Hi all,
I recently finished lifting my 1994 (4.0/AW4/231) using a bastard pack in the rear with a 3/4" lift shackle and ZJ v8 coils with a 1.25" spacer up front. It netted me exactly 3" and I'm running BFG 31" AT's.
As soon as the lift was done I replaced the rear DS U joints and had the shaft professionally balanced by a driveline shop.
First I had slight grinding vibes only on deceleration....so I started to make a homemade T-case drop to see if it would help. Of course, the very first crossmember bolt snapped right off...great. Managed to drill and tap it out (a miracle) and decided to try and go with the skyjacker T-case drop kit so that I wouldn't have to drill and tap either of the studs. This is just a snow beater, not a wheeling rig, I am not interested in the cost or the effort to do an SYE and custom DS. In fact, that's the whole reason I bought a 94 to begin with, to avoid that. I will remove all the lift and bring it back to stock before I go with a SYE.
Now I have serious vibes coming from everywhere, but especially the front at anything over 50-55. I can feel them in the steering wheel AND in my butt now. I swapped out the front shaft and they are still there.
Last night I went out to measure angles and take another look at things. Seems that my angles are as follows in the rear: T case is pointed 6* down from horizontal, rear pinion pointed 9* up from horizontal. Measurements were taken at the valve cover and the flat circles next to the diff cover. They have been checked and rechecked. I figure a 4* shim with the fat part facing forward should put the rear in perfect sync, accounting for spring wrap, BUT:
I can see the stress that this drop is putting on the 120k mile motor mounts. They look horribly deformed and the rubber is almost pulling out of the mount towards the rear now. I guess I know where these front vibes were coming from. They are getting replaced immediately.
So now here is the question - is the skyjacker drop just too big? I think it measures almost 1.5". Would it be better to risk snapping both crossmember studs so that I can use a more reasonable drop, like 3/4"? If I snap them, there is a chance that my drilling and tapping will not go well (don't usually have the best luck with that) and that I will end up having to cut into the floor and using a through bolt and nut, which would suck. Can I even access the back side of the crossmember bolts through the floor or is there a frame rail of sorts in the way above them?
It actually looks like this drop causes so much misalignment in the motor mounts that I would NEVER be able to get a set of stiff mounts (like the MORE mounts) lined up again once I take the stock ones out.
Of course, if I can use a smaller drop, I'm going to also have to use a bigger shim, probably 6* to get the angles back in line...but I'd have to cross that bridge when I came to it.
What do you guys think? Anyone have extreme motor mount problems and such due to the skyjacker drop kit? Anyone having success with this drop over the long term and NOT replacing motor mounts every few months? It looks like it's just too big, is it?
I recently finished lifting my 1994 (4.0/AW4/231) using a bastard pack in the rear with a 3/4" lift shackle and ZJ v8 coils with a 1.25" spacer up front. It netted me exactly 3" and I'm running BFG 31" AT's.
As soon as the lift was done I replaced the rear DS U joints and had the shaft professionally balanced by a driveline shop.
First I had slight grinding vibes only on deceleration....so I started to make a homemade T-case drop to see if it would help. Of course, the very first crossmember bolt snapped right off...great. Managed to drill and tap it out (a miracle) and decided to try and go with the skyjacker T-case drop kit so that I wouldn't have to drill and tap either of the studs. This is just a snow beater, not a wheeling rig, I am not interested in the cost or the effort to do an SYE and custom DS. In fact, that's the whole reason I bought a 94 to begin with, to avoid that. I will remove all the lift and bring it back to stock before I go with a SYE.
Now I have serious vibes coming from everywhere, but especially the front at anything over 50-55. I can feel them in the steering wheel AND in my butt now. I swapped out the front shaft and they are still there.
Last night I went out to measure angles and take another look at things. Seems that my angles are as follows in the rear: T case is pointed 6* down from horizontal, rear pinion pointed 9* up from horizontal. Measurements were taken at the valve cover and the flat circles next to the diff cover. They have been checked and rechecked. I figure a 4* shim with the fat part facing forward should put the rear in perfect sync, accounting for spring wrap, BUT:
I can see the stress that this drop is putting on the 120k mile motor mounts. They look horribly deformed and the rubber is almost pulling out of the mount towards the rear now. I guess I know where these front vibes were coming from. They are getting replaced immediately.
So now here is the question - is the skyjacker drop just too big? I think it measures almost 1.5". Would it be better to risk snapping both crossmember studs so that I can use a more reasonable drop, like 3/4"? If I snap them, there is a chance that my drilling and tapping will not go well (don't usually have the best luck with that) and that I will end up having to cut into the floor and using a through bolt and nut, which would suck. Can I even access the back side of the crossmember bolts through the floor or is there a frame rail of sorts in the way above them?
It actually looks like this drop causes so much misalignment in the motor mounts that I would NEVER be able to get a set of stiff mounts (like the MORE mounts) lined up again once I take the stock ones out.
Of course, if I can use a smaller drop, I'm going to also have to use a bigger shim, probably 6* to get the angles back in line...but I'd have to cross that bridge when I came to it.
What do you guys think? Anyone have extreme motor mount problems and such due to the skyjacker drop kit? Anyone having success with this drop over the long term and NOT replacing motor mounts every few months? It looks like it's just too big, is it?
I have mildly lifted two 1998's and also got vibes even with just like an inch of lift on them....