Driveshaft...

Okay guys, I gotta figure something out on this driveshaft...

Do you see any way to get around going to a CV shaft? I've done some research at the Tom Woods Driveshaft site, and I don't think it's possible to lower the transfercase enough to match the angle on the pinion... The pinion is shimmed up with an 8* shim in order to keep the u-joints from binding (per recommendation from 4WD Hardware - I didn't actually check to see if it would bind).

I have a line on a CV shaft from a Wagoneer, but by the time I buy it and have it cut down, I'm going to have $100 into it. MUCH cheaper than a new one - I know - but still $100 of the "customer's" money that I don't want to have to spend, if it's not necessary.

What do you guys think? Should I go ahead and get the CV shaft, or should I wait until I can test-drive the Jeep to see what it feels like?

 

Tim, this is the Fairway Green '74 CJ with 258/T18? How much lift was added? I know that the factory 258/T18 CJs with both the standard and HD springs had no more problems with u-joint breakage than the rest of the CJ line. Some of the angle will go away when you put the body on... if it's less than 2" of lift, I'd go ahead and try it. Either that, or tell your customer that this drivetrain combination won't work with that much lift unless some mods are made.

 

Tim : Yes, this is the 258/T18 combo in the CJ5. I've added a 3" Black Diamond lift springs and new shackles which probably give 1/4" to 1/2" of lift.

Good points Lynn. The thought of a phone call like this - "Yeah, the rear driveshaft broke, ripped a hole in the tub, snapped off the pinion, and took out the rear half of the t-case" kinda scares me...

I think the CV shaft will be gone if I don't get it now. At $40, I'll just buy it and if the stock shaft works out, I'll sell the CV later.

 

Not a lot of mass in that driveshaft - if it lets go it will just flop around, make noise, and put some dings in the body. At least, that's been my experience.

 

Be sure you check for binding at full axle drop -- lifting the rear end up doesn't accomplish this necessarily. I don't see any way around a CV shaft with the 3" of lift you mentioned. They do have newer ujoints out there that may give you 1/2 to 1 additional degree on the shaft, but I can say with confidence that you are at or exceeding that level already -- certainly at full drop. A donor CV shaft off of a XJ runs about $10.00 here locally. Chop it (4x4 wire article I did with a friend) to length, tack weld, install, and manually turn and adjust using a dial indicator mounted to the frame and you will be fine for speeds up to 55. If this is a street only Jeep and you want to be sure about it, take it out and get it balanced. But you could build your own for $10.00 and about 1 hour of effort.

But then with a CV shaft, you'll need to pop off the axle spring mounts, tilt the pinion to within a 1/2 degree or so of straight into the tcase output shaft and weld them back on to the new location -- more time -- but a much better setup. Not sure you will get enough angle with the shims.

 

I put a 4" suspension lift on my 1980 cj5 and the drive shaft popped off on me. It didnt exactly stay on I saw it in my rear view mirror. Quadratec makes a fix for it. Its two metal bars that go between the skid plate and the frame, in which lower the transfer case so there is no bind in the rear axle. I did it and it hass been working fine for about 4 months now.

 

this is the deal on my jeep right now. i have a '78 cj-5 frame and am running a 304/t-18/d-20. i also have a 4" suspension lift. i used to have a t-15 and with that trany i had no vibs at all. with the t-18 i now have a little.... but i havent gone under to see what i can do to fix it yet. i have looked at going to a cv as well( actualy doing the excact thing you are talking about with a waggy front shaft) but if you look at the distance the shaft needs to point down it will take up more space then a regular shaft. the double cardan does not have very much "flex"

i am very confident all i need to do is tweak the pinion angle a little, clearence the yolks a little with a di-grinder, and i am looking into the new off-set u-joints on the market. they are advertized to offer another 10* of angle on your shaft.
dont forget, that double cardan is a little weeker with that center pin in it, plus they are a huge pain in the a$$ to work on.

just to add.... the important thing is to have the t-case yolk and the pinion at the same angle, or as close to. so if your tcase is sitting at 2*down, then your pinion should be at 2* up. those numbers are just for compareison and dont represent where you should be.
i will try and crawl under the jeep tonight and get a pic of the shaft and the angle i am running now to show you for comparason, trust me its short and steep right now, but i am not worried about it.

 

heres those pics i offered to take







i dont know if its easy to tell from the pics the angle of the shaft. i hope it helps