Alfa Romeo Forums banner

1 - 10 of 10 Posts

·
Registered
Joined
·
39 Posts
Discussion Starter #1 (Edited)
This 750D keeps throwing me curveballs. Every time I remove another bolt it opens up another series of words along the lines of "What in the hell is this? what was the PO thinking?!".

This time, while rebuilding the driveshaft, I've come across a strange assembly of parts resembling the driveshaft center support bearing. When it was removed I thought it looked a bit...off, but had other things on my mind while removing the engine, and gearbox assembly. So now that I've gotten to the reconditioning of the prop shaft. It's apparent this is another abomination created by the PO. What I've come across is a bearing of another origin, bastardized to somewhat fit this car. The bearing itself is of a smaller OD, not that the rubber bushing is factory anyways. The bushing rubber is stamped with 'BMW', but no other identifying marks, or numbers. There was a 10mm thick strip of rubber wrapped around the bushing to seemingly make up for the improper fitment of the wrong bushing. The factory bushing I received from CenterlineAlfa[https://www.centerlinealfa.com/driveshaft-axle/930] doesn't even fit in the bushing cap that was removed from the car.

So, my issue is this. What am I missing here? It seems I'll have to source a used bushing cap, and the metal exterior support for the bearing.

Cheers,

Tyler.



 

·
Super Moderator
Joined
·
11,550 Posts
I believe (but could be wrong, as usual) you can source parts from ANY 101 through 105 1300 -1600 that used this type support. Try Keith Goring at Alfa's Unlimited in Connecticut, Karen McGowan at Alfa's West in Colorado, or Dean Russell at Trail Auto in Michigan. They will have the bits required for a correct re-creation of the original type assembly.
 

·
Registered
Joined
·
7,685 Posts
The primary piece missing is the aluminum bearing carrier which can be found remanufactured at http://classicalfa.com/products/750%2d025{47}1-PROPSHAFT-CENTRE-BEARING-MOUNT-%2d-750,-101,-102-&-106-SERIES.html...The cup slingers on each side are not necessary and were left off some models at the factory and sometimes create more trouble that what they are worth as they sometimes spin causing some unwanted noises. There are springs in there that are impossible to find and you don't need them either.. The bearing is sealed and the outer race is pressed on the carrier then together the unit is pressed on the shaft. The rubber donut is slipped on over the carrier and strapped to the chassis with two bolts with yoke strap you have leaving everything stationary while the shaft and inner race of the bearing spin when moving.

The failure mode (after many many years and thousands of miles) causes the bearing to heat up and literally melt the rubber donut. If your donut looks like it has been in a BBQ grille the bearing is bad.. real bad .. and there won't be an expected bearing failure noise to accompany it necessarily.
 

·
Registered
Joined
·
39 Posts
Discussion Starter #5
Hi Tyler,
Attached are pictures of my 101 half-shaft for reference in case that helps.
Matthew Fox
1962 Giulia Spider
Very helpful, Thank you Matthew! It turns out the strap was modified to accept the bastardized bearing. So in order for me to get back to stock, I'll only need the bearing strap (as mine was modified for this other bushing), and the aluminum bearing retainer.

I believe (but could be wrong, as usual) you can source parts from ANY 101 through 105 1300 -1600 that used this type support. Try Keith Goring at Alfa's Unlimited in Connecticut, Karen McGowan at Alfa's West in Colorado, or Dean Russell at Trail Auto in Michigan. They will have the bits required for a correct re-creation of the original type assembly.
Thanks a lot for the leads, Gordon. I called Keith, as he's somewhat close to me, and he was an absolute pleasure to talk to. He had the parts I needed, but gave me the number to KTR Motorsports, which is even closer to my location. I'm now awaiting confirmation they have everything before I take a short drive to pick things up.
 

·
Registered
Joined
·
39 Posts
Discussion Starter #6
The primary piece missing is the aluminum bearing carrier which can be found remanufactured at http://classicalfa.com/products/750%2d025{47}1-PROPSHAFT-CENTRE-BEARING-MOUNT-%2d-750,-101,-102-&-106-SERIES.html...The cup slingers on each side are not necessary and were left off some models at the factory and sometimes create more trouble that what they are worth as they sometimes spin causing some unwanted noises. There are springs in there that are impossible to find and you don't need them either.. The bearing is sealed and the outer race is pressed on the carrier then together the unit is pressed on the shaft. The rubber donut is slipped on over the carrier and strapped to the chassis with two bolts with yoke strap you have leaving everything stationary while the shaft and inner race of the bearing spin when moving.

The failure mode (after many many years and thousands of miles) causes the bearing to heat up and literally melt the rubber donut. If your donut looks like it has been in a BBQ grille the bearing is bad.. real bad .. and there won't be an expected bearing failure noise to accompany it necessarily.
Thank you for that bit of information. It's good to know I don't need the slingers. I just put a huge order through CA, I wish I had realized I needed the aluminum bearing retainer beforehand. Thankfully, it seems I can source some good used pieces in my area.

Interesting, I assume the aluminum material in the bearing retainer has a lot to do with the bushing failure before the bearing gets bad enough to make noise. As aluminum heats quickly, and holds heat very well. So this was a manufactured failure point?
 

·
Super Moderator
Joined
·
11,550 Posts
Uncles failure diagnostics are right on, as usual. Probably because the older style (unsealed) bearing made little noise and no vibration as it approached failure, only generating heat. This was absorbed, for a while, by the aluminum, then everything fails all at once and you get to smell the melting rubber when you stop.
Ideally, you would have inspected the bearing before things went this far, OR better yet, replaced it when any clutch work was needed, preventing total failure. It is not so much a weak, or failure point as a WEARING component that DOES require periodic replacement.
My own '65 275GTB Ferrari has a similar "steady-rest" bearing on it's small diameter driveshaft, connecting the clutch to trans-axle. This bearing is small, and is always turning at engine speed. These wear out much more often than the Alfa system, but have less cushion, so vibration is obvious, and the solid mount transmits NOISE to the driver. These cannot go to total failure unless you are deaf and insensitive to vibration.
The obvious solution for the Alfa system or Ferrari system is preventative maintence, and constantly being aware of changes in vehicle dynamics!
"Whoa! OMG! Look at THAT!!!"
From my experience.
 

·
Super Moderator
Joined
·
11,550 Posts
Nothing like the smell of melting rubber after a fast run. Yummy!
 

·
Registered
Joined
·
21 Posts
Re: Center bearing failure.
I too had the center bearing fail in my 2 year old 1961 Giulietta spider. I was tooling along Highway 1 in Pacifica California, when all of a sudden the loudest, most god-awful banging and bashing pounded the floor of the car. I just about jumped out of my skin! Upon inspection, the bearing had seized tight without pre-cooking and wrenched loose from the carrier, merrily pounding away on the undersides until I could pull over. After the repair all was well until the next crisis in my somewhat jinxed car (abetted by youthful fecklessness).
Matthew Fox
1962 Giulia Spider
 
1 - 10 of 10 Posts
Top