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Old 02-12-2018, 06:45 PM
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TheBandit TheBandit is offline
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Join Date: Jan 2006
Location: Ventura County CA
Posts: 4,654
I did some more research and found a typical backlash for used gears is around 0.012in. Most recommendations are to measure match the original backlash that the gears have worn into since they've already lapped into that position, but in my case I can only guess they had too much backlash to begin with. What to do?

I decided to swap shims and hope the gears are happy lapping themselves into a slightly new position. After measuring the angle of the gear teeth, I calculated I would need to move 0.011in shim to get the backlash down by 0.008in to hit a target of 0.012in backlash. So that's exactly what I did and that's exactly the result I got (how often does that happen? I had a little engineergasm when the indicator gave me exactly what I was going for).

With that set, I torqued the caps down again and thought I would see how the pattern looked. Unfortunately I used up the last little bit of gear marking compound I had on hand and when I went to get some from my local source, they were out. So I decided to try some old oil based paint I had on hand.

After applying, I let it dry a couple minutes before running a pattern. I was really surprised at how well the paint worked. It definitely does not replace purpose-made gear marking compound, but in a pinch it did the trick.

Now as to the pattern, I really am not sure how to read the tea-leaves. Used gears never give a textbook pattern (heck neither do new ones) and these are no exception. To me the drive side looks like the pinion could have less shim but the coast side looks the other way. Since I haven't messed with pinion depth (same bearings and shims that came out of it), it was running without problems previous, and the patterns average on center, I am not going to make any changes.

At this point I could finally stab the axles in and verify the length was proper to completely engage the splines on the spider gears. Yup! Thank you Strange for providing accurate numbers.

With all that buttoned up it was time to drop the cover on. I used a fiber gasket with some Permatex Gear Oil RTV on the housing side and dry on the cover side. Before I put the cover on I snapped a photo of the leveling feet that are used to add support on the bearing caps.


Ongoing 70 Nova build:
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