HiYa,

I have a dumb question. On the K3 front and rear diffs it states to install a thick and thin shim to adjust the backlash.

What the heck is this and how do I determine if I need to. []

Nice pic, still dont get it...[]

Are those the thick or thin ones? Why do you need them?

use whichever suits you....try thick then thin and whichever works better for you....

they adjust the level of lateral 'springiness' i think (im not sure), i.e. when the car is cornering there will be lateral forces transmitted to the diff, the shims are a kind of shock absorber for the diff

So its really not set in stone which to use, if any.

I think I understand now, its kind of a shock absorber for the diff.


Thanks guys.

I think the shim is more of getting the proper gear mesh between the ring gear and pinion gear than acting as a "shock absorber" for the diff.

then why would kyosho say to adjust the 'backlash' ...though you may be right

backlash is a term used in mechanical engineering etc that basically means freeplay!
you need to shim your rear diff on any buggy as close to the drive pinion as you can get it & still have it turning smoothly without binding once the gearbox screws are all tightened up! it csan be a minor pain to get this right & may take a few goes!
the rear diff is the one that is under the most stress in your buggy due to weight transfer during acceleration etc & this is usually the diff that will strip the drive pinion (IF21 Kyosho part#) & possibly even damage the diff ring gear too!
ignore this at your peril, you do NEED to have this shimmed right if you want your buggy to last

Thanks a ton and now understood!

While your checking to backlash and setting the spacing the way Adam said, hold off on putting in the dif oil til you're all finished and sure it's set the way you want. Just put a little dab of oil on the o-rings so they don't get torn and that ought to be enough til you're done making adjustments. The oil's really thick and you'll have a mess everywhere if not.