I have a 91 Dakota with a 2.5L, manual trans. New clutch, Ujoints. I bought the truck needing the clutch and ujoints and head gasket so I never got a change to test drive. I did test drive after the head gasket replacement, motor runs fine. The drive train shakes bad, especially when shifting into 3rd, seems like possibly a drive shaft is bent, it looks like it had previously broke free since I can see scrapes on the shaft and dents/scratches underneath the bed and a bent gas tank bolt. I can turn the drive shaft about a quarter inch back and forth (turning it). I can also, when in gear, push it back and forth from the rear bumper and watching the rear end I notice where the shaft goes into the rear end, it moves up and down. (the whole rear end moves up and down, like its twisting) There is also a ticking sound while coasting coming from the rear end, maybe a wheel bearing or something. I dont want to buy a bunch of stuff I dont need. Any suggestions from anyone or similar problems? Thanks.

 

Welcome to the site. I moved this thread to the first generation Dakota section,.
FF

 

Sounds like you got lots of problems. Yes bent driveshaft is a possibility as well as a bad pinion bearing and a bad axle. I say rebuild or replace the rear axle all together as well as the driveshaft.

 

Drive the vehicle and note the engine speed at which the vibration (roughness) is most pronounced. Now shift the transmission to a different gear and bring the engine speed to the same point. If the vibration occurs at the same engine speed (rpm) regardless of which gear the transmission is in, the driveshaft is NOT at fault since the driveshaft speed varies. If the vibration decreases or is eliminated when the transmission is in a different gear at the same engine speed, refer to the following probable causes...1, Bent or dented driveshaft. Inspect and replace as necessary. 2, Driveshaft and/or companion flange out of balance. Check for missing weights on the shaft. Remove driveshaft and reinstall 180- from original position, then recheck. Have the driveshaft balanced if problem persists. 3, Loose driveshaft mounting bolts/nuts. 4, Worn transmission rear bushing.

 

Yes, today I am going to take the wheel off and inspect the brake on the driver side where the clicking is coming from, the driveshaft does have a dent in it from when it previously broke loose. I am looking up a shop that can check it for balance today. Im thinking it may be a rear end or possibly from reading other threads the leaf springs could be old and they are wrapping, letting the axle roll back and forth.

 

Im going to take your advice and check the speed to shaking thing. I said the thing shakes but its more like a SHUDDER, I hope it isn't the transmission. I like the idea of flipping the driveline 180, I thought about doing that yesterday but I thought it would have the same results. The axle rocks back and forth on the leaf springs makes me think possible spring replacement but there is still that clicking metallic sound from the rear end.

 

I noticed you copied your comment from the shop manual while reading it today. Anyway, I found the rear U-Joint straps were loose, that took care of the clicking and some vibration. I still get alot of shudder at certain speeds from the transmission, when I push in the clutch it goes away. Im thinking its the transmission. Fresh fluids in it but maybe its bad. Im going to change the rear end fluids today and see what that does. Im taking the driveline to a shop on Monday to have them check it for balance. It could also be a motor or trans. mount. I am able to move the transmission from side to side easily, but all mounts look solid.

 

Make sure to take a good look at the fluids that come out. Be sure to look for pieces of metal or other material in the oil. That can be a tell tale sign if something is wearing, worn or past its lifetime.

Sonmetimes its the simple things that can localize a problem quite easily.

 

I have put about 30 miles on the truck since posting this thread. The problem seems to lessen in severity as I put miles on it. But the shudder is still there at certain low RPM speeds. At higher speeds it goes away. It truly seems like a bad transmission mount, but the mount looks perfectly fine. The oil in the transmission as suggested by someone else to check it out was fine, just old fluid. I replaced it with 10w30 as suggested by Dodge. I put in Synthetic. If its not he transmission mount Im thinking its the bearing at the end of the transmission where the yoke slips over the splines of the shaft coming out of the transmission. It seems a little shaky there. At low RPM that is where the most vibration comes out of any engine and trans. So its got to either be a mount or bearing. I cannot change the bearing myself, well I could but not sure if I want to undertake splitting the trans case.

 

Have you replaced the driveshaft yet?

And if some of the shudder goes away then the driveshaft probably killed bearings or the mount.

One way to check would be to put the truck up on stands and try to move stuf around and see what moves