dilljeepo

Hey guys, I made a bit of a bastard pack on Thursday with two old cherokee leaf packs and my own. All I did was swap out the smallest leaf and added in the second longest leaf (so 5 all together).

I know this will result in sag and some people are against putting in AAL's but I got the two packs from a dude for $50 and it raised my rear end for now so I'm happy.

So anyway, now when I'm in fourth gear accelerating to around 100 km/h theres more vibration than there used to be and there's also a very quick to pass noise. The noise SEEMS to come from before the transmission, but I kinda think it's coming from the driveshaft after tranny. The rear end was only raised about... two or three inches, maybe a bit more, but remember it was sagging before so it might only be an extra inch and a half or so on the normal ride height.

The noise sort of sounds like a low grumbling/gurgling noise accompanied with some vibrations, more so than is normal at highway speeds (when leaf's were sagging I got NO vibes at highway speeds). So now I'm wondering what the noise is coming from and why there are such vibrations at highway speeds, I torqued everything, the steering wheel is right where it should be on the highway. The only thing I can think is that maybe the driveshaft angle changing after so many years of sagging leaf springs has affected U-joints? IDK, any input?

1tonxj

might be pinion angle ,but what shape are your u-joints in and your trans mount ?

SlackJaw

sorta off topic, but not really...i'm looking to redo my stock leaf springs as well...quick question...
?
how did you figure out which leafs to add/or replace? Did you reuse the u-bolts and other hardware? Any issues removing the front bolt for the leaf spring?

thanks.

1tonxj

How much lift you looking to get ?

SlackJaw

mines stock...it's sagging / flattened (no more arch in the leaf spring)

should i just do a bastard pack and add some coil spacers up front to do a ~2" BB?

Aaron N.S.

sounds like your pinion and trans aren't in sync anymore. did the AAL point your pinion up or down compared to before? did you remove the driveshaft when you did the swap, get the driveline out of Phase?

jeepxj19

Id check ur ujoints in the driveshaft, it would help to kno how much lift u got, so u can figure out, other solutions. more then likely a simple tcase drop or shims should correct the problem. did u lift the front at all? If u did make sure u go get an alignment.

jeepxj19

there would be no reason to touch the driveshaft when installing a lift, even doing so removing it and the reinstalling it would have no effect, and not cause and vibs or noise

Aaron N.S.

if it was removed and reinstalled 90* off the ujoints would be out of phase and cause a viberation

jeepxj19

i rlly dont understand how that would happen. And again why would he even of touchd the drifeshaft to install leafs?

dilljeepo

Take your leaf packs apart and see which ones lost arc and which ones still have arc, if you can't see a difference than put them on the ground inverted and stand on them, measure their distance off the ground with your weight on them. Ones with more springs I put back in, and then I added another leaf, I added the second longest leaf from my bought packs. Used old U-bolts, bought new bolts to hold leaf pack together, get bolts from auto store regular bolts have hexagon shape on head of bolt, and it needs to be round to fit back in. Front bolt is a SOB spray it with penetrating foam, if it spins freely without coming out you have to cut a hole on other side to hold the nut in place (many are just tack welded into place and break with considerable force)

To others who have replied:
My U-joints could stand to be replaced, if I replaced them with new ones would that fix the problem?

I didn't life the front, and I didn't touch the driveshaft or U-joints/pinion... nothing. I might have only gotten about an inch and a half of lift up from standard ride height.

Please tell me, is it safe to drive if the U-joints/new pinion angle are "out of sync" and causing vibes? I need to get to school tomorrow and I have no time to change anything but I have another vehicle to take for at least a day, after that I have to drive my Jeep 100 km's a day for at least a week before I can change/fix anything

Edit- if you guys did lifts on yours, did you have vibes or weird noises that you drove around with?

Aaron N.S.

if you didn't remove the driveline or U joints then your joints can't be out of phase (assuming they were in phase to begin with) your pinion and and t-case should be at equal angles to the driveline. if the pinion is pointed up or down then your joints are out of sync. If it's not severe the worst you will do is wear out your joints prematurely.

here is a picture for reference.



Just a thought. does your truck have a SYE? if not your driveline can't be out of phase. I guess I forget not everyone has the same drivelines as me

dilljeepo

I get what you're saying, the pinion angle must have changed a little bit, man... what a delicate thing! I think adding in the second largest leaf was a bad idea, because the way the leaf pack was shaped was a little different over all than the stock one, and I'm pretty sure that now the pinion angle is a little greater than what it used to be, because I think the stiffer leaf pack rotated my axle, pointed the pinion more towards the ground if you know what I mean, because at the back of the pack the leaf with the bushings that connects to the chassis is a little more flexible, at the front of the pack the top leaf is more stiff because of how the leaves are situated, which results in the axle being rotated a bit compared to normal. Anwyays, thanks for your reply, I get it now! It's all trigonometry! lol, I'll have time to fix that later, I'm deeming it safe to drive until I can fix it!

Aaron N.S.

you may be able to simply add a caster shim to correct the pinion angle to fix it

http://www.lowrangeoffroad.com/pinion-castor-shims.html