Learn Me: Vintage gearboxes and shifting

I've been watching a few videos of vintage TA type cars and would like to know what is going on with the shifting of these things.  For example, if you look at this video, Curt Vogt at Road Atlanta

Curt is shifting the car seemingly without any clutch activity.  On both upshifts and downshifts there doesn't seem to be any movement of his left leg, or any audio indication that he is using the clutch.  It just seems like he lifts the throttle and yanks the lever.  On downshifts, there isn't any apparent heel-toe rev matching, it just seems like he knows at what RPM to yank the thing into the next lower gear.  It's just amazing at how fast the gear changes are made.

There is another video of the black corvette in this race and he appears to do the same thing, in fact it seems like he is using left foot braking.  '69 'vette at Road Atlanta

My understanding is that these vintage cars use vintage gearboxes, almost certainly a top-loader for the Mustang and a Muncie for the 'vette.

Anyone here have any experience with this sort of thing?  Are the transmissions modified in some way to allow for clutchless shifting?

BTW, I wouldn't want to drive that 'vette, what a handful!  The Mustang seems much more composed.

Yup.  Possibly a Jericho clutchless setup?  You use the clutch for starting and reverse, outside of that you just bang through.

Any manual gearbox can be shifted without a clutch. Those are likely what we always called a crash box, which has straight cut gears, no synchros, and requires rev-matching to minimize damage of gears meshing. You have to be somewhat forceful, quick, and commit to the shift. Those gearboxes likely get rebuilt very frequently.

Yup, likely dog rings in that transmission instead of synchros.

A well designed box and skilled driver can pull this off almost any time.  I found solid mechanical linkages as opposed to cable operated are easier and german boxes to be the best. Getrag, porsche (except the 914), and VW were what I learned this on, and never broke a single trans.  Now the outback has a bad case of 5th gear  popout and I have a spare so for the last year have been driving 80% clutchless and it takes it rather well.  I will keep doing it until the box blows up, the engine dies or someone buys it.  

How do you downshift ?

I have had a couple very old VWs that were full crashboxes  and I never really  could do it right !

Lift, neutral, rev, downshift. I am not quick but I could upshift and downshift my ACVW easily without the clutch. My BMW... not so much.

What VW was a full crashbox? The Kafer started life constant mesh when it was still the KDF Wagen.

Here's an excellent tutorial from WhistlinDiesel:

Skip to 3:00 for the smooth shifting part.

buzzboy said:

Lift, neutral, rev, downshift. I am not quick but I could upshift and downshift my ACVW easily without the clutch. My BMW... not so much.

What VW was a full crashbox? The Kafer started life syncronized when it was still the KDF Wagen.

Kdf Kafer + Bug  all were full crash until 1952  , and then until the early 1960s on Standard models 

Kubelwagens and shwimmwagens were full crash boxes , as were the first few years of VW buses , 

October 52  is when the split case with crash 1st gear and syncros in 2-3-4th  started

and the first couple years of 356 Porsche used the full crash box from the VW bug.

Hope that helps explain it......

I wouldn't be surprised if the Mustang in the video has something like a Jerico transmission, or is a top loader modified into a 'dog box' so it looks stock on the outside but is heavily modified internally.

In reply to stukndapast :

If the trans has decently close ratios, like most performance 4 speeds did in the late 60s (2.2 1st gear, 1:1 4th gear), you didn't need to use the clutch if you could move the shift lever quickly enough.

Oddly, if you drove them "normally", they are a complete pain in the ass because the engine revs fall under closed throttle faster than the trans can shift.  So maybe shifting clutchless is the way to go.  I never had the ball-balls to do that with a customer's numbers-matching Chevelle/Corvette/Camaro, so I can't say for sure.  (Didn't work on many Fords.  Fords don't break so I never got to work on many )

Apis Mellifera said:

Any manual gearbox can be shifted without a clutch. Those are likely what we always called a crash box, which has straight cut gears, no synchros,

ARG.

I have to nitpick here because there is a common misconception about... a lot of things.  This is not directed at you specifically, this is just an opportune time to vent.

"Crashboxes" physically slide gears in and out of mesh.  A lot of old 3 speeds (lik 1950s era) had a "crashbox" 1st gear.  Class 8 trucks had them up until the 80s. Some manual transmissions did this up until relatively recently for Reverse:: VW 020 transmissions physically moved a gear in and out of mesh to engage Reverse, and I'd like to say Saturns did too.  But for everyone else, the gears always stay meshed and all you are doing is engaging or disengaging sliders (splined to the shaft) to the gears.

You can have nonsynchronized angle cut gears.  You can also have synchronized straight cut gears.  The shifting mechanism has zero to do with the tooth angle.

First those gearboxes aren't exactly vintage; many of the rulebooks allow for the internals to be free so what you may have is a modern racing gearbox inside the old case. More than likely it's something like a Jerico or similar gearbox.

You can do this in formula fords or any other car with a Hewland gearbox. 

The biggest advantage is that it allows you to left foot brake which is a huge advantage.

In reply to Tom1200 :

I raelly wish I could remember who said it, but in a moment of divulging is secrets, and old rallyist said that if he was winning a series championship and there was someone who was coming dangerously close to him in points, he would "drunkenly" "reveal" at a get-together the "secret" of left-foot braking.  And then he wouldn't have to worry about him for the rest of the year, because the other guy would lose so much time that he wouldn't be a threat.

The only time I've really seen any kind of "left foot braking" effective was, admittedly, in a vintage car, and the driver would, about 2-3 seconds before a braking zone, pump the brakes up with his left foot before letting off the throttle, because vintage brakes + vintage wheel bearings = epic levels of brake piston knockback.  We;re talking two or three pumps nearly to the floor, before he took his right foot off the throttle.

In reply to Knurled. :

I have watched several in-car videos of vintage racers who pump the brakes on a straight before really getting into the brake zone because of knockback.  Actually, I race in vintage, though barely, and arguably vintage, in a 85 Mustang SVO and I have to do the same.  If I don't pump the pedal before I really need to brake, I get a soft pedal and it really screws up my heel and toe as the brake is too low for the throttle.  I got interested in the shifting going on in these vintage cars since I spend quite a lot of time actually performing a shift with a standard T5, and having to let off the gas on a turbocharged engine, and then go back to WOT and wait for boost to come back in is costing me a lot of lap time. When I see these guys yanking on the lever without touching the clutch, it makes me jealous, even though they are lifting in the shift which would still wreak havoc with the boost profile on my engine.  What I really need is a flat shift where I can keep the throttle to the floor and upshift while WOT, keeping the boost up.  I have a megasquirt which allegedly has that capability, but I haven't the guts or clutch switch to try it.

In reply to stukndapast :

You don't need a megasquirt for that, you just need an MSD ignition box and a 2-step.  Have used that for over ten years.  I don't lift off the throttle at all when I upshift.  Put force on the shifter and then punch the clutch - lever moves and I'm in the next gear.  Usually.  Sometimes not, sometimes I just get a large amount of grinding because synchronizers do not work at high RPM. 

As far as boost lag on corner exit is concerned... the solution for that is high revs and natural aspiration

In reply to Knurled.

After a little more investigation I think what these guys may be doing is converting the OEM syncho transmissions to dog-ear.  They aren't actually meshing gear teeth to gear teeth on a shift, but the linkage between the gear faces on the countershaft (the sliders) is being done with dog-ear lugs as opposed to syncros.  From a 20 thousand foot view, dog-ear seems very crude and violent, but watching these guys row those transmissions mercilessly under racing conditions would indicate that it is pretty stout, without knowing how often the transmissions need to be serviced or replaced.  I'm pretty sure that the vintage rules, at least in SVRA and HSR for this class of cars requires a vintage transmission in principal, and maybe these cars are running something like a Jerico (not really vintage), but at least they are 4 speeds and not some more modern G-force 5 or 6 speed gearbox,  I think it is interesting that in both of the videos that I originally linked, both the Mustang and the 'vette are running out of RPM way before they get to the braking zone going into 10A at Road Atlanta.  Different gearing or a 5 speed would make quite a difference there.  I still wouldn't want to drive that 'vette.

In reply to stukndapast :

NO automotive transmissions made in the last 60 years move (forward) gears in and out of mesh.  Dog gears work just like synchronizer transmissions except they have "dogs" instead of synchonizers and splines.

Knurled. said:

In reply to stukndapast :

NO automotive transmissions made in the last 60 years move (forward) gears in and out of mesh.

I have to nitpick here because there is a common misconception about... a lot of things.  I assume you're not familiar with British transmissions made for things like MGs all the way up through at least 1974.  I never owned a late 70s/early 80s Midget or Spitfire to know if they eventually resolved the terrible first gear of "what we always called a crash box".  The MGB eventually got synchromesh on first and maybe the TR6 and TR7 did too.  I learned to drive in a '58 MGA, my first car, and I drove a '73 MG Midget daily up until 1999.  I can tell you they most certainly slide first gear into the laygear, hence my reference above.

In reply to Apis Mellifera :

GM might have use a crashbox 1st until 1973 in their 3 speed as well, and I submit that it's a 50s trans that they failed to stop making yet. 

In reply to stukndapast :

You should look into converting your T5 from syncros to dog rings. They do sell conversions for this trans. Check out YouTube as there is a video of one guy who drives one on the street.

stukndapast there are a couple of things you can do:

You can set the rev limiter up to allow you to shift with no lift.

Upshifting is such that it only requires the slightest unloading of the trans to make it happen. On my gutless Datsun (all that turbo lag without that turbo power) I actually put slight pressure on the shift lever a split second before the upshift. I have the clutch adjusted so that you just have to partially disengage the clutch while still making sure there is slight free play. I do this both at the pedal and the slave cylinder. Note I've got a street box in my car.

It's not possible to rapidly downshift without disengaging the clutch in the Datsun but because I trail brake I've adapted a technique I used when I road raced peaky two stroke bikes. While trail braking I actually preload the throttle slightly. So rather than lifting completely off the gas after the downshift I've got the pedal depressed slightly. This takes practice and isn't necessarily easy to master. 

@knurled I now the quote your taking about; I should clarify that rally left foot braking (staying on the gas and pulse the pedal to keep the car rotating) and road racing braking with your left foot (allows you to go instantly from gas to brake) is very different. I use both techniques.

I have always driven British cars and double clutching has become second nature to me, to th extent that I unconsciously use that technique in my two modern sports cars as well (it will certainly be easier on those gearboxes than most of today's ham fisted drivers are).

I once has a clutch slave cylinder fail on me in the first few laps of a race. I drove the rest of the race clutchless and my lap times dropped very little. Biggest issue was the pit marshall that insisted that I stop to let another car proceed while I was going into the pits after the race. He was pissed off when I shut off the engine and told him that I'd need to be pushed up hill into the pits.

I would never shift normally without a clutch as it increases the chance that you might get it wrong and possibly chip a tooth or worse.

And yes, my race car also had issues with pad kick back on the rear, so I just used my left foot to touch the brake pedal while on the straight, just enough to bring the pads back out near the discs. IIRC, some of the Formula Fords used to insert coil springs behind the pistons to dot hat automatically, limited so they didn't actually push the pads into contact with the disc.

In reply to stukndapast :

You may find this interesting. I recently put a G-force dog box in my street/autocross Fairmont. This thread talks about it. 

https://grassrootsmotorsports.com/forum/grm/dog-box-on-the-street/153965/page1/

As you can see, it shifts slowly when using the clutch.