tooth pattern

[76Lark]

You're right, a real lesson in patience!
this is what i started with, 8.5 rear, eaton posi, richmond 3.23 ring and pinion, install kit from JDRACE.

old pinion inner bearing honed out with 052 shim,preload of 14in.lb.
244 pass. side carrier shim, 221 drive
.001 ring gear runout
backlash checked at 90deg. poss. .006 .008, .008, .005
takes slight pop of prybar to dislodge carrier

i think it looks good, but i need your opinion!

[monzaz]

Way too deep. go yo .040 .038 and try that. Jim

[monzaz]

open up the backlash to about .010 see how that looks. Jim

[monzaz]

the red is trouble - the green is where you want your pattern to swipe. Jim

[76Lark]

had it at 038 and was riding on top edge, will try about 045 and get backlash to 010
keith

[76Lark]

ok, today i got this with .041 pinion shim
.080-.010 backlash
keith

[monzaz]

it is definitely better... How does it feel spinning it? Smooth on both sides coast and drive with equal drag?

Throw some oil on it and see how the pattern looks after that ? Might be a hair too deep but it will definitely not blow up or fall apart etc. Could be a runner.

Now you have to get your pinion preload set. One more double check on the pattern and you will be finished. Jim

[monzaz]

Do you see how the pattern moved? from the root to the middle of the tooth? As torque is applied to the gear face it will spread across the gear teeth faces.... you will see after your first oil change at 500-1000 miles. If you keep going with removing shim it will start to climb up the tooth to the peak if the tooth showing it is too shallow. Now there are many different good patterns but you always want to swipe as much of the gear from top to bottom and toe to heel second. Try to always keep the pattern equal on each side of the gear from coast to drive as you can... Sometimes reading the pattern can be a bout tedious after hours of working on it and you need to walk away. come back later with fresh eyes.

Good luck, Jim

[76Lark]

yes, it has been quite an adventure. I really noticed how the flat line at the bottom pretty much went away, and the very thin line across the top. and how the the pattern widened out. setting the backlash was tedious trying to get it as close as possible.
i'll post a pick after final assembly.
thanks for all the help!
keith

[76Lark]

what effect does the backlash have on the pattern?
keith

[monzaz]

IT WILL VERY SLIGHTLY MOVE PATTERN UP OR DOWN the tooth again...BUT very little...It is a fine tune of how you want the tooth engagement to come in and off the gear face.

Backlash is mostly how much oil your going to pad the gear with.

Thumb rules we have used is for DRAG racing go to the tight side .004 ish
Street best is factory (no matter the power out put (.006-.008 ) NEW GM gears Unless stated by the gear manufacturer
Circle track we usually make a bit wider because of the RPMs and needing to cool the gear more and not as much shock load off line. (.010-.013)

Again... It is your differential so you can always make your own choices that YOU think work for your needs.

OH and do not forget your break in procedures.... 5 min heat up for the first run... 45 min cool down
then 3-4 more 10 min heat up run and 1 hr cool down time frames. after this you should be good if you have no issues up to it.
On any aftermarket gear set it is always possible no matter how great your pattern looks may have a gear whine or pitch change in any RPM range.

Hope we have help you get a long running gear installed in your car.

Jim Mitschke
J D Race

[76Lark]

well I just found out that pinion bearing pre-load is a lot more touchier with the crush sleeve, went from less than 10inlb. to 40inlb. in less than 1/8 of a turn!, sooo what do I need to do? just new crush washer or outer bearing also? #$_&%!
keith

[monzaz]

Your dealing in INCH pounds. I guess you never delt with that small of torque before huh?

Depends on how far you went. You can tap the crush sleeve on the shaft of the pinion and get some expansion we do this at the track if we ever need to take the rear apart. Or shims can be used - When tapping the crush sleeve it actually makes it a bit more rigged like a solid spacer. We do this everyday with a impact and do not use wrenches... so know how far to turn the wrench is oblivious anymore...lol.

Try the tap trick on the vice with a 1# ball peen and see if that does not give you the distance you need... after the second time your done so this is your one shot. Measure it with the slide calipers before you start and then after give at least .003-.005 - keep it on the shaft to keep it round ish. You will be ok. Other than that Dealer ship will have 8.5 sleeves they are still used in PU trucks.

[76Lark]

since it's back apart again i'm going to check everything again with the new inner bearing before I put a new crush sleeve in. the outer bearing has been such a tight fir that I've had to heat it each time I take the pinion out,(rear diff to hard to put in my press by myself) that i'm going to replace it also. and I want a new inner bearing just in case. so if you could give me a price on a new crush sleeve, seal,inner and outer bearings and races and nut. I never got the outer bearing real hot because I didn't want to harm the pinion shaft so I had to persuade the bearing a bit.
thanks,keith

[76Lark]

rechecked everything without crush sleeve, looks the same, just need new outer bearing and race, seal, crush sleeve and nut. if you could give me a price on them I will send you a cashiers check.
thanks,keith