View Full Version : R&P pattern- whatcha think?

06-14-2009, 02:08 PM
Getting my 4.88 R&P set up - finally! Good gosh I can't seem to get anything done quickly before I run out of steam, with this knee.

I felt pretty good about these patterns. Sorry for the blurry cell phone pix, I thought they took better than they did. But you can see the pattern and its shape.

BL for this pattern was .006". Carrier bearing preload may be not quite as high as finished will be, but there is a fair amount. TG gears, no appreciable runout, very consistent pattern.

Things I like about it: the heel and toe between coast and drive sides are pretty well placed. Pinion depth looks good, centered on the ring gear teeth.

Things I don't: there is a sharp cutoff to the inside of the pattern (toward the root of the gear teeth), almost as if it is riding the outside of the pinion gear teeth instead of the middle of the face. Maybe I am overthinking this. I would be happier with a true oval with gradual fading of the contact area instead of that sharp cutoff. The confusing part is, it is centered on the ring gear and only the pinion looks to be riding on the outside of the gear tooth; the ring gear teeth look just right in terms of where the pattern is placed.

Whatcha think?



(threw in a pic of the pinion just for the heck of it)

06-14-2009, 06:40 PM
Looks good to me, Bill, seems to be biting just inboard of center which is where you want to be, right? then as things wear it settles in right in the middle..

06-14-2009, 06:42 PM
Wow next time someone local is doing some work like this (diff, pinion, gear settings, axles) I'd love to come help/watch/learn/absorb if possible.

06-14-2009, 06:53 PM
As slow as I am you will be able to come on by and observe this step in the process for the next several days... :lmao: It's only taken me a month to get to this point...

(Hmmm... being a temporary cripple, I wonder if I could lure this young 'un into being slave labor? Hmmm... worth a shot... :lmao:)

Hopefully one of the gurus (Powderpig, UB, Christo, Joe C, ... we have any number of them around here) will get hooked in here...

06-14-2009, 07:10 PM
I guess I am trying to decide whether I am happy, or whether this qualifies as too low contact (per this very helpful chart at http://www.precisiongear.com/pgtechpatterns.htm). Sorry the lousy pic is a bit blurry; the line to the inside of the pattern, toward the root of the tooth, is a clear line whereas I am thinking it should kinda fade at the edges of the pattern.

I am kinda likin' the implications of "Competition Contact"... That's where I try to aim. Seems like I read that somewhere else too.


06-14-2009, 08:46 PM
Looks to be low contact to me but I am not an expert I am sure they will chime in soon :thumb:

06-15-2009, 10:22 PM
Pinion is too deep, try removing .005" shim and see where that puts you. For reference V6 diffs like to be around .070" of total pinion shim. I start there and go up or down depending on the look.

Three Wheel Ben
06-16-2009, 07:23 AM
It'll run, but my opinion is you're 0.001-0.002 too deep on the pinion. Low contact on your chart. Notice the round pattern on the one side of the mark. Pull it out a little and the roundness should diminish.

And then torque the beejeezus out of the side adjusting nuts, while maintaining backlash of course, (As on Zuk's website) and the carrier will never move again. The one's i've built this adds about 7-10in/lb to the total preload spec.

good luck

06-16-2009, 11:17 AM
Thanks Brian and Ben... In fact that is what I did (.005 or so less shim) and the pattern looks better. Sitting at .072 right now. The only downside is, now the bias toward the toe on the drive side ain't there ('Ideal Contact' versus 'Competition Contact'). I may play around a bit more but sooner or later I'd like to actually be able to drive the dang truck - before the snow flies??

Yeah, Ben, I have a 3' bar I made just for carrier bearing preload.

06-18-2009, 03:10 PM
Yep, no matter what I do within reasonable BL limits the pattern on the drive side is right in the middle of the tooth, not down toward the toe.

Ah well, guess I'll have to settle for "Ideal Contact"...

:lmao: :lmao:

I've set up two TrailGear R&Ps now, and I have to say they are very consistent and rather nice to work with, as nice as anything else at least.

06-18-2009, 03:17 PM
Ah well, guess I'll have to settle for "Ideal Contact"...
What is the advantage of the competition contact? I assume it has to do with the flex when you wail on the gears, so that under high load the contact becomes more ideal-like?

06-18-2009, 06:35 PM
What was your total pinion shim thickness? I like to keep a running tab for future differential setups.

06-19-2009, 11:24 AM
Gonna use a solid spacer, I will jot down the shims for that too. (I know you aren't real fond of them but ... oh well, it was in there from before. BTW the pinion preload on the busted pinion wasn't bad. It looks like a 4 cyl. pinion though, the shop that did it shimmed the *&@#%$ out of it. Behind the rear race, .080 beneath the pinion head, not so great a setup. Better now at least.)

06-20-2009, 12:19 PM
Well, one of my oddball personality traits is that if something ain't quite just prezactly how I want it, it bugs me and bugs me and I am a pro at second guessing myself ad nauseum.

After I pulled the carrier and saw everything in better light, it bugs me that the pattern ain't closer to the toe. It would probably be fine, but there is that 'perfect' thing tripping my OCD trigger (trigger is usually set at 3 lbs. but right now sitting at 1 1/2 lbs no doubt due to the meds I am on... ;)).

The confusing thing to me is, though gear setup is actually not that much of a mystery to me as far as what does what (pinion depth, backlash, etc.) I'm a tad stumped because I've not run into this before.

I want to move the pattern toward the toe. I *would* go for more pinion depth and then play with backlash until I got what I wanted, but seems like I am up against too much pinion depth if I go even a few thousandths more shim. IIRC the 'too deep' shim in the first pix was .080. Now it's sitting at .072. That's not much to play with and I am suspicious about moving away from 'normal' for Toy diffs.

Hmmm... as I reread this post I see a lot of indicators I am overthinking this thing... :lmao: Well heck. Gonna spend some more quality time with the press I guess. The alternative is thinking about it every time I go wheeling. :eek: :rolleyes:

No wonder it takes me forever to do stuff like this.
:lmao: :lmao: :lmao: :lmao: :lmao:

The current pattern that is bugging me: [edit: I wonder if TG gears are just cut at the factory to favor the middle versus the toe, and that is what I am finding unusual?]

06-22-2009, 12:02 PM
Well, I just settled back and let the pattern 'speak' to me. First time I've really focused on the pinion pattern, too. If you have a doubt about the ring pattern, the pinion will steer you right (it will be opposite).

So I took the pinion shims down to .070", and the pattern is durn near perfect. Just to the toe side of center on the drive side, and a nice oval on both the ring and the pinion, with .007" backlash.

The backlash seems pretty consistent all around the ring. Have to say, I do like these TG gears, and not just for the price.

Well now I can get to pinion preload, finish the setup, pull the axle shafts, install the diff, and get on with this project!!!

06-22-2009, 12:11 PM

06-22-2009, 12:28 PM
The front should go a bunch faster. This rear diff was... 'creatively' set up by a local shop years ago. I think my V6 diff had your missing I-4 pinion.
:lmao: You're welcome to it if you like; many of the teeth still look fine!

The front was set up by Mike Caskey. The only changes will be the differences between Precision and Trail Gear R&Ps.

Anybody in the market for a decent used Precision (IIRC) 5.29 reverse rotation R&P set (FZJ80 front diff)?

06-24-2009, 10:02 AM
Well now, my diff is all put together and purty. Just have to install the new style air bearing (BIG improvement) and she's done. Shimmed the spacer for 20 in/lbs drag for the pinion, RIGHT on the money. :D
Torqued a new pinion nut into place, blue locktite, tapped the crimp on the nut.
Covered the diff and went inside to eat dinner, watch a movie (In the Electric Mist with Tommy Lee Jones, GREAT movie) and go to bed.

WHEW. World's slowest diff setup.

Did you notice anything missing in the sequence above?

I did, around 11:30 PM, eyes popped open to stare at a dark ceiling. Let's see if you can guess it. Clue: often done.

06-24-2009, 10:44 AM
You forgot to paint the diff a nice shade of periwinkle? You forgot to fill it with 90 wt.?

06-24-2009, 10:57 AM
Did you put in a pinion seal?

06-24-2009, 01:04 PM
Did you put in a pinion seal?

Tell the man what he's won, Bob...

Boy did I feel like a moron...

06-24-2009, 03:56 PM
oh well at least it's not like you didn't set the backlash or something...

and I'm actually surprise I got that right! I must be learning something....

06-25-2009, 08:39 AM
Seal is in, yet another new pinion nut in place and torqued to approx. 150 ft./lbs. 30 in/lbs overall drag without seal (there was at least one good thing to come from forgetting it... :lmao:). That means the carrier bearing preload is double what the FSM says is spec max (5 in/lbs spec, hardly anything; 10 seems hardly excessive).

Ready to slip into the axle housing (well, still gotta mount the air bearing)! Probably a Saturday task if anyone is bored and wants to hang out. Full floaters will make it pretty easy (unless I discover evidence of a dislodged axle shaft seal like last time...). Gonna adapt some IFS hubs using Long hardened inner dealies - as soon as I steal Ige's set screw idea to keep 'friends' from disconnecting a drive wheel in the parking lot.

06-25-2009, 09:02 AM
Just remember Bill, that extra 10inlbs is on the carrier side bearings, after the ring gear. Your running 5.29 gears so torque mutiplication puts you preload at about 50 inlbs on the carrier bearings.

I don't run any more then 10inlbs additional over the spec. I try to stay more around 8inlbs.

06-26-2009, 08:29 PM
It's sitting right there, 10 in/lbs over spec. Thanks though!
4.88s this time though! Much better fit with the 3.4 and 35s, even towing!

06-26-2009, 09:25 PM
Oh for cryin' out loud.

So I went and got the new air bearing and all parts. Cut the line, got everything ready to install... and thinks I, "Huh. The air bearing is grooved. So is the locker. So just how does THIS work with the O-rings??!?"

Answer? Justin was right there with it. "It doesn't. You can't use the new air bearing."

I only spent cubic dollars and many trips to get (almost) all the parts I needed.

Surely there is a way to use the new style air bearing with the first generation V6 ARB? What additional parts do I need? Obviously I get to take the locker apart to install a grooveless bearing surface thingie, at a minimum?

It's gonna toast my granola if I have to buy a new old air bearing. The original is slightly worn from the O-rings.

06-26-2009, 09:47 PM
Ah. I see. New end cap, #10 below:

And new carrier bearing. And re-setup. And more money.

I guess I get to find out just how badly I really want that new air bearing style.

06-26-2009, 09:48 PM

Aren't you done with this yet? Gandma was slow but she was old...:rolleyes:


06-26-2009, 11:40 PM
Told ya I was slow with this knee and everything that goes along with it. Work gets 90% of my energy and the family gets most of what's left, most days I hope. Then the Chili... well...

Wow I really really hope I can finish by July 18... :(

06-30-2009, 12:48 PM
The friendly folks at arbusa.com were happy to send me a new end cap for my locker. It will be here Thursday afternoon, and I have Friday off (except for being on call... :(). So if anyone wants to swing by and help :lmao: - whether with labor or with barleypop disposal - or get some tutoring in gear setup (the slow, proven way :lmao:) ping a note to me and we can make it a social time.