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61-63 4speed and 64-65 4 speed differences
Posted by: garydup ()
Date: January 23, 2010 03:45AM

hi guys,i am learning as im going along about the em 4 speed box.can some
body tell me all the differences between the 61-63 and 64-65 4 speed boxes.here is what i learned so far;

synchro dogs are bigger
synchro hubs and teeth are bigger
selector forks are bigger
1st & 2nd gear ratios are different

this is what i need to know

do all the bigger synchro hubs assemble on the earlier main shaft
are all the blocker rings the same and interchangeble
can anyone send an exploaded view of a 64-65 box

thanks
gary

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: Tom Z ()
Date: January 23, 2010 07:45AM

..Clarks catalog has the diagram you're looking for,taken from a GM book,and lists most all the parts available including what is the same/different..the brass blocking rings,for instance,are different for each 4sp and each synchro..while many 'small parts' are common,the cases are different to the point where you can't "upgrade' a 61-63 box with 64-65 internals..if that's what you're trying to do..

Tom Z,,Rochester NY

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: vairchet ()
Date: January 23, 2010 10:31AM

The only thing you can do is swap 1-2 and 3-4 synchronizers, shift forks, countershaft (not countergear), and many of the small bits and bearings that are common to all early standard 4-speed transmissions. In fact, using '64-'65 synchronizers and matching shift forks in a '61-'63 4-speed does improve shifting and reliability.

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: garydup ()
Date: January 23, 2010 01:40PM

hi vairchet,thanks for your input ,with using the synchronizers do you also have to use the 64-65 blocker rings?is the reason that you cant use the gears because they are longer wider?if the teeth are different on the blocker rings to match the bigger synchronizers how does this all align up with the 61-63 teeth on the gears?

thanks gary

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: cnicol ()
Date: January 23, 2010 02:38PM

Yes, the blocking rings have to be used with the gears. I understand the cone angle is different.

Note that the early gear ratios remained available in the 64-5 redesign and these came in FC models and were sold over the counter for replacement of 61-3 model transmissions. Also note that the gears were repositioned on the mainshaft (3rd went to the front of the central mainshaft flange). Also, the input gear changed (tooth angle, invisibly) and of course the input shaft got larger and went to 14 splines.

If what you're after is a smoother shifting EM trans, just switching the gears and blocking rings won't do it because the main element of the improvement was reducing the rear gear stack from 3 gears (lots of "give" during shifing) to 2 gears.

You can find the parts to make a 2nd design FC trans or put together a nice EM trans with minimal free play in the 123 stack.

I wrote a lengthy article for the Commnuique (I know, what's the benefit of belonging to CORSA). PM me with your email and I'll send you a copy.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: vairchet ()
Date: January 24, 2010 01:55AM

Synchro rings must remain with matching gears. In other words, '61-'63 synchro rings are to remain with '61-'63 gears, same goes for '64-'65. The reason is differences of cone angles as Craig mentioned. The synchronizers themselves don't care what year ring is installed. Wide synchro rings fit 1st & 2nd and narrow rings fit 3rd & 4th.

If you take '61-'63 synchronizers and placed them next to '64-'65 you'll discover they're the same size and dimension. The difference is the fork groove. '61 and very early '62 had short grooves cut into the outer diameter. You must use matching shift forks when swapping synchronizers. '61 and early '62 four speed shift forks are crap.

Also, synchro dogs on '61 and early '62 were stamped steel versus cast and machined steel alloy equivalents on later '62-'65. As for alignment: If you take a close look, you'll notice there are the same amount of engagement teeth on gears themselves as well as synchro rings between '61-'63 and '64-'65. The shape of the teeth also remain the same. This is why later style synchronizers will fit early rings and engagement teeth on early gears.

One other thing I should mention: Synchro hubs (center section of synchronizers that slides onto mainshaft) have the same spline diameter and will interchange with all '61 to '65 mainshafts. Do not mix and match synchronizer parts. That is, synchros with stamped steel dogs will not mix with synchros with alloy dogs.

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: garydup ()
Date: January 24, 2010 05:30AM

thankyou cnicol,vairchet,it would seem that i might have a mixture in this box .for sure the 3-4 synchronizer must be 64-65,not sure about 1-2 synchronizer,does this look 64-65?ok one last question and please dont shoot me,why wont the 64-65 gears fit in the 61-63 housing?

i think my gearbox is a 63 no.R0917 no is stamped at bottom just above shifter.the dogs are also cast not stamped.
thanks gary

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: Bob65 ()
Date: January 24, 2010 11:38AM

This is slightly OT. I have installed the early 4-speed in my 65 Corsa with a 3.08 rear end. I enjoy this combination very much. I went through the transmission (with help) and replaced only first gear as the synchro teeth were worn. My only issue is that I sometimes get a clash going into 4th. Is this an issue of the selector shaft not rotating enough or something more serious? I can find 4th pretty cleanly if I push the gear shift hard right and then down from third. Any ideas?

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: garydup ()
Date: January 24, 2010 12:02PM

hi bob 65,im still learning here myself but this sounds to me more like a gear shifter adjustment problem especially when you say if you force it over to the right a little it shifts no problem,readjust and let us know.

thanks gary

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: vairchet ()
Date: January 24, 2010 01:30PM

Gary,

From what's depicted in your photos, you have a matching set of forks and synchronizers. There is one thing you must do: Closely examine the wear on forks and synchros. If the wear is excessive on the forks, you'll experience incomplete gear engagement. In other words, transmission may pop out of gear. Same goes for worn synchro teeth.... if rounded off, difficult to engage gear and a possibility of jumping out of gear once engaged. I'll try to post some photos within the next couple of days to give you a better idea of what I'm trying to explain.

Clashing of gear engagement is usually due to worn synchro (blocker) rings. Soon, synchro teeth will round off and popping out gear could occur. Again, I'll post photos.

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: vairchet ()
Date: January 25, 2010 09:50PM

Here's some photos with explanations and part numbers:

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: vairchet ()
Date: January 25, 2010 09:54PM

More photos:

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: vairchet ()
Date: January 25, 2010 10:02PM

Even more photos:

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: vairchet ()
Date: January 25, 2010 10:11PM

Last one.

One of the photos is in error. It depicts a pair synchronizers with matching shift forks. It supposed to represent a pair of 3rd & 4th synchro units, not 1st & 2nd. Oh well, can't be perfect all the time.

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: gwydionjhr ()
Date: January 26, 2010 08:46AM

Chet... YOU ROCK! thumbs up

Regards,
Joel Rushworth
1961 Rampside w/Deluxe Scamper Camper
1966 Corsized Cdn Monza Coupe
1967 UV #292
"Kick the Hell out of the Status Quo" - Ed Cole

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: Bob65 ()
Date: January 26, 2010 09:37AM

Excellent photos. A question about sychronizers.What do sychros do when up shifting as opposed to down shifting when they speed up the mating gears to avoid clashing. Thanks, Bob

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: Wabbitkiller ()
Date: January 26, 2010 09:42AM

I second that...You ROCK Chet!

Chris

1965 Monza 95 Convertible 4 speed

Olathe, KS (Kansas City)


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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: garydup ()
Date: January 26, 2010 09:43AM

hi vairchet,wow that must of taken you ages to put together and all the part numbers as well you are really dedecated. thankyou for all the help inow fully understand all the differences and changes thankyou.one more thing if i use the entire inners [gears synchroes revised main shaft] from the 64-65 fc box will they install in the 63 housing with the old style reverse gear.?

thanks gary

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: vairchet ()
Date: January 26, 2010 12:19PM

Gary,

None of the '64-'65 gears (this includes the countergear) will fit inside an early ('61-'63) transmission case due to clearance problems. '64-'65 reverse gear is physically larger, it's centerline (shaft) is placed further away from countergear as opposed to '61-'63 four speeds. '64-'65 FC four speeds that were mated up with 3.27 gearing, their gear ratios mimic those of earlier FC transmissions. But again, because of a difference of gear tooth angles, reverse gear, and physical limitations, swapping gears isn't possible.

If this seems confusing, swapping gears between '61-'63 passenger car and FC isn't possible due to ratios and, get this, gear tooth angles. FC third & fourth gears appear similar but will not swap with passeger car parts 'cause of gear tooth angles. So, if you made a mistake of tossing all your transmission parts into one common bin, you're in for a rude surprise. It'll take you pracically forever to figure out which part went where. Of course, countershafts, synchros, blocker rings, shift forks, reverse gear, bearings, and all the small bits are interchangeable between '61-'63 passenger car and FC four speeds.

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Re: 61-63 4speed and 64-65 4 speed differences
Posted by: cnicol ()
Date: January 26, 2010 02:17PM

Vairchet's statements about swapping gears is basically correct and that's a safe way to approach the issue. Having said that, note that there are FOUR different FC transmissions: 61E 61L-63 64E and 64L-65 The most common FC trans (61L-63) does have guts that can be interchanged with the same series car trans. but like Chet said, identification of these parts can be tricky.

In a PM, garydup asked me about ratio suggestions considering his 110/3.55 powertrain and I thought I'd make the recommendation public as it's of general interest.

With the torque and power of a 110, you won't need the low 3.65 first gear (and especially not the very low 4.26 first gear) ratio transmissions. Your best bet is a complete 64-5 car transmission with its 3.20:1 first gear. This combined with a 3.55 axle yields a sporty and easy overall first gear ratio of 11.36:1 (3.20x3.55) and doesn't have the wide 2-3 ratio gap of the earlier transmission.

If you will be doing a lot of highway driving, you may want to reconsider the 3.55 axle, 3.27 would be better as highway rpms with a 3.55 and regular sized tires are rather high.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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