Using Diffs as handling aids

DaveG28 · #1 04-10-2009

Was giving my 511 it's first run out today and it was a bit fraught (see the Euro setup thread!). Anyway, having destroyed an outdrive I quickly built a new diff from scratch and dropped it in. Hard to tell for sure but I think it gave me a little push into corners. It was the rear diff I changed and I think I had slightly overtightened the new one, would that have this effect?

If so I'll loosen it a bit (assuming it won't them just undo itself!!)

MiCk B. · #2 04-10-2009

A tight rear diff will make the car push in a corner, a tight diff would be closer to a solid rear axle, bigger turning circle.

You can loosen the diff off a touch, but make sure it is not slipping, as that will destroy the diff.

MiCk B. :-)

VinceVegaUK · #3 04-10-2009

Yes diffs can make a big difference.

Tighter diff less turn but more drive, losser diff more turn but less drive. With 4wd you have two diffs so you can blance under and over-steer on coast into corners and the same on throttle out of corners.

You obviously don't want to run the diffs so loose that they constantly slip, you wont get much drive and they will wear quick and you will flatten the balls. If they are too tight you will get more drive but can wear a groove in the plates quickly, its a fine balance. A 1/4 or 1/2 turn in either direction, once you get it it can make the car hit the sweet spot, along with all the other set up options you can do.

If your running a powerfull motor i would run the diffs quite tight as this keeps the car more stable, loose diffs with too much power causes more torque steer (car pulls to one side under hard acceleration). Do a few hard starts and set your slipper to slip enough to ease the drive train but not to much that it slips and becomes inefficient, too tight and the diffs instead of the slipper could slip and wear. A diff slip is less of a nice smooth whine than what the slipper makes, more of a cry.

Hope this helps

Later

VV

sosidge · #4 04-10-2009

Personally speaking I would actually set the rear diff to be quite free (but not free spinning), and the front diff a little tighter. This is on the basis that neither slips under load.

This maintains good traction and stops the car grabbing too much on turn in.

Whenever I see cars with tight diffs (especially at the rear), they tend to be a handful.

Ball diffs are barely adjustable in practice so I just set and forget - helps to get the slipper setting right to protect them.

Rozzy · #5 04-10-2009

whats the best way yo get the slipper right as tamiya gave no setup instructions im still new with offroad

sosidge · #6 05-10-2009

Slipper is there to protect the diffs. Test by holding the spur and one rear wheel, and try and turn the other rear wheel. It should take a decent amount of force before there is any slip, and the slipper should slip first.

On the slipper with the original small spring, 3.5 turns on slipper nut from flush was about right for me.

VinceVegaUK · #7 05-10-2009

Quote:

Originally Posted by sosidge

Slipper is there to protect the diffs. Test by holding the spur and one rear wheel, and try and turn the other rear wheel. It should take a decent amount of force before there is any slip, and the slipper should slip first.

On the slipper with the original small spring, 3.5 turns on slipper nut from flush was about right for me.

If you look on the instructions for the slipper, from memory it says to set the nut 3mm in from the end of the thread, i run a 5.5 brushless which slips too easy on this setting so i have set at about 4mm.

Different tyers and road surface can effect how to set it, if its high grip you may find your slipper slips too much or not enough, it also can loosen bed in and wear after a while so a turn or two maybe needed from time to time to tighten it.

If you set it at the stock 3mm and do a few hard starts on a level surface (0 to full throttle) and listen for the slip, it should slip for a foot or two depending on how powerful your motor is you should adjust accordingly.

T4miy4 Guy · #8 05-10-2009

I run both my diffs quite loose and my slipper is set so it slips on a standing start at full throttle for about a metre.

Andy

stefke · #9 06-10-2009

Diffs on a 4wd car are very important tuning aids which most people tend to overlook.

I ran an TRF501 in 2008 and on that car, I set the front diff very loose (but not slipping) to increase turn in. That's also the reason I used the front oneway diff a lot in the TRF.

In 2009, I switched to a CAT SX and that car really demands a rather firm front diff to increase traction exiting corners and use it to stabilize the rear end on corner exit. The CAT SX has so much inherent turn in, It doesn't really need a loose front diff to get enough turn in.