Dog box - is it worth it?

[dylanp]

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

[dylanp]

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?

[dylanp]

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

[dylanp]

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?

[dylanp]

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?

Edited by dylanp on Saturday 29th December 18:05

[dylanp]

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_...

[dylanp]

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..

[dylanp]

custardtart said:

dylanp said:

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..

That's the great thing about being able to edit clips, only show the good bits

I remember in my first race being 11 secs of pole at snetterton!

Maybe a Marlin will be racing in Kits again this year? They do look great IMO.

FYI I'm running a straight cut non dog type 9 5spd built by phil jones, the only noticeable difference over a standard type 9 is the better ratios, more precise action and noise . Having said that, i'm going to a quaife 4spd straight cut next year as the 5th gear never gets used (other than at Snet)and the 4spd is 13kg lighter.

True.. Here's a clip of a special GTs race - mid 2007 season - just for comparison purposes ;-) (quite good off the line eh?)
http://www.youtube.com/watch?v=VgetW4rFDhg

I doubt there will be any Marlins racing in the 750 club again - we all got too frustrated with the 'have to run carbs' thing and 'nothing is allowed' attitude of scruttineers..
There should be 3-4 green 5exis next year in the special GTs @ Castle Combe though..

[dylanp]

custardtart said:

dylanp said:

custardtart said:

dylanp said:

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..

That's the great thing about being able to edit clips, only show the good bits

I remember in my first race being 11 secs of pole at snetterton!

Maybe a Marlin will be racing in Kits again this year? They do look great IMO.

FYI I'm running a straight cut non dog type 9 5spd built by phil jones, the only noticeable difference over a standard type 9 is the better ratios, more precise action and noise . Having said that, i'm going to a quaife 4spd straight cut next year as the 5th gear never gets used (other than at Snet)and the 4spd is 13kg lighter.

True.. Here's a clip of a special GTs race - mid 2007 season - just for comparison purposes ;-) (quite good off the line eh?)
http://www.youtube.com/watch?v=VgetW4rFDhg

I doubt there will be any Marlins racing in the 750 club again - we all got too frustrated with the 'have to run carbs' thing and 'nothing is allowed' attitude of scruttineers..
There should be 3-4 green 5exis next year in the special GTs @ Castle Combe though..

yes that start looks good, almost too good!!!!

What engine are you running and do you have a copy of the regs for the special GT's at Coombe, it looks great fun with all those expensive ferraris et al?

Have a look here for regulations for 2007 - I don't think anything major is changing for 2008.
http://www.castlecombecircuit.co.uk/circuitchamps....
Good thing about special GT championship is that you can work on your engine/aero/etc - as long as you keep the car within manufacturer's model lineup..

We are currently running Honda B16 1.6Vtec turbo - giving out about 220BHP..
Did I mention that slick tyres are the norm - unlike 750 kits? ;-)

[dylanp]

Scuffers said:

one of the thinks I would comment on here is that people are comparing bad synco boxes with dog boxes...

a decent synco box is not that much of a handicap, and there are some truly shite dog boxes... (read most of the 'kits' for OEM boxes).

worth remebering cars like the 962, a multiple le-mans winning car, ran synco boxes.

that's not to say suff like Hewlands FTR's/NLT's and the like are not top draw boxes, but consider they were designed ground up to be what they are, not some OEM box re-worked (and look how much a decent one costs).

Couldn't agree more!

[dylanp]

custardtart said:

Ooh that looks good, which class do you run and is your type of car competetive with that power?

Also, without giving away too many secrets, what size wheels and type of slicks do you use?

The car is good for top half finishes.. with a little more HP who knows.. Sent you an email..

[dylanp]

Greensleeves said:

In my opinion, and I'm rallying and not circuit racing, it's more important to have the right gears than it is to have more power. OK, I'm not on 100% throttle all the time but when I am on the throttle, I need to have the power there. I broke the gearbox on the last rally and the spare is a bog standard helical cut syncro with road ratios and to be quite honest, it was a liability. I'll be seeing Mr TranX at the Pistonheads show.

Watching the video above, the driver with the in-car seemed to be taking some very interesting racing lines??? I assume defending position from a beying pack behind which we can't see. And the car never really seems to be struggling with lack of power due to long ratio changes.

If your car is turboed, the last thing you want is to keep lifting as you change gear then having to wait for the lag to go away so you would benefit from either long gears or a dog engagement box.

The 'interesting lines' are mostly a result of badly setup aero (going over avon rise was very scary - was not possible to take the 'correct' line as the car would simply slide off at 120mph! The rest was indeed defending ;-) However, the biggest reason is that I'm a beginner - although I'm a lot better now - still a lot to learn!)

[dylanp]

heightswitch said:

flemke said:

Unlike some others on this forum, I'm certainly no technician. However, I can tell you that straight cut gears do not a dog box make.
You can have straight cut gears with or without synchros, the latter being a "dog" box.

This is partially correct

a dog box gets its name from the dog drives on the front of the gear in place of syncro rings. these are an immensly strong method of transmitting drive from cog to cog but are very harsh and very noisy.

at the end of the day to improve lap times you will find a sequential box faster.

The change from syncro to straight cut to dog do not alter change speeds, merely the strength of the driveline for increased power. Your power levels really don't begin to stress the driveline and you would be best spending your money elsewhere.

(edited to say, after reading the rest of the posts, a dog box may be slightly quicker by the virtue of not having to lift and being able to make clutchless changes, with your set up though you will invariably find that this extra violence will damage something else, somewhere else in the driveline.)

Edited by heightswitch on Monday 31st December 15:48

Having read all the helpful posts on this topic - I am convinced that my money would almost certainly be better spent elsewhere if improving my lap times is what I'm after..
Reliability was never really an issue - probably because the power and torque of my engine is not high enough to really do any damage..

[dylanp]

CNHSS1 said:

dylanp said:

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_...

yep i bought one on a whim off US ebay but bolted it to the box but it baulked. its a bit of a fiddly phaff type job to get it set correctly and as mine was s/hand with no instructions, i had to 'play' with it to get it right. That said, i didnt get chance to run it at a test day, so havent used it in anger for fear of it screwing up a run at an event. Bit of fun, but bit heavy and no huuge advantage as its still bolted to a synchro box (still have to use the clutch). be great on a dog box though. i do intend to get it tried properly before season starts, will let you know how it goes.

That's what I figured.. Seems like more of a gimmick than a genuinely useful gadget..

I would be very interested to hear how you get on with it though (once you have a chance to try it properly..)

Cheers,
Dylan

[dylanp]

Nice one - definitely getting one of those!

Seems like fantastic value for money :-)