Slip yoke and vibrations

[atticus032]

My jeep is lifted 4.5 with a 1inch t-case drop. I believe that all of my driveline angles are correct, but i have a vibration when i first press the gas and when i let off. I think this is due to the slip yoke. If this is the case, and all the angles are ok, will this hurt my t-case at all? If so, will the longer slip-yoke from rusty's solve the problem, because i can't afford the SYE at the moment.

[Dirk Funk]

it kind of sounds like very slight spring wrap when you are accelerating and then coasting which might be binding the slip yoke ever so slightly. IMHO I don't think the extended slip yoke will do anything. A rear axle traction bar might.

[atticus032]

will this cause any problems?

[ChuckD]

I agree with Dirk Funk, traction bar is a good solution or a good full leaf pack. Your said you are at 4.5", is it a full leaf pack lift or AAL with block or shackle?

[Eagle]

You are right at the limit for your slip yoke. A friend had a 3" lift on a 95 XJ. He decided to toss in a 2" budget boost, consisting of 1-3/4" coil spacers and 2" rear blocks. So he was at 5" in the rear (no t-case drop). Once everything was bolted up, he went for a short test drive.

I mentioned "short" because less than 1/4 of a mile down the road the drive shaft fell out. There was so little spline engagement that as soon as he gave it some gas, the diff twisted up and pulled it right off the output shaft.

The YJ yoke isn't really very much longer than the XJ yoke (I think someone posted that the difference is 5/16"), but in a borderline situation that could make all the difference. In your case I think it would be worth a try. If nothing else, it has a more open throat, so it would eliminate binding as the cause of your vibration. However, you absolutely should think of this as a short-term solution, because your lift has increased the side loading on your transfer case output, so the longer you drive it that way (regardless of which yoke you use), the more you wear out the bearings.

[atticus032]

its a full leaf pack

[ChuckD]

Then you should look into a rear traction bar. First try a search on NAXJA, I know www.4x4wire.com has a really good article.

Eagle is right that the extended slip yoke isn't much longer, closer to an 1". The length is added on the flanges and not the splined shaft. This alows less u-joint binding in coparison to the oem SY.

The last option is adding some degreed shims to you leaf packs, to point your diff towards the TC. This will give you maybe an extra 1/2" on the driveshaft.

If you have a Automatic, you can find a MT driveshaft, they are longer.

I have 6" in the back of mine, 4.5" leaf pack with shackle and ext slip yoke, still have small vibrations. I maybe getting away with it because I have a MT. My drive shaft has not fallen out even at full flex.

[atticus032]

I have already added the shims that come with the kit. The vibe isn't horribly bad, its just a minor annoyance. It isn't a constant vibe either. It usually lasts about a second and it makes a rubbing type noise if you can picture that.

[ChuckD]

Unfortunately a SYE is probably your best bet, so start saving. However even that may or may not fix the problem, springwrap might still be the underlining issue.

[rmarkham2]

I had the same problem, but fix the problem for cheep. I added 6° Shims to the rear leaf pack correct the driveline angle.