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?
Go to this link;
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.
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.
You could contact the pinion depth tool manufacturer at:
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
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.
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.
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