Weigh in on my panhard
 

Hey folks I get a random vibration at shift points. So basically at 1800 to 2500 rpms depending on my driving. It's happened since my lift. I've gone through 3 drive shafts. My stock 2wd was fine when i killed it but i put a different stock 2wd shaft in just to see if it would change. It didn't. I then completed my 4wd swap so now I'm running that driveline. I've pulled my rear third ( regeared) and put my stock third in and it only changes at what rpm and speeds the vibration is felt. I'm wondering if my rear axle is slightly off causing a wierd angle on the drive line that I can't see with my brakes eye. My axle appears centered to me but my pan hard isn't horizontal. Do i need to extend my pan hard more you think?

Looks like you have adjustable control arms too? Are they at stock length right now? If not have you tried adjusting them back to stock length?

[emoji107] l

Yes they started at stock. Then I slowly pushed them out. The vibration is reduced the most at current setup with those control arms. If I extend further or reduce length the vibration becomes more noticeable again, even at lower speeds.

Could be because your 891’s are giving you too much lift for normal driving maybe? (Just throwing ideas out there) Do you constantly drive around with an extra 6-700lbs in the back of your rig?

If this had all been done with one driveshaft I would say to check the u joints - specifically the rear u joint. Even though you have swapped them out I would still recommend checking the u joint. They go bad easier/faster with lifts. The RPM specific vibrations are a common symptom of a u joint going out.

Could be a notchy ujoint that may need replacing. I have a feeling that's the cause of my rpm specific vib. Have a new one at the ready, just gotta find time to replace um.

U joint makes sense. Adjusting the panhard bar would shift the amount of side-to-side displacement the ujoint has to overcome. When it’s centered it is minimized and the ujoint is only dealing with the up-down displacement.

Haha no...not yet. Getting ready to burn sliders on in the next couple weeks. Hopefully have bumper with tire carrier on to also haul hi lift, 10 gal fuel, etc by end of next month to have that weight there. Also I believe the spring say 300 to 400 pounds. However I will say I've been taking a few hour drive each way the pastcouple weeks moving. When loaded the vibes are worse than when unloaded. This has me worried for all the weight I'm about to add.


To the rest @JZiggy , @HiLife , and the others above. I agree it u joints. Although to be clear when I say rpm specific I'm meaning rpm not speed. This isn't I notice between 60 and 70 mph ( 1800 to 2500 rpm). This is 1800 rpm to 2500 rpm. Speed not a factor. So first gear in that rpm range vibes hit, second gear in that rpm range vibes hit, third gear...you get the idea. I say this cause im used to u joints being speed dependant.

However it does feel driveline and it does feel like u joints. This is what brought me back to my pan hard setting...but no one has commented that it looks off to them.

@JZiggy I agree that the side to side fight with regular up and down fight might be a thing. Again this is why I'm asking about the panhard.

My u joints feel fine when driveline attached. But I know they may not be after enduring this abuse. I will swap them/or driveline once issue is resolved. Or at least lessened as the abuse may have the u joints wrecked enough to be an attributing factor. But like I said same vibration after 3 drive lines so there's something else going on.

Try throwing some grease at them if you haven't already. Won't be permanent, but if it improves I'd say you found your culprit.

Tried a few times already and no change...

Couple different things:

- if it is RPM dependent, it isn't the U-Joints. It could be something like loose torque converter bolts or something like that...
- If you did a 2WD-4WD conversion, make sure you swap out the upper links for the 4WD version. The 4WD runs a different pinion angle than the 2WD. (upper 4WD links are longer, tipping the front of the diff higher)

-Charlie

The 2wd driveshafts (2 joints) and 4wd rear driveshaft (3 joints) require different pinion angles. The 2wd driveshaft requires the transmission output and pinion yoke to be parallel with each other (like this transmission ---- ___ rear axle). The 4wd driveshaft has the rear pinion pointed at the transfer case output flange. You need to use either adjustable lower links or upper links, or use the 4wd upper and lower links. Either the 2wd upper links or lower links are different from 4wd. I can't remember where I saw that. Maybe Phattyduck's swap?

TLDR; I think your pinion angle is wrong for your driveshaft.

EDIT: Phattyduck beat me to it. That's what I get for not refreshing the page before posting lol

Weigh in on my panhard
 

The PN for the 4WD upper link is 4871035040 (The websites don’t usually make it clear which PN is for 2WD vs 4WD)

Thanks @phattyduck and @Bad Luck for the rear link info. I already have adjustable lower links which did help but I do understand that the uppers are specifically what changes your pinion angle. How much longer are the ad uppers than 2wd one? I'm about to order upper adjustables and would like a good starting point for length.