Dog box - is it worth it?
Discussion
Question to all you experienced racers:
Obviously everyone knows that straight cut gears are better/quicker for race cars - the question is, what sort of improvement in lap times is it likely to bring?
I race a reasonably lightweight car (about 550kg) with a honda b16 engine (1.6l, turbo-d to about 220BHP). I'm running completely standard honda 5 speed gearbox out of a civic.
SO if I went for a straight cut gearbox, what sort of improvement would I be likely to see on a 1m:15s circuit? Are we talking noticeable improvement (like second or two a lap) or would it be purely academic?
All opinions welcome...
Cheers,
Dylan
Obviously everyone knows that straight cut gears are better/quicker for race cars - the question is, what sort of improvement in lap times is it likely to bring?
I race a reasonably lightweight car (about 550kg) with a honda b16 engine (1.6l, turbo-d to about 220BHP). I'm running completely standard honda 5 speed gearbox out of a civic.
SO if I went for a straight cut gearbox, what sort of improvement would I be likely to see on a 1m:15s circuit? Are we talking noticeable improvement (like second or two a lap) or would it be purely academic?
All opinions welcome...
Cheers,
Dylan
I have 2 gearboxes for the tuscan, synchro box with a straight cut 5th and a dog box with all gears straight cut..I prefer the dog box rather than the synchro, but some people dont get on with them... It will always got into gear, even if your a bit ham fisted rather than baulking as a synchro box can. up shifts are simply a lift and then bang it in without the clutch, you can down shift without the clutch but that takes a bit more finesse.
If your just talking straight cut versus mr citroens gears, then they have slightly less drag, are a little stronger and a lot more noise.. ultimatley straight cut will soak up less power so give you more at the wheels, but i wouldnt have thought a huge amount. to win if your looking for 10ths then maybe worth it. If your looking for seconds get some more seat time instead more so with the dog box as there is extra to learn as well
G
dylanp said:
Cheers for your advice guys!
So is there some clever logic behind having straight cut 5th on a syncro box?
Does that allow you to upshift into 5th without the clutch?
As you will have seen on any (manual) car, the higher the gear, the easier it is for the dogs to mesh. So is there some clever logic behind having straight cut 5th on a syncro box?
Does that allow you to upshift into 5th without the clutch?
To flip it around, sometimes one will double-declutch into first or maybe second even with synchros.
You are still mixing up terminoligy.
A syncromesh box uses syncro cones to speed match the gear to the shaft and requires some time without seeing any load to make that speed transfer, hence you use the clutch with a syncro box.
A Dog box uses the mechanical mating of the dog ring and the dog on the gear to engage drive with the shaft, this is an instantaneous on/off operation (unless you are rubish), which is why you can do clutchless shifts.
Having the gear drive design straight cut or helical has no bearing on the engagement technique.
Race boxes use straight cut gears to minimise side thrust on the gear assembly so have lower transmition losses and are capable of greater torque transfer for the same size as the equivilent helical cut gear, the downside is they are noisy, which is why road gearboxes feature helical gear mesh arangements.
A syncromesh box uses syncro cones to speed match the gear to the shaft and requires some time without seeing any load to make that speed transfer, hence you use the clutch with a syncro box.
A Dog box uses the mechanical mating of the dog ring and the dog on the gear to engage drive with the shaft, this is an instantaneous on/off operation (unless you are rubish), which is why you can do clutchless shifts.
Having the gear drive design straight cut or helical has no bearing on the engagement technique.
Race boxes use straight cut gears to minimise side thrust on the gear assembly so have lower transmition losses and are capable of greater torque transfer for the same size as the equivilent helical cut gear, the downside is they are noisy, which is why road gearboxes feature helical gear mesh arangements.
Edited by johnfelstead on Saturday 29th December 01:41
what he said!
in reality, straight cut gears to fit a 'std' production box will make zero difference to the power transmitted (if anything they will be worse), gearbox manufacture had moved on a long way, and production stuff like Honda's are as good as it get's efficency wise, compare that with the after-market gear kit's and with a few exceptions, the differences are huge.
Dog engagement (as said above) is another subject, personally, I would avoid any dog kit's for std boxes, they were not designed for the kind of loads dog 's will put on them and usually end in tears (expencive ones at that).
Proper ground-up designed dog stuff is another subject, people like Hewland/Hollinger/Sadev etc. have been making these for years and know what they are doing.
Dog in itself will not make huge differences in lap-times, in your 1:15 lap time, unless your std syncro box is baulking you really badly, I would suggest you *might* get 0.2 - 0.4 sec's improvement at the very best.
gear ratio's themselves are really the area I would suggest you look at, these have a way bigger effect by keeping the engine in it's optimum range for as long as possible.
Last point, Dog boxes are not maintenance free in the same way a std syncro box is, and they also open up the risk of easy miss-shifts (and blown engines), whereas a synco box would baulk you against doing this.
in reality, straight cut gears to fit a 'std' production box will make zero difference to the power transmitted (if anything they will be worse), gearbox manufacture had moved on a long way, and production stuff like Honda's are as good as it get's efficency wise, compare that with the after-market gear kit's and with a few exceptions, the differences are huge.
Dog engagement (as said above) is another subject, personally, I would avoid any dog kit's for std boxes, they were not designed for the kind of loads dog 's will put on them and usually end in tears (expencive ones at that).
Proper ground-up designed dog stuff is another subject, people like Hewland/Hollinger/Sadev etc. have been making these for years and know what they are doing.
Dog in itself will not make huge differences in lap-times, in your 1:15 lap time, unless your std syncro box is baulking you really badly, I would suggest you *might* get 0.2 - 0.4 sec's improvement at the very best.
gear ratio's themselves are really the area I would suggest you look at, these have a way bigger effect by keeping the engine in it's optimum range for as long as possible.
Last point, Dog boxes are not maintenance free in the same way a std syncro box is, and they also open up the risk of easy miss-shifts (and blown engines), whereas a synco box would baulk you against doing this.
In a race car then straight cut gears make sense in that you can easily swap ratios to match circuits.
However damage will occur to the gears dependent on driver skill.
Synchros were invented to prevent this damage.
You can do flat shifts with synchro boxes easily with practice so the time gained these days is minimal. A race box with straight cut gears and no synchro will be lighter that a box with synchros hence used in race situations where the boxes can also be easily replaced when damaged.
In a road car modified for track i wouldn't consider straight cut non synchro gears.
The only potential area where you could save time is on the upchanges on the straight where you want full power all the time which is what? about three times a lap generally max? the rest of the time your changes will be made when slowing so no time to be saved.
However damage will occur to the gears dependent on driver skill.
Synchros were invented to prevent this damage.
You can do flat shifts with synchro boxes easily with practice so the time gained these days is minimal. A race box with straight cut gears and no synchro will be lighter that a box with synchros hence used in race situations where the boxes can also be easily replaced when damaged.
In a road car modified for track i wouldn't consider straight cut non synchro gears.
The only potential area where you could save time is on the upchanges on the straight where you want full power all the time which is what? about three times a lap generally max? the rest of the time your changes will be made when slowing so no time to be saved.
Wow - that's why everyone loves Pistonheads!!
So many useful posts - many thanks to everyone that replied..
The underlying question was - is it worth it?
If the general concesus is that potential lap time improvement is only likely to amount to a few tenths of a second, it seems that my money might be better spent elsewhere on the car.
In all fairness, the honda gearbox is not half bad - it never really baulks and I can't remember the last time I picked the wrong gear - so it sounds like I should just keep it and maybe concentrate my efforts on aero package or the engine itself - I'm sure that an extra 30bhp would make a far more noticable difference...
Cheers,
Dylan
So many useful posts - many thanks to everyone that replied..
The underlying question was - is it worth it?
If the general concesus is that potential lap time improvement is only likely to amount to a few tenths of a second, it seems that my money might be better spent elsewhere on the car.
In all fairness, the honda gearbox is not half bad - it never really baulks and I can't remember the last time I picked the wrong gear - so it sounds like I should just keep it and maybe concentrate my efforts on aero package or the engine itself - I'm sure that an extra 30bhp would make a far more noticable difference...
Cheers,
Dylan
I have raced my old Crossle (220bhp zetec with Hewland Mk9) in the SR & GT series and raced against a chap with a similar car - running a 250bhp Duratec but with a road Audi box.
There was real advantages to running a proper racing gearbox - the hewland does a clutchless change and is miles quicker than a road box, when we raced in close company I think it would make a 20 yard difference each time he changed gear - cause if you abuse a road box it breaks. The other big advantage with a hewland is that you can put the correct gear ratios in for each circuit which makes the car perfectly geared.
I would guess - hewland vs road box 2 - 3 second per typical lap.
You can buy a second hand hewland Mk9 for circa £1,000 and you will get you money back when you come to sell it.
There was real advantages to running a proper racing gearbox - the hewland does a clutchless change and is miles quicker than a road box, when we raced in close company I think it would make a 20 yard difference each time he changed gear - cause if you abuse a road box it breaks. The other big advantage with a hewland is that you can put the correct gear ratios in for each circuit which makes the car perfectly geared.
I would guess - hewland vs road box 2 - 3 second per typical lap.
You can buy a second hand hewland Mk9 for circa £1,000 and you will get you money back when you come to sell it.
dylanp said:
Thanks Kickstart..
A real difference of opinion - if there was 2 seconds to be found by going to a 'proper' gearbox I would definitely do it..
Where would you suggest I look for a second hand box?
Any other opinions on the subject of lap times?
I think the comparison above is a bit like apples and oranges - a road box will always be less effective than a proper box designed for racing.A real difference of opinion - if there was 2 seconds to be found by going to a 'proper' gearbox I would definitely do it..
Where would you suggest I look for a second hand box?
Any other opinions on the subject of lap times?
Like for like comparisons - a straight cut synchro boc vs. straight cut dog box with the same engines are likely to see a small difference in favour of the dog box as the changes would be quicker.
But whatever you get, don't scrimp and get something cheap and marginal - it *will* break. Whatever you get you also need to factor in the cost of maintaining the box and possibly rebuilding it once or twice during the season.
The type of gearbox depends on the car it's going into, but try having a look in Motorsport News for second hand boxes. Also try Road and Race Transmissions (down in Kent I think) to see if he knows of anything suitable for your application. And if you're feeling flush check out Elite sequential gearboxes.
Kickstart said:
I have raced my old Crossle (220bhp zetec with Hewland Mk9) in the SR & GT series and raced against a chap with a similar car - running a 250bhp Duratec but with a road Audi box.
There was real advantages to running a proper racing gearbox - the hewland does a clutchless change and is miles quicker than a road box, when we raced in close company I think it would make a 20 yard difference each time he changed gear - cause if you abuse a road box it breaks. The other big advantage with a hewland is that you can put the correct gear ratios in for each circuit which makes the car perfectly geared.
I would guess - hewland vs road box 2 - 3 second per typical lap.
sorry, 2-3 sec's is laughable, it would have to be a truly hopless synco-box with the world worst ratios to make that kind of difference.There was real advantages to running a proper racing gearbox - the hewland does a clutchless change and is miles quicker than a road box, when we raced in close company I think it would make a 20 yard difference each time he changed gear - cause if you abuse a road box it breaks. The other big advantage with a hewland is that you can put the correct gear ratios in for each circuit which makes the car perfectly geared.
I would guess - hewland vs road box 2 - 3 second per typical lap.
looking though datalogs, with a sportscar round snett doing ~1:16 lap times with a syncro box, I am only spending less than 1 second lap off the thottle (whist changing up - there are only 6 up-changes per lap), no way does 1 sec off the throttle equate to 2-3 sec's laptime, realistically, maybe a couple of tenths...
Slightly off topic, but has anyone used one of these before?
(sequential shifter that bolts onto a H gate)
Looks great in the videos - but is it really any good?
http://www.ikeya-f.co.jp/en/product_notice/sequen_...
(sequential shifter that bolts onto a H gate)
Looks great in the videos - but is it really any good?
http://www.ikeya-f.co.jp/en/product_notice/sequen_...
dylanp said:
Now we are finally starting to get some 'real' evidence..
Data logger facts in Scuffer's case or real life experiences in Darren's case..
Any more?
Have you raced the Marlin in 750mc Kits?Data logger facts in Scuffer's case or real life experiences in Darren's case..
Any more?
Edited by dylanp on Saturday 29th December 18:05
The reason I ask is this clip - if it's you could I cheekily suggest spending all the money on either a different car or some driver tuition!
http://myspacetv.com/index.cfm?fuseaction=vids.ind...
Hehe.. nice clip..
Not me though - I think that was Joe in his Marlin..
In his defence the car was only good for about 140bhp then and I think that was his first race as well...
Today's Marlin 5Exi is a totally different beast - nothing like the car that raced in the 750 kits..
More than capable of keeping up with a Ferrari 360 Challenge stradale for example..
Not me though - I think that was Joe in his Marlin..
In his defence the car was only good for about 140bhp then and I think that was his first race as well...
Today's Marlin 5Exi is a totally different beast - nothing like the car that raced in the 750 kits..
More than capable of keeping up with a Ferrari 360 Challenge stradale for example..
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