348 gearbox noise

If someone is later makin tools to remove mainshaft and layshaft, these are the ones i made. Ill upload layshaft tool pics later but heres my mainshaft tools.

Just hope to get some feedback, as this is my first 348 gearbox that im rebuilding

Thanks buddys
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Jh348, looks like you're making solid progress. Have you checked the gears for any possible damage?

On Post #24, it sort of looks like there are some markings on inside the tooth near the bottom.

I still need to update my thread and post my pics. Work has been kicking my ass lately

 

I have inspected every gear and theres not any significant markings besides 67k miles worth of use. In my case every other locknut was still tight except that clutc shaft nut. Clutchshaft gear has some wear on it(not so on teeths, but the face of the gear), how much i dont know becouse i dont know the thickness of a unworn gear. Other suspect is one of the layshaft center bearings, mine doesnt have a roller cage on it. Tho i havent found any brokeb cage pieces on there either, so thats a mystery to solve, it doesnt look like it has failed but any roller bearing without a cage that ive seen has had the rollers backing up the next one and so on.

 

ok, found a thread with a pics of that bearing. Post #97 has a pic that shows it doesn't have cage either, so i guess thats how it is.

http://www.ferrarichat.com/forum/technical-q/77427-tranny-done-blowd-up-5.html

 

Torqued, or over torqued that pinion ringnut and checked that preload was still on factory spec. Factory torque is 210nm so i tested 240nm. Preload (1.1-1.3kg) didnt change between those values.
Made a little tool to lock that pinion
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Ok, recent progress is fitted mainshaft and made some pre work to the clutchshaft lockring to make some welds to it. I used loctite 660 on those splines and 271 on thread, then torqued it to 240nm. Then i machined excess of that nut to get welds at root better. I havent decided yet wether i tig or mig it? Or go full welds or 4 weld sections.

I know this have been a monoloque but, dunno.. any thoughts?
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Not a 348 gearbox expert by any means, but I'm not sure that I would put weldment where there wasn't previously, in the interest of future serviceability and all.

Nonetheless, great updates and very interesting. Please continue to document the process, since it is a great reference for the rest of us.

 

In normal rebuild/overhaul you dont need to weld it, unfortunately my box is at point where u would replace it with a good used one. So i will replace few bearings and try to get that clutchshaft/gear/bearing to give me x miles with it. My shaft was bad and it would never last without something permanent fix (and this can still go south).
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I've never been that deep into a 348 gearbox so there's nothing for me to add, other than a thanks to you for your updates.

 

In order to fit layshaft, u need to fit 1st-reverse gear assemblies to the shaft. I had occasional hard to get 1st gear on and by looking synchro cone there has been some heat building up. Reaaon for it is uncertain, maybe bad oils. I will try to lap it to match, i think im going to lap every synchro anyway
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Welded that clutchshaft, i decided to tig it. It wasnt nicest material to weld and so on, but i think it fused pretty ok. I measured shaft runout before welding and will check it after it has fully cooled. I dont expect any distortion

Whats annoying, my photos dont show up in correct rotation.
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Have to correct myself, synchro i pictured before was reverse. Strange is that i didnt have any problem to engage it, and the cone in the 1st synchro had no marks whatsoever

 

Jesse -

Which clutch shaft do you have? I've got one here that I'm anxious to get rid of -- if it's what you need.

 

I have "large" spline shaft, but i would also need a good gear to match it. And that seems a rare find

 

Ah, ok. I was looking for a good home for 145427 which is the large spline on one end, and the small spline on the other end.

 

Question, does that clutch shaft now need a rotating balance due to the added material (welds)?

 

Do you have fine spline gear with it?

 

No, if u weld the exact same amount of material that u did on opposite side. Basically it could be little of, but its hard to measure precisely becouse if u would ne able to lock that bearing in place, u cant lock that bearingcage and when that rattles inside it will throw it off. And those welds are done pretty small radius and it will affect less

 

As u need to get differential in before layshaft, u could check preload of that also. After that you need to loosen differential bearing caps to atleast make it easier to fit layshaft. Its pretty straight forward job but you need to workout a way to keep those rollers in together, i used just a basic ziptie. Then just slide that 1st-reverse gear pack through. Again u have to workout how to keep in those springs inside synchro hub. Then just press that one center bearing in
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I dont really know how its supposed to clock those shifter rods and forks, but i just made a tool of 15.00mm bar and bend it to correct shape. I believe that shifter has equal "throw" to every gear. factory has some tool to do this. I tried to get those sleeves and forks as "center" i could. Shifter cables have some adjustment but i guess its better to get these correct first
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The fork pieces are indexed on detents on the shafts.

 

So you mean those little pieces? Yes, they are. But theres a lot of play to tighten those a bit off. I dont have experience whether its important or not. The fork between 4-5 gears have detent also i guess to help fixing it to merely correct location. Forks between reverse-1 and 2-3 dont have so u could potentially fix those waay off, meaning that synchro "collar" engages more on other gear and less to other.

 

No it doesn't. As you gently tighten it all goes home fine. It is a moving shift fork. There is a range.

 

Ok, thanks for the feedback. As i dont have any previous experience in ferrari transaxles, it easily slips to side of overthinking stuff, which dont help.

When i get this thing back on the car, i have to decide what oil im going to use and get shifter linkage/cables out. I want to understand that adjust mechanism and check any worn parts.

Goal is to get that shifter feel nice to use

 

Love your work! Hope it all goes well and she's good for a while yet.