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SYE & Rear Driveshaft Suggestions

2K views 50 replies 12 participants last post by  cyoos 
#1 · (Edited)
Hey guys, I'm new around here, and I just acquired an '88 YJ as a project. The previous owner put as small lift - if I remember right he said 2" but I don't know that for a fact. I've only had it for about a week and yesterday the driveshaft broke so I'm assuming he didn't replace it when adding the lift. It completely departed the vehicle on the freeway, shearing just aft of the transfer case and also breaking at the UV joint entering the rear differential.

I have spent the last several hours trying to research what to repair it with, but frankly I wasn't anticipating this so early in the game, and am not all that well informed on what brands are good what's not so good. This is typically something I would really take my time to research, but given that it's completely out of commission at the moment, I'm up against the clock. I don't want to simply go with the cheapest option, but I am trying hard to come out under $300. Definitely under $500. I was hoping some people might have some suggestions to get me looking in the right places. Any help is greatly appreciated. Thanks.
 
#2 ·
If you do an SYE, you will need to relocate the pinion angle. Either by using a lot of shims, about 15* worth, or move the rear spring perches, this is the best way but does require a welder.

$300..is a hack 'n tap sye and a cut down used driveshaft.
$500 would get an Advance Adapters SYE and a nice new drive shaft.
 
#9 ·
Using shims for that big an angle change is like duct taping two ladders end to end to get yourself higher up for something. Find a welder. Do it right.

You could bolt the whole thing together with everything right and the new perches not welded. Then drive to a nearby welder person (shop or buddy) driving like there is a raw egg taped to the gas and brake pedals. It doesn't take much welding to secure the perch to the axle, can probably be done as is when you get there. Mark a line on the perch and axle before you leave, so you can verify no rotation on the trip, or can put it back if it does rotate a bit.
 
#4 ·
Or, my understanding was that if a lift was installed you pretty much had to upgrade the driveshaft or it would ultimately cause high vibs and fail, but in doing some research I saw a different thread where the poster was putting on a 4" lift and some of the people responding were saying it really wasn't necessary for that size lift if he wasn't doing any crazy off roading. I do plan to do some off roading but nothing insane in the short run, and maybe more in the future after I've had some time and money to invest in further upgrades. Right now I'm just trying to work out the basic kinks. What are your thoughts on just going with OEM? Would it hold up or would I be looking at another sheared driveshaft within a year or two? I mean obviously the upgrade is the best option, but I'm just trying to determine if this is an acceptable, less expensive, less involved, middle ground that will get my by, because ultimately I'd like to go with a more aggressive lift later anyway. So, regardless of what solution I end up implementing, it's like to be replaced in a few years anyhow.
 
#5 ·
A lift usually requires some shims on the leaf spring pack. If they aren't there, then the PO screwed up. The angle has to be right. the best way to get it up and running right now, is to get a used stock driveshaft, and make sure the angle is correct. Also you can get a transfer case drop to help with angle

Then save your money, and do an SYE, double cardan driveshaft, and an 8.8 differential all at once. And then you can get rid of the TC drop, shims.

Done
 
#11 ·
I'm really leaning towards this option, get it up and running again with grand plans for the future. And that way I'm not continually doing and redoing the same job. In the mean time though I really need to know how to determine what angle is needed and what angle I currently have. Also, what are guys using for shims if it turns out I need some? I figure that would be easier than lowering the transfer case.
 
#6 ·
#10 ·
for the shaft portion of your mini project:

to save considerable money and still obtain a solid enough shaft, check out your craigslist or local junkyards for an XJ part out. Grab the front drive shaft and double cardan joint. Get your measurements and bring it into a local driveshaft shop for cut and balance.
 
#12 ·
A TC drop isn't that hard. All you need is a floor jack, preferably a tranny jack, and a socket wrench. Of course the difficulty can rise, depending on what part of the country you're in. If you live in the rust belt, it can be a lot harder. Mine came with a TC drop. It took me maybe an hour to remove it.

For shims, first you have to get the frame on jack stands in the rear, and the diff on stands. Then remove the u-bolts. Install the shims, then replace the u-bolts. You're not supposed to re use u-bolts, because they get stretched and become weaker the second time.

There's lots of threads on here to get the pinion angle right. Just make sure you have the correct thread for your particular setup.
 
#14 ·
I apologize for the fact neither of these images are right side up, I tried uploading them multiple times and they would upload sideways and upside down but never right side up. I ran out of ****s to give and just left them as is because you can still see what's I'm attempting to show just fine.

I have been looking into angles and from what I've seen the max you really want to go is 7° but for such a short distance I don't know how anyone does 7° or less. So, it looks to me like I need to lower the transfer case. I am just looking to have a few people with experience doing this tell me I'm not screwing it all up and my assessment is correct. One photo is the current state of affairs, the other I used a level to show what the approximate angle would be if the driveshaft were present. I used a square and estimated it's currently at approximately 20°. Thoughts?
 

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#17 ·
Sorry to see that you flipped your Jeep. But it sure makes it easier to check your pinion angle.:D

I'm not an expert, but I believe that diff and the TC should point straight at each other. Or they should be at equal angles to each other, as close to straight as you can get them If you did a Motor mount lift and a TC drop, you maybe getting close. But it's hard to visualize upside down.

I've had issues with upside down pics myself, but I think I figured it out with my cell phone. If you have the phone in landscape position with the click button near you right hand all the pics will be right side up. This is counter intuitive to me, because I'm left handed. I have a DSLR that I normally take pictures with. But I don't always have it.

Not sure of the angle, but this is mine.
(no tc drop, no shims)
But you have a double cardon drive shaft, which changes everything.

Here is my set up, with an SYE and double cardon driveshaft.

 
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#16 ·
As I'm continuing to research this job, it looks like what's remaining on the transfer case side is the output shaft but it's sheared. Meaning I will need to remove the transfer case in order to replace the output shaft. I'm having trouble confirming this though because the only videos I can find are people installing SYEs. Anyone care to throw in their $0.02 based on my pictures uploaded above? Thanks.
 
#18 ·
I believe that the output shaft is replaced when installing an SYE. And it may come with the kit. May be a good time to go for it all. You can always replace the diff later.
 
#19 · (Edited)
Yeah the main thing was trying to avoid the welding, which I don't have access to and frankly wouldn't want to do on such a critical component. Nor do I know anyone who's a professional welder. Also, the ultimate plan was to install a more aggressive lift which would require yet another drive shaft.

So I figured I'd go the inexpensive route now and the more expensive route when I'm getting the "permanent" stuff later.
 
#21 ·
What I see in your pic is a broken drive shaft. It looks like the transfer case is intact.
Grab that thing coming out of the tail of the tc and pull on it. It should just slide right out.(have an oil catch under it as the tc will drain.)

(The output shaft is inside the tc, you would not see it without some disassembly, it is inside that tailcone, which is whole in your pic.)
 
#22 ·
You were correct. I really appreciate your help. I know my way around vehicles okay but this is and will be my first time doing a lot of this style stuff. I was under the impression the output shaft protruded from the back of the transfer case.
 

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#24 ·
I think it's doable in the $300 range. I think the JB Conversions SYE mentioned above is the best on the market, second would be Advanced Adapters everything else is an AA clone.

Pull the front drive shaft from a Cherokee for $20-$25 from a pick-n-pull and get it cut down to the proper length at a local driveline shop for about $60.

I have a JB Conversions SYE I won't be using anymore, PM me if you're interested.
 
#25 ·
Did you get the Atlas in already?
 
#27 ·
Go with the drive shaft with the TC drop for now. it's not a big cost.
 
#29 ·
Anyone know where to get a new stock shaft? All the standard auto parts places are wanting ~$800 which is crazy. I would really like to have the part by Friday so I can do the work this weekend. I've been thinking of just going to a junkyard but am always a little hesitant to buy used auto parts.
 
#30 ·
There's nothing wrong with used parts, as long as you make sure they're i good shape. After all, it's only temporary right?
 
#34 ·
I ask because as you can see this lift isn't more than a couple inches. But the current driveshaft angle is approaching 25º. If I measure from 1 inch down as if I were to add a 1 inch drop it's still nearly 20º and if I measure from 2" down it's at almost 15º. That's a lot of angle and surely guys aren't dropping the TC more than 2"?
 

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