Pinion + crownwheel play

[hachi_dk]

Car - ae86

motor - 20v

use - daily/track/dori

problem - assembling my diff and have play in my pinion and crownwheel

occurs/started when - putting diff together

Q: how much play should there be in the pinion as it feeds into the CW?

I understand how to line the pinion with the CW (with marking compound) so it feeds evenly into the CW.
basically want to know how much play there should be. Im assuming that there should be next to none.
anyone properly lined a diff that can give me a bit of advice?

thanks guys

[biggo]

in the wheel or the tail shaft?

tailshaft should have very little. but it depends on age, who set it up, your setup (cw+p and lsd) etc etc

ask a mechanic to look at it. Most of them can tell you its its wrong or not.

[biggo]

i reread you question. there should be no or very little backlash when butting the diff together.

Its very hard to do when reusing a crush spacer.

[hachi_dk]

hate to sound like an idiot but err whats a crush spacer and where is it located.
i probably know it but dont know it as a crush spacer

[biggo]

between the pinion bearings

[hachi_dk]

ahh i getcha.
gonna get some marking compound and give it a hit with that and ill get back to you how that goes.
cheers mate

[H8CHIR6KU]

you do need some backlash, but not alot. if you dont have back lash when it heats up it will seize

[hachi_dk]

alright.

so i've aligned the diff so that the pinion teeth are fed evenly into the CW. (checked with "bearing blue" - some sort of marking compound that is for diffs to check where the teeth are making contact)

the mark left with "bearing blue" is in the middle of each CW tooth. not too far to either side and appears feeding just right.

now, as i spin the pinion by hand, there is about 1mm of play before any actual movement of the CW occurs.

i think that its too much and need to do it all again.

anybody care to comment?

[assassin10000]

I'm 'guessing' your dealing with a S or T series diff. Backlash which should be measured with a dial indicator should be around .005" to .007" per the FSM.

.006" to .008" is acceptable as well, since we typically put a lot of heat through the gears compared to stock usage.

Unless you have a 'ton' of experience setting up diff's, you'll probably not get that close by hand. And guys with experience know better than to do it by feel.

IF you want to read up on some good info on setting diff's up, see here:




Andrew

[hachi_dk]

thanks andrew

i will definately look into getting one of the dial indicators then as i really dont want the same thing to happen to my 4.77's as what happened to my 4.1's.

would somewhere like bursons have one?