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Reading ring & pinion tooth contact?
I have a Richmond chart, one from Jegs, and a couple manuals. Every one is drawn a bit different and I'm a bit confused. They show the pattern moving heel to toe and high to low (root to tip). They also show the shape of the pattern changing.
Some charts show the ideal pattern pretty much centered heel to toe and root to tip. Other charts show the ideal pattern off center closer to the toe but centered root to tip. So what is the more critical dimension heel/toe or root/tip? The too deep and too shallow patterns are sometimes drawn with the pattern being somewhat angled. The ideal is always depicted, as parallel to the tip/root and some what symmetric. So is the shape more important than position? |
Here is a doc that has some great pics towards the end.
http://www.ringpinion.com/Content/Ho...structions.pdf Shape AND position are equally important. |
If you're setting up a set now, post some pics and we'll help you with it.
Aim for a big fat cigar right in the center of the tooth. |
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Elmariachi - The Yukon write up is the best I have read by far. It finally answered my questions.
Blykins - As soon as it cools off, I'm going to set it up. I'll get some pictures when I'm done or if I get stumped. Gaz64 - thanks for the correction. Words I do not spell often. It was late. I don't know the difference between a tow truck and parts of a foot. One of those excuses should be believable. |
This is drive side with 0.023 shim in pinion 9" ford
http://www.clubcobra.com/photopost/d...023_Small_.jpg Cost side 0.023 shim http://www.clubcobra.com/photopost/d...023_Small_.jpg Drive side with 0.025 shim http://www.clubcobra.com/photopost/d...025_Small_.jpg coast side with 0.025 shim http://www.clubcobra.com/photopost/d...025_Small_.jpg Which looks better? Would you suggest a different shim? To me the 0.025 appears to be hitting more area on tooth. |
The .025 looks better. Are you spinning the pinion with a drill? That will create a much more definitive pattern, as will adding a little resistance with a rag stuffed in on the back of the ring. That forces more contact between the the gear faces and pushes the marking compound out of the way.
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.025"-.027" shim is the norm
Olddog The .027" is fine. The more important thing is getting the back lash down to the Min. IF you have a high powered car or drag race with a locker or spool, we run them tight with a .003" of lash. The spec with a posi is the .005" to .012". Over time the bearing with loosen up and the lash number will get a little larger. I set mine at .003" and do a couple of clutch releases to seat the gears and bearings. This will not work on a bench. You should end up with a .005" -.007" when done. You are right on the mark. What oil are you looking to use is the other thing. This needs to do a couple of heat cycles. After this a final check, you should be good for 100K. Rick L.
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I would move it out just a tad more and see if it will move the pattern to the outside of the tooth just a bit.
What's the backlash set at? Also, don't forget to set the preload on the diff bearings... When I set these up, I snug the adjuster rings just in slightly so that they're touching. I then set the backlash to zero, then absolutely lay down on the right adjuster to tighten it up. What usually happens is that you get about .008" backlash and the carrier bearings are preloaded correctly. |
Backlash on both pictures was 0.008 - 0.011 checked 4 places. Gear set paper work said set 0.008 to 0.010. I think a couple more for circle track racing.
On the first shim pack, I checked about a dozen or more places and the backlash varies a little under 0.0035. It is difficult to get exactly 0.008 at the tightest spot and have the hole in the cup lined up. From what Rick said, it sounds like I could let it slip under 0.008 without any problems. Manual I have said to tighten right cup 2.5 to 3 holes after contact and cup should always be turned tighter on its last movement. Both pictures the pre-load was set 3 holes. |
Sounds like you're on the right track. It doesn't really matter how you get there as long as you get there. :-)
The .008" backlash "feels good" to me....I'd leave it. If you wanted to jack with it a little more, I'd try .026-.027" worth of shims and see if it moves the pattern outward a tad. |
Oil -- some sources said 90 wt others say 90-140. I have both. 2 quarts of 75-90 wt and 1 quart of 90-140 wt oil in a synthetic blend. I was thinking of mixing the two, but I am having second thoughts. I'm leaning hard all 90-140 wt. Please advise.
While on the subject, there is no drain hole. How do you change the oil? Siphon tube? What about a magnet? Change oil after 500 miles??? |
If this is a brand new setup, don't use synthetic's or a blend for a while. Break-in is very critical on the gears and they need to burnish in to each other. I usually just throw in a couple bottles of the 80/90 stuff and roll with it. If it's a Trac-Lock, don't forget the additive.
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With no drain hole, you either have to pull the center section away from the housing, or if you're creative, you can jack the rear of the car way up high and just pull the pinion housing off the front. Magnets are always good.
For break-in, I always advise customers to take a couple of 5-10 mile easy drives and let the rearend cool down in between each one. After that, put about a 100 miles on it at one time. Then you should be good to rock and roll. |
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Drive side with 0.027 shim
http://www.clubcobra.com/photopost/d...027_Small_.jpg Coast side with 0.027 shim http://www.clubcobra.com/photopost/d...027_Small_.jpg Pattern is getting very close to the tip of the tooth. I think I will go with the 0.025 shim. |
What's the backlash on that one?
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I think the .025" is about as close as you're going to get.
Good news is that if it whines, you'll never hear it over the sidepipes.... ;-) |
I agree with Brent, you are pretty close to done with that setup. WRT the drain plug, I always drill a 3/8" hole in the bottom of the housing, tap it and thread in an allen plug screw flush, with a tiny dab of blue Loctite. Done a dozen that way and never had a bit of trouble. Your mileage may vary.:)
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