ahyc84

Not that being a tomei or not matters at all. I've done tons of research on installing this and talked to people who's done this. But no one i know has actually bothered to chk the backlash on their FC tomei 2way diff installation. They haven't ran in to any problems yet still. That's like 4 of them now for them.

How exactly do you set the backlash? I checked the FSM, but i'm kinda confused about it still. Plus it uses the engine stand to mount the dial...Better yet, what exactly is the point of setting the backlash? I initially thought it was just to make sure the mating point of the pinion and ring gear is in the right spot, but that turns out to be just another part I gotta check.

Pic of the FSM's backlash instruction
http://members.shaw.ca/ahyc84/FC3S/b...adjustment.JPG

I also just ran in to this picture doing some research on setting the backlash.
http://members.shaw.ca/ahyc84/FC3S/fdint2.jpg
I jacked the above pic from JDuncan on this site. Hope he doesn't mind

it looks from this picture you can mount the dial indicator on the casing?


I'm kind of lost as to what exactly setting the backlash is at this point. I kind of get how to do it(i think), but what exactly does the measurement mean when it gives me a reading of in spec or out of spec. Any one wanna lend a hand?
Oh, and how do I adjust it if it's out of spec? It doesn't really say clearly.

No i don't wanna take it to a shop unless I absolutely cannot do it, because i enjoy doing these things on my own. It's my only source of entertainment now while going to school full time. :p

TIA
-Adrian

staticguitar313

iTrader: (2)

i need to know this too i desperately need to rebuild my rearend and no i'm not just going to "find another used one in the junkyard" i want a permanent solution.

ahyc84

ok i found this. i didn't realize it tells you approximately how to set the backlash on the 3rd to last pic. I thought this was how to get the pattern right

http://www.driftfactory.com/lsdinstall.php

this is for a s13 differential btw. So some of the things are slightly different. concept is the same

still got more researching to figur out, but to my understanding, the link above tells you how to set the pattern in the right spot, and backlash would set the size of the contact patch between the pinion and ring gear right?

staticguitar313

iTrader: (2)

sounds like a simple way to do i as opposed to dials and what not . . . hmmm . . .

Hot_Dog

The picture merely shows how to set the proper pinion depth using Prussian blue dye. Unless you've changed R&P gears, you normally won't need to (re)set pinion depth. Checking the backlash is actually very simple. I normally check the backlash by mounting the dial indicator clamp to the carrier case and positioning the dial indicator push-pin as is indicated in the FSM. After the dial indicator is mounted, grasp the ring gear with your hand and gentely rock it back-and-fourth throughout its "freeplay" range while recording dial the indicator min-max readings. The difference in dial indicator min-max readings is the backlash. When doing this, you need to make sure that the pinion drive and carrier case are stationary. Otherwise, any unwanted movement between pinion and case will affect the backlash readings and induce measurement error. I've found that the best way to hold the unit is to clamp the drive pinion flange (i.e., driveshaft flange) into a vise while having the carrier case sitting firmly on the workbench. After the pinion and carrier are securely positioned, than proceed as I've described above. Hope this helps.

Hot_Dog
90 RX7 GXL

ahyc84

So set up the dial gauge like so in the pic and point the dial gauges TOUCHING one of the gear at 90 degree. Touching it right? or not touching?

Then gently move the ring gear like so shown on the green arrow. (given the pinion gear isn't moved at all) This then measures what they call backlash right? Because whatever movement the ring has in the green arrow direction is the amount of free play between the ring and pinion.

Do i have it correct?

staticguitar313

iTrader: (2)

ok so how much is a dial indicator and the spacers needed to change the backlash

ahyc84

$20-40

Hot_Dog

The dial indicator should be touching the ring gear. Take dial indicator readings at both extremes while rocking the ring gear back-and-fourth within its freeplay range. The difference in these readings is the backlash.

Hot_Dog
90 RX7 GXL

Hot_Dog

Spacers are not needed to adjust backlash. Spacer are used to adjust pinion depth. Backlash is adjusted by moving the ring gear toward or away from the pinion gear using the side bearing adjuster caps. Once the correct backlash is obtained than the side bearing preload must be adjusted by tightening the bearing caps as required.

Hot_Dog
90 RX7 GXL

Hot_Dog

A good Central Tools dial indicator will run you about $100.

Hot_Dog
90 RX7 GXL

ahyc84

wtf really?

everywhere i've looked it runs for under 50bucks even for the ones that comes in a kit.

which ones are you thinking about hotdog?