I was the one who noticed because i was watching the tire jockey spin balance them.the wheel bead was wobbling left and right. I was chasing death wobble at the time.
Getting up to highway speed without shaking apart (05 LJ)
- Thread starter RexTreks
- Start date
I was the one who noticed because i was watching the tire jockey spin balance them.the wheel bead was wobbling left and right. I was chasing death wobble at the time.
OP
I've taken this set back once already for a rebalance (yesterday) and I'd be surprised if they could put any more weights on it honestly.
Most places just do them "good enough, "which never is with larger tires.
The transmission mount is bolted to the center of the skid plate. The spacers between the skid plate and the frame lower the trans and tcase as a whole. Depending on the application, some folks can get by using simple washers to lower the tcase by a marginal amount to lose the vibrations.
An SYE isnt difficult. The hardest part is dealing with the lock rings on the gear set. A quality set of lock ring pliers work well here. I bought a set from NAPA, I think it was $70, but definitely shop around, there are much cheaper ones out there. Correct--the front is already a DC shaft. The rear uses the fixed slip yoke for travel.
Upper and lower control arms are appropriate. THey work in unison to place the axle where it needs to be. Adjusting one will affect the other. It requires cycling the axle with the springs removed to line up your bumpstops at full bump. This also helps to determine the appropriate shock length needed.
Shock relocators help position the shock body away from the spring perch at the cost of shock travel. Trimming the spring perch with a angle grinder is a better option.
I only have a 2.5" lift on my LJ, but I also installed an extra-clearance tranny skid, which raises the TC another couple of inches. That gives a lift (as far as the driveline angles go) of about 4.5". And mine needed an SYE and a DC driveshaft because of driveline vibrations. I replaced my rear upper control arms with double-adjustables (Savvy), keeping the OEM control arms everywhere else.
When you get in the neighborhood of 4" of lift on an LJ, it can go either way. You may or may not need an SYE & DC.
The extended wheelbase certainly helps, but 4" is going to be right at the cusp I believe. I know a few folks who have gotten by on their LJs with the washers to lower the skid, but I also know folks who couldn't get rid of vibes until an SYE and adjustable control arms were installed.
OP
OP
Looks like a great option - also they sell a NP231 Slip Yoke Eliminator (Which I believe is the one for me since I don't have a rubicon - The measurement page of the website seems straight forward enough. I'll get that measurement done and get one ordered tonight.
I used the JB Conversions super short SYE. It's the shortest one out there... Might not matter much in the LJ tho
Not to hijack, but what's the advantage of the sssye vs just a sye?
Longer driveshaft
Longer driveshaft = better operating angle = longer ujoint life but most importantly less drive line vibes
OP
My pinion angle looks
So looking against at my rear pinion / shaft - it appears to me to be almost perfectly straight, which... kind of surprised me.
Theoretically, I would decrease strain on the system by lowering the pinion angle ~5*?
So looking against at my rear pinion / shaft - it appears to me to be almost perfectly straight, which... kind of surprised me.
Theoretically, I would decrease strain on the system by lowering the pinion angle ~5*?
LONGJP2
TJ Expert
Until you switch to a DC driveshaft, the pinion angle should be parallel (or equal to) the transfer case output angle.
Hard to do with fixed arms.
You won't be able to measure before doing the SYE.
However, if you call them, they will probably know exactly what you need.
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OP
Spoke on the phone w/ a fella at Tom Woods, and he (very helpfully) gave me some troubleshooting tips and a few specific things to listen for regarding driveline vibrations, I figure I'd share them here for posterity:
1) DS balance issues tend to be discernable under torque scenarios - if it is a damaged unit or weighting issue you will feel a change in the vibration intensity when you are on/off throttle or when putting it into neutral.
2) Pinion angle / geometry vibrations tend to discernable at low speed, gaining intensity as they rotate faster, they do not tend to activate at a certain frequency.
3) Particular speed frequency vibration tend to be wheel / tire related. if the vibrations are not felt at low speed, its probably not a wheel or tire.
In my case, I went out testing today on some new flat roads for a few hours, and sure enough, I could feel the vibrations at low speeds, 20-30 mph. 55 MPH is about the last bastion before things got too shaky to drive, and there wasn't any ability to 'overcome' the frequency with another 5 or 10 mph. With that info, I'm feeling pretty confident that it is a geometry issue.
After taking a look at the pinion angles with my buddies angle tester, we confirmed the rear pinion is a bit too high (mentioned/noticed earlier in this thread), so I'm going to start off with grabbing a set of adjustable upper control arms for the front and back, and leave in place the extended lower control arms that came with the 4" lift kit; I am thinking that the adjustment offered from the uppers will be enough to bring them into specification without moving the axle too far, since it should be less than 5* needed. of adjustment.
If THAT doesn't fix it, it'll be time to grab the SYE and a DC rear driveshaft from them. I wager that since the LJ has those extra 10" wheelbase that a super short variant won't be necessary; I'd prefer to keep the mechanical speed sensor, though it's not the end of the world to me if I really NEED/SHOULD get a shorter variant. At that point, I'll likely need to get the adjustable lower control arms to bring the diff nice and flat for the new driveshaft.
So at this point - I still need to try unhooking the front driveshaft and isolating the vibrations to just the rear, same for the front. Would be great if this were completely localized to just one end of the Jeep but only testing will tell. I'll order upper control arms for either or both sides once I confirm that we've got the vibrations still. On that note - Are RockJocks the go-to for these arms? They seems like one of the very few greaseable end solutions for this, and I really don't care to be bothered with getting under the truck every few days to blast heim joints with white lithium grease!
1) DS balance issues tend to be discernable under torque scenarios - if it is a damaged unit or weighting issue you will feel a change in the vibration intensity when you are on/off throttle or when putting it into neutral.
2) Pinion angle / geometry vibrations tend to discernable at low speed, gaining intensity as they rotate faster, they do not tend to activate at a certain frequency.
3) Particular speed frequency vibration tend to be wheel / tire related. if the vibrations are not felt at low speed, its probably not a wheel or tire.
In my case, I went out testing today on some new flat roads for a few hours, and sure enough, I could feel the vibrations at low speeds, 20-30 mph. 55 MPH is about the last bastion before things got too shaky to drive, and there wasn't any ability to 'overcome' the frequency with another 5 or 10 mph. With that info, I'm feeling pretty confident that it is a geometry issue.
After taking a look at the pinion angles with my buddies angle tester, we confirmed the rear pinion is a bit too high (mentioned/noticed earlier in this thread), so I'm going to start off with grabbing a set of adjustable upper control arms for the front and back, and leave in place the extended lower control arms that came with the 4" lift kit; I am thinking that the adjustment offered from the uppers will be enough to bring them into specification without moving the axle too far, since it should be less than 5* needed. of adjustment.
If THAT doesn't fix it, it'll be time to grab the SYE and a DC rear driveshaft from them. I wager that since the LJ has those extra 10" wheelbase that a super short variant won't be necessary; I'd prefer to keep the mechanical speed sensor, though it's not the end of the world to me if I really NEED/SHOULD get a shorter variant. At that point, I'll likely need to get the adjustable lower control arms to bring the diff nice and flat for the new driveshaft.
So at this point - I still need to try unhooking the front driveshaft and isolating the vibrations to just the rear, same for the front. Would be great if this were completely localized to just one end of the Jeep but only testing will tell. I'll order upper control arms for either or both sides once I confirm that we've got the vibrations still. On that note - Are RockJocks the go-to for these arms? They seems like one of the very few greaseable end solutions for this, and I really don't care to be bothered with getting under the truck every few days to blast heim joints with white lithium grease!
OP
Anybody running the set from Rustys? They make an all rubber set and a greaseable forged joint set; these also happen to be the brand that Tom Wood's lists on their products page so I can only assume they're just fine...? Getting a greaseable set of 8 arms for $1,000 seems like a pretty good deal too.
LONGJP2
TJ Expert