Gear Install

The ring and pinion have destroyed themselves on my rear of my 86 GMC 4x4 1/2 ton short bed pickup. I have the GM 10 bolt 8.5"axle with 3.73 gears.
It was making a terrible noise while under acceleration. When I removed the cover I found that all of the ring gears are chipped on the toe side, and 2 teeth were completely missing. The pinion is missing most of 2 teeth as well. I have now removed the carrier, cleaned up the diff, and have purchased new gears, and an install kit. I understand the concept of Checking Distance (pinion depth) and backlash, and how to check and adjust both of those. But I have questions on how to accurately measure the checking distance, and backlash. Are there special tools required get these measurements? Something more than just calipers? How do you find the centerline of the axle? Since my old gears are in such bad shape I don't think I can trust taking a pinion measurement off the old pinion. I would really like to set these gears up on my own, but the normal consensus is "take it to a shop". Can you tell me what tools I need, what to look for?
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Go to this link; http://emporium.markwilliams.com/prodinfo.asp?prodid 69
Randy's Ring and Pinion also sells this same unit (I think?) but the picture at the Mark Williams website really gives you a better idea of how nice of a tool it is.
This is probably the best universal pinion depth gauge on the market, very well made and very accurate. Works best with aftermarket gears where the pinion center depth is etched on the end of the pinion, it also comes with instructions on how to use it to measure OEM pinions for depth by taking a few more measurements with a vernier or micrometer. To measure backlash, you'll need a dial indicator with a magnetic stand or a dial indicator that mounts to a flexible clamp on or vice grips mount. You'll need a micrometer for measuring the carrier side shims and pinion depth shims since most in the install kits aren't marked for thickness. You'll need a decent brass or aluminum drift punch for driving the carrier side shims into place. You'll need a way to hold the pinion flange while crushing the crush sleeve, this can be as simple as a rectangular piece of 1/4" steel plate slightly bigger than the pinion flange machined with a hole in the center big enough to pass the socket that fits the pinion nut and two holes placed so it can be bolted up to the flange where the u-joint bolts go, to the plate weld a length of 1 1/2" pipe about 5-6 feet long (you'll need the leverage). You'll need a 3/4" drive ratchet or breaker bar and another cheater pipe that fits over the handle. You'll need a 1/4" torque wrench that reads accurately in the 20in.lb to 50in.lb range for measuring bearing pre-load, a 1/4" beam style will work just fine. You'll need bearing race installing tools, aluminum preferred. You'll need a way to press the rear pinion bearing on and off, off also requiring a bearing splitter or pinion bearing removal tools, naturally, you'll also need the press to press on the carrier side bearings. You'll need a way to warm up the ring gear in order to fit it onto the carrier, a disposable pan of suitable size filled with water on the BBQ grill will work fine. The ring gear bolts are left hand thread, so you'll need a torque wrench that reads accurately in reverse (most clickers do not). Go to a GM dealership parts department and get their gear marking compound, the stuff in the install kits is crap.
There are other cheaper pinion depth gauges on the market sold by places such as Summitt and Jegs, Tavia brand IIRC, these things are a joke and not worth the money.
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wrote:

4x4
gears.
the
and 2

adjust
these
don't
would
for?
All good info. As you have guessed, not an easy job. Did you think of trying to find a complete axle in a salvage yard? 3.73 is a common ratio.
Al
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That is the answer I was looking for, thank you for taking the time to talk about more details. The answer of "better take it to a shop" drives me nuts. Looks like the tools that I would need to purchase will be more than labor to do it locally. But I will want to do gears in my jeep in the future, so now the cost of the tools is cheaper than labor on 3 axles. Do you know of a pinion depth checking tool that will work on the 10-bolt(rear), AMC20( rear), Dana44 (rear), and Dana30(front)? Those are the axles that I could potentially set up this summer. If I can find tools that are common between all of those it will make sense to get set up for them. But if the tools are specific for each axle then it will make more sense to take it to a shop, or find a used axle that I can just bolt it and be back on the road. Once again thanks for your input.
wrote:

4x4
gears.
the
and 2

adjust
these
don't
would
for?
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You could contact the pinion depth tool manufacturer at: snipped-for-privacy@TDmach.com Or, contact Mark Williams Enterprises, (their people are very helpful and service oriented), and ask them if there is other coverage than that which is listed in the product info, or perhaps they could supply you with the needed adaptors.
AFAIK, the only obstacle to doing the AMC and Dana axles is whether the outside diameter of the carrier bearing races is different than any of the axles listed in the product info. One other way of finding out would be to obtain samples of the outer races and measure them/compare part numbers, I could then measure the adaptors I have in my pinion tool kit and see if they are the same.
If you're going to rebuild/gear swap Dana axles, you may need to add a case spreader to the list of tools needed. Ups the total by another $300 or so.
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Dana axles are very difficult to service. The pinion depth shim is behind the outer race of the inner pinion bearing, and the shims that set carrier preload and ring gear backlash are between the carrier bearings and the carrier. I.E., you have to remove both carrier bearings to move the carrier to add or subtract backlash. And you have to remove the outer race of the bearing to change the pinion depth. When I had my shop I had a New Process tool made to set pinion depth on Dana rear axles. It cost over $2,000 in the early 60's. It used a "trick" way to set pinion depth without putting the pinion gear in. For a while I tried this with a "cheapo" depth gauge, absolute torture. Also Dana axles do not have a crush sleeve for pinion preload. They use spacers. Spacers are wonderful if you have to remove the yoke to replace a seal, but hard as hell to get right the first time.
I made a case spreader. Worked for about six months without one and learned that lesson:) Even a 10 or 12 bolt Chevy can be a bear without a spreader.
Al
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