[bellagt]

In the process of rebuilding my driveshaft, I had the "opportunity" to inspect and replace, what was likely the original tranny bushing. With some advice from some fellow BBer's (thanks @Andrew and @divotandtralee) I was able to get the new bushing in without breaking anything (myself included).

I did come across an old thread on the topic with lots of useful information under the Spider" forum:
Trans mount

On post #21, someone suggested to stiffen up the bushing by filling up the large void with three pieces of ~1/2" rubber hose (the also filled the lower open slot with some rubber as well).

Anyone here ever try this? Good, bad or ugly results? The factory knew what they were doing so leave it well enough alone? The Alfa Contabiles wanted to save a few lira so they had the Ingegnere make the rubber bushing hole bigger?

TIA,

 

[Andrew]

No. Alfa designed this like it is on purpose. With the hydraulic clutch the trans and diff assembly is pretty loosely attached to the car, moreso than most makers did. The driveshaft can move too, so if everything's good, it all moves around to the designed extent. These hydraulic mounts are stiffer than you think, but do need changing every few decades. Putting anything in the voids including rubber hose, silicone, urethane, cat fur, will transmit more vibration to the seat of your pants.
Andrew

 

[bellagt]

I always wondered if our brothers in the Spider Group had a few loose screws 😋

 

[Andrew]

I guaran-dang-tee anything in those air spaces, including soft rubber, transmits noticeable vibration to the body. Been there, done it, and undone it.
For a race car a solid mount would give better response, less movement and delay. On a street car it shouldn't matter that much. Alfa used this setup from 1967 on the first 1750s through the last Spiders in 1994, worked pretty well as long as it got maintained, which often is not the case. I have changed trans mounts and done driveshaft work on almost every car I've dealt with in the last couple years.
Andrew

 

[bellagt]

I guaran-dang-tee anything in those air spaces, including soft rubber, transmits noticeable vibration to the body. Been there, done it, and undone it.
For a race car a solid mount would give better response, less movement and delay. On a street car it shouldn't matter that much. Alfa used this setup from 1967 on the first 1750s through the last Spiders in 1994, worked pretty well as long as it got maintained, which often is not the case. I have changed trans mounts and done driveshaft work on almost every car I've dealt with in the last couple years.
Andrew

Thanks Andrew! I will leave well enough alone.

 

[brad fischer]

Others use the earlier firmer mount as an upgrade.

 

[Andrew]

I do the reverse. The mechanical clutch mounts they make now transmit so much vibration that I use the hydraulic one on mechanical clutch cars and put the hood-bumper mount fix in the back of the steel part to stop rear axle hop. There's a service bulletin on it form 1965 or so.
Andrew