348 - How much gearbox noise

FYI. Just use google to search on here.

i.e. Google search:

Ferrarichat 348 Ernie gearbox

You'll probably find what you're looking for.

 

At this point you better strip it down pretty far so you can check everything. I would be for instance concerned about the pinion behind the main shaft. It may not all be good news, or it could - then at least you know and you can assure the job was done properly. It could be for instance that the pinion gear (which is actually part of a shaft so replacement requires quite a stripdown already) was not tempered properly (read about that here: https://en.wikipedia.org/wiki/Tempering_(metallurgy ). The very localised wear could suggest that. But if that is not the problem, then you *need* to do everything to rule out that there is not more to come of whatever damaged that gear.

 

In Google, if using this synthax, without the quotes, "site:ferrarichat.com 348 Ernie gearbox" all results will be from FerrariChat only. However, for each and all three keywords as well.

 

This post is of interest. http://www.ferrarichat.com/forum/139538660-post57.html

It comes from this thread. Interesting comment from FBB at the last sentence! :
http://www.ferrarichat.com/forum/348-355-sponsored-bradan/234915-348-ratio-3.html
Pitting is an issue in about 20% of the boxes I have taken apart. I do not know the cause but I am careful about gear mating. One of our guys here in the states also had gears made. Making gears and shafts is easily doable. But If 10 could be made it would be so much cheaper. You got a great idea doing a group buy if you could work out the logistics.

Steve's grendaded gearbox had perfect shafts by the way. I don't remember seeing a single pit. That would have been the place to see wornout shafts. Seeing such contrast as Steeve's box , I'm almost inclinded to think the pits can that way from the factory on some boxes or some shafts missed the heat treatment cycle or something.

 

Yes the "Bevel Gears" are sold only as a pair as the gears are finely mated during machining. If you mate another small gear (with its spindle) with your large diff. gear, you will probably have pretty loud "singing" from the gears all the time. I can see that the sets are available at Eurospares at GBP 1,945 (USD 2,600 these days) and they show only GBP 58 shipping by FedEx.

 

Quick question, is the pinion shaft gear (the damaged one) viewable without pulling the trans? Say, by using a flex borescope through the drain plug?

 

That is a concern, for which there are three solutions. In that thread I posted there was someone who mentioned he knew a company that can make gears from scratch for lower prices than the originals. That is a good option for cases like these.
Another idea can be to obtain the new original parts and find a company that can re-do the hardening and tempering process for you.
Last is of course to obtain the originals and don't worry about it, depending on your mileage it will be years before any problems (if any) may arise.

 

There are hundreds of threads about "noises" coming from the 348's drivetrain and sometimes it's difficult to isolate the location of these sounds.

Being able to do another non-invasive inspection would certainly help.