Hey Rodger,

while you have it apart, I'd suggest replacing the slider as well as the synchro. I had a similar issue with 3rd - 4th and only replaced the synchro only to find out that it made no difference. A second tear down and slider replacement finally fixed the issue.

Dom.
Thanks for the suggestion. I really don't want to do it again, so I will look closely at everything. Of course, I really don't know what I am looking at, but will do some measurements and take pictures for advice. I read through Bernice's threads on taking apart the transaxle. Her pictures and comments are invaluable. Wish that was available when I did it the first time, but I was going just by the 5-Speed 101 guide. That was great, but the pictures are so helpful.
 
No offense taken. Since Matt didn't have 2nd gear I got it from Orion who cautioned about it being too thick. I took it to a machinist who does lots of aerospace work and he "matched" the dimensions of the original.
I believe the interface with the syncro is too tight (the ring forces it too tightly against the face) and it didn't spin freely, so I need to rev-match and double-clutch to not gronch it going into 2nd. Bizarrely, it's more fun and a badge of honor to have to do every time :) Since it's new it makes a different noise while in gear than other gears. I never threw 2nd away and could put it back in, but the teeth on engagement are severely blunted. I think an OEM could have been bought for less than $200 at that point. Though expensive, it's better than spending a bunch of money modifying a cheap alternative and not have it work properly anyway.

I have the Strada final gearing in mine. It lowers rpms by maybe 500 (?) at highway speeds? I seem to remember being at about 4K rpm at 70ish. Now it doesn't have enough torque at idle to back up an 18 degree incline driveway without slipping the clutch, it used to make it up barely.


At the risk of ruffling a few feathers, I'll go out on a limb (lots of bird references) and say...

And no offense Henway, but I understand the modified Yugo gear is not working so well, still crunches when shifting to second? But I highly admire your attempt at a solution to the supply problem.

Maybe I'm just flapping my wings here (couldn't resist another bird reference).
 
I have the Strada final gearing in mine. It lowers rpms by maybe 500 (?) at highway speeds? I seem to remember being at about 4K rpm at 70ish. Now it doesn't have enough torque at idle to back up an 18 degree incline driveway without slipping the clutch, it used to make it up barely.
Are you happy with the Strada final gearing? I have one and am thinking about putting it in, but am wondering how much it will cut acceleration?
 
Unless you're doing Gymkhana and timing it, you won't notice a difference in acceleration. Besides, X 1/9 horsepower anyway....
 
I found my invoice from when I did the 3rd gear fix a few years ago. I replaced the synchro as well as third gear, the 3rd/4th slider, the 1st/2nd/reverse slider and the reverse idler gear. Those are all good. I looked at the 2nd gear and synchro. I asked Matt about it and he said that if the gap is less than .040", than the cone is worn out and I need a new 2nd gear. Here is a pic of mine. The gap measures about .035". :(
IMG_2769[1].JPG


The gap on the first gear cone is about the same, so does that mean I need to replace 1st gear as well? Just for grins and giggles, I decided to take apart the transaxle from the '81 that I am doing the K20 swap on so I could compare them and see if maybe the gears in it were in better shape. It had about 95,000 miles on it so I wasn't really optimistic.

First off, I noticed that I was not the first one to take this one apart. There were no gaskets to be found, just silicone sealer joining everything. I pulled off the 5th gear cover and saw several chunks of metal in the bottom part of that section. Here is 5th gear. Ouch!
IMG_2768[1].JPG


I can't imagine what someone did to shear off that many teeth. Fortunately, the rest of it was in much better shape. Second gear looked a little better than mine, but still had a gap of about .043", so not much better. I looked on MWB, but only found U8 1st/2nd synchos as well as U8 2nd gear. From what I gather, new 2nd gears are not available. I did find new synchros on Obert's but for considerably more than the used ones from MWB. Not sure where to go from here.
 
Remember, the gap method of evaluating the cone on the gear needs to be done with a new synchro, not a used one. If you use a used synchro to measure, you don't know if the narrow gap is caused by synchro wear, cone wear, or a little of both.
 
Remember, the gap method of evaluating the cone on the gear needs to be done with a new synchro, not a used one. If you use a used synchro to measure, you don't know if the narrow gap is caused by synchro wear, cone wear, or a little of both.
That's what I thought, but Matt said if the gap was less than .040, with the old synchro, that the gear cone was worn too much as well. When I read Steve H's Five Speed 101, I understood him to say that if the synchro bottomed out on the gear, then the gear needed to be replaced. So getting two different thoughts on this.
 
Remember, the gap method of evaluating the cone on the gear needs to be done with a new synchro, not a used one. If you use a used synchro to measure, you don't know if the narrow gap is caused by synchro wear, cone wear, or a little of both.
Exactly! It may be a badly worn syncro more so than a worn gear. After all, the syncro is soft and designed to take the wear vs. the hardened gear. And from what I read, your original symptoms mostly match that of a worn syncro. Consider using the better of the gears (that you already have) with a new syncro. Syncros are available from many sources...search the net.
 
That appears to be the first version 5th gear with the slot-key drive. These were known to be problem prone. Later versions of the 5th gear used a spline drive in place of the slot-key drive.

IMO, get the new syncro ring with the best used 2nd gear possible. If the slider is worn, replace that too. These are Fiat's version of the Borg-Warner syncro but inverted. These syncros do wear out from shifts, time and abuse.

The other syncros are Porsche, with a different set of wear problems.


Bernice




I pulled off the 5th gear cover and saw several chunks of metal in the bottom part of that section. Here is 5th gear. Ouch!

I can't imagine what someone did to shear off that many teeth. Fortunately, the rest of it was in much better shape. Second gear looked a little better than mine, but still had a gap of about .043", so not much better. I looked on MWB, but only found U8 1st/2nd synchos as well as U8 2nd gear. From what I gather, new 2nd gears are not available. I did find new synchros on Obert's but for considerably more than the used ones from MWB. Not sure where to go from here.
 
Remember, the gap method of evaluating the cone on the gear needs to be done with a new synchro, not a used one. If you use a used synchro to measure, you don't know if the narrow gap is caused by synchro wear, cone wear, or a little of both.
What Dan said. There probably is a spec for the gap in the service manual. On my Beta it was 1mm +/-0.13mm. Really there is nothing magic about the nominal value of the gap except as an indication of wear and how it relates to the specification. The syncro being soft metal should see most of the wear so I'd buy a new syncro first and re-measure. The points on the gear don't look so bad.
That 5th gear picture looks interesting. Aren't those gears supposed to be in-mesh ;-) Looks like maybe a bearing failed and the rolling elemens fell out and allowed the gears to seperate and the teeth to tip load and break off. I would have thought it would have given the driver adequate warning. Any bearing pictures to look at?
 
What Dan said. There probably is a spec for the gap in the service manual. On my Beta it was 1mm +/-0.13mm. Really there is nothing magic about the nominal value of the gap except as an indication of wear and how it relates to the specification. The syncro being soft metal should see most of the wear so I'd buy a new syncro first and re-measure. The points on the gear don't look so bad.
That 5th gear picture looks interesting. Aren't those gears supposed to be in-mesh ;-) Looks like maybe a bearing failed and the rolling elemens fell out and allowed the gears to seperate and the teeth to tip load and break off. I would have thought it would have given the driver adequate warning. Any bearing pictures to look at?
New 1st/2nd synchos on the way. Once those are in, then I will check the gap again. Regarding the mashed 5th gear, yes, they were engaging, but I had already taken them out when I took that picture. Here they are as I found them. The bearings were all intact.
IMG_2766[1].JPG
 
I would bet something went through them. (did that gear even work)?

Was the amount of carnage(metal chunks, broken pieces in the bottom about right for much missing metal?
 
I would bet something went through them. (did that gear even work)?

Was the amount of carnage(metal chunks, broken pieces in the bottom about right for much missing metal?
Yes, when I took off the 5th gear cover, there was a whole pile of metal chunks and shards collected at the bottom. Whoever rebuilt this transmission, really didn't do a very good job. The silicone that was substituted for the gaskets looks for all the world like clear bathtub silicone caulking. They even used it to substitute for the o-ring that goes on the reverse idler shaft. The magnet in the main case is missing. All of the bolts that held the shift forks and dogs did not unscrew nicely once I loosened them. The threaded holes of the various shift rods all seem kind of reamed out, compared to the nice crisp threads in my '79 rods, so not sure if they crossthreaded them or if that is the way they were. I can't believe that they could crossthread all of them, so I am wondering if there was a design change to make the screws self tap? There was definitely metal shards around those screw threads.

I did decide that the second gear and the 1st/2nd and 3rd/4th shift forks are in better shape than mine were so I am swapping those.
 
I did decide that the second gear and the 1st/2nd and 3rd/4th shift forks are in better shape than mine were so I am swapping those.
Sounds like a good plan, along with the new syncros you ordered.

As to the condition of the damaged trans, let me repeat something I mentioned earlier...
we have all seen extremely worn/damaged parts come out of a tranny that was still being driven daily
 
When I got this car, I could not drive it because it had no working brakes. The engine ran and I should have put it up on jack stands to run it through the gears, but didn't think of that until I was well into disassembling it. The guy I bought it from was selling it for a friend and had no knowledge of its history.
 
I got two new synchros from Eurosport and checked the fit on the cone. There really was not a significant difference in the gap between the used synchro and a new one, so I am a bit puzzled. It measures at .042" on the second gear that I got out of the '81 which is a little better than the original gear, but not a lot.
 
I have bought some really great parts from them and I don't want to start another Vendor bashing thread but......when I rebuilt my trans last year I used a new 1st / 2nd gear slider from them that was out of spec, which I didn't know until I tried to drive it and couldn't shift from first to second without a Big Crunch.
Ended up going through the whole process again and using a used OE slider I found on eBay, got lucky on that find.
 
New 1st/2nd synchos on the way. Once those are in, then I will check the gap again. Regarding the mashed 5th gear, yes, they were engaging, but I had already taken them out when I took that picture. Here they are as I found them. The bearings were all intact.
View attachment 4079

this transmission has been apart before... stake nut has been re-used and re staked ...not to mention the silicone spewing out of the gasket joins.

There's not a lot that can get between the gears to break the teeth off in the fifth gear extension housing... most of the time it's a lack of lubrication that will cause something to fail.

SteveC
 
So I measured the inner diameter of the used synchro that has 105,000 miles on it. 2.397". Measured the new synchro. 2.399". Hmmmm. :mad:
 
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