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Post by **Zamani** » Wed Jul 02, 2008 9:34 am

Has anyone ever had the middle section of the transmission (the piece which is sandwiched by the 2 casing and holds the bearings) break? This is the 2nd transmission that I had which failed on me. $$$$. It totally polluted my gearbox oil (all silver now due to aluminum shavings) so I hope it has not spoiled the synchros or gears.

Mats · Post by **Mats** » Wed Jul 02, 2008 11:18 am

Never heard of it, what actually happened?

gtv6sa · Post by **gtv6sa** » Wed Jul 02, 2008 11:43 am

sounds like the sandwhich bearings collapsed

Post by **Zamani** » Wed Jul 02, 2008 12:35 pm

Mats,

I wish I knew what was the root cause. This 2nd transmission has the same component failure as my last one. I'll try to get some pics when I'm at my mechanic's place.

GTV6sa,

I didn't look at the part which failed yet, but my mechanic said it's the aluminum piece which holds the bearings. I don't think it's the bearing themselves.

Prior to this the transmission made funny rattling noise, which I originally thought were the 2 bearings in the clutch cover. They made the noise regardless of the clutch's position. I think from now on I'll just check the transmission oil every 6 months to see if there is so sort of failure.

Luckily the differential is ok, my lightened gear set is ok too

. After this I'll stock one spare transmission.

MD · Post by MD » Wed Jul 02, 2008 1:27 pm

Zamani, that's very odd. Been driving transaxles since they came out, never had that happen. Shredded a wheel barrow full of rubber donuts but that's another story..

twinspark6 · Post by **twinspark6** » Wed Jul 02, 2008 5:40 pm

please do post some pictures.

Barry · Post by **Barry** » Wed Jul 02, 2008 8:46 pm

The sandwich plate has reinforcing webs that support the bearing..Much like superchargers of old,the webs are thin and do break off under normal use.
This will leave a section of halfround ally to float around the box,more critical though is the bearing is even less supported now.
In all the years with Alfa`s Ive probably had 5 such failures..
Never on my own cars though..obviously these were channeled through the workshop..

Post by **Zamani** » Wed Jul 02, 2008 9:21 pm

Marcelo,

I'll try to snap some pics tomorrow.

Baz,

In your experience what was the usual cause? Just bad luck or something? As you said even under normal driving conditions this could happen. I guess 5 in 20-30 years could mean, bad luck.... ??

Murray · Post by **Murray** » Thu Jul 03, 2008 1:43 am

Z about 4 years ago I rebuilt my transaxle and at the time I discovered a large chunk of the intermediate plate was cracked and came off in my fingers (see highlighted area) .What I did was fabricate a half-moon brace out of steel similar to the one the factory used which is seen at 7 o'clock in image 1.I didn't take a photo of my fix at the time.My thinking was that this would help stabilize the bearing in this area where the casting was obviously weak.It's been about 60k kms. and many track miles since and so far so good.

Mats · Post by **Mats** » Thu Jul 03, 2008 3:18 am

Hang on one minute here, Roller bearings??

All the Gearboxes I have come across have angular contact ball bearings with loose inner sleeves, why the h-ll are there tapered roller bearings in your gearbox?

As a theoretical side note: A brace might look like the correct solution but may be counter productive as a very stiff section will take up a lot of the force from the bearing and focus it in a single point like one of the screws. I'm not saying it does in this instance but making it stiffer isn't always a way to make it stronger.

mjr · Post by **mjr** » Thu Jul 03, 2008 9:59 am

that area looks to be subject to stress from both the bearing, but also the two bolts. Im not surised that area is weak, stress from 3 different directions compounded in a very small area, over time and mileage = premature embrittlement. There is very little material around the lower bolt in the first place. .Im surprised how much porosity there is in this casting though, that is piss poor, even for the early eighties. Are these boxes thoriated at all? anyone got a giger counter?

Barry · Post by **Barry** » Thu Jul 03, 2008 10:49 am

Bingo Murray !! Could not find my pics ..THanks.

Murray · Post by **Murray** » Thu Jul 03, 2008 3:00 pm

why the h-ll are there tapered roller bearings in your gearbox?

Good question Mats - one to which I don't have an answer

This is a 1986 Isostatic link transaxle which has been in my car since I bought it 6 or so years ago.Should I consider myself privledged or was it a production run change - not that Alfa would do that eh!

tectoteam · Post by **tectoteam** » Sat Jul 05, 2008 12:40 am

In some models(ol ones ?) in the middle flange, its not tapered, but cylindrical roller bearing on the clutch side. and roller beaering on rear side on both axles.

Mats · Post by **Mats** » Mon Jul 07, 2008 12:02 am

I find that incredibly hard to believe, there would be severe problems when reversing drive on the pinion if you don't have anything to hold it in that direction.

Broken transmission