1986 bronco shuddering

[famousguy_fsas]

so my 87 bronco just got stolen by the cops so i just bought a 86 tonight and its super clean and runs great. plenty of power. but..... it has a sort of shudder. mostly noticable durring acceleration. but also at cruising also. its the super worst at about 35 mph. it shifts fine and everything. it almost feels as if the truck was being tugged on from behind. kinda like pullin a car with a rope and having slack in the line then tightening the slack and feeling that tug. its like that all the time. what is it. is it bad. is it expensive? o its a 5.0

 

[BroncoJoe19]

Could be bad universal joint/s in the driveshaft.

Could also be a bent or out of balance driveshaft.

 

[famousguy_fsas]

whats the likely hood it would be a bad trans? cause it seems to shift fine and strong. i know the guy replaced one universal joint in the shaft. the rear one i thing. so maybe its the one closer to the trans. any other ideas so i can check every possible option. thank you

 

[famousguy_fsas]

o and also i dont think it would be the out of balance driveline cause its not a vibration. its more of a tugging?

 

[BroncoJoe19]

I am sorry, I can't relate to the tugging sensation.

It isn't uncommon for more than one U joint to go bad at pretty much the same time. Unless they are REALLY bad it is next to impossible tell that they are bad without taking them out, and inspecting them. Well at least that is the case with my limited experience.

With the few I have replaced, I noted a vibration, that was stronger at higher speeds, but that it was more noticible when I applied throttle. On some there was a noticable squeeking sound. Its pitch changed with speed.

Should you need to tackle this project, this post may be helpful

http://broncozone.com/forums/index.php?showtopic=12560

 

[Bronc76]

The shudder you describe sounds like it could a faulty torque convertor or valve body malfunction if its not the drive shaft. When was the last time the engine was tuned?

 

[famousguy_fsas]

engine was rebuilt 2 years ago. i just talked to a friend who know like everything about cars and he said its not my tranny casue if it was i would know. he said it most likely somethin in my drivline. prob my universal joint. he told me how to check it so im going to do so now. if thats the prob then i work at pick and pull and will just grab a new driveline at work tomorrow at work.

 

[Maddog]

Alright my turn,

I had a shudder in my 91 Beast. I took the drive line in had it balanced replaced the U-joints only to find one of my rear wheels is cracked. The tugging could be totally different problems. Maybe the previous owner hit a curb went off road at a speed higher then one should ect.. Try a balance job.

The tugging need some more specifics:

Is it constant?

If not what range, rpm, speed?

does it happen in all 4 x modes of operation?

Coasting?

Accelerating?

Have you jacked it up off the ground and tried turning the wheels?

Depending on the year what about the outer wheel bearings going bad, yeah they usually make noise but on the off chance they're not making noise or you can't hear it when its running down the road. What's the e brake feel like? is it operational? If there's too much tension you might just get a tugging sensation.. Any odd smells after operation?

GL

 

[famousguy_fsas]

k so new info. so i had just bought the truck like a day before i started this post but now its been almost a week and im drivin it more and im realizing thats it feels like a tugging but its also just a heavy vibration. it does it when just cruising. when im on the gas gettin speed its smooth. another thing i realized about it is that my truck shakes more when at idle and in drive more than it should. so at a stop i put it in drive and stepped on the break and also gave a little gas and realized it shakes real bad. so i now know its not the driveline. its something thats constantly turning when the truck is on. my guess is torque converter? any ideas?

 

[BroncoJoe19]

Does it shake while at idle when it is in neutral or park?

 

[famousguy_fsas]

it shakes while in park and in drive when at a stop. its like a heavy vibration. like not a fast one more like a have a big beefy suped up motor. and i dont.

 

[Maddog]

Check you compression in all cylinders.

GL

 

[famousguy_fsas]

so no one thinks it could be the t converter?

 

[BroncoJoe19]

Could it be a misfiring cylinder?

You have 8 cylinders, each must have gas, and then spark at a designated time for the engine to have the power it should have, and to run smoothely. If you have a dead miss in one or more cylinders, or if by chance a pair of wires got crossed, then it would run poorly. I think a dead miss would explain your tugging sensation.

Make sure all your wires are fully seated, both in the cap, and onto the plugs.

Next take a picture or your distributor cap, and where the wires go.

Then pull the cap and see if it is clean inside, and if the contacts look new, or pitted. (dirt and grease may conduct spark, or pitted contacts may offer too much resistance for the spark to jump, and then travel down through the wire/s to the plug/s.)

If pitted, replace the cap, and rotor. (change only ONE WIRE at a time) The cap can go on in only one position. If you happen to put the wires on in the wrong position the engine will not run at all.

Next step would be to pull the plugs and examine them, also the wires can be tested with an ohm meter.

 

[suprakilla1425]

Although it wouldn't explain your "tugging" problem. The shaking at idle could simply just be a broken motor mount. I know my fathers 86' f-150 is broken and his shakes like an old muscle car (i-300 /emoticons/[email protected] 2x" width="20" height="20" />). My bronco is also starting to shake itself. I'm convinced that it's a motor mount. If I sit in drive with the brake on and give it gas, it feels like I'm about to twist the motor from under the hood. So, check it out just a thought.

 

[Maddog]

Ok.. One more question. After you get done checking all the, firing order and if your wired right, plugs, timing (you might even have to go as far as checking to see if your timing gears are lined up properly) and compression. Does it have a visible shudder (you can see the engine moving in time with the shuddering) or is it audible (metalic, exhaust or odd noises from the tranny) or both? I would also check my flywheel to see if the bolts are tightned down and include the torque converter if you haven't fixed by then. Defenitly check the bolts and motor mounts (could be a broken bolt don't just check for worn or torn motor mounts).

 

[famousguy_fsas]

all my ignition system i just put in. new cap and rotor new coil new wires new plugs. all eccel stuff. honestly it truly seems to run great engine wise. when driving it i feel as if its comin from somewhere behind the motor. ie.. torque converter tranny. ect.... when its doing the shuttering i do notice the exhaust sounds kinda poppy. and i know u would say well then thats ur engine. but still i dont feel that it is. i feel like whatever is causeing the shutter is just puttin more stress on the engine and making it work harder causeing the shudder. i gues u would have to drive it. hmm. gonna take it to my dad and let him drive and see what he thinks.

 

[Bronc76]

The shudder you describe sounds like it could a faulty torque convertor or valve body malfunction if its not the drive shaft. When was the last time the engine was tuned?

i know its alot of work but i still think that it might be the torque convertor if you have gone through and eliminated everything else that you could think of

 

[BroncoJoe19]

He said... "it shakes while in park "

Would the torque converter cause that?