Never Late

I just installed an IRO hack an tap sye on Wednesday using the stock front XJ driveshaft, on the same day i also installed 1.5" spacers bringing my front from 4.75" to 5.5" to level out with my rear. My initial driving experience was that it was very smooth and felt great. I realized that my friend didn't uninstall the 1" TC drop kit I had previous to the SYE, so yesterday I had him remove it for me and remove the linkage drop bracket as well (thinking i don't need it now that i have an SYE).

When i picked up my jeep last night, i noticed that between 15-20mph it sounded and felt like i was in 4wd. I had vibes and a grumbling/humming sound coming from trans area that i could feel in the gas pedal. The sound/feeling would disappear after I went below 15mph.. I drove the jeep more today and it seems like it is doing it less, however I am not sure if i am just imagining this. I did not shim my rear axle at all after the SYE, but it seems like when I had the 1" drop installed with the SYE that maybe the angles were better. Should i just put the drop back in?

FWIW it engages 4wd without any issues, so I am not sure if that is the issue or the front driveshaft is making the noise?

All help is appreciated!

Never Late

In doing more research - I am thinking the sound/vibes I feel may be directly related to raising the TC up 1" by removing the spacer kit. I think with the spacer the angles were probably better and now they may be off, and in need of shims. However my initial thought when i heard/felt it was it resembled when you put your XJ into 4H and you here the front engage and everything moving...

Jeepin'_Aint_EZ

You have non adjustable short arms on 5.5" of lift, your front driveshaft angle is probably insane. We told you not to do that without adjustable arms or better yet, go with long arms for that amount of lift. Can't say we told ya so, but we told ya so.

Martlor13

So I see you decided against better control arms. Sigh....

You very well possibly do need shims at that height. Possibly rebuild the driveshafts as well. But whatever you do, don't put the transfer case drop back in.

Never Late

I understand the control arm aspect, but this new noise didn't start until i removed the TC drop. I've read stock lower control arms are 15.75" and stock uppers are 15" for 6" of lift you need adjustable lowers to be 15.875" and uppers 15.125" respectively. That is only 1/8" difference in length, also My LCAs are longer than stock already so that amount is probably off by 1/16". I don't think this could cause my drive-line angles to be insane..The sound is directly related with removing the TC drop.

Fred/N0AZZ

The Control Arm issue is a big problem as stated not using adj. one's. I agree on the "Insane" angles has to be, no way around it.


With most SYE's you need shims in the rear differential after the install, I had to use them at 4 1/2" of lift.


The driveshaft at that height for the rear in most cases needs a custom one not a stock XJ front, length isn't correct. With any lift the driveshaft's both need to be rebuilt and if a front is used a larger joint installed for the rear. The front need new u-joints as well to replace the worn ones from stock height, the old worn ones will cause problems.


I hope you do reconsider and replace the parts needed for that size lift with the correct ones. Short cuts do cost you more money and problems.

Never Late

I will try to take some drive line angle measurements later and post them...

Never Late

I need to rebuild my front DS even though it only has 75k babied miles on it? I also read that you are able to use the stock XJ DS up to around 6" of lift..and it was measured to make sure it fit..

Never Late

I will plan on getting some 4 or 6 degree shims and adjustable control arms and see if that helps it all.

EvstaG

Spend some time taking some measurements, and let us know what you find, I'm sure something is just a little awry.

With a lifted XJ, adjustable control arms aim to find a balance between good pinion angle (as close to 0* as possible) and proper caster (>5*), but usually end up with a compromise of both, at least on taller lifts.

First step for me would be to remove the front DS and see if the problem goes away.
No? Measure the rear pinion angle and shim accordingly.
Yes? Check the condition of the front driveshaft. As Fred said, driveshafts wear according to the height their used at, and introducing more extreme angles can warrant a rebuild.
Once that is sorted, get yourself some adj. arms and research on how to set those up, or have a competent 4x4 shop do it for you.

Jeepin'_Aint_EZ

You're right, the problem is with the fact you took the TC drop out. So now that the Tcase is back in it's proper position, the angle on your driveshafts have increased.
You can use a stock front driveshaft in the rear up to 6" of lift no problem. This is what I do. BUT, you need to shim the rear axle as Fred stated. My rear is shimmed, no issues.

As for the front, adjustable control arms take the place of shims. The front driveshaft is probably on a pretty steep angle as well.

Martlor13

Either way you look at it, you need new control arms. If all your research and numbers were correct, don't you think all of us woukd agree and justv not spend on control arms either? You need new control arms plain and simple. So you have longer lowers? Great but not for the lift height you have. Plus your on STOCK uppers! At 6 inches!! That's insane!

Never Late

What shim degree are you running? my research is telling me i should be good with 6 degree shims.

Never Late

Well i will be looking into getting adjustable uppers and lowers and go that route.

Martlor13

Great. It's crazy man. People post a thread asking for advice and questions and what nother. People respond with what should be done. The poster then comes back with a few weeks later that something bad happened and we come to find out he did nothing that we told them and they went rogue haha. Like why ask if your just going to do what you want anyway?

Your situation is nothing bad. Just control arms. But those angles can lead to bad things. My little story above was from about 5 months ago and the guy blew his motor because he didn't believe whatv we told him and did his own thing. I was just laughing lol.

Pics of your jeep? And your driveline as well and we should be able to help along.