Transmission Rebuild

[SteinOnkel]

Ooooh buddy! We figured it out. It shifts very nicely (on the bench).

Now I just need evacuate the 120 degree air from my garage and put it in.

[18Fiatsandcounting]

The winds down here in Liver-gulch are 40 mph and above, with the temps dropping into the high 60s. Should be sufficient up your direction to lower that heat in the garage.

Onward and upward, Steiny!

-Bryan

[SteinOnkel]

Found a nice, thick spacer on the work bench while cleaning up. Whoopsies!

Good thing we didn't fire it up yet. Brb, going to dismantle rear housing for the upteenth time.

[18Fiatsandcounting]

Found a nice, thick spacer on the work bench while cleaning up. Whoopsies!

Ha! Same thing happened to me back in the late 80s, but the difference was that I only found the thick washer (on the kitchen table) after putting the transmission back in the car and driving it down the road for the first time since the rebuild.... The first thing I noticed was the loud whining sound from the gears as they weren't meshing properly... 10 hours and another gasket set later, it was fixed and back on the road. Double-whoopsies!

-Bryan

[dinghyguy]

glad to see that others use the kitchen table for important projects like tranny rebuilds. Having it close to the dish (parts) washer helps too. Not to mention being near the fridge and coffee pot.

I have been using the coffee table in the living room as a perfect location for varnishing dash parts.

Glad to hear the end of the tranny rebuild, did you ever figure out what was special about your tranny relative to others? Also can you list the parts you changed, i always wonder exactly what bits other than sychros and perhaps bearings people end up changing.

cheers
dinghyguy in the too small tent while the new garage get built

[Nanonevol]

Shirt forks often wear and prevent gear change. Good idea to replace.

[18Fiatsandcounting]

Also can you list the parts you changed, i always wonder exactly what bits other than sychros and perhaps bearings people end up changing.

While we await Steiny's answer, here is what I would change if I were to rebuild my transmission and assuming no monetary limitations and no issues like chipped gear teeth, etc: Synchros, shift forks, sliding shift collars, bearings, gaskets (including the o-ring on the speedometer drive), oil seals, perhaps the plastic pivot ball "cup" that the shift lever rests in (some designs were more prone to wear than others), and of course the oil.

And, if these parts had a lot of mileage on them, here's what else I would change while the transmission was out: clutch disc, pressure plate, and release bearing, rear engine oil seal if it appeared to be leaking, rear transmission mount.

-Bryan

[SteinOnkel]

It took us 35 minutes flat out to open up the rear cover and put the missing spacer in and button everything back up. We got this down to a science now.

The driveline has the following new parts:

- Rear main Seal
- Pilot bearing
- Pressure plate
- Clutch Disc
- Throw out bearing
- Flywheel resurfaced
- U-joints
- Engine and transmission mounts

The transmission has the following new parts:

- Seals (@ Bryan, I don't think I had an o-ring on the speedometer drive? Can't seem to find it on the drawings either)
- All bearings
- All circlips
- Detent Springs, Balls and Pins (<- these prevent gears from popping out and were very worn)
- Synchronizer rings
- Synchronizer springs

I think if your replace any more than that you are better off just buying a new transmission. The other components showed almost no wear, at least on mine.

Parts that are different in my transmission:

- 5th gear
- 5th gear hub
- 5th gear sleeve
- 5th gear synchronizer (same style as 1-4 and MUCH cheaper*)
- 5th gear shift fork (maybe, not sure)
And the reverse idler gear needs to be installed exactly mirrored to how it's drawn in the schematics. That may not be exclusive to my gearbox though.

*I'm still not going to bitch. We are thinking of rebuilding my brother's 914 5-speed gearbox and each synchro is $100. There's a plate in there too that's a wear and tear item - $500.

Cheers
Steiny

[18Fiatsandcounting]

- Seals (@ Bryan, I don't think I had an o-ring on the speedometer drive? Can't seem to find it on the drawings either)

Thank you for that list, Steiny, and you caught a few items I had forgotten about (or simply haven't changed in the past, like the synchro springs). Regarding that o-ring on the speedometer drive, opinions seem to vary on this. Some new speedometer cables come with an o-ring slipped around the outer housing (to keep it from getting lost in storage/shipment), and my only guess for its function is where the flange on the speedometer cable pushes against the threaded lip on the speedometer drive. Speedometer drives often leak transmission oil over time, and my thinking is that oil works its way through the drive gears, past the input of the drive housing, and then weeps past the threaded collar of the speedometer cable.

Always interested in whether the above is complete nonsense, or ??

-Bryan

[SteinOnkel]

I've made a mental note to take a closer look at it. For now, here's the drawing I have. For what it's worth.



No o-ring drawn...



And here's 5th/Reverse. On mine the following components are different:

17 (definitely)
19 (sleeve may be the same, not sure)
1 (possible)
2 needs to be installed 180 degrees flipped

We had to install 18 yesterday. Also, 15 is a spring washer not a spacer. The manual loves to throw these terms around willy-nilly. Furthermore, there was no way to install 9, although it may be redundant as the new bearing is sealed.

See what I've been dealing with

[18Fiatsandcounting]

I think the o-ring on the speedometer drive is an "aftermarket fix" rather than factory original. In other words, some people found that transmission oil leaked from this joint, and so some smart dude (that would not be me) said, "Hey, let's put an o-ring in there!!!" Can't hurt, I guess.

Onward and upward Steiny.

-Bryan

[SteinOnkel]

Well, it appears I already have one in there. Cool beans.

If I could find my jug o' gearbox oil, I could actually put the transmission back in...

[maxm50]

Steiny, what a saga! This has been fun to read through.

Your comment about gear oil got me thinking: has anyone tried Motorcraft manual transmission fluid in a Spider transmission? I heard about it on a Miata forum - folks who have used it really rave about it. Apparently you can find it at some (all?) Ford dealers. The main drawback seems to be its price (~$15/qt).

I'd been planning on flushing my transmission and filling with Redline MT90, but then I remembered that I had MT90 in my Miata years ago and never really liked it that much (notchy when cold). That led me down an internet rabbithole that ended at Motorcraft fluid. I can't find any references to it here on our forum. It's a GL4 fluid and Ford says it's OK for older transmissions that needed GL3 fluid, so it must be OK for brass synchros just like Redline MT90 is.

Cheers,
Max

[18Fiatsandcounting]

Your comment about gear oil got me thinking: has anyone tried Motorcraft manual transmission fluid in a Spider transmission?

Max, I have not tried Motorcraft oil, but I do know that Fiat spider transmission oil is a topic that gets a lot of debate. I did some quick research on MT90 and that looks like it would work, but isn't that a synthetic oil? I've heard synthetic oil can cause more leaks with seals as they weren't designed for synthetic oils, although I have no direct experience because I've always used conventional oils.

Since GL-1 is still available, although mostly online, why not just go with that?

-Bryan

[SteinOnkel]

Steiny, what a saga! This has been fun to read through.

Your comment about gear oil got me thinking: has anyone tried Motorcraft manual transmission fluid in a Spider transmission? I heard about it on a Miata forum - folks who have used it really rave about it. Apparently you can find it at some (all?) Ford dealers. The main drawback seems to be its price (~$15/qt).

I'd been planning on flushing my transmission and filling with Redline MT90, but then I remembered that I had MT90 in my Miata years ago and never really liked it that much (notchy when cold). That led me down an internet rabbithole that ended at Motorcraft fluid. I can't find any references to it here on our forum. It's a GL4 fluid and Ford says it's OK for older transmissions that needed GL3 fluid, so it must be OK for brass synchros just like Redline MT90 is.

Cheers,
Max

What you want is Ford Tractor Transmission oil. It's $20 for a big honkin' 2 gallon pail at Tractor Supply Company.

I was also extremely tempted yesterday to just say fuck it and put in the Motul Gear300 that I have a whole case of. But no, that's for the VWs only. It's an amazing gearbox oil though, my other cars shift phenomenally well with it.

Don't mess around with the gear oil and get the right stuff, no matter what some manufacturer states. The whole reason I'm rebuilding this transmission is most likely because I found a half empty jug of GL5 in the trunk when I bought the car. Evidently, this transmission has been extensively serviced before, but then the following dpo decided synthetic is the way to go and here we are.