I have an 84 Firebird S/E that has always had drivetrain problems. The transmission's input shaft had to be replaced two years ago because of three broken teeth, and there has always been a whining sound coming from what I presumed to be the transmission. The car has a stock 3.73 posi rear end that makes a rumbling sound while at speeds greater than 60 mph, and last year right before I stopped driving it, it had been producing a loud knocking noise from what sounded like the rear of the car. The knocking occurred in every gear, and became more frequent when the car accelerated. I never really checked the car out to see what the problem was, but it always seemed like the rear end to me. Has anyone else had a similar problem? Do you think it could have been the rear making the whining noise, not the transmission?

 

Yes.
Yes.

 

What was wrong with your rear end? Why did it make that noise? What would I have to do to fix it? Please help.

 

I didn't say I had had the problem. Lots of people's rears whine. Many, if not most people experience whining after they have their gears swapped. Since you didn't, the whining probably started due to wear. I'm also going to guess that you only hear the whine on accel or deaccel.

A one-clunk, check your trans mount. But it sounds like you could have nicked a gear. There's probably a few other things you could have done, but this is the one I know of. Unless you're pretty experienced and have the tools, you're not going to fix it yourself. So whoever fixed it for you could better diagnose it first. OR, you can just let it go till it breaks. That way, you KNOW what it is. Sorry, I'd think about it more if I wasn't late for class.

 

Yep, the whine occurrs on both accel and deceleration. Do you mean a nicked gear in the transmission or the rear? The reason I ask is when the transmission's input shaft was broken, the sound was coming from right under the shifter console. Now the sound is definitely not coming from the same area, its more to the rear of the car. Also, when the input shaft was broken, it would produce a clunking noise even if the car wasn't moving. All I would have to do was shift into gear from a stand-still and it would start making noise. Now the clunking only occurrs when the car is in motion, and it happens in every gear. I'll still check out the other things you suggested, though. By the way, thanks for your help :hail:

 

go check your ujoints (your driveshaft shouldn't turn when you grab and twist), they go bad and are a fairly easy fix. also you could just pull the cover off out back and take a look-see if everything looks intact on the ring and pinion. finally, to check your transmission mount, try crowbar-ing your transmission upwards....it shouldnt.

 

Thanks man, I'll definitely check all those things out. I was thinking of replacing the ring & pinion anyway, I really don't like the 3.73 ratio. I was looking at the technical data for the '84 models and I saw some of the other gear ratios were 3.08, 3.23, and 3.42, and I was thinking of changing to one of those. Which should I pick? Do they even make replacement ring & pinions at those ratios? I'm not looking to totally change the way the car drives, I just want to lower the rpm's a bit for driving on the highway & at higher speeds.

 

what eng. do you have? do you plan on making it faster as some point or just to drive?

 

It has the LG4, 305 4bbl V8. Right now its just to drive. I want to put an exhaust system in it, and thats probably the full extent of anything aftermarket I'll put in the car. I'd like to get some more horsepower out of the engine, but someone told me a good exhaust system, and a better camshaft (and who the hell knows what else) would be needed to get the HP of the LG4 up to around 200, and I really don't know anything about stuff like that.

 

Unless what you're really looking for is a 4cyl, I think those gears are your friend right now, whether you want the car "just to drive" or not. You could probably step down a notch or two on the ratio, but if you go too far like to 3.08 or even 2.73 you're gonna FEEL like you're driving a 4cyl.

If you're just looking for that extra mpg, or that couple hundred rpm drop, 3.42 isn't terrible. And sure, everyone makes them. Look at Summit's or Jegs' websites and look to spend about $200 for a set. And of course that then brings into the picture whether or not you want to replace your carrier and axles as well. You might be able to get it all from a junkyard, but new, it can add up fast, and aside what the parts cost, you're not gonna save any by doing it yourself because the typical person can't. For a shop to replace everything will probably cost you another $200-300.

Did you try any of the 3 things I suggested?

 

That is what I'm looking for, but you sound like you wouldn't really recommend it. Would a 3.42 make the car accelerate noticeably slower? If so then maybe I will just stick with 3.73. Oh, and I didn't try anything you suggested yet, because I'm at school and the car's at home 1.5 hours away I'm going to try to get a ride home tomorrow though so I can check it out.

Dammit, I really need a car.