Tom Heath
Tom Heath UberDork
10/8/08 11:47 a.m.
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After the $2008 Challenge, we knew something wasn't right with our Berzerkeley's driveline. During our first run in the autocross competition, the car lost the ability to drive. We had spent quite a bit of time on testing for the car, so suffering a component failure was especially frustrating. However, now that the milk had been spilled, we could only …

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iceracer
iceracer PowerDork
10/10/08 10:17 a.m.

I would bet on the housing flexing. Look at any differential and even with cast iron they have reinforcing ribs.

bluej
bluej GRM+ Memberand SuperDork
10/10/08 2:27 p.m.

A simple answer could be an ATV differential. I considered it for the Toyzilla but i'm going to see how long the flipped ring and pinion last first. Some of the Honda ones have a torque sensing LSD front diff. Not sure how it would work out as far as needing a front or rear depending on engine rotation... Good news is that they are CHEAP!

Gonzo_Bmod
Gonzo_Bmod Reader
10/14/08 9:01 a.m.

Talk to Scott at Taylor Racing. They make several different chain drive diffs for DSR's and Formula SAE cars. I wouldn't be surprised if you had some flex in there. Also, that short chain run with the two small sprockets was gonna generate some heat, chains need some free length to cool off.

If you are really hung up on a reverse gear, another system to check is the one found in MC engined Gloria race cars. I think they have a reverse incorporated somehow.

Gonzo_Bmod
Gonzo_Bmod Reader
10/14/08 9:11 a.m.

The Gloria MC cars use an electric reverse. It's a separate gear on the rear that is driven by a starter motor.

oldopelguy
oldopelguy SuperDork
10/16/08 3:01 p.m.

Since you need to change directions anyway, sounds like the perfect time to fab up something with a pair of quick-change gears and stub shafts with sprockets welded on them. Since the covers hold support bearings already, you could cut the intermediate shafts (or use two-speed ones) and maybe even get by with a couple of covers bolted together with a simple plate in the middle. Sprockets on one side (with the chains entering and exiting through a couple holes on each end) and gears on the other. Would also make for some killer options when it comes to gearing.

Wonder if one of those starter/generator thingies they used to use on old riding lawn mowers could be made to charge a battery one way and run the other way as a motor? Then you could just belt drive it off the driveshaft and use it to back-up the tiny bike alternator as well as give you reverse?

Fueled by Caffeine
Fueled by Caffeine MegaDork
10/17/08 9:14 a.m.

We had a similar diff on our SAE mini baja car. Case flex was an issue and produced similar results.

jstein77
jstein77 SuperDork
10/28/08 11:15 a.m.

What about dumping the idea of gears altogether and use a CVT like the A Mod guys do?

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