Gears/Differential Strengthening

[Guest]

I was wondering what I could do to strengthen this stock differential. Here are the specs:

Housing Material:      High strength die cast aluminum alloy
Width:                 5 1/2" from side to side, not including axles
Height:                4 1/2" from top to bottom, not including sprocket
Bevel & pinion gears:  High quality, steel cut gears
Gear shafts:           Stress-proof steel
Bearings:              Self-lubricating
Maximum Torque:        Static tested to 500 ft. lbs.
Weight:                7 pounds, not including axles
Lubricant:             Bison Grease #1650
Horsepower Rating:     2 thru 14hp

Clearly is'nt probably not good enough for the 80+ HP 4-Cylinder Motorcycle engine that I plan to use with it. I was thinking I could certainty stiffen up the Cast aluminum housing, but could I add strength to the steel cut gears? Heat treat them? Or would they just become too brittle? I could also pack very heavy grease inside the diff to help make it more limited slip, but also maybe give it extra strength..

Any ideas on how I can really beef this up inside? It's going into my next project (PsychoBuggy).





-Adrian

[topct]

What's it out of. This is a standard spyder gear diff and grease will not make it a slipper.

It looks like you got the idea though. The differential that you use for this should and could be something out of a situation that at least equalls the horsepower that you are going to apply to it.

------------------
Gene

[jburstein]

In a well designed drive train all the components are designed for a certain amount of torque/power--there isn't any one weak point in the system. You may beef up the housing, for instance, and the housing won't break. But that will just enable the housing to transmit torque to something else, which will break.

In other words, if you're putting more power through that differential than it was designed for, then you'll probably need to beef up each component of it, by which point you might as well have used a beefier one in the first place.

-Justin

[This message has been edited by jburstein (edited 08-10-2005).]

[3 Phase Lightbulb]

<font face="Verdana, Arial" size="2">Originally posted by topct:
What's it out of. This is a standard spyder gear diff and grease will not make it a slipper.

It looks like you got the idea though. The differential that you use for this should and could be something out of a situation that at least equalls the horsepower that you are going to apply to it.

</font>

It's a general multi-purpose Comet SCD-1 self-contained differential. I'm wondering what's the best way to beef it up inside. I can beef up the housing easily enough. I'm wondering if I add a second pair of spyder gears (4 total) and weld additional spyder gear shaft (X) and beef up the pinion gears if that might do it.

-Adrian

[3 Phase Lightbulb]

I was thinking I could beef it up like this:



Add 2 more spyder gears and weld up a new 4-way spyder gear shaft. Drill out the housing for the new 4-way spyder gear shaft, and maybe beef up the axle gears by welding backing plates onto them.

-Adrian

[Evan]

The axles usually break at the end of the splines.

[QSIMDO]

http://members.aol.com/pullingtractor/transaxl.htm

This might give you some ideas.

[3 Phase Lightbulb]

<font face="Verdana, Arial" size="2">Originally posted by QSIMDO:
http://members.aol.com/pullingtractor/transaxl.htm

This might give you some ideas.</font>

Thanks for the link.. I might not need to worry too much about my setup because my traction is going to be limited enough where the wheel spin might occur before differential dammage.

I'm building one of these:




And I'm going to power it with the engine from this GSX750E:





-Adrian



[This message has been edited by 3 Phase Lightbulb (edited 08-10-2005).]

[CCWKen]

I'd leave it as is. (design wise) 500 ft.lbs. of torque is more than you'll get out of any motorcycle engine and most car engines. I think the weak link is the case and higher RPMs you'll be running. I'd modify or remake the case for seals so you could run hypoid--80w90. Also add reinforcement at the spider gear shaft to case area.

Another item to watch is balance. At high RPMs, you want that "saw tooth" and case running smooth. Using hypoid will help balance the spinning case and lube where it's needed. Make sure there is no flex in/at the frame mountings. A 4-point mount (bearings) with two close to the case and two out board should do it.

Before final assembly, Prussian Blue the gears to make sure you're getting the best contact (full) and alignment. The pattern should be at the strongest part of the gear teeth--centered on both contacts.

[CCWKen]

Well, I just noticed you'll have rear suspension. So the 4-point may need mods. Put bearings behind the axle gears or make sure you have a LONG bushing. I'd still use a double bearing mount near the case on both sides. You DO NOT want the axles to flex in the case or the case to be pulled out of axle axis by the chain (torque).

[3 Phase Lightbulb]

<font face="Verdana, Arial" size="2">Originally posted by CCWKen:
I'd leave it as is. (design wise) 500 ft.lbs. of torque is more than you'll get out of any motorcycle engine and most car engines.</font>

If this differential can only withstand 500 ft lbs of torque (like the specs say), then it's extremely weak. All I have to do is pop the cluch and that will easily produce well over 500 ft lbs of torque (For a short period of time) and probably shatter the spyder gears.

-Adrian

[topct]

Let's see, tested to 500 ft lbs. static. And then it says Horsepower rating 2 thru 14. God I hate math. Whatever.

Your using an 80 horse motor in a situation that niether the engine or this drive line piece is designed for.

If you were to look at the ring gear carrier of a small car you will see that it is identicle to what you are thinking of useing. Save for a major differance. Something out a little Toyota say, would not only be designed to handle the horsepower( what could that be, maybe 120 ), but the wieght of the vehicle.

They are very small and very strong. Just as they are. No hardening of gears. No special shafts. Whatever.

Since you would have to come up with a way to support axles in the diff you are looking at, you might as well go for a diff that will work and that part of the equation is completed.


------------------
Gene

[This message has been edited by topct (edited 08-10-2005).]

[3 Phase Lightbulb]

Torque and HP really don't have much in common... 500 lb/ft of torque can be generated easily with a motor from a wrist watch and enough gearing.

-Adrian

[CCWKen]

<font face="Verdana, Arial" size="2">All I have to do is pop the cluch and that will easily produce well over 500 ft lbs of torque...</font>

LOL... That's some motor cycle engine! I doubt that you'd keep the tires stuck in any case. Most car tires will break loose around 150 ft.lbs. Sticky gumbos used on Indys break loose around 300. If you applied 500 ft.lbs. to locked axles, you'd be picking up pieces of your engine as well.

[CCWKen]

Forgot to mention: Your cycle clutch will not handle 500 ft.lbs. of torque so I wouldn't worry about it. When you "Pop the clutch" you will still get slip. Besides that, there's no way in hell that engine produces more than about 150ft.lbs., if that.

I just looked it up. 44.83ft.lbs. of torque at 7,000rpm. When you take into account 1st gear ratio, it goes to 115.26.



[This message has been edited by CCWKen (edited 08-10-2005).]