Driveshaft Thunk

[hamsterball]

*EDIT!!* Its not the driveshaft. LOOK BELOW! *EDIT!!*

Hi.

I have a 1990 Nissan 240SX 5SPD NON-ABS fastback. I was always having a problem with something in the drivetrain of the car when I bought it.

After like 50-55MPH or higher speeds, when you let off the gas, there is a LOUD THUDDERR-THUDDERR vibrating-type noise that goes away when your foot is on the gas.If you take your foot off the gas at that speed, it will make that THUDDER-THUDDER noise as it is slowing down to 50MPH where the noise finall goes away.

Also, whenever you are pushing the gas in any gear (1,2,3,4) and let go of the gas, it makes a *THUNK!* noise. If i was to tap the gas on and off while coasting in gear, it would go *THUNK*THUNK*THUNK*!!

It makes a *CLUNK/THUNK!!* noise on every single gear shift I do except for when shifting from gear 3-4. It is very loud on 1-2.. like, it sounds like something is hitting.

Me and my friend put it up on jacks.. and he checked my driveshaft for me. It wiggled around alot and was loose. :*(He then told me to get in the car and shift in every gear while looking at the drive shaft.He said it was moving around and making noises (louder than his car when he did the same thing . he has a 240 too) when shifting.

So of course I am thinking it is my driveshaft, but am not sure. I thought I could just balance it or re-align it or something.. but my mechanic said "You need to replace the driveshaft" without even looking at my car.

I am not very sure. I called a few driveshaft shops, and one of them said it sounded like my U-Joint and I have searched on NICO too of course. All I can find is threads about people wanting to buy a performance driveshaft, but nothing about the problem.Except for one thread in which somebody mentions a "Carrier bushing".

Do you guys think I need to buy a new driveshaft? Or should I replace things around the driveshaft?What's your diagnosis?

please help out.Thanks in advance for any assistance.

-Mansoor
Modified by hamsterball at 3:14 AM 9/30/2004

[180fan]

with the drive shaft out, check the joints for play. If you move one side of the shaft, and try to move the other side of the joint in opposite directions and up and down then you need to replace the joint. If it's the carrier bushings, it's at the back behind the diff where it bolts up to the car.

before replacing stuff, find out what could be busted on your own.

[hamsterball]

Thanks for the advice.

I wasn't just replacing it out immediately. I told him to hold off on the driveshaft and fix the other issues.

so besides the carrier and u-joints, are there any other things that I should check for ?(besides inspection for dents and stuff)

I really appreciate that test you gave, it would definitely pinpoint my driveshaft.

Also, if I was to order a driveshaft from "driveshaftshop.com" welded and pre-balanced (in the case that my joints are bad), do you think they would have U-joints included on the driveshaft?(forgive me for being so n00b. I'm at school and don't have my FSM on me right now. I know what a driveshaft is, but am not exactly too sure of what a U-joint is)

[s13sr20chris]

i think a new driveshaft will include u-joints. more likely than the carrier bushing(and what you prob meant) is a carrier bearing. the carrier bushings go on the diff carrier and the carrier bearing goes in the middle of the driveshaft. if the angle is wrong on the driveshaft it will cause the u-joints to bind. this could be as simple as a missing carrier bearing bolt shim. they are the little washers and stuff that keep the bearing in place. easiest fix would be a one-piece driveshaft.

[hamsterball]

well.. i hope it's something simple as a carrier bearing bolt shim..

if it's not, then i might as well just get a 1-piece driveshaft from driveshaftshop.com

oh well.. *sigh.. it will be for the better of the car.

gonna check on driveshaft when i get car back from shop.. ill update.

[hamsterball]

um... you guys?

I feel like a complete idiot. And I'm going to explain why.

There is a great difference between a "driveshaft" and a "propellor shaft"

The part that my friend and I visually checked out, touched, spun, observed during shifting... was not the driveshaft.

IT WAS THE PROPELLOR SHAFT!!The propellor shaft is the shaft that comes out of the front of the car to the rear.

We thought that rod we were looking at was a driveshaft.

Thank the lord that I didn't buy a driveshaft.. Because it is the propellor shaft that is making a noise.

How did I figure out we were touching the propellor shaft just right now?The propellor shaft runs from the front to the rear.The driveshaft is facing a different direction. (basically pointing towards rear wheels; Left to right).

I sound like an idiot .. I know.

Here are pictures:

Propellor Shaft (What we checked out under the car. This is what we touched, rotated, the thing that had alot of movement/freeplay, the thing that made noises when shifting)

And here is what my stupid self said was the problem. I didn't even TOUCH this part!!

See. You learn something new every day.Well, ****.. Now I don't know what to do. It looks like I already did what the FSM told me to, rotate, check play, etc..it's off.

It says right there in the pic too. "If vibration is present at high speed.."I HAVE THAT PROBLEM! More like vibration + NOISE + thunking in every shift.

Can you guys help me out a bit and give me an idea of what I can do?All the symptoms and problems are listed in the first post (please ignore the "it's the driveshaft!" part)..Do I need to re-install the propellor shaft?

Is it possible that BOTH my driveshaft and my propellor shaft are making the noise/THUMP!?

Sorry for the mistake. Thanks again for all the help.
Modified by hamsterball at 3:29 AM 9/30/2004

[hamsterball]

geez.. i'm so confused.

i took it to my mechanic. he said that the propellor shaft and driveshaft are fine...and that it's definitely my differential. (they're all connected)

so i'm really like "wow... wtf"

oH well. VLSD time..

[s13sr20chris]

difference of terminology. generally when i say driveshaft i am refering to the propellor shaft. generally when i say halfshaft or axle i am refering to the driveshaft(s). i imagine that when you shift(if you were under the car) you would see the transmission twist(due to torque) and the rear end pivot axialy on the driveshaft(s) or axles(also due to torque). one of theese reactions is likely your issue.

[gogg]

no pics!