Question About Non-Synchro-First-Gear Manual Transmissions

[Cdn17Sport6MT]

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....

 

[Chris142]

Yes you can rev match if you are good. I find it easier to rev match without using the clutch at all. Ymmv.

 

[MolaKule]

What vehicle, what specific transmission?

 

[zrxkawboy]

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?

...

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

IMO, there's no need to downshift to first EXCEPT at a "walking pace".

 

[clinebarger]

I rev matched my '39 Buick after I got the hang of it, It had a torquey straight 8 but relatively high rear gearing which made 1st gear downshifts while moving beneficial. You really had to get it perfectly timed though to avoid clash.

I couldn't say if it was designed for it, I can see people just lugging around in 2nd at low speeds.

 

[Cdn17Sport6MT]

What vehicle, what specific transmission?

None, particularly. It just was in the early sixties, say, when Ford designed and built the Falcon, I believe it had a non synchro first. So if you were going up a steep hill, with its small displacement six, you would not have been able to downshift, yet the engine wouldnt have enuf torque to pull second .. so you'd hafta come to a stop and select first. Not totally driveable or practical...

 

[Cdn17Sport6MT]

Yes you can rev match if you are good. I find it easier to rev match without using the clutch at all. Ymmv.

Yeah, I agree... cuz if double-clutching, soon as you kick in that clutch to engage that lower gear, the countershaft revs slow dn and it's no longer matched... You need to overshoot the revs.

 

[DGXR]

I had a couple 60's Mustangs with the straight six and 3-speed manual, 1st gears were not synchronized. H pattern with reverse in the upper left position (where 1st gear is nowadays), 1st in lower left and gears 2-3 on the right side. I was able to rev match 1st gear anywhere under 20 MPH just for giggles but I didn't make a habit of it. When speeds were low, I could very closely estimate idling in 1st gear around 3-4mph and glide it into 1st without the clutch. Anywhere above 6-8 MPH I would usually use 2nd with a bit of clutching, those engines didn't mind bogging a little. The 1967 transmission was very tough, the 1965 not so much.

 

[Shel_B]

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 can't address your mechanical questions, but to the point above, the answer is certainly. Double clutching, also known as double declutching, is a technique many drivers learned at an early age, My uncle, for example, explained the technique and taught me how to do it when I was about 11 years old. When you downshift by double clutching you engage in rev-matching. Into neutral, blip the throttle, clutch in, drop to 1st (or any lower gear, really)

 

[Cdn17Sport6MT]

I can't address your mechanical questions, but to the point above, the answer is certainly. Double clutching, also known as double declutching, is a technique many drivers learned at an early age, My uncle, for example, explained the technique and taught me how to do it when I was about 11 years old. When you downshift by double clutching you engage in rev-matching. Into neutral, blip the throttle, clutch in, drop to 1st (or any lower gear, really)

I do it a lot. All downshifts... and some upshifts. Having said this, I do it on transmissions that have synchromesh cones, rings, be they in as-new condition, or be they somewhat "knackered". My question related to 'boxes where you have zero partial assistance from the synchro's... because they simply don't have synchro's by design. In those circumstances I think you either need to NOT use the clutch (and of course rev-match) or be darned accurate with your double declutching!

 

[ammolab]

What vehicle, what specific transmission?

My first car (64 AH Sprite) had a non syncro 1st gear. Double clutch was the way to get into 1st while moving. A No clutch Rev match is not easier had to be EXACT to avoid a grind and quite a stress on a locked up drivetrain. Use the clutch and keep the mass of the drivetrain out of the inertia involved.

 

[Cdn17Sport6MT]

@ammolab , you answered my question (as did @clinebarger - thx); you can double-clutch into first... but the way you do it cannot be ham-fisted; it has to be "on-the-money" accurate).

Thx All!

 

[Fabulous50s]

I've driven several 10, 12, and 15 speed trucks with no syncros.

Same double clutching as used in the economy cars which had unsyncronized 1st. But much easier to rev match on a 15L diesel which only has 1500 RPM operating range, than a rev happy gas engine.

 

[Cdn17Sport6MT]

I've driven several 10, 12, and 15 speed trucks with no syncros.

Same double clutching as used in the economy cars which had unsyncronized 1st. But much easier to rev match on a 15L diesel which only has 1500 RPM operating range, than a rev happy gas engine.

I agree, the same double-clutching... but those transmissions are built for doing that. The dog teeth are robust, and I believe the moveable sleeves (that are engaged/slid-over by the shift forks) have wider "slots" and therefore can tolerate a 'wee bit of rpm inaccuracy. That's really, actually, what I'm trying to establish. If I'm wrong, here, please, folks, point that out.

 

[Fabulous50s]

I agree, the same double-clutching... but those transmissions are built for doing that. The dog teeth are robust, and I believe the moveable sleeves (that are engaged/slid-over by the shift forks) have wider "slots" and therefore can tolerate a 'wee bit of rpm inaccuracy. That's really, actually, what I'm trying to establish. If I'm wrong, here, please, folks, point that out.

I don't think it makes any difference. A few degrees of extra slots would only compound gear train slop and loading/unloading could become very bouncy in low gears.

A sliding spline vs wide dog teeth really only makes for stronger gearsets, still driven the same.

 

[Cdn17Sport6MT]

I don't think it makes any difference. A few degrees of extra slots would only compound gear train slop and loading/unloading could become very bouncy in low gears.

A sliding spline vs wide dog teeth really only makes for stronger gearsets, still driven the same.

Fair comment. Just seeking to understand ...

Cheers!

 

[SeaJay]

I drove one like that for a short while. Only downshifted into first at a stop. Second kept going at any other slow speed without any noticeable lugging. It was a 1950 something pickup with a slow engine.

 

[Cdn17Sport6MT]

I had a couple 60's Mustangs with the straight six and 3-speed manual, 1st gears were not synchronized. H pattern with reverse in the upper left position (where 1st gear is nowadays), 1st in lower left and gears 2-3 on the right side. I was able to rev match 1st gear anywhere under 20 MPH just for giggles but I didn't make a habit of it. When speeds were low, I could very closely estimate idling in 1st gear around 3-4mph and glide it into 1st without the clutch. Anywhere above 6-8 MPH I would usually use 2nd with a bit of clutching, those engines didn't mind bogging a little. The 1967 transmission was very tough, the 1965 not so much.

This is helpful. Thx

This demonstrates, I guess, the origin of the Falcon, evident in the Mustang. Falcons didn't, early-on, have synchro first gears. The '67 you mention, was it, too, non synchro first? Was it a "TopLoader"?

 

[DGXR]

I guess these 3-speeds were top-loaders because they had the cover on top? Can't say for sure.
The 1967 and 1965 transmissions were both non-synchro first gear. The 1967 transmission was more robust than the 1965.

 

[Cdn17Sport6MT]

I guess these 3-speeds were top-loaders because they had the cover on top? Can't say for sure.
The 1967 and 1965 transmissions were both non-synchro first gear. The 1967 transmission was more robust than the 1965.

You know... I should know... but I don't know what makes for a "TopLoader" ... @Fabulous50s would know... Pls chime-in! What I DO know is that they are good, robust transmissions, and especially when paired with a BorgWarner overdrive unit, they make for a wonderful and very useable combination with unique features and performance.

PS I might have this wrong... @Fabulous50s may have said all Toploaders were all-synchro...?