Dog box

[Z350]

Hi all this is my first post and would like to ask what may be a dumb question. What are the advantages of a dog box they seem to be a lot more money than syncro boxes. I just wondered if they are worth the extra? Oh car is a Seven used for sprints only.

Many thanks Z350

[Tim Falce]

Welcome to T-tenths Z350. BTW what's a dog box?

[Z350]

Originally posted by falcemob
BTW what's a dog box?

Oh thanks for the welcome.

Its to do with the way the gears are engaged

[ranoff]

Welcome to the forum Z350.

First thing to say is that this thread should probably be in the racing technology area of the site, but thats just an observation. A moderator may move it but you should not take that personally. Thats just the way it is.

Rather than go into a long winded explanation of a dog box here is a link to a page on a subaru forum. I do not plug their site, in fact I am not a lover of scoobies, but if you scroll down the page in the link you will see some very good definitions of a dog box. The further down the page you get the more accurate the definitions get!

http://bbs.scoobynet.co.uk/showthread.php?t=367362

Hope this helps

Eddie

[Z350]

Thanks for that and I will try to post in the correct section next time.

[Chris Griffin]

Dog boxes use straight cut gears and have no synchro rings. They can handle greater loads (torque) and have less friction losses. They also whine like a b*st*rd and you need to heal n toe to change down thru the box.

[ianpearson]

Originally posted by Chris Griffin
Dog boxes use straight cut gears and have no synchro rings. They can handle greater loads (torque) and have less friction losses. They also whine like a b*st*rd and you need to heal n toe to change down thru the box.

Heal n toe! It is not necessary, granted it sounds good, probably saves on component life. Modern dog boxes just slip in no worries

[simon drabble]

if you dont heel and toe wont you just lock the car up? I only race historics but I no when I havent done it the back has got very lively!!! It should prolong the life of the gearbox. In respect to dogboxes the main advantage is the speed you can change gear...

[zefarelly]

are dog boxes allowed for hstrics ? I thought for FiA we had to keep the original change mechanism ? (not that I can afford a dog box!)

[ianpearson]

Your right you will lock the back wheels if you change down too early. I would imagine heal n toe is necessary with a historic because the gearbox's are weaker/older. I've never Bothered to heal n toe in the seven years i've raced single seaters, one thing i will say is that i do eat clutches more often than most, but at £45 a shot thats not the end of the world, gearbox is still fine though.

[greenamex2]

I run a dog engagement (as well as do leg first) box in my Corolla.

It is quite an old Quaiffe design, based around the standard gear casing/selection method and a right pain.

Heel and toe is essential going down the box. I tend to use the clutch going up but have clutchless changed when I've needed that extra couple of tenths.

The change improved a bit when I went to a much lighter flywheel and clutch.

I have also driven a Vectra challenge car fitted with a more modern conversion kit and it was an absolute delight to use.

[zefarelly]

I've killed synchros in 3rd this year, thats 2 1 hours and 8 15-20 minuters (and practices) so whatever my box is I need to improve my H&T technique, killled a clutch to !

[Chris Y]

A bit like left-foot braking, heel-n-toe can be practiced on the road. It does require some patience, as the timing is critical, but it is unbelievably satisfying when you get it right!

The name 'heel and toe' actually puts a lot of people off, because they can't use their heels correctly on most standard pedal setups. Perhaps it's best to think of it as 'ball-and-edge' which is what some Americans call it. Really, you use the ball of your foot (left hand edge) on the brake, and the right-hand edge of your foot to blip the throttle. When learning, it's best to use shoes/trainers with thin soles, but as wide as you can, because most road car pedals are widely spaced.

Once I learned, that was it. I heel-n-toe *everything* now. If I drove a milk float, I would probably try to blip the throttle on the downshifts

I changed my shoes recently, and was amused at the greatest patches of wear on the soles - one at the ball of the foot, and one at the edge...

[ianpearson]

Originally posted by Chris Y
A bit like left-foot braking, heel-n-toe can be practiced on the road. It does require some patience, as the timing is critical, but it is unbelievably satisfying when you get it right!

The name 'heel and toe' actually puts a lot of people off, because they can't use their heels correctly on most standard pedal setups. Perhaps it's best to think of it as 'ball-and-edge' which is what some Americans call it. Really, you use the ball of your foot (left hand edge) on the brake, and the right-hand edge of your foot to blip the throttle. When learning, it's best to use shoes/trainers with thin soles, but as wide as you can, because most road car pedals are widely spaced.

Once I learned, that was it. I heel-n-toe *everything* now. If I drove a milk float, I would probably try to blip the throttle on the downshifts

I trust you do race a car?
I changed my shoes recently, and was amused at the greatest patches of wear on the soles - one at the ball of the foot, and one at the edge...

[ianpearson]

well i mucked up that last post big time

What i was trying to say was
"chrisY do you race a car?

[simon drabble]

I wonder if left foot braking is something for the rally drivers amongst us rather than track, to date I have never used it (except when doing kart races with mates!)
I fear that space is so damn tight by my feet I wouldnt have room to bring my left foot over!! I have just started racing with a Hewland gearbox with spring loaded first (down and left) and having now almost got used to it think they are fantastic. Previous gearboxes were close ratio historic gearboxes. Failure to toe and heel on historics does lead to risking locking the diff up however modern stuff I gather doesnt need it - they have it easy these modern racers!!

[ianpearson]

i have to admit i have always been spoilt by modern machinery, nothing older than 1995. However next season i may try to fit in some classic FF2000 races with a rough old Hewkand Mk 9 box, last time i drove one it took me nearly a lap to get it out of 2nd into 3rd, apparently i was treating it too gently. maybe I'll be a converted heal n toe jockey after a run in a classic, but don't hold your breath

[simon drabble]

that is what I have
the hardest part is trying to remember what gear your in! as 2-5 is in an H pattern you think you are in 3rd but its 4th and you are off cam!!

[zefarelly]

sounds like the Aston box, I just drove it as if it was a 4 speed box, although being off cam with a 7 litre V8 on the public highway is almost impossible !

[Chris Y]

Originally posted by ianpearson
well i mucked up that last post big time

What i was trying to say was
"chrisY do you race a car?

Yes, I've raced a few

The best thing to do is *try* heel-n-toe, and left foot braking. LFB may not be everyone, but it *can* help you drive smoother, and it's not just for rally drivers. It can help you brake right up to the apex without destabilising the car for one thing, or to ease the front end round a corner if you're understeering...

H'n'T will preserve your gearbox, particularly with a syncro, and will actually make your synchro shifts faster if you match the revs up properly. Also, it has been said, but in a RWD car, under heavy braking the rear is light, and a clumsy downshift can lock the rears. Waiting for the clutch to take up the slack slows you down.

On a FWD car the effect can be similar - as you're braking you're loading up the fronts, and if you're turning, or on the edge of threshold braking, and let the clutch up quickly, the fronts will lock and you'll understeer off.

Sure, neither skill is necessary, but if you master them both, you'll be a smoother driver, and particularly in the wet, your times will come down.

[avsfan733]

Originally posted by ianpearson
i apparently i was treating it too gently.

always heard them called crashboxes as well as dog boxes, never driven one though now i know where the name comes from

[Z350]

Thanks for all the help sounds like I may need to alter my driving technique if I am to think about a dog box

[Mike Holmes]

I put a Jack Knight dog box in the Midget this year due to breaking ordinary straight cut boxes. I can honestly say it is the best thing since sliced bread!! Positive short throw changes, no need to double declutch on downshifts and easy selection of first gear when changing down. I was very wary of fitting it thinking it would take some getting used to but it has been a dream to use.

[zefarelly]

H&T is very worthwhile on the down shift, when I put a proper clutch in my car I was locking the rears the first few times on the down shift, obviously I still have a lot to learn about race driving!

[DSM]

Does this help?


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.

N.B. 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.
Another method is to load the gear lever with your hand, stay flat on the throttle and dab the clutch to release the dog ring. The overall effect on the gear shift is similar to the above method, but clutch wear may become a big issue.
The worst method (most destructive and definitely slowest) is to attempt to change gear in a `passenger car / synchromesh` way, i.e. lifting off the throttle, dipping the clutch, moving the gear lever, letting the clutch up and re-instating the throttle. The method causes unnecessary clutch wear, does absolutely nothing to help come out of gear and usually causes dog wear whilst engaging the next gear. This wear is due to several reasons. Firstly, it is impossible for a driver to co-ordinate the complicated sequence of all five physical movements accurately. Consequently the engagement dogs often find themselves engaging whilst the throttle is applied. The lever is usually pulled more slowly as it was not pre-loaded, lengthening the `danger zone`.

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.