Transmission Rebuild

[SteinOnkel]

The plot, as they say, thickens.

This particular spider used to be owned by the owner of Auto Italia in San Rafael...like as in it was his personal car. That's clue number one. Clue number two is that there was silicone on all the gaskets, so I'm not the first to open this transmission. Clue number three was that some (not all) bearings were stamped "Poland". Now, that's a pretty weak indicator, bearings are made under license in all sorts of places.

I'm not blind and my 5th gear synchro is clearly identical to 1-4th. The transmission's cases and most of the parts insideare all stamped FIAT.

Now it's also rumored that the Lada tranmsission's 5th gear has a better ratio, no?

What if homeboy decided to mix and match some parts? Throw a Lada 5th into a Fiat gearbox, for example? Besides the better gear ratio, the difference in cost of the synchro is also non-negligible ($20 vs $92).

Exciting. I'll keep you guys posted and take some pictures.

Cheers
Steiny

[18Fiatsandcounting]

I'm also thoroughly confused about the 5th gear Synchro. According to all the vendors, that one is unique. According to what I have on the bench, it's exactly the same as 1-4th. Super strange.

You could be on to something Steiny. Maybe you should have a different 5th gear synchro, but what you actually have is a synchro for 1 to 4 (or a poor knock off copy), and so maybe that's why it's popping out of gear?

I had to say it, but maybe the DPO has struck again. Decades ago on my '69, I put in a combination of parts for 5th gear that lowered the 5th gear ratio from 0.93 to 0.91 (going by memory here). It's worked just fine for decades and probably 100K miles, but if someone other than me were to open that transmission, they would be scratching their head just as you are. I think the only way to tell would be to actually count the number of teeth, which most people are unlikely to do.

-Bryan

[SteinOnkel]

I'm also thoroughly confused about the 5th gear Synchro. According to all the vendors, that one is unique. According to what I have on the bench, it's exactly the same as 1-4th. Super strange.

You could be on to something Steiny. Maybe you should have a different 5th gear synchro, but what you actually have is a synchro for 1 to 4 (or a poor knock off copy), and so maybe that's why it's popping out of gear?

I had to say it, but maybe the DPO has struck again. Decades ago on my '69, I put in a combination of parts for 5th gear that lowered the 5th gear ratio from 0.93 to 0.91 (going by memory here). It's worked just fine for decades and probably 100K miles, but if someone other than me were to open that transmission, they would be scratching their head just as you are. I think the only way to tell would be to actually count the number of teeth, which most people are unlikely to do.

-Bryan

I don't think so. I've driven the car for...oh...maybe 5000 miles. The popping out of 5th is very recent development, maybe the last 500 miles or so.

[18Fiatsandcounting]

Yep, I see your point. Too bad I can't see the parts in person, as maybe it would make more sense for me.

But, just to clarify, are we talking about the synchro rings, or the sliding forks, or the sliding hubs? There are 3 sliding hubs and 3 forks that move around based on those levers that have the beans/springs associated with them, and there are 5 synchro rings, 2 for each hub, and reverse does not have a synchro. So, for gears 1 and 2, there is one fork, one sliding hub, and two synchro rings. Same for 3 and 4. 5th and reverse is similar, but no synchro for reverse.

But back to popping out of gear: I think this is usually an issue with the hubs, forks, or the gear selection rods, or play in the overall shafts or bearings. Sometimes a binding of the rubber boot or the decorative outer boot that goes on the shift lever. What happens is that 5th gear doesn't fully engage onto the teeth, so when you put force on it (either accelerating or decelerating), it pops out of gear. The only function of the synchro rings is to rapidly bring the two gears that you're trying to mesh together both spinning at the same speed as the gears actually start to mesh, so you don't get the grinding sound followed by, "Hey, Steiny, grind me a pound while you're at it, will ya!!"

-Bryan

[SteinOnkel]

Can't find it, grind it!

Here's a bit of a clarifaction:

https://autoricambi.us/transmission-syn ... -2-or-3-4/

Note please how it says "4 required per transmission". My transmission has five of those rings. Yes, five.

And furthermore, this friend:

https://autoricambi.us/transmission-syn ... -5th-gear/

Is missing completely. As are all the little dogs and what have you to hold it on. My 5th gear is just like all the others. Synchro, Spring, Circlip and all.

I'll take some pictures tonight of what's on the bench.

Cheers
Steiny

[SteinOnkel]

Okay,

here it is:



1) Just shows the main case with the main shaft currently assembled. Shows 1/2 and 3/4 sliders and the four brass synchros



2) 5th gear assembly as I pulled it off of the rear section of the main shaft. Note brass synchro shining through



3) That's the 5th/Revers slider. Only has a notch for one Synchro - makes sense as reverse is not synchronized.



4) Slider removed to show 5th gear synchro. Clearly, totally different from what AR/VAS etc sell as a 5th gear synchro. Notice how there are not dogs, no split in the ring etc.



5) Overlaying one of the 1/2/3/4 synchro rings. Clearly shows 5th gear synchro is identical to the rest.




6) Just the slider for 5th. Inner machined surface is where the synchro grabs, just like on the other sleeves.



7) Whole transmission case as is.

So yeah.

Cheers
Steiny

P.S: The 5th gear has 23 teeth.

[18Fiatsandcounting]

Maybe an issue on my end, but I'm not seeing the pictures... Not that they aren't awesome, mind you, just that I can't see them.

-Bryan

[SteinOnkel]

Should be visible now. Took me a minute of fiddling with the html code.

[18Fiatsandcounting]

Looks kinda like what I remember. But, that link that you sent with the AutoRicambi 5th gear synchro doesn't look like anything that I've come across... Weird.

My only other comments are your hands are not nearly dirty enough to be actually working on a transmission. Maybe with some more cuts and scratches and grease, might be believable.

-Bryan

[SteinOnkel]

Ha I just took pictures today.

Here's a link to VAS 5th gear synchro:

https://www.vickauto.com/FIAT-PARTS/FIA ... KU-75-7340

And Midwest Bayless:

https://www.midwest-bayless.com/p-21348 ... go-oe.aspx

[SteinOnkel]

We're still at this.

My reverse idler seems...weird. Can't really install it the way its drawn. Has to be 180 degrees flipped. But then, if you bolt everything together it binds and the transmission locks up.

Fun times, we'll get there eventually. Always do

[18Fiatsandcounting]

I'm pulling for you, Steiny. I'm just waiting to see who's first: Me driving my '71 Fiat up to Santa Rosa to visit you, or you getting your tranny back together to drive down to Livermore to see me. Right now, my '71 is back on the road and registered. So there! Next steps are longer trips, but Santa Rosa might be a little too far for now. But we'll see.

-Bryan

[SteinOnkel]

I'm pulling for you, Steiny. I'm just waiting to see who's first: Me driving my '71 Fiat up to Santa Rosa to visit you, or you getting your tranny back together to drive down to Livermore to see me. Right now, my '71 is back on the road and registered. So there! Next steps are longer trips, but Santa Rosa might be a little too far for now. But we'll see.

-Bryan

Oh, I already took the easy way out: buy another car

An absolutely museum-worthy condition 1988 Volkswagen Fox followed me home the other day in all its 81hp, 4-speed glory. It's no frills motoring taken to the extreme. Although it does have air conditioning - oh, the luxury.

Still, I'm missing my Fiat for late evening top down cruises through Sonoma. This is certainly an uphill battle, but we're close now and this car is so, so worth it.

[18Fiatsandcounting]

Although it does have air conditioning - oh, the luxury.

Air conditioning...?! What, do you live in a hot climate or something? For God's sake man, put the top down on your Fiat, and there's your air conditioning. Of course, you have to be moving for that to work, and for that, you need the transmission back in your car.

-Bryan

[SteinOnkel]

Although it does have air conditioning - oh, the luxury.

Air conditioning...?! What, do you live in a hot climate or something? For God's sake man, put the top down on your Fiat, and there's your air conditioning. Of course, you have to be moving for that to work, and for that, you need the transmission back in your car.

-Bryan

That is correct, Bryan. And in a perfect world, the transmission wouldn't lock up. It would be fine if it had launch control...