should be installing this fitting in COMPRESSION rather than in TENSION for the greatest strength.
4) When you go to a CV (or double-cardan 'DC' shaft, whichever you want to call it) you can investigate using an XJ front shaft as a rear shaft. Just have it cut down (and rebalanced if you choose to). Unless you're using a lot of motor, this driveshaft should hold up for you. Many people are using this. I got mine for I think it was $35 each, shortened and balanced for about $75 each, so I've got a shaft and a spare for about $200. No doubt Tom Woods, etc., make a great product if you've got the $, but I don't. I've also heard that the manual tranny XJ shafts have a larger tube (stronger) than the auto tranny shafts. Not sure on that one. I think mine were auto tranny shafts.