planitary gear sets at the axle hubs

[carnage1]

does anyone have any experience with mounting a transmission in the area of the rear axle and then elimination the ring and pinion gear and using a planetary gear set in each hub instead?

Luck is a difficult thing to verify and therefore should be tested often. - Me

 

[carnage1]

hmm big and heavy isn't good.

Luck is a difficult thing to verify and therefore should be tested often. - Me

 

[EdDanzer]

Chevy power glide planetary gear sets may work in conjunction with an additional reduction set. Most transmission gear sets are narrow ratio and you would still need a reduction set to take the place of the ring gear and pinion. The final reduction set must be heavier than the transmission set. Some of the class 2B and larger truck automatic transmissions use planetary sets that may work.

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com

 

[pontiacjack]

As I remember the old planetary overdrive units, they could not be upshifted under power. You had to let off the throttle to let them upshift. To modify one to upshift under power, you'd wind up with a mini-automatic-transmission- with all the attendant systems- hydraulics, clutch pack, valve body, etc.

Dragrace motorcycles employ a unique gearbox design which allows upshifting without power interruption. I don't remember the details of the mechanism- read about it a few years ago, and remember thinking it was quite clever. You could look into building a two-speed manual transmission with this shifting design, for your "small" car.

Higher power drag race cars (such as Pro-Stock, over 1,000 HP) have used "clutchless" dog-ring-shifting manual transmissions, like the four-speed Jerico.

A single two-speed Lenco unit is not very heavy, considering the torque capacity (1,000 ft.lb.?). It's maybe 7" diameter by about 8" long.

 

[BrianPetersen]

The drag-race motorcycle transmissions have the back-sides of all the engagement dogs machined to a taper, and relief cuts in the shift drum so that when upshifting to the next gear, it does not pull the shift fork for the previous gear out of engagement (which is what normally happens). What this does is allow the next gear's engagement dogs to be slid in under power without disengaging the previous gear, and then as soon as the next gear starts taking up the load, the reverse torque on the previous gear drives it up against the tapered backside of its engagement dogs and pushes it out of engagement.

Sounds fine at first, but there are some bad side effects to this. You can no longer downshift except at a standstill, but even worse, the gears for which this has been done can no longer transmit engine braking torque. Once you have applied load to the transmission in first gear you MUST upshift through all of the subsequent gears that have had this treatment done without ever backing out of the throttle to the point that the transmission is back-driving the engine (engine braking). If you do, the transmission smashes its internals to smithereens.

 

[pontiacjack]

Thanks, Brian, for filling us in on the drag bike boxes. Even with the drawbacks noted, it seems to me that a two-speed version could possibly have application to the "small" drag race car being discussed here.