Abnormally Loud Chatter From Getrag 284

[jmgtp]

I’ve noticed that my “new” Getrag 284 that I installed with my LX9 swap is making some loud gear rattle. The trans is only new to the car, not a new unit. I purchased it years ago as a good working unit on the sellers word. It is supposedly from a 92 lumina and had roughly 90k miles.

The symptoms are that at idle with the clutch engaged (pedal out) there is a loud chatter. My old Getrag/clutch chattered but this is a whole other kind of chatter. It is almost like a metallic slapping sound and is considerably louder than the old clutch chatter. It sounds almost like an engine that has a really loose rocker arm.

I can make the sound go away instantly by pushing the clutch pedal. On the other hand with the clutch engaged I can make the sound go away by raising the engine revs. Sometimes ~1000-1200 rpm will make it go away, sometimes it needs ~1500.

I want to also say that on a cold start it doesn’t seem to be that bad and worsens as the engine/trans warm up. However, this could be a direct result of the engine idle speed at a cold start which is much higher than a hot idle speed.

I’m just trying to understand the problem at this point and determine whether it is the clutch or a loose input shaft bearing in the trans or just abnormally loud gear rattle. If it was the release bearing I imagine it would be worse when I pressed the clutch pedal and loaded the release bearing up. Is there a way to quickly determine if the issue is clutch or input shaft or other?

The trans currently has Redline MTL in it. It doesn’t like it and the shifter is stiff but it is all I had on hand at the time. I’m going to drain it and fill with Pennzoil Synchromesh. I’m thinking that it won’t make a difference for this issue but I suppose it is possible.

[NateD4]

Is it a dohc trans?

If not I have two spare 5 speeds and parts to rebuild one if you are interested.

[pocket-rocket]

The Getrag 284 IS the DOHC transmission.

John, Since you and I both know the 284 is pretty picky when it comes to fluid, I would change to the Synchromesh before going any further. I believe Michael from FFP ran Redline in his and found it didn't like it. Others have tried other stuff as well to find better or get around the dealer price tag, but everyone seems to go back to Synchromesh to make the trans happy and make it shift nice again. At least we know Pennzoil makes the Synchromesh for GM. How much does that run? I still have yet to find it around here, and I doubt it's still $10 a bottle at the dealerships anymore since the bottle has changed and all...

[robert 1980]

I just picked up two bottles of it at a gm dealer.17 bucks my trans has been doing the same since i installed my spec clutch.But i have a fresh one going in very soon.

[hoosierloser]

My brother picked up a 92 grand prix with a 284 about a month ago. We were having a hard time trying to figure out what the problem is with the trans, which is why he got is so cheap. But the symptoms you described are EXACTLY the same, except it sounds more like a bearing problem a whirring noise when the clutch is engaged. And it goes away after 30mph and when the clutch pedal is depressed. We are thinking input shaft bearing is the only possible part that could make this noise under the given circumstances.

Also I think the noise is at all RPMs while sitting still and clutch engaged, but under load above 2000 or so it goes away.

[jmgtp]

I got the Pennzoil Synchromesh for $5/qt at Advance Auto. I haven't done a drain/fill yet. It is what I ran in my old 284 and it liked it. I just didn't have any at the time and I wanted to start up my new motor without spinning a dry trans so in went the Redline.

I fear that it could be the input shaft bearing. I bought this trans as a good working unit and it just went in the car so that would suck completely.

I know what the normal 284 clutch chatter is, and this isn't it. I'm getting a 'clack, clack, clack' sound and it is louder than the 'normal' chatter. Ever hear an SBC with a loose rocker? It is similar to that in sound.

Mine seems to disappear over 1500rpm in all circumstances. Sometimes even just a hair above idle speed and it is gone. And in all cases, pushing the clutch pedal causes the noise to stop. I've also noticed I get some metallic chatter as I slowly ease the clutch out to allow the car to creep at idle.

Step 1 is changing the fluid. If I am incredibly lucky all I am hearing is excessive gear rattle caused by improper fluid. I might get around to it tonight.

The noise seems to worsen as the car warms up which could be a two fold issue, one the idle speed decreases and two as the trans oil warms it thins and doesn't deaden gear clatter as much or perhaps doesnt cushion a loose input shaft bearing as good as when thick/cold.

Hoosierloser, a whirring/whining sound would make sense that it is a bearing. However, I did google my issue some to get a more general perpsective and across all makes/models many people report a clacking type sound as a worn out input shaft bearing.

[hoosierloser]

We plan to start tearing into his car soon to remove the tranny for a reman unit. Then hopefully we can inspect the old one and get down to the bottom of this noise. Looking around this forum I have seen atleast one other thread targeted at getting someone to create new input shaft bearings for these trannies but nothing ever came of it. Unfortunately it looks like this problem is shared by more than a few people all with similar symptoms.

There has to be a way to get someone to make a new bearing for these things, I would hate to see all these cars parked because of one bad bearing in the tranny.

[jmgtp]

Well, I don't think the input shaft bearing going south is a common problem at least. The 284 is more well known for wearing out the synchronizers. And it is true that once something breaks in it, the parts just are not available to fix it, you need to replace the whole thing.

If you're ripping into the car be sure to remove the accumulator on the clutch line. It is a round cylinder bolted to the top of the trans. The fluid from the clutch master cylinder is forced through this cylinder and then on to operate the slave cylinder. The cylinder basically acts as a giant restrictor in the hydraulic line intended to smooth things out. But in fact I found it to be detrimental to a good clutch pedal feel. After removing it and going with a line direct from master to slave cylinder the clutch pedal feels so much better and clutch actuation is much improved. I used air brake hose, it has not degraded at all and its been in there at least 10 years I'd guess. I think it was rumored that in '93 GM no longer equipped with the accumulator but I don't know if that is fact.

Back on topic... I switched to the Pennzoil Synchromesh last night. I didn't get a chance to drive the car though (it was blocked in). I did however fire it up and let it idle for about 10 minutes. It was idling around 800 rpm and the 'chatter' seemed MUCH reduced and only the normal chatter. I have some sense of relief from this but the real test will be driving and then idling since before it seemed the worst only after it had been driven a while and things were hot. Shift lever feels much better rowing through the gears as well.

[pocket-rocket]

Marc at TCE also makes new roll pin retained nipples that adapt to AN line that replace the barbed ones used in the original clutch hydraulics. I have a set as a "door prize" from the last 60v6 meet. I was more than happy to get something so simple despite other cool things being there since my air brake hose has popped off once (and only once, thankfully). What sucked the most about doing air brake hose was getting it warm enough to press onto the barbed fitting, and you can't heat the fitting and press it on, or it melts the inside of the line and seals the hole shut... I don't know how I know that one...

[gpse3400]

I've had two of these gear boxes and they both had gear rattle, my orginal one more than the one I have now, eitherway it's not a pleasent sound but its normal. Sometimes I disengage the clutch at the drive-thru so we can all hear better as the sound really reflects off walls.

When I busted my gear box , it made sounds that I will never forget.

Definately use Synchromesh. The Aftermarket seels the slave cylinder with the accumulator from what I know as I bought one a year ago. And if I can recall I saw the accumulator in my '93 FSM...

[jmgtp]

Speaking of master/slave cylinders, I'm still using my 1991 originals! They work perfectly and don't leak a drop. It's just really surprising to me that they've held up so well.

Anyway, my engine is still running like crap. Trying to figure out a manifold vacuum issue (MAP sensor is indicating nearly NO vacuum at part throttle and ~2k rpm, but thats for another thread). Once, the engine is sorted out I think I may raise the idle from 800 to 1k rpm. That extra 200 rpm seems to really smooth out the getrag noises considerably.