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I Hate My Lift! Can I Lose the Shackles?

2K views 18 replies 10 participants last post by  jonelby90 
#1 ·
I bought this 1990 YJ a few months ago. It was already lifted, converted to a 350sbc/TH350/NP231. I don't really know what springs were installed on it. The shackles look homemade, 7.5" Center of Bolt to Center of Bolt. I would like to lose these shackles and go back to a stock size, or just a 3/4" shackle lift. My worry is the change it is going to make in the rear drive line. No existing SYE has been installed. There is a TC drop of 1 1/2" and the engine is probably as high as it can go. I have already shaved down the air cleaner lid to keep it from rubbing the hood. The rear drive shaft angle looks pretty good right now. The rear axle has been shimmed. Please take a look at these pictures and let me know if I'm ok just putting in shorter shackles, without having to make a drive line change. I am already in turmoil about the drive shaft. It's going to need u-joints and I have no idea what size these are! I have a very mild vibration from the drive train, and I believe it is either the u-joint at the TC end of the shaft or the bit of side play in the TC output cone. I will be rebuilding the TC case very soon. Thank you for your help!
 

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#4 ·
question is, do you have vibes now? and how fast have you had the jeep up to without vibes?

I second Can's choice on 5".

The shims look like 6* or 8* aluminum shims (based on the thickness and that I own, not use, a set of each). dropping to 5" will affect your angle, but it might still be ok (or better) because it looks like your rear pinion is actually pointed higher than needed, but that could be camera trickery with that angle.
 
#5 ·
Thank you for the fast replies! I am ready to get some 5" shackles right now. Your advise will be heeded! I just use the jeep for daily use and some beach fishing. I'm not crawling rocks, just pot holes.

I do have a very slight vibration at about 50MPH. But, as I mentioned, I do have a bit of play in the TC tail cone, and slight play at the u-joint near the TC. I hate not knowing what u-joints these are, so I will probably just pull the shaft and take it somewhere to get fitted with new joints. Then at least I will have a part number for next time. I will be putting new guts in the TC case while the shaft is out.

Yes, the pinion does look higher than may be required. I'm not sure how to approach this yet. I don't know if I can lose the Drop Kit on the Transfer Case, yet. I really don't what to cut the hood, or re-locate the engine mounts. The engine has a Edelbrock RPM Manifold with a 650CFM carb on it, which I hope to keep. I had to install a 3/4" spacer between the carb and manifold to keep the heat from boiling the fuel out of the carb. I offset this gain in height by getting a 2" air cleaner element. I have already "adjusted" the air cleaner lid, so it stops rubbing the hood.

This jeep has everything I wanted. An automatic and a 5.7 liter with some guts, and as rust free as can be. Just all of the dumb little things that were done to it (or not done to it) during the swap, has my wife questioning me, if this was really such a great deal.
 
#6 ·
shorter shackles will rotate the rear diff's pinion down some and that may actually help you.

As for U-joints in the Driveshaft, they are 1310's. Spicers are good, moogs are good, napa golds are good. Cant comment on other brands. Changing a u-joint on a driveshaft isnt hard. If you can replace your own shackles you could do a u-joint. (pliers for snap ring, hammer and socket) driveshaft joints are easier to do than wheel joints.

On those shackles look like they have extra holes, can you bolt your rear spring to the one above, looks like a 1 " difference maybe?
 
#7 ·
You should have bad driveline vibes with that setup. It definitely would kill your u-joints. Your diff pinion angle is up too far. The driveshaft u-joint angles should be complementary to each other; i.e. total driveline should look like a slight 'Z', not a slight 'U' (for non-CV applications). Your angle pics show you measuring the wrong side of the ujoint. Measure the slip yoke side and the axle pinion side. Check out this picture I found that best describes what I am trying to say. http://ww2.justanswer.com/uploads/dt69nova/2011-03-26_210629_pic1.jpg

The pictures of your pinion looks like diagram 4 and that's BAD.

EDIT: Oh and save some bucks and just drill more holes in the shackles closer together and cut off the excess. Wait and buy new shackles a a part of a well thought out lift project later.

-jim
 
#8 ·
Thank you! I have no problem changing the ujoints. My learning curve to over come is finding the correct size. I just started to read up on sizing ujoints. I always thought that there would be a multitude of cap sizes and cross lengths. i never would have guessed that they a rated or sized by With this Jeep, I don't know what or where the drive shaft was sourced from.

But Hey! I found this read: http://www.therangerstation.com/Magazine/summer2008/ujoints.htm

So now I know, Cheers!
 
#9 ·
jimbob78cj said:
You should have bad driveline vibes with that setup. It definitely would kill your u-joints. Your diff pinion angle is up too far. The driveshaft u-joint angles should be complementary to each other; i.e. total driveline should look like a slight 'Z', not a slight 'U' (for non-CV applications). Your angle pics show you measuring the wrong side of the ujoint. Measure the slip yoke side and the axle pinion side. Check out this picture I found that best describes what I am trying to say. http://ww2.justanswer.com/uploads/dt69nova/2011-03-26_210629_pic1.jpg

The pictures of your pinion looks like diagram 4 and that's BAD.

EDIT: Oh and save some bucks and just drill more holes in the shackles closer together and cut off the excess. Wait and buy new shackles a a part of a well thought out lift project later.

-jim
Thank you for that link. I need to get a magnetic angle indicator and try again. My iPhone app works well but my iPhone case is non magnetic. Hmm maybe I'll glue a magnet to the side of the case.

Anyway, I think perhaps my picture makes it look worse that it is. I will take another one in the morning. True enough, the pinion is steep, though the output seems close to parallel. I will check again. The vibration I have is very slight, and doesn't develop until 50ish MPH.
 
#10 ·
1310 is the classification you want. Manufacture part #'s maybe different, but you want a 1310 joint. 1330 is bigger, 1350, bigger yet.

Example:
Moog 280 is a 1310 joint
Spicer 5-153x is a 1310 joint
both fit the same.

you have the stock driveshaft. 1310 is also what your front shaft uses, being easy to change, it's worth picking up an extra.

What jimbob said about your shackles is an excellent idea.
 
#13 ·
Those are aluminum wedge shims
ll either way..they are probably 'lowering' it and inch..... :rofl:

and holy fricking shackles..... I would remove it ALL....shackles, shims, and tcase drop and take it for a drive and see how it drives, my guess is it will be fine.... removing it all will basically bring u back to stock.....unless u hve lift springs in there which it kinda looks like u do, not flat enuff to be stockers.... it will be a trial and error thing
 
#16 ·
If you want to buy a cheap angle grinder from Harbor Freight ($15) and some cutting wheels you could just hack those shackles into what you want. You could also just slip them into that next bolt hole and cut off the excess. No need to order any new parts....

You could also play with removing the transfer case drop or just swap it out with some washers instead. You might need it at all.
 
#18 ·
Thanks again for all of the comments. I didn't get a chance to take a better picture of the angles, but it seems moot anyway. I'm going to order some 5" shackles, tomorrow. I'm not going to expend any time or spend any money farting around with those crappy shackles. I'm also looking at getting a Tom Woods SYE kit. I don't mind spending the money for this, I just keep telling myself I won't get carried away.

Once I have the new shackles in and the wedges pulled out, I will reset the pinion angle and then decide if I should lose the TC drop. I need to check clearance between the top of the TH350 and the floor. I may need to compromise the drop as suggested.

I will post an update soon.
 
#19 ·
giggityjeeper said:
ll either way..they are probably 'lowering' it and inch..... :rofl:

and holy fricking shackles..... I would remove it ALL....shackles, shims, and tcase drop and take it for a drive and see how it drives, my guess is it will be fine.... removing it all will basically bring u back to stock.....unless u hve lift springs in there which it kinda looks like u do, not flat enuff to be stockers.... it will be a trial and error thing
Yeah they must be lift springs. The current measurement to the rocker is 24.5". The crappy shackles only account for 1 1/2" lift.
 
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