Alez
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| posted on 9/11/11 at 11:04 PM |
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Car and motorbike dog gearboxes
Are there any fundamental differences between race car application dog gearboxes such as offered by Hewland or Quaife and road motorbike application
dog gearboxes as found on modern day superbikes?
I used to think they were essentially the same thing (rated torque capability aside), but a friend has discouraged me from buying a Seven type kit car
which has a Ford four pot coupled to a Hewland dog gearbox. He says this type of gearbox is tricky to use and therefore not enjoyable for road use
(and noisy too). He also says you can damage one easily by not getting the rpms right in a downshift. I have used bike engined cars on the road and
haven't had any problem or taken any special precaution with rpms whatsoever so I'm very surprised to hear that.
PD: I've been away from these forums for a long while and for some reason I haven't received email notifications for the U2Us sent to me,
so apologies for the late responses, now sent...
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MikeRJ
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| posted on 10/11/11 at 08:31 AM |
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Typically the quicker you make a change with a dog box, the smoother it is. Using an H pattern dog box as you would a synchromesh box will result in
lots of grinding and ultimately chipped teeth on the dog clucthes. Since a a bike gearbox is sequential, you only have to move the lever a short,
fixed distance which makes it easy to make fast changes.
I'd personally avoid it for road use, you'd have to be focused all the time to make half tidy gear changes and it will be an expensive
gearbox to repair.
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mcerd1
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| posted on 10/11/11 at 08:41 AM |
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but you could swap it out for a std. synchro box (e.g. a ford type 9) and sell the dog box to cover your costs 
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madrallysport
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| posted on 10/11/11 at 10:46 AM |
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Is it a dog box or a straight cut box, dog boxes are big big money
UNDERSTEER is when you hit the wall with the front of the car.
OVERSTEER is when you hit the wall with the rear of the car.
HORSEPOWER is how fast you hit the wall.
TORQUE is how far you take the wall with you.
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onenastyviper
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| posted on 10/11/11 at 01:11 PM |
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quote:
Originally posted by madrallysport
Is it a dog box or a straight cut box, dog boxes are big big money
What is the difference?
I thought dog box meant no-syncromesh and straight-cut referred to the actual gear teeth?
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Alez
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| posted on 10/11/11 at 05:41 PM |
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quote:
Originally posted by MikeRJ
Typically the quicker you make a change with a dog box, the smoother it is. Using an H pattern dog box as you would a synchromesh box will result in
lots of grinding and ultimately chipped teeth on the dog clucthes. Since a a bike gearbox is sequential, you only have to move the lever a short,
fixed distance which makes it easy to make fast changes.
I'd personally avoid it for road use, you'd have to be focused all the time to make half tidy gear changes and it will be an expensive
gearbox to repair.
That would explain it. I find it strange that given what you just said, they make H dog boxes, I find the sequential bike ones very convenient.
Nice explanation and advice, thanks.
quote:
Originally posted by onenastyviper
quote:
Originally posted by madrallysport
Is it a dog box or a straight cut box, dog boxes are big big money
What is the difference?
I thought dog box meant no-syncromesh and straight-cut referred to the actual gear teeth?
I'm confused, I too thought it was the same thing?
I can't remember which one it was and the add isn't there any more, it was probably one of these boxes made by Hewland for "roadster
type" configuration (N-S engine at the front and RWD).
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mcerd1
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| posted on 10/11/11 at 06:04 PM |
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quote:
Originally posted by Alez
I thought dog box meant no-syncromesh and straight-cut referred to the actual gear teeth?
I'm confused, I too thought it was the same thing?
they often go together, but they are different:
the dog's are used in place of the syncro
the strait cut gears are stronger than helical ones, but make alot of noise (think of the whining noise you get in reverse)
see here if you want to know more:
http://www.carbibles.com/transmission_bible.html
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Alez
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| posted on 10/11/11 at 06:08 PM |
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quote:
they often go together, but they are different:
the dog's are used in place of the syncro
the strait cut gears are stronger than helical ones, but make alot of noise (think of the whining noise you get in reverse)
see here if you want to know more:
http://www.carbibles.com/transmission_bible.html
Ah! Is it correct to say that motorbike ones are both dog type and straight cut gears?
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britishtrident
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| posted on 10/11/11 at 06:09 PM |
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Hewland gearbox or Hewland transaxle ?
If it is the early 1960s RWD Hewland dog box based on Ford Anglia/Mk1 Cortina box they were regarded as a weak box -- they are however very
very rare.
Later (end of the 1970's) Hewland brought out a front engine rwd conversion kit for their FT400 transaxle which was intended for Special
Saloon racing.
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Alez
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| posted on 11/11/11 at 04:57 PM |
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It was a Seven type car so I suppose it would need to be a gear box not a transaxle, but I really can't remember even the make, I was too naive
to think these all were pretty similar. I've looked for the original advert on Pistonheads but it's gone, I suppose it expired a while
ago.
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