Vibration after 8.25, help me think it through...

[Dredwolf]

:confused:

So I swapped the D35 ABS axle in my '99 for a JY '99 8.25 today, and used the 8.25 driveshaft from the same '99 XJ. Same lift (approx. 4.5"), but I get an acceleration vibration now, but it disappears once past 30 mph.

Did not have this vibration with the D35. I did NOT rebuild the 8.25 on purpose, I have rear leaves on the way, and will be re-gearing anyway.

Rear leaf packs will be 3.5" RE units. An SYE is planned, because of the nose lenght of the 8.25, do I need shims in the meantime?

I need to go buy an angle finder.

[4.3LXJ]

Here is how to get that sorted out

http://www.xjtalk.com/showthread.php?t=7299

[Dredwolf]

Here is how to get that sorted out

http://www.xjtalk.com/showthread.php?t=7299

Thanks for the reference! A lot of my driveline tools from my CJ days disappeared when my mother got "help" cleaning the "shop" area of my father's garage when I worked overseas.

I'll get an angle finder. I could just go ahead and bite for an SYE I guess.

[4.3LXJ]

If you have a smart phone, you can get a free app for leveling

[Dredwolf]

If you have a smart phone, you can get a free app for leveling

True, I have that app on my work phone, but I found a new HF angle finder in the top of my tool box.

Working on the XJ is an excuse to NOT have the work phone with me.:D

[Brasscatz]

I could just go ahead and bite for an SYE I guess.

I remember a tip from an XJ Talk Show from a long while back that Steve (4.3LXJ) suggested. (Steve please correct me if I'm wrong) But if you feel like going back to the JY or even looking around craigslist/ebay you could get a slip yoke from a YJ instead of an SYE because they are made to work with steeper angles. That's my plan for the future :wink:

[4.3LXJ]

That is correct. YJ slip yoke is 1/2" longer and will accommodate more bend than the XJ yoke

[Dredwolf]

okay, today was the 1st day it was not raining, so I tried to get a measurement on the two angles....not too successful.

But visually,my driveline angle looks like the CV one....the axle pinion is almost a straight line with driveshaft.....but the transfer case has almost NO angle, 3-4 degrees?:confused:

Lower the transfer case?

[4.3LXJ]

You could lower the tcase, but you might need to shim the axle instead. That would be my first option. IMHO better than lowering, but both acceptable

[Dredwolf]

You could lower the tcase, but you might need to shim the axle instead. That would be my first option. IMHO better than lowering, but both acceptable

I am used to shims for the axle to rotate the pinion angle UP....but on this 8.25, the pinion and driveshaft are almost perfectly aligned....shim it more?

I did not want to post the numbers until I checked again this weekend, with perfect light, 2 cups coffee, vitamins and a good breakfast....I got 3 degrees on the t-case and 13 on the pinion......:confused:

I'll check it again after I get the springs installed.

[LizardRunner]

Sounds like the pinion is in need of a reduction in angle by around 10 degrees if your using a conventional set up, ie. the stock 8.25 drive shaft. MIght only be a few degrees out or dead on if going CV joint style.

[Dredwolf]

I am using the stock 8.25 drive shaft from the same donor vehicle that supplied the 8.25. My XJ has a estimated 4.5" lift..., pinion angle appears to be straight in line with the driveshaft. That is one potential problem. I am used to shimming the pinion UP, is shimming the pinion angle DOWN common?

I did find the source of at least part of the "felt" vibration...the PO took a sawsall to the exhaust near the cross member......so the exhaust is suspended by the header.....and the cross member :bang: but the exhaust stops before the rear axle, so no place to easily fab hangers:mad:

The little cheap exhaust hanger installed by PO is literally supporting none of the exhaust weight, so besides the banging, it sends vibration through the chassis anytime you accelerate.:rolleye0012:

HD Offroad Engineering shackle brackets are on the way, so I am holding on trying to measure pinion angle until the 3.5" leaf packs and shackle brackets are installed.

Plus an SYE is in the near future, Carolina Driveline runs a special on the SYE kit and matching driveshaft.

[4.3LXJ]

yes, shimming down is common

[Dredwolf]

yes, shimming down is common

Thanks for the info, I'll see if I can't sort all of this out when the shackle brackets and new leaf packs get installed. Still trying for around 4.5" of lift and 33's that clear well.

I have been tempted to just order a couple of sets of shims to have on hand, but I'll wait.

[Sandman4182]

I also had a vibration on min but not due to changing to the 8.25 it was after I lifted it I do have a 8.25 I dropped the TC 1 1/2 I think and it went away. Till I can get a SYE. I might still have the template I used for it let me know.

[Jeepster19]

If you have a smart phone, you can get a free app for leveling

Which app did you pick?

[4.3LXJ]

It just says level. It measures in tenths of degrees

[Jeepster19]

It just says level. It measures in tenths of degrees

Thanks.:D

[Dredwolf]

Which app did you pick?

I have a free one on my smartphone that is "carpenters" set of levels, etc, I think there is such for Android and iOS.

And they have such at your local HF...not bad if you are not using one every day.

[Dredwolf]

I also had a vibration on min but not due to changing to the 8.25 it was after I lifted it I do have a 8.25 I dropped the TC 1 1/2 I think and it went away. Till I can get a SYE. I might still have the template I used for it let me know.

I have been looking the dropped cross members too, but I guess I need to install everything first....this XJ ran smooth with the same lift and a D35. I swapped the D35 for the 8.25, and used the drive shaft from the donor vehicle, and picked up this vibration under gentle acceleration....runs smooth at 55-60 mph.