Use a drop gear to lower/raise gearbox?

[Jac Mac]

Bear in mind that you have only shown a drawing, not an actual picture of what you want yet, so you might be looking down the barrel of paying to get this made... not a road I would want to go down.., my thoughts within text..

Yes, clearer than mud. Thanks for the clarification.

So, a disadvantage is the possible noise increase. Do you think it will be noisier than a non-hypoid spiral bevel?Doubt you could say so definitely, depends more on the caliber of the people who design/cut the teeth & their ability to set them up.


Am I right thinking that the advantages of a commercial vehicle hypoid CWP pair (given the same size) are as follows? :-

• Has higher torque strength than motor car hypoid bevelTough call, plenty of Hewlands failed R&P in saloons while racing against 9" Ford equipped cars
• Does not slip, thus no power consumptionCurved tooth & not @ right angles to one another, gotta be some slip
• Runs cooler than motor car hypoid bevelYou would have to be in a very high load/power/Rpm situation to notice
• Does not require hypoid oilMaybe?
• Runs cooler than non-hyoid spiral bevelFalse in your drawing you still have some slippage & hypoid.. while the pinion tooth is straightish, the CW tooth is curved
• Can sustain higher rpm’s (10,000+ rpm) Doubt it, Nascar Stockcars run @ 9000 plus on Talledega etc for around 2 hrs on basicly an old 9" Ford, why do you want more?

 

[middy]

Doubt it, Nascar Stockcars run @ 9000 plus on Talledega etc for around 2 hrs on basicly an old 9" Ford, why do you want more?

OK, 9000 rpm.


I'm no longer interested in drop gears but just thought I'd post this pic as I just saw this while surfing Google - the legendary Ferrari F40 used a drop gear! Wow! Oh by the way, notice the opposite handed CWP (pitch reversed)?

 

[Jac Mac]

OK, 9000 rpm.


I'm no longer interested in drop gears but just thought I'd post this pic as I just saw this while surfing Google - the legendary Ferrari F40 used a drop gear! Wow! Oh by the way, notice the opposite handed CWP (pitch reversed)? Not Hypoid tho, just spiral bevel.

So whats your latest flight of fancy?

 

[Scott]

Well, the G50 crown wheel is on the "wrong" side anyway ('box in upright position) so that would be very advantageous for me.

Keep in mind reversing input rotation of a gearbox won't always work. Helical gears produce a thrust force, and reversing input rotation will result in a thrust force in the opposite direction as the manufacturer intended meaning very bad things will happen. If you have straight cut gear teeth then you have little to worry about.

 

[middy]

Not Hypoid tho, just spiral bevel

So whats your latest flight of fancy?

Yeah I know it's just spiral bevel.
Well, just because I said that I'm no longer interested in drop gears, it doesn't mean I'm not planning to get a CWP set made.

 

[middy]

Keep in mind reversing input rotation of a gearbox won't always work. Helical gears produce a thrust force, and reversing input rotation will result in a thrust force in the opposite direction as the manufacturer intended meaning very bad things will happen. If you have straight cut gear teeth then you have little to worry about.

Flip the gear ratios? :laugh: (not going to reverse the gearbox rotation on mine ayway)

 

[middy]

Bear in mind that you have only shown a drawing, not an actual picture of what you want yet, so you might be looking down the barrel of paying to get this made... not a road I would want to go down..,

Well, the actual picture of what I want is a upright Getrag G96.96 trans (GT3) with a flipped CWP. It's similar to the G50.50 but with slightly different casing. Yes, it has 10mm hypoid but I will try to get a "commercial vehicle hypoid" CWP set made by a reputable company. I wish to explain how I think the casing could be modified. Would you mind send me a PM of your email address and I'll send you the pics with details on them?

 

[Cliff Beer]

OK, 9000 rpm.


I'm no longer interested in drop gears but just thought I'd post this pic as I just saw this while surfing Google - the legendary Ferrari F40 used a drop gear! Wow! Oh by the way, notice the opposite handed CWP (pitch reversed)?

All the ferrari 1980's transverse V8s (308/328/Mondial) also use drop gears....two, in fact..in a longitudinal fashion, though the drive is sent back 180 degrees relative to the crank output. Bevel cut, works pretty well, makes for very easy clutch changes as neither the engine nor gearbox has to come out of the car to replace the clutch.

 

[middy]

Jac, I'm not going to do a commercial vehicle hypoid afterall so please ignore my last post above.

Been reading more stuff (particularly page 20):
http://www.draftingzone.com/shoppingzone/4-9-1.pdf

 

[middy]

All the ferrari 1980's transverse V8s (308/328/Mondial) also use drop gears....two, in fact..in a longitudinal fashion, though the drive is sent back 180 degrees relative to the crank output. Bevel cut, works pretty well, makes for very easy clutch changes as neither the engine nor gearbox has to come out of the car to replace the clutch.

I'm surprised that 308/328 were transverse engined. Here is a pic of the Testarrosa trans (where is the drop gear, clutch & bellhousing? :huh: ):

Regarding F40, it seems to me that the distance between the bellhousing and centre of driveaxles is about 300mm (100mm more than Boxster) so, coupled with the V8 motor, how did they manage to fit it all in a relatively short wheelbase (96.5") of the F40? By comparison, the Boxster wheelbase is only 1.5" shorter (same as original GT40) and yet it's a tight fit with the flat 6 motor with half shafts angled slightly.

 

[middy]

There is a F40 gearbox for sale (No affiliation):

Ferrari Ferrari 40 Spec Sheet

Interesting, but no, I'm not going to buy it.