Rear Driveshaft Opinions

So on the way to work this morning I threw my rear driveshaft. '73 CJ5, T-18 tranny, 2.5" of lift, and no shims on rear axle. I've read a bunch over the months about Tom Woods, etc. and driveshaft angels, but I was wondering what guys are running with this set-up. Should I go ahead and buy steel shims and angle the axle up and run stock U-joints, or should I run a CV set-up and not worry about it? There's a local shop that builds them pretty cheap but I'm indecisive about what I need to run.

 

I am building my jeep now and my rear shaft is going to be real short. How long is your shaft??

 

I had the perches redone for cj7 springs, pinion turned up .....and a cv made .I have a T-18 /texas dana 300 transfercase .roughly 17 1/2" CL of joints. you have a Dana 20/300 ? I think the output is in the same spot. I found a cv driveshaft out of the front (I think) trooper/montero ,cut it and made a spare that will bolt right up.you could hit the j-yard for $20.I paid good money to have the real one fabed the first time .

 

The front driveshaft from a Wagoneer is also suitable material for a CV shaft... you'll have to shorten it of course.

If you want to predict whether your driveshaft will work or not, you need to measure the length and the angles. There is lots of good info on the Tom Woods site about measuring angles and driveshaft geometry: http://www.4xshaft.com/techinfo.html

According to Tom Woods, the CV joint will provide an angle of somewhere between 20 to 30 degrees before binding. Assuming that you use a CV shaft, all of the angularity (at rest) will be at the CV end and the pinion end will be aligned straight-through with the driveshaft.

Some simple geometry. Let the angle be theta, then rise divided by run equals the tangent of theta: y/x = tan(theta). So, let the angle be 20 degrees and the length of the driveshaft be 12", then (set your calcuator to degrees) tan(20)*12 = 4.34" - this is the maximum drop or rise the CV joint can tolerate. Thus the pinion cannot move vertically more than about 9", or the CV joint will bind.

You need to take the same approach with the pinion end of the driveshaft. Measure the excursion and the length, calculate the angle, and see if the joints will tolerate the design. Measure, measure measure. And some simple math.

If you want a really short driveshaft, Tom Woods sells custom high-angle driveshafts that may work in your application. Custom is expensive though. High-Angle Driveline http://www.highangledriveline.com/ is also well regarded.

 

Do you know what year models these shafts will work from???

 

it was the year they looked square ,,,,,like a toaster,ready to tip over .the early years I think. ......... I know they all look like that.

 

Click - Save.
mmm Geometry

 

Front shaft off of a early 90's Explorer is also a good choice.

 

or an xj cherokee

 

I just talked to our knowledeable driveshaft guy, and he is afraid I dont have enough length for a cv. Also I need the yolks on both the axle and t.c. Anyone know where I can find these? If I find a shaft from the vehicles listed about, do they directly bolt up after shortening? and do I need stock yolks?

 

whats your combo again mine is T-18,D300 and reweld perches on centered 44 in a short fender 5. driveshaft is 17 1/2 " running lengh. mine bolted right up with mitsubisi ujoint.stock yokes are used(the pic of one on the floor is the mitsu) ..... you carefully cut the tube at the yoke with grinder and seperate ,cut and weld . you would still need to balance the assembly (i did not balance my spare ) but the one you would run needs it..I don't know about the other drivlines ........ call tom woods www.4xshaft.com ,www.DriveShaftSuperStore.com -------

 

You'll need a CV yoke on the transfer case end.

 

I'm running a T-18, D20, stock axle and currently without rear shims. I'm thinking I might just order one from Tom Woods. This part search is getting ridiculous. I need a front CV yoke, a stock rear yolk, and a driveshaft, along with probably 4-6 degree steel shims to get my rear pinion angled up.

 

The shaft in the last pic just has a ujoint. Why would you need a CV yoke for that???

 

I wish I would have took some pictures of my rear driveline before the fact. When I put the 2.5" spring lift (+ 3/8" shackle) on, the P.O. had installed some pos aluminum shims. I removed those and the angle on the pinion end was not excessive. However, I think the angle on the T.C. end was excessive, as my total running lenth of my driveshaft was 16". I have no idea what the PO completely did, but he installed a Chevy 327, along with a fabbed crossmember. So who knows what was moved back in order for the 327 to fit? I was just interested what others where doing with the T-18 and D20 with a small lift. I know the only thing that could've actually caused me to throw my driveshaft was the fact my T.C. yolk was worn more than I would've liked.

 

wow really,I totally do not agree.driving on the street it might get by,,,,, but wheeling it and drooping the suspension the angle would be bad , I remember feeling the tight spots in the driveline when unloaded . the u joint was over ex-ing.the normal cv cuts the angle a little bit by spliting the angle. they now sell u-joints that just have more angle built into them .I really thought this was a common addition for a short 5.

 

I run a 73 cj5 with a 2 1/2 lift and some conferr longer shackles, t-18 with dana 20 and now a dana 60 rear. When I changed to the bigger rear end I went with a cv joint drive line. What a difference, no more vibrations. I wish I would have done it years ago. I always had issues with the drive line vibrating. Not a lot of room for a drive line in one of these things but still can be done. Had to change trans yoke. I think the whole setup cost about $350. Here are some pictures.

 

with no cv and droop that old set -up would vib bad /with it drooped out it would just lock up and not turn or at least fight turning. I don't think this mod is just for modified rigs .

 

I just did a 3 inch lift on my 74 CJ-5 with the T-18.... had to put a cv driveline in to stop the vibaration. They had to take my old driveline and re-tube it (making it longer). It was a bit pricy though, you might look into other options.