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Hack N Tap vibes, need to fix

W

Whiskey'sXJ

NAXJA Forum User
Location
Verdi, NV
I have a '99 XJ 4.0 with a 3.5" RE Super Ride lift with full leafs in the back. I was never able to dial the angles in on the driveline so I opted for a RE Hack n Tap and RE CV driveshaft. I had some difficulties with the install (broken drill bit stuck in the shaft, etc) but eventually got it resolved and the end result looked great. However, when all was done, I still had some minor vibes under load at 60+ mph which is probably due to a slightly off-centered tap (not sure). Regardless, at the time (few years ago), the Jeep was not my daily driver and rarely saw highway speeds so it didn't concern me. However, now things have changed and the Jeep is my daily driver and I do about 70 miles per day. The minor vibes are starting to ruin seals, causing leaks and who knows what else is to come. That said, I need to finally eliminate the vibes and am wondering what my options are. I have some ideas of my own, but I'm a novice compared to most of the guys on this site, so I thought I'd throw this out to the rest of you with more experience. Note, I have the 242 transfer case. Any suggestions are appreciated. Thanks.
 
What's your pinion angle? Your pinion angle should be about 3* below your driveshaft angle. This is because the pinion tries to "climb" the ring gear under acceleration (so 3* difference will turn into 0* difference under acceleration).

Other than that, i haven't had good luck with HnT's. It seems like they all eventually wear out. Mine was almost instantly horrible and my install was flawless (IRO crap?). But...you've got the 242 so i guess that's what you've got to choose from...
 
I would take a good look at TW's sye kit,its really the only other kit out there.
 
Even if the hole wasn't drilled center for the hack n tap you shouldn't have vibes from it. The yoke should center itself on the splines from the output shaft. The bolt is there just to hold it in place. I would check piñon angle first ot perhaps you have a bent output shaft. But not likely.
 
Its not due to an off-center hole and bolt. Did you add shims to the rear end to point the axle up to the tcase?

Take 2 pics and post them here: 1 picture of where the driveshaft meets the tcase, the second picture is where the driveshaft meets the rear differential. Let's check the driveline angles first.
 
That's odd because it looks to me like you need to shim the pinion up a little (which goes against what you are saying about vibes only under load). How did you measure the angles?

Also, cut your ubolts down.:cheers:
 
Interesting...... I'm thinking it's a little to close to being in line with the DS. Pinion 2* below DS is ideal for pinion to rotate up. What deg shims you running? I would also have the DS checked just for piece of mind. As said befor a little offset on the bolt for your H-n-T shouldn't be a big deal.
 
It actually looks like the pinion is too far UP to me, it is almost straight into the driveshaft. When you accelerate that is going to translate into the pinion pointing up too much, and at freeway speeds it will do exactly what you're describing. But...pictures are kind of pointless. You need to measure the angles.

Couldn't hurt to pull the driveshaft and check the u-joints, either.
 
FWIW, I have a H&T SYE and I get resonance / vibes starting right around 60+ mph as well. But, I know mine has to do with the front driveshaft or axle because as soon as I remove the front driveshaft the vibes disappear entirely. I'd recommend trying it, it's a good way to isolate the source of the vibrations.
 
the_weirdo said:
How did you measure the angles?
Click to expand...

Just curious, how are you supposed to measure the drive shaft angles?

I put an angle finder on the flat spot of the rear axle, next to the diff cover. That measurement was 80deg. Then I put the same angle finder on the underside of the rear drive shaft and that measurement was 77deg. So the difference is 3deg correct? And the pinion is pointing down when compared to the drive shaft.

The reason I'm questioning it is because I actually took the shims out of my rear springs to get this angle and I have vibes 65+. But, I just finished a complete change of the axles, tires and lift so I'm still working the bugs out.

/end thread jack
 
SolarBell said:
FWIW, I have a H&T SYE and I get resonance / vibes starting right around 60+ mph as well. But, I know mine has to do with the front driveshaft or axle because as soon as I remove the front driveshaft the vibes disappear entirely. I'd recommend trying it, it's a good way to isolate the source of the vibrations.
Click to expand...

I have the same problem.

I thought I had hack n tap vibes, but I don't. It's smooth with the front shaft removed.

3 different front driveshafts, a new front axle, and multiple pinion angle settings, it still vibes.
 
srmitchell said:
I have the same problem.

I thought I had hack n tap vibes, but I don't. It's smooth with the front shaft removed.

3 different front driveshafts, a new front axle, and multiple pinion angle settings, it still vibes.
Click to expand...

I rebuilt my front driveshaft and rebalanced it, no change. I replaced the front output bearing on my t-case, no change. I was considering all new front axle R&P bearings, but maybe not now that you say that..
 
Yeah, here's a list of things I've changed

-Swapped a hp d30 from a 94 xj (my 01 had a low pinion)
-It was rebuilt with a new ring and pinion, and all new bearings
-New front hubs, u joints
-Pinion angle at zero degrees, as well as up and down from zero
-2 junk yard shafts
-A new tom woods shaft. I suspected that the centering ball was binding, so they rebuilt it, re balanced it, and no change still.

It's not the tires or anything like that because it's totally smooth with the front DS removed.
 
srmitchell said:
Yeah, here's a list of things I've changed

-Swapped a hp d30 from a 94 xj (my 01 had a low pinion)
-It was rebuilt with a new ring and pinion, and all new bearings
-New front hubs, u joints
-Pinion angle at zero degrees, as well as up and down from zero
-2 junk yard shafts
-A new tom woods shaft. I suspected that the centering ball was binding, so they rebuilt it, re balanced it, and no change still.

It's not the tires or anything like that because it's totally smooth with the front DS removed.
Click to expand...

That do your upper control arm bushings look like? If those are on there way out pinion could still be moving under load causing it to be off? Maybe stretch or worn out ujoint straps? Just throwing other stuff out there for you to look at.
 
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