Synchronize ring strut key (dogs)

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sidestep
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Synchronize ring strut key (dogs)

Post by sidestep » Wed May 02, 2018 10:48 pm

Would anybody be able to tell what material the keys are made from? The transmission I am working on is not one that has any support or replacement parts available. I've slowly aquired one full hub, slider, key/ring assembly but am in need of another set. I would like to have these made locally if I can. Any suggestions on what material would work?

fdicrasto
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Re: Synchronize ring strut key (dogs)

Post by fdicrasto » Thu May 03, 2018 1:26 pm

What tranny are you working on? Some synchro dogs are stamped steel and I have seen some made from solid steel, no hollow portion.

sidestep
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Re: Synchronize ring strut key (dogs)

Post by sidestep » Thu May 03, 2018 2:15 pm

These are solid, some were broken in half at the bottom of the case. The transmission is a Muncie hd 3 speed sm 330. From a 6cylinder 1973 pick up truck. The small wear items are unlike the Saginaw or any other Muncie.

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Re: Synchronize ring strut key (dogs)

Post by fdicrasto » Thu May 03, 2018 5:20 pm

If you can locate the stamped steel ones, they won't break though they do wear quicker.

sidestep
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Re: Synchronize ring strut key (dogs)

Post by sidestep » Fri May 04, 2018 1:01 pm

Okay thanks, I'll do a search for stamped steel ones, see if one is close in shape/dimensions

autogear
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Re: Synchronize ring strut key (dogs)

Post by autogear » Wed May 09, 2018 12:54 pm

Not sure how I missed this - my apologies.
I asked my boss what kind of pitfalls we ran into when we transitioned to billet struts, and explained your problem. I'll post his response below.
George (my boss) uses 8620 steel that is then heat treated; but if you were making them yourself, you could use a tool-steel like A2, D2, or O1 and not heat treat.

These will all be a little heavier than the powdered metal ones. You also need to watch your corners, you want a very small radius, to prevent digging into the bronze ring. Lastly, the geometry of the 'hump' on top of the strut is important.

I have no idea what the price would be, but we could modify our program to produce them for you if you send me a sample; these would be $5 a set like the PM ones lol

That HD Muncie 3spd has a LOT of cool features, the 2nd design Muncie 4 speed (the 32-spline 71-74 one) should have been a 4speed version of THAT.

Here's George's comments:
"We do not have GM prints for any of the Muncie struts, but we do have a
nearly illegible print for 3911 974, the synchro ring for the H/D 3
speed. It shows that 3911 974 and 3880 850 (the 4 speed ring) are
identical except for the strut pockets, which are wider on the H/D 3 speed.

Wider struts are usually stamped or hollow-backed (to reduce mass and
speed shifting). The steel stampings are also more resistant to shear
failures than the powder-metal production struts (like those in the 4
speed). As "Sidestep" has several broken struts I'm guessing GM used
powder-metal on the H/D 3 speed. Cutting new billet replacements from
SAE 8620 and hardening them would probably solve his problem, but the
dimensions and accuracy are critical to best performance."
George Sollish
Chief Engineer - Auto Gear Equip.

sidestep
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Re: Synchronize ring strut key (dogs)

Post by sidestep » Sat May 12, 2018 5:53 am

Autogear, thank you for the time and response. I will take a picture and post to show the shape and size of the strut key. A while back I was able to locate and purchase a nos united delco 3911 968 1st/reverse assembly which was cool, but, the search is getting pretty desperate.

Yes its neat how the shaft has the taper for each gear, as opposed to the 4 speeds have the bushing for first only. Most impressive being the input retainer seals.

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Re: Synchronize ring strut key (dogs)

Post by sidestep » Sat May 12, 2018 5:38 pm

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