Question About Non-Synchro-First-Gear Manual Transmissions

[Fabulous50s]

A Toploader as coined by Ford was designed in 1963 and used from the 63.5 MY on in all big power Fords. Previously Ford used the Borg Warner T10 which has a side cover. Those had unsyncronized 1st gears. In Toploadeds all forward gears have syncros, 3 and 4 speed.

Some of the economy cars still used the BW T10 or a variation of it. To save pennies the 1st was not syncronized. GM, Ford, and Chrysler all did this.

A Toploader was a name coined by Ford for their new transmission made for the muscle car era. GM made the Muncie M21 and M22 which is a side loaded Aluminum case, which is known for its less precise shifts due to the shift linkage.

The toploader gets its strength from the iron case, and the design of the shift rails which the shift forks slide on, making for better shift quality. And continuous iron sides on the case where the stresses of the gearset are strongest. The Muncie with aluminum case and open side is weaker.

By today's standards, they are all slow and heavy.

Lighter gear sets make for faster shifts at HIGH RPM, back then everything was heavy with big forged bronze syncro rings.

This is a late 60s 3 speed next to a late 70s 3+OD. The unpainted case is the 3 speed capable of holding 400HP. The width of the gears being the limiting factor. You can see on the main shafts the difference. The longer one being the 400HP one. A true 4 speed toploader in the 31 spline output and 1-3/8 input is the 500+ HP version.

 

[DGXR]

By that definition, the 3-speed transmissions in my 6-cylinder cars were not top loaders. Thank you Fabulous for the thoughtful reply.

 

[Astro14]

You can double clutch into first with a non-synchro transmission. It requires precise rev-matching as was said.

As a practice - I do not.

Second is low enough that I can pull away from a stop sign in second. No good reason to stress a 90 year old gearbox.

 

[thastinger]

Your problem with "double clutching and speed matching) is going to be that most non-synchro transmissions (like the one in my 49 Farmall C) run 80-90 as the lube. You can only "match" on the downshift, never one the upshift because the thickness of the oil will slow the drive shaft more than the driven shaft.

 

[wings&wheels]

I occasionally drive old Land Rovers w/ non-synchro first gears as well as other older mostly British cars and my rule of thumb is to avoid shifting into first while moving. There are really few instances where you need to downshift to first in motion but my two main reasons; 1) it is a learned skill as noted above and 2) I don't drive these vehicles enough to become proficient.

 

[vwmaniaman]

my 1929Model A Ford Town sedan had no synchronizers. Every gear was double clutch till you got used to driving it and then you didn't double clutch anymore. Of course the gears were well protected in 600W gear oil too. Of course you needed to warm it up in winter before you drove it.

 

[barryh]

Second is low enough that I can pull away from a stop sign in second. No good reason to stress a 90 year old gearbox.

The owners manual for my car actually recommends pulling away in 2nd provided the car is on the flat so that's what I do. I only use 1st for hill starts and in normal free flowing driving would never need to change down into 1st while on the move. I can just about remember driving cars with no synchro on 1st but again avoided as far as possible changing down in to 1st on the move. I suppose that's why it was commonly left off 1st back then.

I ride a 44 year old BMW motorcycle with a bit of a reputation for clonky gearchange. On the forums people will say the change down to 1st is particularly bad. I say, well then don't do it, why would need to change down into 1st before coming to a stop unless in very slow moving traffic. It will pull away in 2nd with ease anyway. Bikes of course have no synchros, just dogs to engage a gear so it has to be all about rev matching. Part of the fun of riding a bike.

 

[ecotourist]

My '63 Chevy II I6 was non synchro in 1st gear. My '65 Mercury Comet V8 was synchro in all 3 gears.

I didn't try to shift into 1st gear while moving in the Chevy II. I either stopped to get into 1st gear or slipped the clutch a little/lugged the engine a bit in 2nd gear. You learn to live with it. Never replaced that clutch either so we must have done something right.

 

[totegoat]

Fairly easy to downshift a 3-speed into low with experience. Seldom needed to downshift to very low 1st gear while moving in old 4-speed pickups but could be done.

 

[Fabulous50s]

My '63 Chevy II I6 was non synchro in 1st gear. My '65 Mercury Comet V8 was synchro in all 3 gears.

I didn't try to shift into 1st gear while moving in the Chevy II. I either stopped to get into 1st gear or slipped the clutch a little/lugged the engine a bit in 2nd gear. You learn to live with it. Never replaced that clutch either so we must have done something right.

Your ChevII would be a Borg Warner T10 (the economy transmission by that time) and the Merc would be a Toploader. If the Merc was a 6cyl and had an unsyncronized 1st it too would have the BWT10.

 

[Fabulous50s]

By that definition, the 3-speed transmissions in my 6-cylinder cars were not top loaders. Thank you Fabulous for the thoughtful reply.

Remember that much could have changed since then. Someone could have put a syncronized 1st in by now....

But if you have a 1960s unsyncronized 1st from any of the American companies it would be a Borg Warner T10, it was cheap and reliable. Plenty strong for the modest power of a 6cyl engine. In the 1950s the BWT10 was pretty much used by everyone.

Muncies and Toploaders were designed specifically for muscle cars and always came from the factory with all forward gears syncronized. Aftermarket gears could be swapped in in which were not syncronized however for more extreme holding power.

 

[Kiwi_ME]

.. could a person (say, by double-clutching or by NOT using the clutch at all, but rather by rev-matching in neutral) ever get the car to go into low gear without clashing, other than at a walking pace or less?

I'm interested in how these non synchro first gear boxes... how they differ from a "dog box"...

Yes, with practice, but normally there was no need to as you would come to a stop first.

Generally these did not have dogs per se but the gears had rounded lead-ins and engaged sideways along splines. That did generate more wear particles than we would be used to seeing today.

 

[Cdn17Sport6MT]

Yes, with practice, but normally there was no need to as you would come to a stop first.

Generally these did not have dogs per se but the gears had rounded lead-ins and engaged sideways along splines. That did generate more wear particles than we would be used to seeing today.

View attachment 145030

@Kiwi_ME , that's a great graphic, and it totally answers my question(s). You intimate that most non-synchro-low-gear 'boxes are not constant-mesh in low gear...?

I guess the other thing is that when the lubricant is at OP temp, the move from neutral to part engagement of second and then to low (to stop the countershaft from turning) has to be quick!

 

[Kiwi_ME]

You can probably find cutaway views of older transmission online but I'm not aware of a passenger car design that uses large dogs like a motorcycle, racing or heavy truck gearbox. In fact one box I disassembled as a teen (probably a Saginaw, looked exactly like the one below) did not have blocking rings despite having cone synchronizers on 2nd/3rd gears.

In a modern synchro design the blocker ring bronze teeth have a lead-in that is pushed against a similar set of steel teeth attached to the gear you're engaging. From the force applied at the shifter the angle between the teeth produces reaction forces both axially and tangentially to the shaft. The axial force is reacted through the blocker and gear cone faces to encourage them to turn together, producing the synchronising effect. The harder you push the shifter, the stronger the force that is placed on the cones and the faster they will synchronize. Once the cones reach the same speed the blocker ring rotates backwards one half of the tooth pitch allowing the teeth to slip past each other and 'engage' the gear.

The Saginaw below uses only the axial retention provided by radially-positioned spring-loaded ball detents to provide a fixed axial force to the cones when a shift is started. There is nothing stopping you from slamming it into gear and grinding the shift. The design relies on the driver having the skill to apply a balance of force and timing to achieve a quiet shift.

But this is a clever design in terms of packaging. You can see that the first gear on the main shaft is helical but slides on helical splines on the outside of a drum, balancing out thrust forces. It can engage the first gear on the countershaft or the reverse idler. Second and third gear syncros and dogs are inside that drum which can slide left and right when required by the shift fork acting on flange (7). It's hard to visualise without having one in front of you but it's really quite ingenious as the gearbox length is keep short by taking advantage of the otherwise unused space inside the large-diameter first gear.

 

[Fabulous50s]

You can probably find cutaway views of older transmission online but I'm not aware of a passenger car design that uses large dogs like a motorcycle, racing or heavy truck gearbox. In fact one box I disassembled as a teen (probably a Saginaw, looked exactly like the one below) did not have blocking rings despite having cone synchronizers on 2nd/3rd gears.

In a modern synchro design the blocker ring bronze teeth have a lead-in that is pushed against a similar set of steel teeth attached to the gear you're engaging. From the force applied at the shifter the angle between the teeth produces reaction forces both axially and tangentially to the shaft. The axial force is reacted through the blocker and gear cone faces to encourage them to turn together, producing the synchronising effect. The harder you push the shifter, the stronger the force that is placed on the cones and the faster they will synchronize. Once the cones reach the same speed the blocker ring rotates backwards one half of the tooth pitch allowing the teeth to slip past each other and 'engage' the gear.

The Saginaw below uses only the axial retention provided by radially-positioned spring-loaded ball detents to provide a fixed axial force to the cones when a shift is started. There is nothing stopping you from slamming it into gear and grinding the shift. The design relies on the driver having the skill to apply a balance of force and timing to achieve a quiet shift.

But this is a clever design in terms of packaging. You can see that the first gear on the main shaft is helical but slides on helical splines on the outside of a drum, balancing out thrust forces. It can engage the first gear on the countershaft or the reverse idler. Second and third gear syncros and dogs are inside that drum which can slide left and right when required by the shift fork acting on flange (7). It's hard to visualise without having one in front of you but it's really quite ingenious as the gearbox length is keep short by taking advantage of the otherwise unused space inside the large-diameter first gear.
View attachment 145122

So in this fully unsyncronized design you would be literally grinding gears? Not constsnt mesh. Sliding gears, with the force of the helical teeth opposed by the helical grooves cut into the drum thar the gear rides on?

Thanks!

 

[97prizm]

This may be a stretch for most of the Forum participants due to the median age of people here, but I have a question - related, as the title suggests, to mostly three-speed domestic car manual transmissions. There was a time when synchromesh was only on second and "high" gear. Now I know in domestic pickup trucks there were many a four speed 'box with a bull-low. They often were labeled L, 1, 2, 3 on the gear lever. Bull low was really, really low, gear ratio-wise, and almost invariably you'd start in "1", and L would only be reserved for the heaviest of loads.

But my question is: for normal, non synchro first gear three speed passenger car transmissions, could a person (say, by double-clutching or by NOT using the clutch at all, but rather by rev-matching in neutral) ever get the car to go into low gear without clashing, other than at a walking pace or less?

I'm interested in how these non synchro first gear boxes... how they differ from a "dog box"..
I believe a dog box has coarse and robust (and few) dog teeth and wide and "sloppy" engagement slots in the moveable, call them "synchro" rings or engagement rings (i.e. the components that are moved by the shift forks).
By comparison, non synchro first gear boxes, I'm surmising, have fine and numerous ("small-module" or "low-module") dog teeth, actually very similar to those where the synchromesh cones ARE present. As such, non synchro first gear 'boxes, truly, are NOT meant to shift into first gear except at a stop.

Can folks double-clutch into first gear at a reasonable roadspeed?

Please humour me, with these "weird" questions....

If by dog box those are used in alot of race car transmissions.

 

[Kiwi_ME]

So in this fully unsyncronized design you would be literally grinding gears? Not constsnt mesh. Sliding gears, with the force of the helical teeth opposed by the helical grooves cut into the drum thar the gear rides on?

Thanks!

That transmission is a 3-speed with syncro on 2nd and 3rd. The synchros are just not as sophisticated as we find today.

 

[Kiwi_ME]

Thanks!

The easiest way to learn about this stuff is to obtain a scrap manual transmission from an auto recycler and tear it apart!

 

[FishFry]

This may be a stretch for most of the Forum participants due to the median age of people here, but I have a question

Not a stretch at all, I'm very familiar with those boxes, especially pre-war Borg Warner.
And yeah, it's totally doable by double clutching or rev matching - I do it some times with my 41 Chevy, not a problem.

Frank

 

[Cdn17Sport6MT]

You can probably find cutaway views of older transmission online but I'm not aware of a passenger car design that uses large dogs like a motorcycle, racing or heavy truck gearbox. In fact one box I disassembled as a teen (probably a Saginaw, looked exactly like the one below) did not have blocking rings despite having cone synchronizers on 2nd/3rd gears.

In a modern synchro design the blocker ring bronze teeth have a lead-in that is pushed against a similar set of steel teeth attached to the gear you're engaging. From the force applied at the shifter the angle between the teeth produces reaction forces both axially and tangentially to the shaft. The axial force is reacted through the blocker and gear cone faces to encourage them to turn together, producing the synchronising effect. The harder you push the shifter, the stronger the force that is placed on the cones and the faster they will synchronize. Once the cones reach the same speed the blocker ring rotates backwards one half of the tooth pitch allowing the teeth to slip past each other and 'engage' the gear.

The Saginaw below uses only the axial retention provided by radially-positioned spring-loaded ball detents to provide a fixed axial force to the cones when a shift is started. There is nothing stopping you from slamming it into gear and grinding the shift. The design relies on the driver having the skill to apply a balance of force and timing to achieve a quiet shift.

But this is a clever design in terms of packaging. You can see that the first gear on the main shaft is helical but slides on helical splines on the outside of a drum, balancing out thrust forces. It can engage the first gear on the countershaft or the reverse idler. Second and third gear syncros and dogs are inside that drum which can slide left and right when required by the shift fork acting on flange (7). It's hard to visualise without having one in front of you but it's really quite ingenious as the gearbox length is keep short by taking advantage of the otherwise unused space inside the large-diameter first gear.
View attachment 145122

@Kiwi_ME, that Saginaw 3 speed, then, is non synchro 1st (and Reverse)???... but differs from the first graphic you sent, in that i) first and reverse are helical but they axially slide on the helical synchro sleeve (said synchro sleeve only catering for second and "direct" gears); and ii) synchro's for 2nd and top gears are compactly housed inside the barrel. Correct?
Also, it's only due to low gear being on a helically grooved barrel that it's possible to (very accurately) double-declutch into low...Correct?

Cool!

I'm not sure about the detents, though. They comprise spring-energized balls in pockets... in the bore of the helical sliding gear???

Do you intimate, then, that low gear IS synchronized?