Transmission Rebuild

[maxm50]

Bryan, Steiny, thanks for the tip on the tractor oil... I think I'll play it safe (and cheap!) and go with that. Probably not a good idea to make myself a guinea pig on an untested oil. Much appreciated!
-Max

[18Fiatsandcounting]

Sounds like a plan, Max. I'm no expert on transmission oils, but what I can tell you is that I have heard no complaints or issues with two different options: 1) the original mineral based GL-1 oil, or 2) tractor oil that is also mineral based. Both do not have any of the sulfur additives that are necessary for modern transmissions or differentials but that are harmful to the soft metal (brass) synchros of the Fiat tranny. So, either of those two options would work.

At the same time, I have heard lots of back-and-forth discussion about synthetic oils, various specialty brands, etc, and while these appear to work just fine for some people, they don't work for others. Could be differences in climate, age of the transmission, whether the car is driven aggressively, etc. I tend to just go with "simpler is better" and so I just ordered (online) a few quarts of GL-1 for my two spiders.

-Bryan

[SteinOnkel]

Transmission is back in. All four bolts are in too.

My goodness, what a disaster. I've never had that much trouble lining up an engine with a transmission.

Getting pretty tired of the 20-minute-bolts. Take 20 minutes to loosen or fasten (looking at you driver's side upper transmission bolt). It's really starting to take the fun out of working on this car; it fights me every step of the way.

Too hot in the garage to continue now. We should be back on the road next week though.

[SteinOnkel]

Sit rep.

Still left to do:

- Guibo and prop shaft
- Tighten up shift tower bolts*
- Install downpipe

*It is an absolutely bone-headed tip on this forum to install the transmission without the shift tower attached. Yes, the transmission itself is easier to get into place, but it makes life much harder for you down the line. First, getting the shift tower on. There is no way to do it with the actual shift lever installed, so you must remove this. It slides out towards the bottom, but you can't re-install it that way. You need to loosen the m8 nut on the button, catch the bazillion springs, cups and washers and then slide the lever in through the top of car. Then you get to reassemble all the other stuff from the bottom. By the time you realize the cover is directional, you will be more than a little fed up. Getting the shift tower, gasket and all four bolts to go where you want them to requires telekinesis. Don't ask me how or why, but it decided to just go "clunk" after 15 attempts. Then comes tightening the obnoxiously long fasteners. The rear ones are...well at least somewhat reachable. Get ready for a long-term relationship with your 1/4"ratchet, because you can only turn it two clicks at a time. For the front ones, I'm going to have to bust out my chopped up 13mm wrench (it's ground down and cut to about 1/4 normal length). I don't think there is no room for any other tools.

So, word to the wise, don't do it this way.

Compared to the Derby (on which I have removed and re-installed the transmission eighteen thousand times), there are a few things I like. The speedo drive is MUCH easier to reattach. And the shifter does not need to be adjusted - which is a two man job that takes ages on an old school VW. There is a tool for it, but it is unobtainium. Oh and you know what VW's 085 transmission family doesn't have? A clutch alignment tool. Yep, you read that right. You get to eyeball it and then pray to the deity of your choice that that's not the reason the transmission won't slide into place.

Cheers
Steiny

[18Fiatsandcounting]

I hear you Steiny, and remember my advice about waving chicken bones with some incense as you do the work. Organic, free range, shade grown, farmers get a living wage, NAFTA compliant, etc.

But all jokes aside, yes, your advice about the transmission tower is sound. I tried to install my transmission many years ago without the tower, and I think I finally gave up and lowered the transmission again and put the tower on, and then back up into the car. Perhaps you have greater patience than I do.

One of these days I need to rebuild the transmission on my '69 (leaks oil), and so I will get to a chance to experience my own version of joy and happiness. I seem to recall there was neither joy nor happiness in this job, but there you have it.

-Bryan

[SteinOnkel]

Well....so I drove the car.

The experience takes the cake for the biggest disappointment in my 15 year wrenching career. It shift as well, maybe slightly worse than before. But the noise in 1st,2nd,3rd and 5th are 5x louder. My right ear is ringing after a ten minute test drive. It still has the classic throw-out-bearing-whine at idle, but it's brand new.

I suspect the shafts are worn or who knows.

There's someone selling an engine and transmission combo out of a 74. I will pick that up this weekend, give the transmission fresh oil and put it in.

If that doesn't significantly improve things, the car is going up for sale and I'll be shutting the Fiat chapter. There's too many cars out there that I haven't owned to be fiddling around with this ungrateful car. Every fastener is a challenge, every installation goes completely sideways. And the payoff just isn't there. Never mind the complete failure of a transmission rebuild. Even if it went swimmingly, I'm left with a slightly ratty looking 84hp convertible...

This hobby, it's not for the faint of heart.

Cheers
Steiny

[TwinFast]

A lot of interesting things on this post.
I replace my broken 5th gear last summer and it was a good opportunity to replace some used bearings and all the gaskets but I don't replace the synchros and it was a big mistake. One year later the 2nd gear becomes hard and noisy when shifting from 1st to 2nd or from the 3rd with a bad grind when it goes in. One told me that I have to replace the clutch first and see if this disappear, before going into a new gearbox job. I don't think it's a good ideas but it's on the table (not in the kitchen one )

Another issue is that the new 5th gear is too short on highway with a higher RMP than the one I previously have. Is there 2 differents kinds of fifth gear with different ratios or it's just an idea ?

[SteinOnkel]

There's definitely more than one 5th gear. I think I have the longer one. The synchro is then installed like this: ???

Who knows. Shoddy documentation is shoddy.

I suspect whoever tore into it before didn't do it right and left out a spacer, spring washer, clip. I now can't find it in the drawings, because this transmission is different. So I am just guessing. All I know for sure is that this transmission is now essentially unfixable.

[18Fiatsandcounting]

Well, shucks, Steiny, I was hoping to hear that you were back to a lean, mean, drivin' machine. This is really frustrating, and while I know you're not likely to tear down this transmission again, it kinda sounds like the layshaft gears are mis-aligned with their corresponding gears on the main shaft. 4th gear is a "direct drive" down the mainshaft, so it doesn't involve the layshaft which is perhaps why your noise only appears in 1, 2, 3, and 5 but not 4th. Could be worn shafts as you note, or perhaps a spacer washer or the like is installed in the wrong order.

To answer TwinFast's question: Yes, there are two different 5th gear ratios, depending on model year. I vaguely recall that earlier 5th gear ratios were 0.91 while the later years were 0.88, but my memory is weak on this stuff. On my '69 spider transmission, I was able to change the earlier 5th gear ratio to the later ratio, and the conversion seemed to work fine. Dropped the rpms a tad, so 3300 rpm at 60 mph instead of 3400. Not a huge difference.

And now for a bit of levity. I always believe that there is a rock and roll song for every situation in life, and so I offer you a few lines from Led Zeppelin's "Trampled Under Foot":

Ooh, trouble-free transmission
Helps your oil's flow
Mama, let me pump your gas
Mama, let me do it all
Talking 'bout love, ah
Talking 'bout love, oh
Talking 'bout

Check that heavy metal
Underneath your hood
Baby, I can work all night
Believe I got the perfect tools
Talking 'bout love
Talking 'bout love
Talking 'bout

Me again. Somehow, I don't get the impression Robert Plant was singing about a Fiat transmission...

-Bryan

[SteinOnkel]

In any case, it doesn't seem like we can fix it.

If there is a spacer missing or installed wrong, there's no telling which one. Both my brother and I have engineering degrees and we poured over the parts and documentation for hours. And if the shafts or case are worn, it's not worth it.

I'll be in Stockton on Friday evening to pick up that engine/tranny combo. Apparently it's out of a car that hasn't ran for years. They were going to restore it, but too many parts were missing and then somebody passed away. You know how it goes sometimes. The engine may be just fine. I can see a blown rear main seal in the pictures, but I bet you could get it running.

No that I will. I'm really only interested in the gearbox. I'll pull the heads and see if they are better than mine (lots of broken threads). And those can easily live on a parts shelf, I've got room. The block I'll most likely junk.

Unless somebody here needs an engine from a '74 1800?

[18Fiatsandcounting]

Before you junk the 1800 block, let me know. My main issue is space, but if the block is in reasonable shape, I might be interested. Also, if you're looking to junk your current transmission that has so much love bestowed on it, let me know.

-Bryan

[SteinOnkel]

Lovebox transmission: I think I will take the new parts out of it (bearings and synchros) and hold on to them. Might be in the future this second-hand transmission will need some love. I'm almost counting on it, but I want to get at least a year out of it. The other parts I would not feel comfortable using. Could be that you end up installing problematic parts into a gearbox.

As for the engine, yeah I'll take a closer look on friday. It looks pretty picked clean in the pictures though.

I'll let you know what's left over. Not trying to stash a bunch long-term, so you'll have an answer from me fairly soon.

[aj81spider]

Just to add some information for future people searching this thread. Fifth gear is not the only one that has different values. From the Fiat Service Manual for cars 1975 and on, here are the gear ratios:

............................1975-78........1979-80......1981 on

1...........................3.667............3.612.........3.667
2...........................2.100............2.045.........2.100
3...........................1.361............1.357.........1.361
4 ..........................1...................1...............1
5...........................0.881............0.830.........0.881
Reverse.................3.244............3.244.........3.244

I'm not sure if the pre-1975 ratios are different as that service manual is downstairs and I haven't checked it.

Sorry for the formatting - The site takes multiple spaces out and a single space rendered the table unreadable.

[SteinOnkel]

It would be great if you post the older value too. I'm installing a 1974 transmission this weekend. Would love to know the gear ratios.

[aj81spider]

I dug into the early service manual. It is much less intelligible, as it's a series of manuals with addenda (you have a 124 sedan manual with an addendum for the Spider and Sport Coupe - then an addendum for the 1970 model year, then an addendum for the '73 model with a 1600, then an addendum to that for the '74 with an 1800). However as best I can ascertain there were only two versions of the transmission, the original with the 1400 and the 1970 and on, which matches the 75 and on, except for reverse:


.............Original 1400 ............. 1970 and on

1............3.422..........................3.667
2............2.100..........................2.100
3............1.361..........................1.361
4............1.................................1
5............0.912...........................0.881
Rev.........3.526..........................3.526

Hope that is of some help.