901 5 speed Gearbox

landyman96 · 07-11-2022, 10:32 AM

Hello Pelican members,

I recently purhcased a 1966 912 project. I put it all together, rebuilt the carbs and finally took it for a drive on the public road and when i hit 50/60 miles an hour i get an awful growl from the gearbox. It seems to be worse in 5th gear but not sure if its 5th gear related or speed related. When i down shift to 4rth it still has this growl. I drained the oil and it had a bit of metal on the magnetic plug but nothing too extreme. The oil level was 1 liter low. When i put the oil to the sun it had a bit of metallic shine to it. I put some generic 80w90 oil to see if new oil would help but it didnt. I know the 901 gearbox should use Swepco oil but thats what i could get on short notice and before I spend the big bucks on expensive oil I wanted to see if the correct oil level helped at all. Also, I will use this oil as a flush.

Anyways my question to you guys is, what are your thoughts? Bad pinion bearing? Bad 5th gear bearing? The gearbox shifts beautifully, much better than my 915 which is really frustating. It also has red gasket sealant so I know someone has already been in there. What would you guys suggest doing next?

Is rebuilding a 901 box decently easy? I rebuilt my 3.0 911 engine so I am mechanically inclined per se. Are parts available, are they ridiculously expensive? Like all of us I am on a budget. The below is my car, was hoping to make it a rolling restoriation but this potential gearbox issue has really put a stop to that idea. Odometer reads 77,000 miles and this car hasnt driven in 20 years.

landyman96 · 07-11-2022, 10:38 AM

More questions, I cleaned and packed the front bearings but I havent even looked at the rear wheel bearings. Could that create my growl? Rear wheels dont have any play. This is my first 901 gearbox, how quiet are they in 4/5th gear when in good shape?

landyman96 · 07-12-2022, 08:32 AM

Bump

JT912 · 07-12-2022, 12:46 PM

With the clutch in at speed does it still make the growl? Could be CV joint or bearing or transmission.

Steve F · 07-13-2022, 03:24 AM

You might have better luck posting here..............

https://www.912bbs.org/forum/

landyman96 · 07-13-2022, 03:26 AM

John, I will try the clutch thing. The CV joint had very loose bolts and where covered in grease even though the boots are fine. I will inspect that next. thank you.

landyman96 · 07-16-2022, 02:37 PM

Hi John, one of the CV shafts is definitely bad. It has a hard spot when turning the wheel. Hard spot goes away when you remove the CV shaft. Not 100% thats my growl but the CV joint is definietly bad. While testing I noticed that the noise is speed related not gear related. So will do it only 50+. It only has the noise under load.

Will a newer CV shaft/CV rebuild kit fit my car by any chance?

P912928 · 07-25-2022, 10:31 AM

Hi, just wondering if anyone can help with the 912 1967 original gearbox number. First it is noted as a 901.301.101.0R number and then it says: 99/07. And final number is hard to read, but looks like:
Ko. 2476/2. And final number does not correspond with how a 911 serial number is listed.

JT912 · 07-25-2022, 10:58 AM

Quote:

Originally Posted by P912928

Hi, just wondering if anyone can help with the 912 1967 original gearbox number. First it is noted as a 901.301.101.0R number and then it says: 99/07. And final number is hard to read, but looks like:
Ko. 2476/2. And final number does not correspond with how a 911 serial number is listed.

Pictures would help. Are you certain it isn't a 901/07? Or maybe a 29/67? The KO might be a factory rebuilt unit?

cmpski · cmpski's Garage

Go to www.912bbs.org as recommended. It is focused on 912 only.

jess p · 07-30-2022, 02:20 PM

Before you attempt anything on the transaxle make sure it’s not something on the drivetrain, Cv joints. Jake up the rear, is there any play on each rear wheel, ie wheel bearings. Does it growl in every gear. The 912 5 speeds had a 901 type transaxle with designation 902/1, 902/2 and 902/5
There are 6 bearings in that transaxle, carrier bearings on each side of the differential, 2 bearings for the drive shaft and 2 bearings for the pinion shaft. I’ve rebuilt a few of these transaxles and the bearings are very robust. If it is a bearing inside the transaxle changing fluid will not help, it’s too late for that.

roy gray · 07-30-2022, 09:41 PM

Hey bro,greetings from the Pacific NW!My first thoughts are,It's a wheel bearing.Manual transmissions very rarely groan loud enough to be noticeable.Metal in the oil of an old 901 or 915,totally normal.Also,worn rear wheel bearings very often show NO excessive play.So wiggling the wheel tells you nothing.Also,CV joints don't groan,ever.On a rear wheel drive car they generally make no noise at all.Is the transmission worn out? very likely.You already said it shifts better than your 915,so....Get the rear end off the ground.You'll need a helper,and a long screwdriver,like 3 ft.Put the tip of the screwdriver on the underside of the bearing housing section of the banana(where the axle passes through)and have your helper spin the wheel,while you put the screwdriver handle in your ear.Do this caveman test on both sides.After you get the hang of listening to the variuos noises,you will notice a huge difference between a normal bearing,which is just faint whirring,and a bad wheel bearing,which sounds like rocks in a tumbler.You can also do this test engine running,car in gear with a helper,but I can't reccomend it to amateurs,no offense intended.I've been doing this for 40 years and still don't like doing it myself.If you built a 911 motor,you can figure this out.Cheers,Roy.If you need additional help,email me at rg3po@comcast.net