Clutchless shifting Q's

Don, I think in the previous comments, its pretty clear that the bottom line is that for the dog box to make the difference you need to be able to drive it like in the videos - fast and smooth. The rules are meant to bring parity among the competitiors and different makes. So, in this case, if you go with alternate gearbox, you are going to pay with a weight penalty.

Since you are vintage - and using the SVRA rulebook as an example - your new box nets you a 75lb weight penalty. If my MGB at the time was sitting next to yours with its SC/CR gearbox, it would weigh considerably less, because I don't get the penalty. So, all things being equal, your new gearbox should make you faster than me, but for you to beat me, you are going to have to drive it. But, on paper, I should still be very competitive, even without the top tier gearbox.

This thread is of interest to me, only because I talked with Jesse about what gearbox I should go with in my Miata, and this affirms the choice I made to go with the Quaife SC/CR gear set and not the dog box.
 
I realize it's a formula car with a paddle shifter, but this guy does a great job of waiting really late in the braking zone to downshift... never seems to have any trouble setting himself up to get back on the throttle at the right time. (Something I struggle with and I'm sure will be a struggle with my Quaife.)

http://www.youtube.com/watch?v=OI7x706ODVM

Skip forward to the 2:45 mark.
 
We should all pause and say thanks for YouTube. I remember when the Internet was new and I found a clip of a lap around Road Atanta (pre-9a,b) from an open cockpit prototype.

It would take forever to load, but once it did, I'd watch it over and over again.
 
Jesse Prather":3c0vdqs6 said:
dcharnet":3c0vdqs6 said:
Do you all agree that clutchless shifting, even with skill, is harder on the box?
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Certainly, but a race car is designed to be abused. It's harder on the entire driveline. I would also comment that 50% of drivers are wasting their time with a dog box because they can't utilize it properly. One advantage would be the ability to change individual gear ratio's but a lot of dog boxes don't allow this either, like the Quaife. I'd suggest anyone thinking about it also think about a good synchro alternate ratio box as well. These can be cheaper and just as fast without the added weight penalty. You have to be able to utilize a dog box properly and it's not for everyone.
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Were going with the PBS in the RX-8, the beauty of that is if I'm inept at or break the dog box, I can use my EMCO or Miata gearset box as a backup, plus the PBS has drop gears.

Question - the dog boxes can be used with the clutch as you would a normal transmission with no adverse effect on anything, correct? The dogs act like syncros?
 
disquek":3ncn2jb7 said:
Are flat shift ECUs legal in prod? They make the upshifts MUCH easier.
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9.1.5.n. Transmission
1. The Transmission is unrestricted, providing that it is fit in
the same basic location as stock.
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I believe that would be yes.
 
"This thread is of interest to me, only because I talked with Jesse about what gearbox I should go with in my Miata, and this affirms the choice I made to go with the Quaife SC/CR gear set and not the dog box."

Fred, I discussed dog vs. synchro with Quaife. What I took from the discussion is that their dog box is the strongest product they make. The gears are bigger, and there are no wear-prone synchros. The shifts are faster. You just slam it in--fastest is best---and don't wait for a slower -acting synchro to do the work. If you use the clutch and have reasonable technique, it is the most robust choice. If you shift without the clutch, and thus take advantage of left foot braking, wear will be somewhat accelerated. My choice was between a Quaife dog, a Quaife synchro, and a SC CR MGB box. After much thought and discussion I chose the Quaife dog because I conluded that it was the strongest and would last the longest, was the fastest-shifting, gave me the option of left-foot braking if I want to go that route and trade some increased wear for some speed, and offered the closest ratios for the top three gears. I am convinced that the choice was optimal for vintage racing a serious MGB short of perhaps a Schwitters Alfa box with Hewland gears. The Schwitters was much more expensive, and Steve did not answer e-mail requests, which always ends the inquiry for me. Knowing you, and who you are working with, and the class you are in, I am sure you made the best choice for you.
 
cpa7man":2apt86ar said:
Jesse Prather":2apt86ar said:
dcharnet":2apt86ar said:
Do you all agree that clutchless shifting, even with skill, is harder on the box?
Click to expand...



Question - the dog boxes can be used with the clutch as you would a normal transmission with no adverse effect on anything, correct? The dogs act like syncros?
Click to expand...
Click to expand...

The dog rings do NOT act like synchro's. You must shift the transmission faster or else you will feel a clunk with every shift. That clunk is your dog ring wearing against it's gear. A synchronizer meshes the slider into the gear so you can take your time if you want to. Yes, you can use the clutch on the dog box but make sure you're shifting fast. On a downshift, if you get stuck into neutral and can't find a gear it can be a real bugger to match the rpm's to your speed just right. Pushing in the clutch and trying to slide it in a gear will not work, you must be rev matched. If you're new to a dog ring box, plan on replacing the dog rings after the first few weekends. Once you get used to it you should be able to go for a couple of years before you have to replace them.
 
Here is a useful uplink explaining the nuances of a dog box:

http://www.albinsgear.com.au/SyncroVsDog.php

As I remember it, my prior dogbox experience with a Hewland in a Royale RP31 was largely positive, and the "largely" equivocation I think had more to do with contorted formula car shift linkage and apex joint limitations than with basic dog design.
I began downshifting that great car with a very quick synchronized (no pun intended) clutch stab/rev/shift, and moved to clutchless shifting as my proficiency increased. It worked, mainly, and I did not have to rebuild after two weekends; so your comment is puzzling, Jesse.
And, there are two other VSCDA vintage B's which have Quaife Rocket dogs and no reported problems after multiple years of usage. One reason I chose the Quaife was the "bulletproof" recommendation of these two drivers who had "nothing to sell," especially relative to the 4-synch MGB CR SC with its reported baulk ring issues. I believe that both of
these racers use the clutch, so maybe that is an instructive difference.
But, there is absolutely no question that a dog requires special techniques that need to be understood, and that there there is a learning curve and definitely some potential for getting it wrong. Your words of caution and input are greatly appreciated, Jesse.
 
While I have not used up a set of dogs in my first weekend it was a learning experience. You do really have to learn to wait on the down shifts because their is only in or out of gear. There is no clutch to slip if you shift too early or clutch you can hold in to wait for the right time. With the dog box it is either in gear or not.

When I do my up-shifts I put a little pressure on the shifter and then I very deliberately jump off the gas and at the same time I very deliberately make the up-shift trying to make it very fast and quick. Then I am back on the gas just as fast. I really don't think about it because it becomes one fluid motion.

I am now also left foot braking because I seam to down shift better when I forget about the clutch. I learned to left foot brake back in my autocross days so it was easy to pick back up. Yes, I have downshifted to early and locked out the rear tires. The later you wait into the brake zone the easier it is to match the RPMs. Again a quick blimp on the throttle while pulling down to the next lower gear and you are done. The blimp is just like you would do in a heel toe downshift.

One thing that amazed me about the dog box is how simple they are inside.

Here is a write up on shifting a dog box.

Methods of Changing Gear.

By William Hewland.
July 2000

The following is some info regarding shifting gear and face dog wear. I am in the fortunate position where I have a good amount of knowledge on the subject, as I understand the mechanical side and the user (driver) side equally well. For succesful gear shifting, remember that it is critical to ensure that all mechanical elements between the drivers hand and the dog faces are in good order and properly set. This includes the gear linkage in the chassis!

Successful up-shifting, (defined as fast and non dog-damaging) will be achieved by fully moving the dog ring as rapidly as possible from one gear to the next, preferably with the engine's driving load removed until the shift is completed. (The opposite is true of a synchromesh gearbox as used in passenger cars, where slow movement helps). It should be remembered that it is not possible to damage the dogs when fully engaged (in gear). The damage can only take place when initiating contact during a shift, (the `danger zone`) therefore this element must be made as short as possible. If a driver moves the gear lever slowly, or if the linkage is not rigid and effective, dog wear will occur. We always recommend lightweight yet solid rod linkage, not cables ideally.

I list below the different methods of up-shifting that are used in racing most commonly. The best at the top, the worst at the bottom:

Automated (semi automated). The movement of the dog ring is powered and the engine is cut / re-instated in a co-ordinated manner. Gear-shifts take milliseconds. This system produces zero dog wear when set up well. It is not applicable to most cars, but it illustrates that speed of shift is a good thing.

Manual with engine cut. This system is almost as good as an automated one as long as the driver pulls the lever very quickly. Again it is not applicable to many cars, but it illustrates that speed of shift is a good thing. A `cheat` version of this is to shift on the engine rev limiter, which can work well. With this system it is especially important to move the lever ultra fast, otherwise the engine will be reinstated during partial dog engagement, causing damage. The damage can usually be felt by the driver.

Manual.
Best method: With no assistance from the engine management, the driver must lift off the throttle sufficiently to allow the dog ring to be pulled out of engagement. He should then stay off the throttle long enough to allow the dog ring to engage with the next gear. In practice, the driver can move the gear lever faster than he can move his foot off and back on to the throttle. Therefore the effective method is to apply load to the gear lever with your hand and then lift the throttle foot off and back on to the pedal as fast as physically possible. In lifting your foot, the loaded gear lever will almost involuntarily flick to the next gear before the foot is re-applied to the throttle.

Down Shifting
Successful down-shifting, has similar rules applied regarding speed of shift. Unloading the dogs is done in the opposite manner obviously. Whilst braking, the dogs must be unloaded by either touching the throttle pedal or- my preferred method- by dipping the clutch. However, one sharp dab of clutch or throttle is appropriate per shift. Continued pressure on either will cause dog damage for different reasons. `Blipping the throttle` just before engagement is advisable if the rev drops between gears are over 1300 rpm, as this will aid engagement and stabilise the car.

TOP TIP for ease of downshifting: Make the downshifts as late as possible in your braking zone (i.e. at lower road speed), because the rev drops between each gear are then lower. So many drivers make the mistake of downshifting as soon as they begin braking, causing gearbox wear, engine damage and `disruption` to the driving wheels.

This is a subject which can be much expanded on, but I feel that these are the basics, which I hope are of use.
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Ron. I am glad you mentioned the possibility of downshifting to early. I have to watch this carefully because it is easy to do in the heat of battle, doesn't upset the car if a minor miss, but does buzz the engine and cause it to exceed redline. Telltale tach tells on me even though I don't notice on track
 
dcharnet":7oyxqk56 said:
Here is a useful uplink explaining the nuances of a dog box:

http://www.albinsgear.com.au/SyncroVsDog.php

As I remember it, my prior dogbox experience with a Hewland in a Royale RP31 was largely positive, and the "largely" equivocation I think had more to do with contorted formula car shift linkage and apex joint limitations than with basic dog design.
I began downshifting that great car with a very quick synchronized (no pun intended) clutch stab/rev/shift, and moved to clutchless shifting as my proficiency increased. It worked, mainly, and I did not have to rebuild after two weekends; so your comment is puzzling, Jesse.
And, there are two other VSCDA vintage B's which have Quaife Rocket dogs and no reported problems after multiple years of usage. One reason I chose the Quaife was the "bulletproof" recommendation of these two drivers who had "nothing to sell," especially relative to the 4-synch MGB CR SC with its reported baulk ring issues. I believe that both of
these racers use the clutch, so maybe that is an instructive difference.
But, there is absolutely no question that a dog requires special techniques that need to be understood, and that there there is a learning curve and definitely some potential for getting it wrong. Your words of caution and input are greatly appreciated, Jesse.
Click to expand...

Ok, one last post on this topic for me. Every driver is different. Fortunately you're getting the rocket box which is one of the nicest shifting dog boxes on the market. The hewland transaxle's also work great in formula cars with the small dogs and nice linkage. My point is this. If you've never ever shifted a dog ring transmission, you WILL hurt your dog rings in the first couple of weekends figuring it out. After that, you'll be fine. If you use the clutch all the time up and down you will be slower than a guy who doesn't use the clutch and is at the top of his transmission shifting game. Yes, this lack of use of the clutch is harder on everything but like I said earlier, it's a race car and gets abused anyway. I hope this helps to understand my point of view and perspective. Good luck!!
 
One point I forgot to mention is a process that Quaife is doing to all of the internals before they assemble and ship. I can't remember the exact name, but it involves tumbling the internals and subjecting them to material of some kind which collides with them and hardens the surfaces. Like shot-peening, I guess, and probably familiar to many of you. I believe that the cost is $600 or so. My hope is that this offsets partially if not totally the added stress of clutchless shifting,at least in the box.
 
REM or something similar? Yields quicker/smoother action (less friction when moving shift mechanism), much greater fatigue life and a tad less power transmission friction loss.

Al Seim
 
Al Seim":2gy7jt9b said:
REM or something similar? Yields quicker/smoother action (less friction when moving shift mechanism), much greater fatigue life and a tad less power transmission friction loss.

Al Seim
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Yes, all that. And I think it also hums the overture from La Boheme instead of making all that awful SC noise. :boohoo:
 
The other advantage to a dog box is that if your car is underpowered and you are in a slow turn, you can shift into first. If the cars around you are lugging in second, you can power away from them. First gear is usable on the track
 
The usefulness of 1st gear during a race depends entirely on the ratio, and has nothing to do with dog vs. synchro; except that dog boxes might tend to offer a more usable 1st gear ratio, such as 1.7.
 
Well, and the fact that it's possible to actually get the tranny into first.. with my stock synchro box, even with double-clutching, it's nearly impossible to get the thing into 1st gear above 25mph-- even though it's usable to about 40mph.
.. Although I can't ever imagine a race track that requires you go to THAT slow into a corner. T2 at Hallett is the tightest turn I've seen on track, and it's still a solid 2nd gear turn for me. For someone with better racing ratios like a 1.7 1st gear, then it's definitely a 1st gear turn.. Just not with a stock tranny and a >2.5 1st gear.
 
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