Jeep shakes violently . . .

Jeep shakes violently . . .

ParsonMac

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Location
Canon City, CO
Vehicle(s)
1984 CJ7 with a 1993 4.0 Inline 6; T5 transmission; Dana 300 transfer case; Dana 44's with ARB lockers
I took the Jeep I'd just purchased to Moab on it's debut run and it performed great, no problems. Took it for a spin the other day and ran over some railroad tracks and while coming off them the Jeep started a violent shaking with the shifter moving from side to side. Reproduced it on the return trip and clutched and braked to see if that would stop it - no go. Seems now (or did I not notice it before?) the shifter is closer to the rear of the hole and hits the tub in 2nd and reverse. I noticed this shaking will not occur at speeds of 20 mph or less. Checked the engine mounts - practically new and tight. Transmission mount? Ordered both the main mount and the stabilizer rod and bushings. Front end seems tight - nothing loose etc. Help!:dunno:
 
You know, come to think of it, it's not really in the wheel at all. It's in the drive train and body.
 
ok, first, you have a converted driveline, check all mounts for tightness and no binding and for alignment, then the body mounts, second finish up the conversion by getting those holes realigned so the drivetrain is not hitting anything, t case torque mount, just get under there with a jack and move things around looking for what is loose. It also could be the drive train and body hitting each other when rocking about. finish the conversion.
Now I take it the suspension unloaded when you went over that track and when you loaded up again it started shaking. Is this what happened?
 
Now I take it the suspension unloaded when you went over that track and when you loaded up again it started shaking. Is this what happened?[/QUOTE]

You got it - like the washboard affect on a bad road - and it just remained in the Jeep when I hit the smooth pavement.
 
OK then, if you are sure it is not the suspension it is happening then when the suspension is being banged around causing the other parts of the jeep to bang around?
I think you are saying this. Body mounts? all drive line mounts? clearance for moving parts?
get the jack out, climb under......... If that is not it, start with the springs and axles, are the bump stops tuned, does it have a lift that is put in as badly as the drive line conversion seems to be? Looks Like a PO gave you his half finished problems and you need to just spend time and elbow grease figuring out problems to clean up what he was to lazy to.
remember, these vehicles are antique, and have questionable service/modification histories
here is a link
http://www.jeep-cj.com/forums/f49/what-do-after-getting-cj-home-3563/
even if you have had that Jeep a while, going down that list will get it back in to great shape
 
I've checked all body mounts and driveline mounts. Stabilzer is loose. Will take load off wheels and check front end, bearings etc. Mods seem to have been done right by a knowledgeable individual. Thanks for the link.
 
Mods seem to have been done right by a knowledgeable individual.
can I ask why the shifter hits the body then? First sign he cut corners or did not pay any attention to tuning in the mod, I would think again about him being knowledgeable.

If you have checked all that, then the most likely problem is Death Wobble, which 90% of the time is caused by the guys who lifted not tuning in the steering geometry, and it will shake that jeep like a witch on steroids. There are fixes and it is once again to check all joints and mounts to make sure they are in great shape, and then getting the geometry correct by getting the parts to set it up like stock. That is a step soooooooooooo often overlooked, ask anyone here about that.
 
PS, did you check to see if he moved the crossmember after he put in the conversion, you could have a bound up driveline and when the Jeep flexes at speed like over that track it shakes trying to straiten out, I am just offering help because you say it does not do it at any time but like the tracks I am looking for why the driveline wants to shake in there, one big part I can think of is a bound up drive train trying to settle back into the conditions it was squeezed into.
 
Regarding the crossmember - I do not think it's been moved. I'll check that when I replace the stabilzer bushings.
 
if you unbolt it from the frame, see if it wants to move, most of the time when you put in a longer transmission you end up with a cross member that is in the wrong place for the mount, so they adapt the mount with a piece of metal to hold onto the tranny and do not remount the torque mount on the t case,
If you unbolt the cross member with the tranny supported with a jack, check to see if they have a bogus looking mounting system for the tranny because it was not aligned, you can easily move the cross msmbsr by redrilling new frame holes. then bolt down the tranny tight, a t case should have a mount on it also so that the torque does not twist it out of there, both of these are important to that vehicle being correct. And both are easy to get right.
a tranny that is not solidly tied down will move back and forth. Sound familiar?

About POs, we all have tales, and we all have bought a pile of troubles that was past off as a pristine Jeep, just look at the current thank you thread in Misc CJ department. I just recently put a extra 4 grand into a jeep I bought last year as when digging in I found problems due to a PO that cost me time and money, they have not sold these things for25 years, can you tell who has owned it?
Now it would be very easy for someone to put in a new engine and tranny, and mount it to the old case, then find out that the easy fit up in the engine bay has created a lot of fixes he has no ingenuity to cure. One of those is the shifter hitting, you know a guy with a torch and a mig welder can have that fixed in a hour and a half, so you see why I am concerned about binding or a loose fit. I feel that if it were more related to the front end you would have felt bump steer in Moab, or you would have felt death wobble at certain speeds on the freeway. So off of what you have described and the statement about the fit of the engine/tranny mod, I would like to see if the things are in there correct before moving on to the front end.:chug:
 
Baja,

Just for info sake - couldn't the T5 be the original transmission? If that's the case, would the cross member be an issue? . Also, there is no wander or shaking at highway speeds from 40 mph - 65 mph. It's on course with pretty tight steering. Please understand, I'm new at all this. Thanks!
 
Last edited:
nope
the 1980 CJ series came with 3 engines a 4 popper , a 258 six and the 304
behind the 4 popper was a BW sr4 4 speed, behind the 6 and 8 was a T 176 4 speed.
your profile says you have a 1996 4.0 and a T5, a 5 speed, that would be a nothing like they had in jeeps in 1980, in 1996 the 4.0 was matched to a AX15, a 5 speed, so even getting a t5 to match could take a bit of work, it did match to the 4.2 in earlier wranglers from the factory. A T5 is a light duty transmission but it is short so a lot of guys like them, however they are not the strongest tranny in the world, found in jeeps from 82 to 86. I would wonder why the owner pulled a 258 for a 4.0, or even pulled a 304, so I would imagine your jeep started with a 4 popper and the BW sr4, I would identify the tranny in there.
Owning a Cj you are going to get a quick lesson in how mechanics of a vehicle work, And be amazed at what guys have done to the thing before you, but you will end up with a nice vehicle if you just plod along and handle issues as they come.
 
Sorry Baja - that would be a 4.0 from 1993 Wrangler.
 
can I ask why the shifter hits the body then? First sign he cut corners or did not pay any attention to tuning in the mod, I would think again about him being knowledgeable.

If you have checked all that, then the most likely problem is Death Wobble, which 90% of the time is caused by the guys who lifted not tuning in the steering geometry, and it will shake that jeep like a witch on steroids. There are fixes and it is once again to check all joints and mounts to make sure they are in great shape, and then getting the geometry correct by getting the parts to set it up like stock. That is a step soooooooooooo often overlooked, ask anyone here about that.

I agree.
The whole RR track thing sure makes it sound like Death Wobble.
 
I agree.
The whole RR track thing sure makes it sound like Death Wobble.
I know, but lets get the drive train issue handled first and se if it is in place solidly, then attack the death wobble. He states the entire drivetrain shakes, not a good thing.
 
nope
the 1980 CJ series came with 3 engines a 4 popper , a 258 six and the 304
behind the 4 popper was a BW sr4 4 speed, behind the 6 and 8 was a T 176 4 speed.
your profile says you have a 1996 4.0 and a T5, a 5 speed, that would be a nothing like they had in jeeps in 1980, in 1996 the 4.0 was matched to a AX15, a 5 speed, so even getting a t5 to match could take a bit of work, it did match to the 4.2 in earlier wranglers from the factory. A T5 is a light duty transmission but it is short so a lot of guys like them, however they are not the strongest tranny in the world, found in jeeps from 82 to 86. I would wonder why the owner pulled a 258 for a 4.0, or even pulled a 304, so I would imagine your jeep started with a 4 popper and the BW sr4, I would identify the tranny in there.
Owning a Cj you are going to get a quick lesson in how mechanics of a vehicle work, And be amazed at what guys have done to the thing before you, but you will end up with a nice vehicle if you just plod along and handle issues as they come.



IMHO your a little off base on this one Baja.
They stopped putting 304 V8's in CJ's in 81'
I could easily see someone swapping in a 4.0 to gain more HP & fuel injection.
Also the T-5, T-4 & T-176 were all factory options in 84' with a 4.2 6 cyl.
Now front & rear Dana 44's on the other hand were definitely not a factory option.
I'd be interested to know exactly what vehicle they came out of & how they were modified.
As far as Death wobble goes I've seen cases where every thing in the truck seems like it's coming apart.:eek:

How about some pictures of the tranny mount from different angles.
 

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