How to build a Limited Slip Differential

[twissted]

This picture shows what to do and also shows what spring to use and what not to use.


The lower heavy spring is the one needed.
Guys I bought these springs years ago at Home Depot is a verity pack of springs. Finding the right spring rate is key. Also The aluminum Diff housing is key as it will no warp over time from the pressure that is on the gears that put the pressure on the housing. I'm not saying it will not work I just don't know because I haven't tried it. I'm going to though. Also when you cut the spring I use a dremel cut wheel. Feather the cut edge so that it is not going to bind against the gear. You get this right and you will not need locks hardly ever. Good luck!

 

[LiftedAWDAstro]

Nice tip! I will have to do this when I get aluminum cups.

 

[twissted]

I would install the set up in what you have now. I took the CNC diff cup out of the front and put in the stock plastic diff cup to see if there is any problems. I will run it until it does, then put the aluminum cup back in. This should be a good test since My build is 22'' wheel base and 18'' wide and weighs 18 pounds loaded.

 

[twissted]

By adding nonferrous metal washers add more surface area and locks it up even tighter.

 

[OSRC]

Nice, just did the same to a Wraith diff....stuffed with Tamiya AW grease to boot. Not sure how it's going to work out, but time will tell. Feels great on the bench.

 

[twissted]

You went with a soft spring. I don't think you can do any harm with it. Try adding some aluminum washers on each end of the spring and you should see a big improvement.

 

[fyrstormer]

Cool idea, but a true torque-sensing limited-slip differential would tighten in response to driveline torque. I've been thinking that rubber pads stuck to the back sides of the output gears might do the trick, because the output gears would be jammed against the sides of the cups only when the diff is transferring power to the axle.

 

[klampykixx]

This thread interests me also, i have done what OSRC had done with the spring and a heavier oil, around the 500k weight. I'd say most of it leaked out coz my diff housing is leaking what looks like silicone oil lol. It's a jeep thing....

Point is, while it had the oil in, it was nice n tight and helped with traction but as mentioned it's more of a constant friction rather than torque sensing.

 

[fyrstormer]

Admittedly it might be just the ticket for a vehicle that can't seem to get enough anti-slip using even the thickest diff oils, but as you said, since it's a constant source of friction whenever the diff internals are moving, it won't loosen-up to allow the wheels to roll smoothly when coasting through corners.

I wish I could quit my job, buy a CNC lathe, and start fiddling. I know I could make real LSDs for off-road vehicles. I'd have to charge hundreds of dollars apiece to make ends meet, though.

 

[twissted]

The best system that I have found yet is to fill a aluminum diff cup and the spider gears with silicone glue and let it dry. It will run like a locker for a while but will break loose and then it run very tight but not as a locker. I have broke 2 spoolss in the rear now one was a traxxas and the weaker of the 2. and the 2nd was a HR Spool.

 

[klampykixx]

Twissted, does the spring from an Axial slipper clutch fit inside? im considering using one when i rebuild my front diff in my SCX. currently running a pen spring with heavy oil and its leaking.

 

[twissted]

I don't know if it does. I do know that if more friction is needed that Dremel cutting discs on each side of the spring will help lock it up a little tighter.

 

[klampykixx]

Cutting discs like that of a dremel?

 

[klampykixx]

Never mind just reread ur post. Tips for drilling it out without breaking them?

 

[twissted]

ya a well used up one thats small. you need a diamond tapered bit to drill out the hole.