Funny transmission noise

[Nate]

You guys are the transmission experts of the Saab forums...I need your help.

I rebuilt the trans in my '85 due to whining pinion bearings. I replaced all of the bearing, syncros, and primary chains.

In April I got everything back together and drove it 15 miles before I realized I had a bad oil leak coming from the bottom of the timing cover because I didn't drop the transmission to change the timing chain. There were no funny noises during this time except a real quiet whinning that you could hear at idle. If you pushed the clutch in, it would stop.

So I pulled the engine again and changed the engine/trans gasket. Ever since the second pull and installation there is a funny noise that I suspect is coming from the trans.

It happens in any gear, though I can't really hear it in 5th because of the engine and wind noise. At about 1500 rpm to whatever there it makes this noise,

Whhhrrrrraaaa (brief pause) arrrrraaarra (brief pause) rrrrarara (brief pause) raaaa (brief pause) rrraaa (brief pause) etc.

At about 1500 to 2800 the noise is more constant. Between 2800 to redline there are brief pauses to the noise. As soon as you push the clutch in to shift it stops. In the next gear it will do the same thing. If you put it in neutral and rev the engine there is no noise. Sometimes at a smooth constant speed in like 3rd, its quiet.

It is much louder and less consistent than any pinion whine I ever had heard and is quite embarrassing to drive.

The trans has the following modifications: Steel diff cover, aluminum side cover from a '91 and redline mtl.

I suspect either the primary chains or the input shaft bearings. I have replaced the throw-out bearing but it was fine. Any ideas?

[Raul]

thanks Nate for some transmission noise humor. Your transmission noise is funny and am laughing now how funny it is Whats the noise again? Whhhrrrrraaaa (brief pause) arrrrraaarra (brief pause) rrrrarara (brief pause) raaaa (brief pause) rrraaa (brief pause), this is so funny man, ha ha ha ha ha ha.

What gasket did you use at the oil pan? thin metal one or thick paper one? Seems like you did not space the gear set right and you might of overtorqed that big nut and crushed the spacer. Also I don't understand why would you buy upgrades for '85 tranny? they have small pinion and small bearing at counter gear, they are not as good as '89-'90 years

[TRAILINGTHROTTLE]

Hey, Raul...why do you waste all of your time trying to get an old saab to be fast. It seems to me your could just buy a new Lamborghini Murcielago for that.

You are an ass.

[Nate]

I don't mind Raul. This is the last saab forum he can post on except for maybe uksaabs. I don't think there is a better way to put this noise into words...anyways

I don't think its pinion whine since it happens in the lower gears at low speeds. The bearings are pre-loaded at 12 ft lbs.

[Geoff]

I'd get an automotive stethoscope and jack the car up and support it securely and put it in gear while running. Then go around the transmission with the stethoscope to see if you can pinpoint where the noise is coming from. You'll probably hear it all over but you might be able to hear it loudest in one area. It isn't the clutch throw-out bearing is it?

[Nate]

I did not mention that the car has a rattle when idling hot that sounds the same as the noise I hear when driving. It's very intermittent. Once every 3-4 seconds.

I have a automotive stethoscope and stuck it to the transmission when this is happening. I can hear the rattle all over it.

I tore out the clutch and replaced the throw-bearing... it wasn't it.

I'll try to block it up and see what happens.

[Raul]

Ok so nate you did not answer my question, so I can't help you then. TRAILINGTHROTTLE you did not contribute to this thread other than to bash me, you are a troll.

[Crazyswede]

Ok so nate you did not answer my question, so I can't help you then. TRAILINGTHROTTLE you did not contribute to this thread other than to bash me, you are a troll.

Raul....you get points for using a swedish insult.

[TRAILINGTHROTTLE]

no, wait.....

[Nate]

Ok so nate you did not answer my question, so I can't help you then. TRAILINGTHROTTLE you did not contribute to this thread other than to bash me, you are a troll.

What question?

I used a metal pan gasket. Is there even a paper one available? The pinion bearings aren't too tight. The gear spacing is correct. I even bought a set of parallels to check it.

[Jordan]

What about the pilot bearing in the flywheel? I'm thinking if the noise immediately started after your engine/trans separation it wouldn't be something in the trans but in the clutch area. Input shaft not sitting right, pilot bearing, TO bearing (which you changed). Or something in the primary chain oiling system/tensioner/bearings. This is all using the assumption that it was noise free before 2nd trans removal.

[Nate]

Thread bump.

The engine is out of the car again and I have the primary cover off. Everything looks ok, the bearings seem tight. When I drained the oil, the plug didn't have any shavings on it. There were a few metal specks in the oil, but that is to be expected. It has a 1000 miles on the rebuild.

The only thing that is obvious right now is the primary chains seem kinda of loose. I replaced them, maybe it's the tensioner? The Saab rebuild manual has nothing about checking the spring tensioner for wear and they don't state anything about replacing it.

Again the symptons are: a whining coming from the transmission when the car is ilding in neutral and this when you drive it. Raul gets a kick out of my description.

It happens in any gear, though I can't really hear it in 5th because of the engine and wind noise. At about 1500 rpm to whatever there it makes this noise,

Whhhrrrrraaaa (brief pause) arrrrraaarra (brief pause) rrrrarara (brief pause) rrrrraaaarrr (brief pause) rrraaa (brief pause) etc.

At about 1500 to 2800 the noise is more constant. Between 2800 to redline there are brief pauses to the noise. As soon as you push the clutch in to shift it stops. In the next gear it will do the same thing. If you put it in neutral and rev the engine there is no noise expect for the whine. Sometimes at a smooth constant speed in like 3rd, its quiet.

[happyandy]

let me start by saying that I have never been inside a c900 gear box, I have been lucky so far. In my day job I repair forklifts and the noise that you describe sounds just like a forklift engine with a worn out pto chain, which BTW is a lot like a c900's primary drive chain. You said that you have some slack in the chain, I don't know how much is normal but I'm sure it shouldn't be much. Also do you have soild motor mounts? I recently added a solid front mount and now notice a lot more noises than before, including a bit of chain, or possibly T/O bearing noise, but it ran and shifted well before and after the solid mount so I am not concerned.

[Geoff]

The tensioners on those are kind of strange because they are double sided and can float side to side. I also don't remember the spring being very stiff in them. This can make the chain seem loose, but I don't know how lose it should be. Can you squeeze the two sides of the chain together to see how lose things feel?

Did you check the pilot bearing in the flywheel like Jordan suggested? A certain forum member was missing his and the chains got noisy and then broke because the input shaft was only supported in the middle (by the bearing in the trans). The second time this occurred I was lucky enough to be behind the wheel of his car

[Nate]

The the pilot bearing is ok, I replaced it when I was putting this all together last spring. I have a new theory now and it hit me as I was starring right at it when I was turning the trans with a speed handle. I replaced the reverse gears with some used ones because the old ones had a couple of big chips in the teeth.

I noticed that the reverse idler gear spins all the time with 1st gear on the laygear. (duh!) Maybe that is my noise since the gears aren't worn into each other. I don't know how long it would take for them to wear together, maybe I'd be better off putting the old idler gear back in.