Why only 1 check strap in 1rst gear synchro?

[paulsle]

I'm in the midst of a complete rebuild of my 150,000 mile '72 GTV transmission. It was shifting very well, but bearing noises were on the rise. Gears, Dogteeth, synchro sleeves all look good. Have the factory shop manual and both of Pat Braden's books that actually have good tips and instructions lacking in the factory manual.

When disassembling my 1rst gear synchro, I noticed there's only 1 check strap where all the other sychros have two. Can't find any mention of this in anything I've read in the manual or BB threads. The factory diagram shows only one in 1rst gear, with two in all other gears, so I'm thinking it's ok.

It might seem like I'm answering my own question here, but this gearbox had an earlier rebuild limited to replacement of all the synchros and the 2nd gear , so just want to confirm that this is right and wondering why it is.

Note to those contemplating a rebuild... check those bronze bushings located inside the gears on the mainshaft . Mine were worn quite thin and required replacement. These are now hard to find. Only IAP seems to have'em at the very special price of $57usd each. Other bearings not cheap either, and I had no luck sourcing them from bearing suppliers or auto parts stores.

[jarrington]

Paul, there's some very good information in this thread:
First Gear Fix

-Jason

[paulsle]

Jason,

Thanks for clueing me in to that thread. There's my answer, and from what I read by quickly skimming the posts, it seems an improvement can be made for little expense and effort.
I'll have to sit down and read the entire thread before going back out to the shop.... now to find some spare synchro parts.

[Joe Papa Sr]

Man, 150,000m, and your dog teeth are still looking decent?? Congratulations!! You are a role model for gear shifting!!

[Joe Papa Sr]

Yeah, definitely do the gear fix by 60sracer......

[Craig]

G'Day Guys,

I don't really want to burst any bubbles here but the dog gear in that (somewhat fuzzy) photo look a little rounded and concave on top.

As noted above, it's a little hard to be sure from that photo so I may be wrong.

See this thread for what to look for when assessing dog gears.

[paulsle]

Quote:

I don't really want to burst any bubbles here but the dog gear in that (somewhat fuzzy) photo look a little rounded and concave on top.

[Craig]

G'Day Paul,

Based on those photo's I'd rate 1st as scrap and hope to have something better for 2nd. It all depends on your access to spares (and budget of course).

I tend to rate each dog gear on a scale of 1 to 10 with this gear being a 9


and this one being a 0 (yes, I know that's less than 1)


and I would hope not to use anything less than a 5 or 6 on my car/s.

Based on your photo, I'd probably rate your 2nd as a 4 to 6 so probably good for 5th and maybe 4th.

You want the best you have or can get on 2nd then the next best on 3rd or 1st (depends on driving style but probably 3rd then 1st) then 4th then 5th.

So examine your dog gears and rate them. Post photo's of each if you like (take the photo from further away and crop it to just show a selection of a few teeth before reducing the file or image size to meet the BB requirements).

[paulsle]

Craig,
Thanks for posting the photos showing good & bad dog gears.

Friday I had the good luck to find local Alfa guru Paul Glynn at his shop, usually open only on Fridays and occasionally Saturdays. I brought the whole box of transmission parts for Paul to look over. He agreed that 1rst & 3rd dog gears were the worst, with 2nd gear a good candidate for replacement too. We could find only 2 serviceable used gears, so only 1rst & 3rd got changed. Thanks to Paul having all the necessary press plates at hand, included one he machined for 1rst gear, I was in & out of there within an hour. That included heating the dog gears to R & R them, and chucking the input shaft into a lathe to radius the end. That was done to ease installation of the transmission, since I'll be doing that from under the car.

Anyway, the gearsets are now assembled onto their shafts with new bushings and bearings. A new synchro sleeve was install on 1rst-2nd gear, and the other used ones swapped around to where they'll do the most good.
The 1rst gear now has the additional check strap installed too.
The photos show the dog gears in order from 1 to 5.
In the 1rst and 3rd photos the old worn dog teeth are there for comparison to the new. As bad as the old ones were/are, the gearbox shifted pretty smoothly before the teardown, which was done due to bearing sounds becoming more apparent.

Comments are always welcome. Thanks

[Craig]

G'Day Paul,

Still not crazy about 2nd, from those pics I would probably put 4th onto 2nd, 5th onto 4th and 2nd onto 5th.

Second needs to be the best in the box.

[Alfacliff]

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