Pinion depth tool
 

I'm getting closer to rebuilding my spare rear end. It's going to be great switching out from 2:78 to 3:55's.
I'm just wondering if anyone has used an inexpensive pinion depth tool. Something like this:
https://www.summitracing.com/parts/p...SABEgIYjPD_BwE

Of course, a good one costs 500.00- 1000.00. I'm sure that if someone was doing it for a living, they would buy one of those.

Frankly, I'd leave it up to someone else to do it, but in calling around, the local shops couldn't even give me a timeframe of when they could do it.

I did see one guy on youtube who used a caliper tool, with a strip of metal bolted to the housing. He measured from the metal down to the bearing cap mating surface, zero'd out the tool at that point, and then extended it down to the pinion from there, getting the dimension.

Yeah they "kinda" work.

Basically the idea with those is you have to hold it or bolt it to the bearing cap mating surface and measure from there to the face of the pinion. It's not quite as accurate this way and you'll find you'll triple check your measurement and get 3 different readings. It gets a little frustrating. I'm talking maybe a couple thou one way or the other but it's enough to make you second guess. You'll also find that if you rotate the mount slightly while it's on the rearend mating surface it also changes the readings and that's even more frustrating. That surface isn't perfect and that's where this style of tool has it's issues. Every time you remove it to make a pinion adjustment there is no guarantee it's in the same spot giving you the same reading as before, in fact I'll guarantee that'll change every time making you chase your tail, LOL. One problem with it is that main cap bolt it torqued to 60-65 ft lbs. What that does to the housing, even when you can't see it with the naked eye, is it pulls the metal out slightly around the threads. It's distorted, and you're now trying to bolt that tool to it, you'll find it rocks around a bit, and there is no way to really make that surface perfectly flat again, can't get a file on it, it just is what it is.

The other issue, and you can measure for this, is that the break (parting line) between the housing surface and the bearing cap may not be exactly center. It can be .002-.003" either way. It's supposed to be, or assumed to be exactly half but that's not always the case. Those are reasons why the donut style pinion gauges (the expensive ones) are more accurate as it takes all these variables out of the equation.

Something you can do to make the process a bit easier is to take your old pinion bearing use a sanding drum on the inside of the race where it goes on the pinion use the slip fit bearing to get a good pattern on your new gears establish a shim dimension then press the new bearing and shim on for final install

during the slip fit bearing use you use the yoke and new outer pinion bearing omit the crush sleeve for now and tighten down the pinion nut to get a few inch pounds of turning force on pinion ( everything seated well)

I have no experience with that one, but we bought the T&D Pinion Depth Finder, and it works excellent for eveything we have used it on so far. We have used it for Ford 9", Dana 30, and both GM 10 and 12-Bolt....

I made my own.

I had a piece of aluminum flat stock laying around and chopped it down to fit. I shoot through the hole with a depth gage or my vernier and subtract the thickness of the plate (0.250) from the measurement.

K

https://forums.maxperformanceinc.com...1&d=1711634506

That's awesome. Better than the guy that did it from the "top" of the housing.

Two T&D Deluxe Pinion depth tools here. For near 15 years, at least one was in use nearly every week as I knocked out bench build sessions. Only issue ever had with my T&D tool was early on when i damaged the first ones original dial indicator. Ended up buying another dial indicator & magnetic target plate from T&D.

In the mid 90's bought a mid 60's era Kent Moore pinion depth tool kit from a SD Pontiac restorer friend. He had used it a few times over 30 years & thought i could use it. Tried using that setup once in conjunction with an early Pontiac Service manual. End up digging out the sheets from T&D to obtain the correct master head dimension & went what I'm comfortable with. As Larry mentioned in his post, too many variables get thrown into the mix with the use of the cheepee Piniion depth tools, doubt I'd feel comfortable using one.

using old one is bad idea
buy 2 new ones,modify one
bearings are cheap

I do this too (that is, have a "set up" bearing in addition to the new bearing to be used).

K

I have the tool pictured in the first post, but think I bought it long enough ago that it was about half that price. Formulajones brought up a good point that most parting lines are not centered so most measurements will be off. Also, the rough backing on the current pinion gears will give readings varying by .004" to .006" depending on the spot you measure. I can't remember the manufacturer that does create a little flat area that is accurate but most don't touch the face. so even very good measuring tools are just going to put the measurement in the ball park and it's going to be trial and error from there.

old, but not wore out are still Made in the USA parts