HELP!! Drivetrain Issues...

[96LX450-Nick]

I have noticed a "stutter" or "shimmey" in my 96LX-450 when driving from 0-~30mph. When I push on the gas it hesitates and does not accelerate smoothly. Initially I thought it was U joints that we bad. I had it to my mechanic for inspection and he told me he checked the U joints and they seemed fine. He went ahead and lubed them up for me also. I am hoping its not somthing more complex in the differential...

As soon as I reach around 35 or so it goes away. Somtimes its worse going up hill or down hill *again leading me to U joint issue*

any Ideas what may be causing this hesitation/ shimmey?

Thanks

 

[sleeoffroad]

Need more info. Lift? Stock? Mileage?

Our experience is that u-joints can feel fine, even to the trained monkey, but they can be worn.

 

[jjhancock]

How many miles does it have? Are they original u-joints that the truck came with? If not, what kind of u-joints are you using? Is your truck lifted, and if so, how much? Give us some more info please

 

[96LX450-Nick]

sorry guys...
truck has 140k on it. All stock except for oversize tires no lift just 33"s I could fit. I am 2nd owener and I have some records of PM but nothing on U joints so I would bet they are original.

 

[landtank]

I'd start with the basics and check out the entire front axle.

 

[96LX450-Nick]

A little more info...
I have noticed that as I drive when it starts to hesitate I can watch the Tach bounce by 100 rpm or so. For example I will be climing a slight incline (road driving) and when it starts to hesitate *(say at 15mph or so ) I will keep the pressure on the gas constant like I normally would to acclerate from a stop and the RPMs will start to jump up and down by 100 rpm or so...
Still a U-joint / front end issue?

 

[BrettinSanAntonio]

If the tach is bouncing it sounds like an engine or vacuum issue. Plug wires? Cap? Rotor? Vacuum leak?

 

[Jacques Villeneuve]

Sounds like either an ignition issue or a tranny slip. How long since the plugs/wires/etc. were changed? Check your fluid levels.

 

[anderaa13]

When it hesitates, does the tach jump up or down? If rpms drop when it hesitates I would guess its something with the engine, if they jump up when it hesitates then its something in the drivetrain

 

[SDTLC80]

Have you figured out what caused yor hasitation problem yet? I have the same problem, when I push on the gas pedle the Tach would jump up and the truck does not go any faster. Feels like a slipperage or something. If anyone has figured this one out please let us know. Thanks!

94FZJ 80 with 3" lift, 35" tires, stock gears, with about 150K miles.

 

[96LX450-Nick]

New Update (Long Term)
- So I noticed that it was spotty on the "shimmey" issue. I thought its probibly not U-joints becase if they were bad I would expect it to be more consistant. The wife had the car one day and took it for an oil change... (I know I should have done it myself) they sold her on this magical fuel injector cleaner that takes 20 minutes and works miracles. When she got home and told me initally I was frustrated she fell for it. To my surprise however it actually "worked". For the following 3 weeks the car ran great without incident. Then it started again.

With this new found info I believe the source of my shimmey is the ethanol they are cutting the gas with. It appears to be causing some issue with flow or exaust on my engine. Does anyone have any methods other then running fuel injector cleaner thru every 3-4 tank fulls?

 

[RedTacoma]

New Update (Long Term)
- So I noticed that it was spotty on the "shimmey" issue. I thought its probibly not U-joints becase if they were bad I would expect it to be more consistant. The wife had the car one day and took it for an oil change... (I know I should have done it myself) they sold her on this magical fuel injector cleaner that takes 20 minutes and works miracles. When she got home and told me initally I was frustrated she fell for it. To my surprise however it actually "worked". For the following 3 weeks the car ran great without incident. Then it started again.

With this new found info I believe the source of my shimmey is the ethanol they are cutting the gas with. It appears to be causing some issue with flow or exaust on my engine. Does anyone have any methods other then running fuel injector cleaner thru every 3-4 tank fulls?

What fuel are you running in it. ? Can you try to fill tank with Shell 91 ? Also Do oyu want to try to run on 2 nd gear (setting on Tranny and going up to the 2700 RPM to see if you hitting stumble again?